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• Unusually high dentry cache usage

  - by Wolfgang Stengel

  Problem A CentOS machine with kernel 2.6.32 and 128 GB physical RAM ran into trouble a few days ago. The responsible system administrator tells me that the PHP-FPM application was not responding to requests in a timely manner anymore due to swapping, and having seen in free that almost no memory was left, he chose to reboot the machine. I know that free memory can be a confusing concept on Linux and a reboot perhaps was the wrong thing to do. However, the mentioned administrator blames the PHP application (which I am responsible for) and refuses to investigate further. What I could find out on my own is this: Before the restart, the free memory (incl. buffers and cache) was only a couple of hundred MB. Before the restart, /proc/meminfo reported a Slab memory usage of around 90 GB (yes, GB). After the restart, the free memory was 119 GB, going down to around 100 GB within an hour, as the PHP-FPM workers (about 600 of them) were coming back to life, each of them showing between 30 and 40 MB in the RES column in top (which has been this way for months and is perfectly reasonable given the nature of the PHP application). There is nothing else in the process list that consumes an unusual or noteworthy amount of RAM. After the restart, Slab memory was around 300 MB If have been monitoring the system ever since, and most notably the Slab memory is increasing in a straight line with a rate of about 5 GB per day. Free memory as reported by free and /proc/meminfo decreases at the same rate. Slab is currently at 46 GB. According to slabtop most of it is used for dentry entries: Free memory: free -m total used free shared buffers cached Mem: 129048 76435 52612 0 144 7675 -/+ buffers/cache: 68615 60432 Swap: 8191 0 8191 Meminfo: cat /proc/meminfo MemTotal: 132145324 kB MemFree: 53620068 kB Buffers: 147760 kB Cached: 8239072 kB SwapCached: 0 kB Active: 20300940 kB Inactive: 6512716 kB Active(anon): 18408460 kB Inactive(anon): 24736 kB Active(file): 1892480 kB Inactive(file): 6487980 kB Unevictable: 8608 kB Mlocked: 8608 kB SwapTotal: 8388600 kB SwapFree: 8388600 kB Dirty: 11416 kB Writeback: 0 kB AnonPages: 18436224 kB Mapped: 94536 kB Shmem: 6364 kB Slab: 46240380 kB SReclaimable: 44561644 kB SUnreclaim: 1678736 kB KernelStack: 9336 kB PageTables: 457516 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 72364108 kB Committed_AS: 22305444 kB VmallocTotal: 34359738367 kB VmallocUsed: 480164 kB VmallocChunk: 34290830848 kB HardwareCorrupted: 0 kB AnonHugePages: 12216320 kB HugePages_Total: 2048 HugePages_Free: 2048 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 5604 kB DirectMap2M: 2078720 kB DirectMap1G: 132120576 kB Slabtop: slabtop --once Active / Total Objects (% used) : 225920064 / 226193412 (99.9%) Active / Total Slabs (% used) : 11556364 / 11556415 (100.0%) Active / Total Caches (% used) : 110 / 194 (56.7%) Active / Total Size (% used) : 43278793.73K / 43315465.42K (99.9%) Minimum / Average / Maximum Object : 0.02K / 0.19K / 4096.00K OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME 221416340 221416039 3% 0.19K 11070817 20 44283268K dentry 1123443 1122739 99% 0.41K 124827 9 499308K fuse_request 1122320 1122180 99% 0.75K 224464 5 897856K fuse_inode 761539 754272 99% 0.20K 40081 19 160324K vm_area_struct 437858 223259 50% 0.10K 11834 37 47336K buffer_head 353353 347519 98% 0.05K 4589 77 18356K anon_vma_chain 325090 324190 99% 0.06K 5510 59 22040K size-64 146272 145422 99% 0.03K 1306 112 5224K size-32 137625 137614 99% 1.02K 45875 3 183500K nfs_inode_cache 128800 118407 91% 0.04K 1400 92 5600K anon_vma 59101 46853 79% 0.55K 8443 7 33772K radix_tree_node 52620 52009 98% 0.12K 1754 30 7016K size-128 19359 19253 99% 0.14K 717 27 2868K sysfs_dir_cache 10240 7746 75% 0.19K 512 20 2048K filp VFS cache pressure: cat /proc/sys/vm/vfs_cache_pressure 125 Swappiness: cat /proc/sys/vm/swappiness 0 I know that unused memory is wasted memory, so this should not necessarily be a bad thing (especially given that 44 GB are shown as SReclaimable). However, apparently the machine experienced problems nonetheless, and I'm afraid the same will happen again in a few days when Slab surpasses 90 GB. Questions I have these questions: Am I correct in thinking that the Slab memory is always physical RAM, and the number is already subtracted from the MemFree value? Is such a high number of dentry entries normal? The PHP application has access to around 1.5 M files, however most of them are archives and not being accessed at all for regular web traffic. What could be an explanation for the fact that the number of cached inodes is much lower than the number of cached dentries, should they not be related somehow? If the system runs into memory trouble, should the kernel not free some of the dentries automatically? What could be a reason that this does not happen? Is there any way to "look into" the dentry cache to see what all this memory is (i.e. what are the paths that are being cached)? Perhaps this points to some kind of memory leak, symlink loop, or indeed to something the PHP application is doing wrong. The PHP application code as well as all asset files are mounted via GlusterFS network file system, could that have something to do with it? Please keep in mind that I can not investigate as root, only as a regular user, and that the administrator refuses to help. He won't even run the typical echo 2 > /proc/sys/vm/drop_caches test to see if the Slab memory is indeed reclaimable. Any insights into what could be going on and how I can investigate any further would be greatly appreciated. Updates Some further diagnostic information: Mounts: cat /proc/self/mounts rootfs / rootfs rw 0 0 proc /proc proc rw,relatime 0 0 sysfs /sys sysfs rw,relatime 0 0 devtmpfs /dev devtmpfs rw,relatime,size=66063000k,nr_inodes=16515750,mode=755 0 0 devpts /dev/pts devpts rw,relatime,gid=5,mode=620,ptmxmode=000 0 0 tmpfs /dev/shm tmpfs rw,relatime 0 0 /dev/mapper/sysvg-lv_root / ext4 rw,relatime,barrier=1,data=ordered 0 0 /proc/bus/usb /proc/bus/usb usbfs rw,relatime 0 0 /dev/sda1 /boot ext4 rw,relatime,barrier=1,data=ordered 0 0 tmpfs /phptmp tmpfs rw,noatime,size=1048576k,nr_inodes=15728640,mode=777 0 0 tmpfs /wsdltmp tmpfs rw,noatime,size=1048576k,nr_inodes=15728640,mode=777 0 0 none /proc/sys/fs/binfmt_misc binfmt_misc rw,relatime 0 0 cgroup /cgroup/cpuset cgroup rw,relatime,cpuset 0 0 cgroup /cgroup/cpu cgroup rw,relatime,cpu 0 0 cgroup /cgroup/cpuacct cgroup rw,relatime,cpuacct 0 0 cgroup /cgroup/memory cgroup rw,relatime,memory 0 0 cgroup /cgroup/devices cgroup rw,relatime,devices 0 0 cgroup /cgroup/freezer cgroup rw,relatime,freezer 0 0 cgroup /cgroup/net_cls cgroup rw,relatime,net_cls 0 0 cgroup /cgroup/blkio cgroup rw,relatime,blkio 0 0 /etc/glusterfs/glusterfs-www.vol /var/www fuse.glusterfs rw,relatime,user_id=0,group_id=0,default_permissions,allow_other,max_read=131072 0 0 /etc/glusterfs/glusterfs-upload.vol /var/upload fuse.glusterfs rw,relatime,user_id=0,group_id=0,default_permissions,allow_other,max_read=131072 0 0 sunrpc /var/lib/nfs/rpc_pipefs rpc_pipefs rw,relatime 0 0 172.17.39.78:/www /data/www nfs rw,relatime,vers=3,rsize=65536,wsize=65536,namlen=255,hard,proto=tcp,port=38467,timeo=600,retrans=2,sec=sys,mountaddr=172.17.39.78,mountvers=3,mountport=38465,mountproto=tcp,local_lock=none,addr=172.17.39.78 0 0 Mount info: cat /proc/self/mountinfo 16 21 0:3 / /proc rw,relatime - proc proc rw 17 21 0:0 / /sys rw,relatime - sysfs sysfs rw 18 21 0:5 / /dev rw,relatime - devtmpfs devtmpfs rw,size=66063000k,nr_inodes=16515750,mode=755 19 18 0:11 / /dev/pts rw,relatime - devpts devpts rw,gid=5,mode=620,ptmxmode=000 20 18 0:16 / /dev/shm rw,relatime - tmpfs tmpfs rw 21 1 253:1 / / rw,relatime - ext4 /dev/mapper/sysvg-lv_root rw,barrier=1,data=ordered 22 16 0:15 / /proc/bus/usb rw,relatime - usbfs /proc/bus/usb rw 23 21 8:1 / /boot rw,relatime - ext4 /dev/sda1 rw,barrier=1,data=ordered 24 21 0:17 / /phptmp rw,noatime - tmpfs tmpfs rw,size=1048576k,nr_inodes=15728640,mode=777 25 21 0:18 / /wsdltmp rw,noatime - tmpfs tmpfs rw,size=1048576k,nr_inodes=15728640,mode=777 26 16 0:19 / /proc/sys/fs/binfmt_misc rw,relatime - binfmt_misc none rw 27 21 0:20 / /cgroup/cpuset rw,relatime - cgroup cgroup rw,cpuset 28 21 0:21 / /cgroup/cpu rw,relatime - cgroup cgroup rw,cpu 29 21 0:22 / /cgroup/cpuacct rw,relatime - cgroup cgroup rw,cpuacct 30 21 0:23 / /cgroup/memory rw,relatime - cgroup cgroup rw,memory 31 21 0:24 / /cgroup/devices rw,relatime - cgroup cgroup rw,devices 32 21 0:25 / /cgroup/freezer rw,relatime - cgroup cgroup rw,freezer 33 21 0:26 / /cgroup/net_cls rw,relatime - cgroup cgroup rw,net_cls 34 21 0:27 / /cgroup/blkio rw,relatime - cgroup cgroup rw,blkio 35 21 0:28 / /var/www rw,relatime - fuse.glusterfs /etc/glusterfs/glusterfs-www.vol rw,user_id=0,group_id=0,default_permissions,allow_other,max_read=131072 36 21 0:29 / /var/upload rw,relatime - fuse.glusterfs /etc/glusterfs/glusterfs-upload.vol rw,user_id=0,group_id=0,default_permissions,allow_other,max_read=131072 37 21 0:30 / /var/lib/nfs/rpc_pipefs rw,relatime - rpc_pipefs sunrpc rw 39 21 0:31 / /data/www rw,relatime - nfs 172.17.39.78:/www rw,vers=3,rsize=65536,wsize=65536,namlen=255,hard,proto=tcp,port=38467,timeo=600,retrans=2,sec=sys,mountaddr=172.17.39.78,mountvers=3,mountport=38465,mountproto=tcp,local_lock=none,addr=172.17.39.78 GlusterFS config: cat /etc/glusterfs/glusterfs-www.vol volume remote1 type protocol/client option transport-type tcp option remote-host 172.17.39.71 option ping-timeout 10 option transport.socket.nodelay on # undocumented option for speed # http://gluster.org/pipermail/gluster-users/2009-September/003158.html option remote-subvolume /data/www end-volume volume remote2 type protocol/client option transport-type tcp option remote-host 172.17.39.72 option ping-timeout 10 option transport.socket.nodelay on # undocumented option for speed # http://gluster.org/pipermail/gluster-users/2009-September/003158.html option remote-subvolume /data/www end-volume volume remote3 type protocol/client option transport-type tcp option remote-host 172.17.39.73 option ping-timeout 10 option transport.socket.nodelay on # undocumented option for speed # http://gluster.org/pipermail/gluster-users/2009-September/003158.html option remote-subvolume /data/www end-volume volume remote4 type protocol/client option transport-type tcp option remote-host 172.17.39.74 option ping-timeout 10 option transport.socket.nodelay on # undocumented option for speed # http://gluster.org/pipermail/gluster-users/2009-September/003158.html option remote-subvolume /data/www end-volume volume replicate1 type cluster/replicate option lookup-unhashed off # off will reduce cpu usage, and network option local-volume-name 'hostname' subvolumes remote1 remote2 end-volume volume replicate2 type cluster/replicate option lookup-unhashed off # off will reduce cpu usage, and network option local-volume-name 'hostname' subvolumes remote3 remote4 end-volume volume distribute type cluster/distribute subvolumes replicate1 replicate2 end-volume volume iocache type performance/io-cache option cache-size 8192MB # default is 32MB subvolumes distribute end-volume volume writeback type performance/write-behind option cache-size 1024MB option window-size 1MB subvolumes iocache end-volume ### Add io-threads for parallel requisitions volume iothreads type performance/io-threads option thread-count 64 # default is 16 subvolumes writeback end-volume volume ra type performance/read-ahead option page-size 2MB option page-count 16 option force-atime-update no subvolumes iothreads end-volume

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• Android programming. Application stopped unexpectedly.

  - by user277704

  I've just created a prototype of interface for my android app and tried to run it. Unfortunately I get an error that my app has stopped unexpectedly (my reputation doesn't allow me to post images so follow my links): screenshot of error message This is layout mode of editing. Everything looks as I want so there shouldn't be errors: mobileka.freehostia.com/3.png (I can post only one hyperlink...) This is my main.xml code: <code> <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" android:gravity="top" android:background="@drawable/back" > <TextView android:id="@+id/score" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text = "@string/scoreT" android:textColor="@string/scoreColor" android:gravity = "left" android:typeface="serif" android:textStyle="bold|italic" android:textSize="16sp" android:paddingLeft = "10px" android:paddingTop="4px"/ <TextView android:id = "@+id/scoreTxt" android:layout_toRightOf="@+id/score" android:textSize="16sp" android:paddingTop = "5px" android:paddingLeft="4px" android:typeface="serif" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text=" 0" android:textColor="@string/scoreTextColor" android:gravity = "left"/> <TextView android:id = "@+id/scoreSeparator" android:layout_toRightOf="@+id/scoreTxt" android:textSize="16sp" android:paddingTop = "3px" android:paddingLeft="4px" android:typeface="serif" android:textStyle="bold" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="|" android:textColor="@string/scoreColor" android:gravity = "left"/> <TextView android:id = "@+id/timerTxt" android:layout_alignParentRight="true" android:textSize="16sp" android:paddingRight="10px" android:paddingTop="4px" android:typeface="serif" android:layout_width="wrap_content" android:layout_height="wrap_content" android:textColor="@string/scoreTextColor" android:gravity = "right" android:text="00:00" /> <TextView android:id = "@+id/timer" android:layout_toLeftOf="@+id/timerTxt" android:textColor="@string/scoreColor" android:layout_width="wrap_content" android:layout_height="wrap_content" android:textSize="16sp" android:padding = "3px" android:typeface="serif" android:textStyle="bold|italic" android:text="@string/timerT" android:gravity = "left"/> <TextView android:id = "@+id/timerSeparator" android:layout_toLeftOf="@+id/timer" android:textSize="16sp" android:paddingTop = "3px" android:paddingLeft="4px" android:typeface="serif" android:textStyle="bold" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="|" android:textColor="@string/scoreColor" android:gravity = "left"/> <ImageButton android:id="@+id/buttonOne" android:layout_below="@+id/score" android:layout_marginTop="40px" android:layout_marginLeft="14px" android:layout_width="wrap_content" android:layout_height="wrap_content" android:clickable="true" android:src="@drawable/inactive"/> <ImageButton android:id="@+id/buttonTwo" android:layout_toRightOf="@+id/buttonOne" android:layout_marginTop="63px" android:layout_marginLeft="10px" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/inactive" /> <ImageButton android:id="@+id/buttonThree" android:layout_toRightOf="@+id/buttonTwo" android:layout_marginTop="63px" android:layout_marginLeft="10px" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/inactive" /> <ImageButton android:id="@+id/buttonFour" android:layout_toRightOf="@+id/buttonThree" android:layout_marginTop="63px" android:layout_marginLeft="10px" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/inactive" /> <ImageButton android:id="@+id/buttonFive" android:layout_below="@+id/buttonOne" android:layout_marginTop="40px" android:layout_marginLeft="14px" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/inactive" /> <ImageButton android:id="@+id/buttonSix" android:layout_toRightOf="@+id/buttonFive" android:layout_marginTop="164px" android:layout_marginLeft="10px" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/inactive" /> <ImageButton android:id="@+id/buttonSeven" android:layout_toRightOf="@+id/buttonSix" android:layout_marginTop="164px" android:layout_marginLeft="10px" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/inactive" /> <ImageButton android:id="@+id/buttonEight" android:layout_toRightOf="@+id/buttonSeven" android:layout_marginTop="164px" android:layout_marginLeft="10px" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/inactive" /> <ImageButton android:id="@+id/buttonNine" android:layout_below="@+id/buttonEight" android:layout_marginTop="40px" android:layout_marginLeft="14px" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/inactive" /> <ImageButton android:id="@+id/buttonTen" android:layout_toRightOf="@+id/buttonNine" android:layout_marginTop="264px" android:layout_marginLeft="10px" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/inactive" /> <ImageButton android:id="@+id/buttonEleven" android:layout_toRightOf="@+id/buttonTen" android:layout_marginTop="264px" android:layout_marginLeft="10px" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/inactive" /> <ImageButton android:id="@+id/buttonTwelve" android:layout_toRightOf="@+id/buttonEleven" android:layout_marginTop="264px" android:layout_marginLeft="10px" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/inactive" /> And this is my logcat errors (p.s. line #12 is the first TextView in main.xml): 03-26 22:59:31.670: WARN/dalvikvm(185): threadid=3: thread exiting with uncaught exception (group=0x4001b188) 03-26 22:59:31.727: ERROR/AndroidRuntime(185): Uncaught handler: thread main exiting due to uncaught exception 03-26 22:59:31.784: ERROR/AndroidRuntime(185): java.lang.RuntimeException: Unable to start activity ComponentInfo{kz.androidmarket.www.randomtest1/kz.androidmarket.www.randomtest1.randomTest1}: android.view.InflateException: Binary XML file line #12: Error inflating class 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2496) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.app.ActivityThread.access$2200(ActivityThread.java:119) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.os.Handler.dispatchMessage(Handler.java:99) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.os.Looper.loop(Looper.java:123) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.app.ActivityThread.main(ActivityThread.java:4363) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at java.lang.reflect.Method.invokeNative(Native Method) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at java.lang.reflect.Method.invoke(Method.java:521) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at dalvik.system.NativeStart.main(Native Method) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): Caused by: android.view.InflateException: Binary XML file line #12: Error inflating class 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.view.LayoutInflater.createView(LayoutInflater.java:513) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:56) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:563) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.view.LayoutInflater.rInflate(LayoutInflater.java:618) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.view.LayoutInflater.inflate(LayoutInflater.java:407) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.view.LayoutInflater.inflate(LayoutInflater.java:320) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.view.LayoutInflater.inflate(LayoutInflater.java:276) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:198) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.app.Activity.setContentView(Activity.java:1622) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at kz.androidmarket.www.randomtest1.randomTest1.onCreate(randomTest1.java:11) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2459) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): ... 11 more 03-26 22:59:31.784: ERROR/AndroidRuntime(185): Caused by: java.lang.reflect.InvocationTargetException 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.widget.TextView.(TextView.java:320) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at java.lang.reflect.Constructor.constructNative(Native Method) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at java.lang.reflect.Constructor.newInstance(Constructor.java:446) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.view.LayoutInflater.createView(LayoutInflater.java:500) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): ... 22 more 03-26 22:59:31.784: ERROR/AndroidRuntime(185): Caused by: android.content.res.Resources$NotFoundException: File #ffff9900 from drawable resource ID #0x7f040002: .xml extension required 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.content.res.Resources.loadColorStateList(Resources.java:1820) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.content.res.TypedArray.getColorStateList(TypedArray.java:289) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): at android.widget.TextView.(TextView.java:627) 03-26 22:59:31.784: ERROR/AndroidRuntime(185): ... 26 more Could anybody help me?

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• Compare images after canny edge detection in OpenCV (C++)

  - by typoknig

  Hi all, I am working on an OpenCV project and I need to compare some images after canny has been applied to both of them. Before the canny was applied I had the gray scale images populating a histogram and then I compared the histograms, but when canny is added to the images the histogram does not populate. I have read that a canny image can populate a histogram, but have not found a way to make it happen. I do not necessairly need to keep using the histograms, I just want to know the best way to compare two canny images. SSCCE below for you to chew on. I have poached and patched about 75% of this code from books and various sites on the internet, so props to those guys... // SLC (Histogram).cpp : Defines the entry point for the console application. #include "stdafx.h" #include <cxcore.h> #include <cv.h> #include <cvaux.h> #include <highgui.h> #include <stdio.h> #include <sstream> #include <iostream> using namespace std; IplImage* image1= 0; IplImage* imgHistogram1 = 0; IplImage* gray1= 0; CvHistogram* hist1; int main(){ CvCapture* capture = cvCaptureFromCAM(0); if(!cvQueryFrame(capture)){ cout<<"Video capture failed, please check the camera."<<endl; } else{ cout<<"Video camera capture successful!"<<endl; }; CvSize sz = cvGetSize(cvQueryFrame(capture)); IplImage* image = cvCreateImage(sz, 8, 3); IplImage* imgHistogram = 0; IplImage* gray = 0; CvHistogram* hist; cvNamedWindow("Image Source",1); cvNamedWindow("gray", 1); cvNamedWindow("Histogram",1); cvNamedWindow("BG", 1); cvNamedWindow("FG", 1); cvNamedWindow("Canny",1); cvNamedWindow("Canny1", 1); image1 = cvLoadImage("image bin/use this image.jpg");// an image has to load here or the program will not run //size of the histogram -1D histogram int bins1 = 256; int hsize1[] = {bins1}; //max and min value of the histogram float max_value1 = 0, min_value1 = 0; //value and normalized value float value1; int normalized1; //ranges - grayscale 0 to 256 float xranges1[] = { 0, 256 }; float* ranges1[] = { xranges1 }; //create an 8 bit single channel image to hold a //grayscale version of the original picture gray1 = cvCreateImage( cvGetSize(image1), 8, 1 ); cvCvtColor( image1, gray1, CV_BGR2GRAY ); IplImage* canny1 = cvCreateImage(cvGetSize(gray1), 8, 1 ); cvCanny( gray1, canny1, 55, 175, 3 ); //Create 3 windows to show the results cvNamedWindow("original1",1); cvNamedWindow("gray1",1); cvNamedWindow("histogram1",1); //planes to obtain the histogram, in this case just one IplImage* planes1[] = { canny1 }; //get the histogram and some info about it hist1 = cvCreateHist( 1, hsize1, CV_HIST_ARRAY, ranges1,1); cvCalcHist( planes1, hist1, 0, NULL); cvGetMinMaxHistValue( hist1, &min_value1, &max_value1); printf("min: %f, max: %f\n", min_value1, max_value1); //create an 8 bits single channel image to hold the histogram //paint it white imgHistogram1 = cvCreateImage(cvSize(bins1, 50),8,1); cvRectangle(imgHistogram1, cvPoint(0,0), cvPoint(256,50), CV_RGB(255,255,255),-1); //draw the histogram :P for(int i=0; i < bins1; i++){ value1 = cvQueryHistValue_1D( hist1, i); normalized1 = cvRound(value1*50/max_value1); cvLine(imgHistogram1,cvPoint(i,50), cvPoint(i,50-normalized1), CV_RGB(0,0,0)); } //show the image results cvShowImage( "original1", image1 ); cvShowImage( "gray1", gray1 ); cvShowImage( "histogram1", imgHistogram1 ); cvShowImage( "Canny1", canny1); CvBGStatModel* bg_model = cvCreateFGDStatModel( image ); for(;;){ image = cvQueryFrame(capture); cvUpdateBGStatModel( image, bg_model ); //Size of the histogram -1D histogram int bins = 256; int hsize[] = {bins}; //Max and min value of the histogram float max_value = 0, min_value = 0; //Value and normalized value float value; int normalized; //Ranges - grayscale 0 to 256 float xranges[] = {0, 256}; float* ranges[] = {xranges}; //Create an 8 bit single channel image to hold a grayscale version of the original picture gray = cvCreateImage(cvGetSize(image), 8, 1); cvCvtColor(image, gray, CV_BGR2GRAY); IplImage* canny = cvCreateImage(cvGetSize(gray), 8, 1 ); cvCanny( gray, canny, 55, 175, 3 );//55, 175, 3 with direct light //Planes to obtain the histogram, in this case just one IplImage* planes[] = {canny}; //Get the histogram and some info about it hist = cvCreateHist(1, hsize, CV_HIST_ARRAY, ranges,1); cvCalcHist(planes, hist, 0, NULL); cvGetMinMaxHistValue(hist, &min_value, &max_value); //printf("Minimum Histogram Value: %f, Maximum Histogram Value: %f\n", min_value, max_value); //Create an 8 bits single channel image to hold the histogram and paint it white imgHistogram = cvCreateImage(cvSize(bins, 50),8,3); cvRectangle(imgHistogram, cvPoint(0,0), cvPoint(256,50), CV_RGB(255,255,255),-1); //Draw the histogram for(int i=0; i < bins; i++){ value = cvQueryHistValue_1D(hist, i); normalized = cvRound(value*50/max_value); cvLine(imgHistogram,cvPoint(i,50), cvPoint(i,50-normalized), CV_RGB(0,0,0)); } double correlation = cvCompareHist (hist1, hist, CV_COMP_CORREL); double chisquare = cvCompareHist (hist1, hist, CV_COMP_CHISQR); double intersection = cvCompareHist (hist1, hist, CV_COMP_INTERSECT); double bhattacharyya = cvCompareHist (hist1, hist, CV_COMP_BHATTACHARYYA); double difference = (1 - correlation) + chisquare + (1 - intersection) + bhattacharyya; printf("correlation: %f\n", correlation); printf("chi-square: %f\n", chisquare); printf("intersection: %f\n", intersection); printf("bhattacharyya: %f\n", bhattacharyya); printf("difference: %f\n", difference); cvShowImage("Image Source", image); cvShowImage("gray", gray); cvShowImage("Histogram", imgHistogram); cvShowImage( "Canny", canny); cvShowImage("BG", bg_model->background); cvShowImage("FG", bg_model->foreground); //Page 19 paragraph 3 of "Learning OpenCV" tells us why we DO NOT use "cvReleaseImage(&image)" in this section cvReleaseImage(&imgHistogram); cvReleaseImage(&gray); cvReleaseHist(&hist); cvReleaseImage(&canny); char c = cvWaitKey(10); //if ASCII key 27 (esc) is pressed then loop breaks if(c==27) break; } cvReleaseBGStatModel( &bg_model ); cvReleaseImage(&image); cvReleaseCapture(&capture); cvDestroyAllWindows(); }

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• Upload File to Windows Azure Blob in Chunks through ASP.NET MVC, JavaScript and HTML5

  - by Shaun

  Originally posted on: http://geekswithblogs.net/shaunxu/archive/2013/07/01/upload-file-to-windows-azure-blob-in-chunks-through-asp.net.aspxMany people are using Windows Azure Blob Storage to store their data in the cloud. Blob storage provides 99.9% availability with easy-to-use API through .NET SDK and HTTP REST. For example, we can store JavaScript files, images, documents in blob storage when we are building an ASP.NET web application on a Web Role in Windows Azure. Or we can store our VHD files in blob and mount it as a hard drive in our cloud service. If you are familiar with Windows Azure, you should know that there are two kinds of blob: page blob and block blob. The page blob is optimized for random read and write, which is very useful when you need to store VHD files. The block blob is optimized for sequential/chunk read and write, which has more common usage. Since we can upload block blob in blocks through BlockBlob.PutBlock, and them commit them as a whole blob with invoking the BlockBlob.PutBlockList, it is very powerful to upload large files, as we can upload blocks in parallel, and provide pause-resume feature. There are many documents, articles and blog posts described on how to upload a block blob. Most of them are focus on the server side, which means when you had received a big file, stream or binaries, how to upload them into blob storage in blocks through .NET SDK.  But the problem is, how can we upload these large files from client side, for example, a browser. This questioned to me when I was working with a Chinese customer to help them build a network disk production on top of azure. The end users upload their files from the web portal, and then the files will be stored in blob storage from the Web Role. My goal is to find the best way to transform the file from client (end user’s machine) to the server (Web Role) through browser. In this post I will demonstrate and describe what I had done, to upload large file in chunks with high speed, and save them as blocks into Windows Azure Blob Storage.   Traditional Upload, Works with Limitation The simplest way to implement this requirement is to create a web page with a form that contains a file input element and a submit button. 1: @using (Html.BeginForm("About", "Index", FormMethod.Post, new { enctype = "multipart/form-data" })) 2: { 3: <input type="file" name="file" /> 4: <input type="submit" value="upload" /> 5: } And then in the backend controller, we retrieve the whole content of this file and upload it in to the blob storage through .NET SDK. We can split the file in blocks and upload them in parallel and commit. The code had been well blogged in the community. 1: [HttpPost] 2: public ActionResult About(HttpPostedFileBase file) 3: { 4: var container = _client.GetContainerReference("test"); 5: container.CreateIfNotExists(); 6: var blob = container.GetBlockBlobReference(file.FileName); 7: var blockDataList = new Dictionary<string, byte[]>(); 8: using (var stream = file.InputStream) 9: { 10: var blockSizeInKB = 1024; 11: var offset = 0; 12: var index = 0; 13: while (offset < stream.Length) 14: { 15: var readLength = Math.Min(1024 * blockSizeInKB, (int)stream.Length - offset); 16: var blockData = new byte[readLength]; 17: offset += stream.Read(blockData, 0, readLength); 18: blockDataList.Add(Convert.ToBase64String(BitConverter.GetBytes(index)), blockData); 19:  20: index++; 21: } 22: } 23:  24: Parallel.ForEach(blockDataList, (bi) => 25: { 26: blob.PutBlock(bi.Key, new MemoryStream(bi.Value), null); 27: }); 28: blob.PutBlockList(blockDataList.Select(b => b.Key).ToArray()); 29:  30: return RedirectToAction("About"); 31: } This works perfect if we selected an image, a music or a small video to upload. But if I selected a large file, let’s say a 6GB HD-movie, after upload for about few minutes the page will be shown as below and the upload will be terminated. In ASP.NET there is a limitation of request length and the maximized request length is defined in the web.config file. It’s a number which less than about 4GB. So if we want to upload a really big file, we cannot simply implement in this way. Also, in Windows Azure, a cloud service network load balancer will terminate the connection if exceed the timeout period. From my test the timeout looks like 2 - 3 minutes. Hence, when we need to upload a large file we cannot just use the basic HTML elements. Besides the limitation mentioned above, the simple HTML file upload cannot provide rich upload experience such as chunk upload, pause and pause-resume. So we need to find a better way to upload large file from the client to the server.   Upload in Chunks through HTML5 and JavaScript In order to break those limitation mentioned above we will try to upload the large file in chunks. This takes some benefit to us such as - No request size limitation: Since we upload in chunks, we can define the request size for each chunks regardless how big the entire file is. - No timeout problem: The size of chunks are controlled by us, which means we should be able to make sure request for each chunk upload will not exceed the timeout period of both ASP.NET and Windows Azure load balancer. It was a big challenge to upload big file in chunks until we have HTML5. There are some new features and improvements introduced in HTML5 and we will use them to implement our solution.   In HTML5, the File interface had been improved with a new method called “slice”. It can be used to read part of the file by specifying the start byte index and the end byte index. For example if the entire file was 1024 bytes, file.slice(512, 768) will read the part of this file from the 512nd byte to 768th byte, and return a new object of interface called "Blob”, which you can treat as an array of bytes. In fact,  a Blob object represents a file-like object of immutable, raw data. The File interface is based on Blob, inheriting blob functionality and expanding it to support files on the user's system. For more information about the Blob please refer here. File and Blob is very useful to implement the chunk upload. We will use File interface to represent the file the user selected from the browser and then use File.slice to read the file in chunks in the size we wanted. For example, if we wanted to upload a 10MB file with 512KB chunks, then we can read it in 512KB blobs by using File.slice in a loop.   Assuming we have a web page as below. User can select a file, an input box to specify the block size in KB and a button to start upload. 1: <div> 2: <input type="file" id="upload_files" name="files[]" /><br /> 3: Block Size: <input type="number" id="block_size" value="512" name="block_size" />KB<br /> 4: <input type="button" id="upload_button_blob" name="upload" value="upload (blob)" /> 5: </div> Then we can have the JavaScript function to upload the file in chunks when user clicked the button. 1: <script type="text/javascript"> 1: 2: $(function () { 3: $("#upload_button_blob").click(function () { 4: }); 5: });</script> Firstly we need to ensure the client browser supports the interfaces we are going to use. Just try to invoke the File, Blob and FormData from the “window” object. If any of them is “undefined” the condition result will be “false” which means your browser doesn’t support these premium feature and it’s time for you to get your browser updated. FormData is another new feature we are going to use in the future. It could generate a temporary form for us. We will use this interface to create a form with chunk and associated metadata when invoked the service through ajax. 1: $("#upload_button_blob").click(function () { 2: // assert the browser support html5 3: if (window.File && window.Blob && window.FormData) { 4: alert("Your brwoser is awesome, let's rock!"); 5: } 6: else { 7: alert("Oh man plz update to a modern browser before try is cool stuff out."); 8: return; 9: } 10: }); Each browser supports these interfaces by their own implementation and currently the Blob, File and File.slice are supported by Chrome 21, FireFox 13, IE 10, Opera 12 and Safari 5.1 or higher. After that we worked on the files the user selected one by one since in HTML5, user can select multiple files in one file input box. 1: var files = $("#upload_files")[0].files; 2: for (var i = 0; i < files.length; i++) { 3: var file = files[i]; 4: var fileSize = file.size; 5: var fileName = file.name; 6: } Next, we calculated the start index and end index for each chunks based on the size the user specified from the browser. We put them into an array with the file name and the index, which will be used when we upload chunks into Windows Azure Blob Storage as blocks since we need to specify the target blob name and the block index. At the same time we will store the list of all indexes into another variant which will be used to commit blocks into blob in Azure Storage once all chunks had been uploaded successfully. 1: $("#upload_button_blob").click(function () { 2: // assert the browser support html5 3: ... ... 4: // start to upload each files in chunks 5: var files = $("#upload_files")[0].files; 6: for (var i = 0; i < files.length; i++) { 7: var file = files[i]; 8: var fileSize = file.size; 9: var fileName = file.name; 10:  11: // calculate the start and end byte index for each blocks(chunks) 12: // with the index, file name and index list for future using 13: var blockSizeInKB = $("#block_size").val(); 14: var blockSize = blockSizeInKB * 1024; 15: var blocks = []; 16: var offset = 0; 17: var index = 0; 18: var list = ""; 19: while (offset < fileSize) { 20: var start = offset; 21: var end = Math.min(offset + blockSize, fileSize); 22:  23: blocks.push({ 24: name: fileName, 25: index: index, 26: start: start, 27: end: end 28: }); 29: list += index + ","; 30:  31: offset = end; 32: index++; 33: } 34: } 35: }); Now we have all chunks’ information ready. The next step should be upload them one by one to the server side, and at the server side when received a chunk it will upload as a block into Blob Storage, and finally commit them with the index list through BlockBlobClient.PutBlockList. But since all these invokes are ajax calling, which means not synchronized call. So we need to introduce a new JavaScript library to help us coordinate the asynchronize operation, which named “async.js”. You can download this JavaScript library here, and you can find the document here. I will not explain this library too much in this post. We will put all procedures we want to execute as a function array, and pass into the proper function defined in async.js to let it help us to control the execution sequence, in series or in parallel. Hence we will define an array and put the function for chunk upload into this array. 1: $("#upload_button_blob").click(function () { 2: // assert the browser support html5 3: ... ... 4:  5: // start to upload each files in chunks 6: var files = $("#upload_files")[0].files; 7: for (var i = 0; i < files.length; i++) { 8: var file = files[i]; 9: var fileSize = file.size; 10: var fileName = file.name; 11: // calculate the start and end byte index for each blocks(chunks) 12: // with the index, file name and index list for future using 13: ... ... 14:  15: // define the function array and push all chunk upload operation into this array 16: blocks.forEach(function (block) { 17: putBlocks.push(function (callback) { 18: }); 19: }); 20: } 21: }); 22: }); As you can see, I used File.slice method to read each chunks based on the start and end byte index we calculated previously, and constructed a temporary HTML form with the file name, chunk index and chunk data through another new feature in HTML5 named FormData. Then post this form to the backend server through jQuery.ajax. This is the key part of our solution. 1: $("#upload_button_blob").click(function () { 2: // assert the browser support html5 3: ... ... 4: // start to upload each files in chunks 5: var files = $("#upload_files")[0].files; 6: for (var i = 0; i < files.length; i++) { 7: var file = files[i]; 8: var fileSize = file.size; 9: var fileName = file.name; 10: // calculate the start and end byte index for each blocks(chunks) 11: // with the index, file name and index list for future using 12: ... ... 13: // define the function array and push all chunk upload operation into this array 14: blocks.forEach(function (block) { 15: putBlocks.push(function (callback) { 16: // load blob based on the start and end index for each chunks 17: var blob = file.slice(block.start, block.end); 18: // put the file name, index and blob into a temporary from 19: var fd = new FormData(); 20: fd.append("name", block.name); 21: fd.append("index", block.index); 22: fd.append("file", blob); 23: // post the form to backend service (asp.net mvc controller action) 24: $.ajax({ 25: url: "/Home/UploadInFormData", 26: data: fd, 27: processData: false, 28: contentType: "multipart/form-data", 29: type: "POST", 30: success: function (result) { 31: if (!result.success) { 32: alert(result.error); 33: } 34: callback(null, block.index); 35: } 36: }); 37: }); 38: }); 39: } 40: }); Then we will invoke these functions one by one by using the async.js. And once all functions had been executed successfully I invoked another ajax call to the backend service to commit all these chunks (blocks) as the blob in Windows Azure Storage. 1: $("#upload_button_blob").click(function () { 2: // assert the browser support html5 3: ... ... 4: // start to upload each files in chunks 5: var files = $("#upload_files")[0].files; 6: for (var i = 0; i < files.length; i++) { 7: var file = files[i]; 8: var fileSize = file.size; 9: var fileName = file.name; 10: // calculate the start and end byte index for each blocks(chunks) 11: // with the index, file name and index list for future using 12: ... ... 13: // define the function array and push all chunk upload operation into this array 14: ... ... 15: // invoke the functions one by one 16: // then invoke the commit ajax call to put blocks into blob in azure storage 17: async.series(putBlocks, function (error, result) { 18: var data = { 19: name: fileName, 20: list: list 21: }; 22: $.post("/Home/Commit", data, function (result) { 23: if (!result.success) { 24: alert(result.error); 25: } 26: else { 27: alert("done!"); 28: } 29: }); 30: }); 31: } 32: }); That’s all in the client side. The outline of our logic would be - Calculate the start and end byte index for each chunks based on the block size. - Defined the functions of reading the chunk form file and upload the content to the backend service through ajax. - Execute the functions defined in previous step with “async.js”. - Commit the chunks by invoking the backend service in Windows Azure Storage finally.   Save Chunks as Blocks into Blob Storage In above we finished the client size JavaScript code. It uploaded the file in chunks to the backend service which we are going to implement in this step. We will use ASP.NET MVC as our backend service, and it will receive the chunks, upload into Windows Azure Bob Storage in blocks, then finally commit as one blob. As in the client side we uploaded chunks by invoking the ajax call to the URL "/Home/UploadInFormData", I created a new action under the Index controller and it only accepts HTTP POST request. 1: [HttpPost] 2: public JsonResult UploadInFormData() 3: { 4: var error = string.Empty; 5: try 6: { 7: } 8: catch (Exception e) 9: { 10: error = e.ToString(); 11: } 12:  13: return new JsonResult() 14: { 15: Data = new 16: { 17: success = string.IsNullOrWhiteSpace(error), 18: error = error 19: } 20: }; 21: } Then I retrieved the file name, index and the chunk content from the Request.Form object, which was passed from our client side. And then, used the Windows Azure SDK to create a blob container (in this case we will use the container named “test”.) and create a blob reference with the blob name (same as the file name). Then uploaded the chunk as a block of this blob with the index, since in Blob Storage each block must have an index (ID) associated with so that finally we can put all blocks as one blob by specifying their block ID list. 1: [HttpPost] 2: public JsonResult UploadInFormData() 3: { 4: var error = string.Empty; 5: try 6: { 7: var name = Request.Form["name"]; 8: var index = int.Parse(Request.Form["index"]); 9: var file = Request.Files[0]; 10: var id = Convert.ToBase64String(BitConverter.GetBytes(index)); 11:  12: var container = _client.GetContainerReference("test"); 13: container.CreateIfNotExists(); 14: var blob = container.GetBlockBlobReference(name); 15: blob.PutBlock(id, file.InputStream, null); 16: } 17: catch (Exception e) 18: { 19: error = e.ToString(); 20: } 21:  22: return new JsonResult() 23: { 24: Data = new 25: { 26: success = string.IsNullOrWhiteSpace(error), 27: error = error 28: } 29: }; 30: } Next, I created another action to commit the blocks into blob once all chunks had been uploaded. Similarly, I retrieved the blob name from the Request.Form. I also retrieved the chunks ID list, which is the block ID list from the Request.Form in a string format, split them as a list, then invoked the BlockBlob.PutBlockList method. After that our blob will be shown in the container and ready to be download. 1: [HttpPost] 2: public JsonResult Commit() 3: { 4: var error = string.Empty; 5: try 6: { 7: var name = Request.Form["name"]; 8: var list = Request.Form["list"]; 9: var ids = list 10: .Split(',') 11: .Where(id => !string.IsNullOrWhiteSpace(id)) 12: .Select(id => Convert.ToBase64String(BitConverter.GetBytes(int.Parse(id)))) 13: .ToArray(); 14:  15: var container = _client.GetContainerReference("test"); 16: container.CreateIfNotExists(); 17: var blob = container.GetBlockBlobReference(name); 18: blob.PutBlockList(ids); 19: } 20: catch (Exception e) 21: { 22: error = e.ToString(); 23: } 24:  25: return new JsonResult() 26: { 27: Data = new 28: { 29: success = string.IsNullOrWhiteSpace(error), 30: error = error 31: } 32: }; 33: } Now we finished all code we need. The whole process of uploading would be like this below. Below is the full client side JavaScript code. 1: <script type="text/javascript" src="~/Scripts/async.js"></script> 2: <script type="text/javascript"> 3: $(function () { 4: $("#upload_button_blob").click(function () { 5: // assert the browser support html5 6: if (window.File && window.Blob && window.FormData) { 7: alert("Your brwoser is awesome, let's rock!"); 8: } 9: else { 10: alert("Oh man plz update to a modern browser before try is cool stuff out."); 11: return; 12: } 13:  14: // start to upload each files in chunks 15: var files = $("#upload_files")[0].files; 16: for (var i = 0; i < files.length; i++) { 17: var file = files[i]; 18: var fileSize = file.size; 19: var fileName = file.name; 20:  21: // calculate the start and end byte index for each blocks(chunks) 22: // with the index, file name and index list for future using 23: var blockSizeInKB = $("#block_size").val(); 24: var blockSize = blockSizeInKB * 1024; 25: var blocks = []; 26: var offset = 0; 27: var index = 0; 28: var list = ""; 29: while (offset < fileSize) { 30: var start = offset; 31: var end = Math.min(offset + blockSize, fileSize); 32:  33: blocks.push({ 34: name: fileName, 35: index: index, 36: start: start, 37: end: end 38: }); 39: list += index + ","; 40:  41: offset = end; 42: index++; 43: } 44:  45: // define the function array and push all chunk upload operation into this array 46: var putBlocks = []; 47: blocks.forEach(function (block) { 48: putBlocks.push(function (callback) { 49: // load blob based on the start and end index for each chunks 50: var blob = file.slice(block.start, block.end); 51: // put the file name, index and blob into a temporary from 52: var fd = new FormData(); 53: fd.append("name", block.name); 54: fd.append("index", block.index); 55: fd.append("file", blob); 56: // post the form to backend service (asp.net mvc controller action) 57: $.ajax({ 58: url: "/Home/UploadInFormData", 59: data: fd, 60: processData: false, 61: contentType: "multipart/form-data", 62: type: "POST", 63: success: function (result) { 64: if (!result.success) { 65: alert(result.error); 66: } 67: callback(null, block.index); 68: } 69: }); 70: }); 71: }); 72:  73: // invoke the functions one by one 74: // then invoke the commit ajax call to put blocks into blob in azure storage 75: async.series(putBlocks, function (error, result) { 76: var data = { 77: name: fileName, 78: list: list 79: }; 80: $.post("/Home/Commit", data, function (result) { 81: if (!result.success) { 82: alert(result.error); 83: } 84: else { 85: alert("done!"); 86: } 87: }); 88: }); 89: } 90: }); 91: }); 92: </script> And below is the full ASP.NET MVC controller code. 1: public class HomeController : Controller 2: { 3: private CloudStorageAccount _account; 4: private CloudBlobClient _client; 5:  6: public HomeController() 7: : base() 8: { 9: _account = CloudStorageAccount.Parse(CloudConfigurationManager.GetSetting("DataConnectionString")); 10: _client = _account.CreateCloudBlobClient(); 11: } 12:  13: public ActionResult Index() 14: { 15: ViewBag.Message = "Modify this template to jump-start your ASP.NET MVC application."; 16:  17: return View(); 18: } 19:  20: [HttpPost] 21: public JsonResult UploadInFormData() 22: { 23: var error = string.Empty; 24: try 25: { 26: var name = Request.Form["name"]; 27: var index = int.Parse(Request.Form["index"]); 28: var file = Request.Files[0]; 29: var id = Convert.ToBase64String(BitConverter.GetBytes(index)); 30:  31: var container = _client.GetContainerReference("test"); 32: container.CreateIfNotExists(); 33: var blob = container.GetBlockBlobReference(name); 34: blob.PutBlock(id, file.InputStream, null); 35: } 36: catch (Exception e) 37: { 38: error = e.ToString(); 39: } 40:  41: return new JsonResult() 42: { 43: Data = new 44: { 45: success = string.IsNullOrWhiteSpace(error), 46: error = error 47: } 48: }; 49: } 50:  51: [HttpPost] 52: public JsonResult Commit() 53: { 54: var error = string.Empty; 55: try 56: { 57: var name = Request.Form["name"]; 58: var list = Request.Form["list"]; 59: var ids = list 60: .Split(',') 61: .Where(id => !string.IsNullOrWhiteSpace(id)) 62: .Select(id => Convert.ToBase64String(BitConverter.GetBytes(int.Parse(id)))) 63: .ToArray(); 64:  65: var container = _client.GetContainerReference("test"); 66: container.CreateIfNotExists(); 67: var blob = container.GetBlockBlobReference(name); 68: blob.PutBlockList(ids); 69: } 70: catch (Exception e) 71: { 72: error = e.ToString(); 73: } 74:  75: return new JsonResult() 76: { 77: Data = new 78: { 79: success = string.IsNullOrWhiteSpace(error), 80: error = error 81: } 82: }; 83: } 84: } And if we selected a file from the browser we will see our application will upload chunks in the size we specified to the server through ajax call in background, and then commit all chunks in one blob. Then we can find the blob in our Windows Azure Blob Storage.   Optimized by Parallel Upload In previous example we just uploaded our file in chunks. This solved the problem that ASP.NET MVC request content size limitation as well as the Windows Azure load balancer timeout. But it might introduce the performance problem since we uploaded chunks in sequence. In order to improve the upload performance we could modify our client side code a bit to make the upload operation invoked in parallel. The good news is that, “async.js” library provides the parallel execution function. If you remembered the code we invoke the service to upload chunks, it utilized “async.series” which means all functions will be executed in sequence. Now we will change this code to “async.parallel”. This will invoke all functions in parallel. 1: $("#upload_button_blob").click(function () { 2: // assert the browser support html5 3: ... ... 4: // start to upload each files in chunks 5: var files = $("#upload_files")[0].files; 6: for (var i = 0; i < files.length; i++) { 7: var file = files[i]; 8: var fileSize = file.size; 9: var fileName = file.name; 10: // calculate the start and end byte index for each blocks(chunks) 11: // with the index, file name and index list for future using 12: ... ... 13: // define the function array and push all chunk upload operation into this array 14: ... ... 15: // invoke the functions one by one 16: // then invoke the commit ajax call to put blocks into blob in azure storage 17: async.parallel(putBlocks, function (error, result) { 18: var data = { 19: name: fileName, 20: list: list 21: }; 22: $.post("/Home/Commit", data, function (result) { 23: if (!result.success) { 24: alert(result.error); 25: } 26: else { 27: alert("done!"); 28: } 29: }); 30: }); 31: } 32: }); In this way all chunks will be uploaded to the server side at the same time to maximize the bandwidth usage. This should work if the file was not very large and the chunk size was not very small. But for large file this might introduce another problem that too many ajax calls are sent to the server at the same time. So the best solution should be, upload the chunks in parallel with maximum concurrency limitation. The code below specified the concurrency limitation to 4, which means at the most only 4 ajax calls could be invoked at the same time. 1: $("#upload_button_blob").click(function () { 2: // assert the browser support html5 3: ... ... 4: // start to upload each files in chunks 5: var files = $("#upload_files")[0].files; 6: for (var i = 0; i < files.length; i++) { 7: var file = files[i]; 8: var fileSize = file.size; 9: var fileName = file.name; 10: // calculate the start and end byte index for each blocks(chunks) 11: // with the index, file name and index list for future using 12: ... ... 13: // define the function array and push all chunk upload operation into this array 14: ... ... 15: // invoke the functions one by one 16: // then invoke the commit ajax call to put blocks into blob in azure storage 17: async.parallelLimit(putBlocks, 4, function (error, result) { 18: var data = { 19: name: fileName, 20: list: list 21: }; 22: $.post("/Home/Commit", data, function (result) { 23: if (!result.success) { 24: alert(result.error); 25: } 26: else { 27: alert("done!"); 28: } 29: }); 30: }); 31: } 32: });   Summary In this post we discussed how to upload files in chunks to the backend service and then upload them into Windows Azure Blob Storage in blocks. We focused on the frontend side and leverage three new feature introduced in HTML 5 which are - File.slice: Read part of the file by specifying the start and end byte index. - Blob: File-like interface which contains the part of the file content. - FormData: Temporary form element that we can pass the chunk alone with some metadata to the backend service. Then we discussed the performance consideration of chunk uploading. Sequence upload cannot provide maximized upload speed, but the unlimited parallel upload might crash the browser and server if too many chunks. So we finally came up with the solution to upload chunks in parallel with the concurrency limitation. We also demonstrated how to utilize “async.js” JavaScript library to help us control the asynchronize call and the parallel limitation.   Regarding the chunk size and the parallel limitation value there is no “best” value. You need to test vary composition and find out the best one for your particular scenario. It depends on the local bandwidth, client machine cores and the server side (Windows Azure Cloud Service Virtual Machine) cores, memory and bandwidth. Below is one of my performance test result. The client machine was Windows 8 IE 10 with 4 cores. I was using Microsoft Cooperation Network. The web site was hosted on Windows Azure China North data center (in Beijing) with one small web role (1.7GB 1 core CPU, 1.75GB memory with 100Mbps bandwidth). The test cases were - Chunk size: 512KB, 1MB, 2MB, 4MB. - Upload Mode: Sequence, parallel (unlimited), parallel with limit (4 threads, 8 threads). - Chunk Format: base64 string, binaries. - Target file: 100MB. - Each case was tested 3 times. Below is the test result chart. Some thoughts, but not guidance or best practice: - Parallel gets better performance than series. - No significant performance improvement between parallel 4 threads and 8 threads. - Transform with binaries provides better performance than base64. - In all cases, chunk size in 1MB - 2MB gets better performance.   Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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• wxWidgets in Code::Blocks

  - by Vlad

  Hello all, I'm trying to compile the minimal sample from the "Cross-Platform GUI Programming with wxWidgets" book but the following compile errors: ||=== minimal, Debug ===| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_frame.o):frame.cpp:(.text+0x918)||undefined reference to `__Unwind_Resume' | C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_frame.o):frame.cpp:(.text+0x931)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_frame.o):frame.cpp:(.text+0xa96)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_frame.o):frame.cpp:(.text+0xada)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_frame.o):frame.cpp:(.text+0xb1e)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_frame.o):frame.cpp:(.eh_frame+0x12)||undefined reference to `___gxx_personality_v0'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_datacmn.o):datacmn.cpp:(.eh_frame+0x11)||undefined reference to `___gxx_personality_v0'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_gdicmn.o):gdicmn.cpp:(.text+0x63a)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_gdicmn.o):gdicmn.cpp:(.text+0x696)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_gdicmn.o):gdicmn.cpp:(.text+0x6f2)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_gdicmn.o):gdicmn.cpp:(.text+0x74a)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_gdicmn.o):gdicmn.cpp:(.text+0x7a2)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_gdicmn.o):gdicmn.cpp:(.eh_frame+0x12)||undefined reference to `___gxx_personality_v0'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_menu.o):menu.cpp:(.text+0x88f)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_menu.o):menu.cpp:(.text+0x927)||undefined reference to `__Unwind_Resume' | C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_menu.o):menu.cpp:(.text+0x9bf)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_menu.o):menu.cpp:(.text+0xb8b)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_menu.o):menu.cpp:(.text+0xc87)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_menu.o):menu.cpp:(.eh_frame+0x12)||undefined reference to `___gxx_personality_v0'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_menucmn.o):menucmn.cpp:(.text+0xbc0)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_menucmn.o):menucmn.cpp:(.text+0xc59)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_menucmn.o):menucmn.cpp:(.text+0xcf5)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_menucmn.o):menucmn.cpp:(.text+0xda6)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_menucmn.o):menucmn.cpp:(.text+0xdce)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_menucmn.o):menucmn.cpp:(.eh_frame+0x12)||undefined reference to `___gxx_personality_v0'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_icon.o):icon.cpp:(.text+0x1ff)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_icon.o):icon.cpp:(.text+0x257)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_icon.o):icon.cpp:(.text+0x2af)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_icon.o):icon.cpp:(.text+0x2fc)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_icon.o):icon.cpp:(.text+0x36d)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_icon.o):icon.cpp:(.eh_frame+0x12)||undefined reference to `___gxx_personality_v0'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_gdiimage.o):gdiimage.cpp:(.text+0x4a8)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_gdiimage.o):gdiimage.cpp:(.text+0x73a)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_gdiimage.o):gdiimage.cpp:(.text+0x813)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_gdiimage.o):gdiimage.cpp:(.text+0xc06)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_gdiimage.o):gdiimage.cpp:(.text+0xd3e)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_gdiimage.o):gdiimage.cpp:(.eh_frame+0x12)||undefined reference to `___gxx_personality_v0'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_event.o):event.cpp:(.text+0x970)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_event.o):event.cpp:(.text+0xa80)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_event.o):event.cpp:(.text+0xb8c)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_event.o):event.cpp:(.text+0xc78)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_event.o):event.cpp:(.text+0xd4f)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_event.o):event.cpp:(.eh_frame+0x12)||undefined reference to `___gxx_personality_v0'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_appcmn.o):appcmn.cpp:(.text+0x2ef)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_appcmn.o):appcmn.cpp:(.text+0x32b)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_appcmn.o):appcmn.cpp:(.text+0x43d)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_appcmn.o):appcmn.cpp:(.text+0x586)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_appcmn.o):appcmn.cpp:(.text+0x601)||undefined reference to `__Unwind_Resume'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_appcmn.o):appcmn.cpp:(.eh_frame+0x12)||undefined reference to `___gxx_personality_v0'| C:\SourceCode\Libraries\wxWidgets2.8\lib\gcc_lib\libwxmsw28u_core.a(corelib_app.o):app.cpp:(.text+0x1da)||undefined reference to `__Unwind_Resume'| ||More errors follow but not being shown.| ||Edit the max errors limit in compiler options...| ||=== Build finished: 50 errors, 0 warnings ===| Here's the code sample from the book: #include "wx/wx.h" #include "mondrian.xpm" // Declare the application class class MyApp : public wxApp { public: // Called on application startup virtual bool OnInit(); }; // Declare our main frame class class MyFrame : public wxFrame { public: // Constructor MyFrame(const wxString& title); // Event handlers void OnQuit(wxCommandEvent& event); void OnAbout(wxCommandEvent& event); private: // This class handles events DECLARE_EVENT_TABLE() }; // Implements MyApp& GetApp() DECLARE_APP(MyApp) // Give wxWidgets the means to create a MyApp object IMPLEMENT_APP(MyApp) // Initialize the application bool MyApp::OnInit() { // Create the main application window MyFrame *frame = new MyFrame(wxT("Minimal wxWidgets App")); // Show it frame->Show(true); // Start the event loop return true; } // Event table for MyFrame BEGIN_EVENT_TABLE(MyFrame, wxFrame) EVT_MENU(wxID_ABOUT, MyFrame::OnAbout) EVT_MENU(wxID_EXIT, MyFrame::OnQuit) END_EVENT_TABLE() void MyFrame::OnAbout(wxCommandEvent& event) { wxString msg; msg.Printf(wxT("Hello and welcome to %s"), wxVERSION_STRING); wxMessageBox(msg, wxT("About Minimal"), wxOK | wxICON_INFORMATION, this); } void MyFrame::OnQuit(wxCommandEvent& event) { // Destroy the frame Close(); } MyFrame::MyFrame(const wxString& title) : wxFrame(NULL, wxID_ANY, title) { // Set the frame icon SetIcon(wxIcon(mondrian_xpm)); // Create a menu bar wxMenu *fileMenu = new wxMenu; // The “About” item should be in the help menu wxMenu *helpMenu = new wxMenu; helpMenu->Append(wxID_ABOUT, wxT("&About...\tF1"), wxT("Show about dialog")); fileMenu->Append(wxID_EXIT, wxT("E&xit\tAlt-X"), wxT("Quit this program")); // Now append the freshly created menu to the menu bar... wxMenuBar *menuBar = new wxMenuBar(); menuBar->Append(fileMenu, wxT("&File")); menuBar->Append(helpMenu, wxT("&Help")); // ... and attach this menu bar to the frame SetMenuBar(menuBar); // Create a status bar just for fun CreateStatusBar(2); SetStatusText(wxT("Welcome to wxWidgets!")); } So what's happenning? Thanks! P.S.: I installed wxWidgets through wxPack wich afaik comes with everything precomplied and i also added the wxWidgets directory to Global variables-base in Code::Blocks so everything should be correctly set, right?

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• Custom ASP.NET Routing to an HttpHandler

  - by Rick Strahl

  As of version 4.0 ASP.NET natively supports routing via the now built-in System.Web.Routing namespace. Routing features are automatically integrated into the HtttpRuntime via a few custom interfaces. New Web Forms Routing Support In ASP.NET 4.0 there are a host of improvements including routing support baked into Web Forms via a RouteData property available on the Page class and RouteCollection.MapPageRoute() route handler that makes it easy to route to Web forms. To map ASP.NET Page routes is as simple as setting up the routes with MapPageRoute:protected void Application_Start(object sender, EventArgs e) { RegisterRoutes(RouteTable.Routes); } void RegisterRoutes(RouteCollection routes) { routes.MapPageRoute("StockQuote", "StockQuote/{symbol}", "StockQuote.aspx"); routes.MapPageRoute("StockQuotes", "StockQuotes/{symbolList}", "StockQuotes.aspx"); } and then accessing the route data in the page you can then use the new Page class RouteData property to retrieve the dynamic route data information:public partial class StockQuote1 : System.Web.UI.Page { protected StockQuote Quote = null; protected void Page_Load(object sender, EventArgs e) { string symbol = RouteData.Values["symbol"] as string; StockServer server = new StockServer(); Quote = server.GetStockQuote(symbol); // display stock data in Page View } } Simple, quick and doesn’t require much explanation. If you’re using WebForms most of your routing needs should be served just fine by this simple mechanism. Kudos to the ASP.NET team for putting this in the box and making it easy! How Routing Works To handle Routing in ASP.NET involves these steps: Registering Routes Creating a custom RouteHandler to retrieve an HttpHandler Attaching RouteData to your HttpHandler Picking up Route Information in your Request code Registering routes makes ASP.NET aware of the Routes you want to handle via the static RouteTable.Routes collection. You basically add routes to this collection to let ASP.NET know which URL patterns it should watch for. You typically hook up routes off a RegisterRoutes method that fires in Application_Start as I did in the example above to ensure routes are added only once when the application first starts up. When you create a route, you pass in a RouteHandler instance which ASP.NET caches and reuses as routes are matched. Once registered ASP.NET monitors the routes and if a match is found just prior to the HttpHandler instantiation, ASP.NET uses the RouteHandler registered for the route and calls GetHandler() on it to retrieve an HttpHandler instance. The RouteHandler.GetHandler() method is responsible for creating an instance of an HttpHandler that is to handle the request and – if necessary – to assign any additional custom data to the handler. At minimum you probably want to pass the RouteData to the handler so the handler can identify the request based on the route data available. To do this you typically add  a RouteData property to your handler and then assign the property from the RouteHandlers request context. This is essentially how Page.RouteData comes into being and this approach should work well for any custom handler implementation that requires RouteData. It’s a shame that ASP.NET doesn’t have a top level intrinsic object that’s accessible off the HttpContext object to provide route data more generically, but since RouteData is directly tied to HttpHandlers and not all handlers support it it might cause some confusion of when it’s actually available. Bottom line is that if you want to hold on to RouteData you have to assign it to a custom property of the handler or else pass it to the handler via Context.Items[] object that can be retrieved on an as needed basis. It’s important to understand that routing is hooked up via RouteHandlers that are responsible for loading HttpHandler instances. RouteHandlers are invoked for every request that matches a route and through this RouteHandler instance the Handler gains access to the current RouteData. Because of this logic it’s important to understand that Routing is really tied to HttpHandlers and not available prior to handler instantiation, which is pretty late in the HttpRuntime’s request pipeline. IOW, Routing works with Handlers but not with earlier in the pipeline within Modules. Specifically ASP.NET calls RouteHandler.GetHandler() from the PostResolveRequestCache HttpRuntime pipeline event. Here’s the call stack at the beginning of the GetHandler() call: which fires just before handler resolution. Non-Page Routing – You need to build custom RouteHandlers If you need to route to a custom Http Handler or other non-Page (and non-MVC) endpoint in the HttpRuntime, there is no generic mapping support available. You need to create a custom RouteHandler that can manage creating an instance of an HttpHandler that is fired in response to a routed request. Depending on what you are doing this process can be simple or fairly involved as your code is responsible based on the route data provided which handler to instantiate, and more importantly how to pass the route data on to the Handler. Luckily creating a RouteHandler is easy by implementing the IRouteHandler interface which has only a single GetHttpHandler(RequestContext context) method. In this method you can pick up the requestContext.RouteData, instantiate the HttpHandler of choice, and assign the RouteData to it. Then pass back the handler and you’re done.Here’s a simple example of GetHttpHandler() method that dynamically creates a handler based on a passed in Handler type./// <summary> /// Retrieves an Http Handler based on the type specified in the constructor /// </summary> /// <param name="requestContext"></param> /// <returns></returns> IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext) { IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; // If we're dealing with a Callback Handler // pass the RouteData for this route to the Handler if (handler is CallbackHandler) ((CallbackHandler)handler).RouteData = requestContext.RouteData; return handler; } Note that this code checks for a specific type of handler and if it matches assigns the RouteData to this handler. This is optional but quite a common scenario if you want to work with RouteData. If the handler you need to instantiate isn’t under your control but you still need to pass RouteData to Handler code, an alternative is to pass the RouteData via the HttpContext.Items collection:IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext) { IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; requestContext.HttpContext.Items["RouteData"] = requestContext.RouteData; return handler; } The code in the handler implementation can then pick up the RouteData from the context collection as needed:RouteData routeData = HttpContext.Current.Items["RouteData"] as RouteData This isn’t as clean as having an explicit RouteData property, but it does have the advantage that the route data is visible anywhere in the Handler’s code chain. It’s definitely preferable to create a custom property on your handler, but the Context work-around works in a pinch when you don’t’ own the handler code and have dynamic code executing as part of the handler execution. An Example of a Custom RouteHandler: Attribute Based Route Implementation In this post I’m going to discuss a custom routine implementation I built for my CallbackHandler class in the West Wind Web & Ajax Toolkit. CallbackHandler can be very easily used for creating AJAX, REST and POX requests following RPC style method mapping. You can pass parameters via URL query string, POST data or raw data structures, and you can retrieve results as JSON, XML or raw string/binary data. It’s a quick and easy way to build service interfaces with no fuss. As a quick review here’s how CallbackHandler works: You create an Http Handler that derives from CallbackHandler You implement methods that have a [CallbackMethod] Attribute and that’s it. Here’s an example of an CallbackHandler implementation in an ashx.cs based handler:// RestService.ashx.cs public class RestService : CallbackHandler { [CallbackMethod] public StockQuote GetStockQuote(string symbol) { StockServer server = new StockServer(); return server.GetStockQuote(symbol); } [CallbackMethod] public StockQuote[] GetStockQuotes(string symbolList) { StockServer server = new StockServer(); string[] symbols = symbolList.Split(new char[2] { ',',';' },StringSplitOptions.RemoveEmptyEntries); return server.GetStockQuotes(symbols); } } CallbackHandler makes it super easy to create a method on the server, pass data to it via POST, QueryString or raw JSON/XML data, and then retrieve the results easily back in various formats. This works wonderful and I’ve used these tools in many projects for myself and with clients. But one thing missing has been the ability to create clean URLs. Typical URLs looked like this: http://www.west-wind.com/WestwindWebToolkit/samples/Rest/StockService.ashx?Method=GetStockQuote&symbol=msfthttp://www.west-wind.com/WestwindWebToolkit/samples/Rest/StockService.ashx?Method=GetStockQuotes&symbolList=msft,intc,gld,slw,mwe&format=xml which works and is clear enough, but also clearly very ugly. It would be much nicer if URLs could look like this: http://www.west-wind.com//WestwindWebtoolkit/Samples/StockQuote/msfthttp://www.west-wind.com/WestwindWebtoolkit/Samples/StockQuotes/msft,intc,gld,slw?format=xml (the Virtual Root in this sample is WestWindWebToolkit/Samples and StockQuote/{symbol} is the route)(If you use FireFox try using the JSONView plug-in make it easier to view JSON content) So, taking a clue from the WCF REST tools that use RouteUrls I set out to create a way to specify RouteUrls for each of the endpoints. The change made basically allows changing the above to: [CallbackMethod(RouteUrl="RestService/StockQuote/{symbol}")] public StockQuote GetStockQuote(string symbol) { StockServer server = new StockServer(); return server.GetStockQuote(symbol); } [CallbackMethod(RouteUrl = "RestService/StockQuotes/{symbolList}")] public StockQuote[] GetStockQuotes(string symbolList) { StockServer server = new StockServer(); string[] symbols = symbolList.Split(new char[2] { ',',';' },StringSplitOptions.RemoveEmptyEntries); return server.GetStockQuotes(symbols); } where a RouteUrl is specified as part of the Callback attribute. And with the changes made with RouteUrls I can now get URLs like the second set shown earlier. So how does that work? Let’s find out… How to Create Custom Routes As mentioned earlier Routing is made up of several steps: Creating a custom RouteHandler to create HttpHandler instances Mapping the actual Routes to the RouteHandler Retrieving the RouteData and actually doing something useful with it in the HttpHandler In the CallbackHandler routing example above this works out to something like this: Create a custom RouteHandler that includes a property to track the method to call Set up the routes using Reflection against the class Looking for any RouteUrls in the CallbackMethod attribute Add a RouteData property to the CallbackHandler so we can access the RouteData in the code of the handler Creating a Custom Route Handler To make the above work I created a custom RouteHandler class that includes the actual IRouteHandler implementation as well as a generic and static method to automatically register all routes marked with the [CallbackMethod(RouteUrl="…")] attribute. Here’s the code:/// <summary> /// Route handler that can create instances of CallbackHandler derived /// callback classes. The route handler tracks the method name and /// creates an instance of the service in a predictable manner /// </summary> /// <typeparam name="TCallbackHandler">CallbackHandler type</typeparam> public class CallbackHandlerRouteHandler : IRouteHandler { /// <summary> /// Method name that is to be called on this route. /// Set by the automatically generated RegisterRoutes /// invokation. /// </summary> public string MethodName { get; set; } /// <summary> /// The type of the handler we're going to instantiate. /// Needed so we can semi-generically instantiate the /// handler and call the method on it. /// </summary> public Type CallbackHandlerType { get; set; } /// <summary> /// Constructor to pass in the two required components we /// need to create an instance of our handler. /// </summary> /// <param name="methodName"></param> /// <param name="callbackHandlerType"></param> public CallbackHandlerRouteHandler(string methodName, Type callbackHandlerType) { MethodName = methodName; CallbackHandlerType = callbackHandlerType; } /// <summary> /// Retrieves an Http Handler based on the type specified in the constructor /// </summary> /// <param name="requestContext"></param> /// <returns></returns> IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext) { IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; // If we're dealing with a Callback Handler // pass the RouteData for this route to the Handler if (handler is CallbackHandler) ((CallbackHandler)handler).RouteData = requestContext.RouteData; return handler; } /// <summary> /// Generic method to register all routes from a CallbackHandler /// that have RouteUrls defined on the [CallbackMethod] attribute /// </summary> /// <typeparam name="TCallbackHandler">CallbackHandler Type</typeparam> /// <param name="routes"></param> public static void RegisterRoutes<TCallbackHandler>(RouteCollection routes) { // find all methods var methods = typeof(TCallbackHandler).GetMethods(BindingFlags.Instance | BindingFlags.Public); foreach (var method in methods) { var attrs = method.GetCustomAttributes(typeof(CallbackMethodAttribute), false); if (attrs.Length < 1) continue; CallbackMethodAttribute attr = attrs[0] as CallbackMethodAttribute; if (string.IsNullOrEmpty(attr.RouteUrl)) continue; // Add the route routes.Add(method.Name, new Route(attr.RouteUrl, new CallbackHandlerRouteHandler(method.Name, typeof(TCallbackHandler)))); } } } The RouteHandler implements IRouteHandler, and its responsibility via the GetHandler method is to create an HttpHandler based on the route data. When ASP.NET calls GetHandler it passes a requestContext parameter which includes a requestContext.RouteData property. This parameter holds the current request’s route data as well as an instance of the current RouteHandler. If you look at GetHttpHandler() you can see that the code creates an instance of the handler we are interested in and then sets the RouteData property on the handler. This is how you can pass the current request’s RouteData to the handler. The RouteData object also has a  RouteData.RouteHandler property that is also available to the Handler later, which is useful in order to get additional information about the current route. In our case here the RouteHandler includes a MethodName property that identifies the method to execute in the handler since that value no longer comes from the URL so we need to figure out the method name some other way. The method name is mapped explicitly when the RouteHandler is created and here the static method that auto-registers all CallbackMethods with RouteUrls sets the method name when it creates the routes while reflecting over the methods (more on this in a minute). The important point here is that you can attach additional properties to the RouteHandler and you can then later access the RouteHandler and its properties later in the Handler to pick up these custom values. This is a crucial feature in that the RouteHandler serves in passing additional context to the handler so it knows what actions to perform. The automatic route registration is handled by the static RegisterRoutes<TCallbackHandler> method. This method is generic and totally reusable for any CallbackHandler type handler. To register a CallbackHandler and any RouteUrls it has defined you simple use code like this in Application_Start (or other application startup code):protected void Application_Start(object sender, EventArgs e) { // Register Routes for RestService CallbackHandlerRouteHandler.RegisterRoutes<RestService>(RouteTable.Routes); } If you have multiple CallbackHandler style services you can make multiple calls to RegisterRoutes for each of the service types. RegisterRoutes internally uses reflection to run through all the methods of the Handler, looking for CallbackMethod attributes and whether a RouteUrl is specified. If it is a new instance of a CallbackHandlerRouteHandler is created and the name of the method and the type are set. routes.Add(method.Name,           new Route(attr.RouteUrl, new CallbackHandlerRouteHandler(method.Name, typeof(TCallbackHandler) )) ); While the routing with CallbackHandlerRouteHandler is set up automatically for all methods that use the RouteUrl attribute, you can also use code to hook up those routes manually and skip using the attribute. The code for this is straightforward and just requires that you manually map each individual route to each method you want a routed: protected void Application_Start(objectsender, EventArgs e){    RegisterRoutes(RouteTable.Routes);}void RegisterRoutes(RouteCollection routes) { routes.Add("StockQuote Route",new Route("StockQuote/{symbol}",                     new CallbackHandlerRouteHandler("GetStockQuote",typeof(RestService) ) ) );     routes.Add("StockQuotes Route",new Route("StockQuotes/{symbolList}",                     new CallbackHandlerRouteHandler("GetStockQuotes",typeof(RestService) ) ) );}I think it’s clearly easier to have CallbackHandlerRouteHandler.RegisterRoutes() do this automatically for you based on RouteUrl attributes, but some people have a real aversion to attaching logic via attributes. Just realize that the option to manually create your routes is available as well. Using the RouteData in the Handler A RouteHandler’s responsibility is to create an HttpHandler and as mentioned earlier, natively IHttpHandler doesn’t have any support for RouteData. In order to utilize RouteData in your handler code you have to pass the RouteData to the handler. In my CallbackHandlerRouteHandler when it creates the HttpHandler instance it creates the instance and then assigns the custom RouteData property on the handler:IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; if (handler is CallbackHandler) ((CallbackHandler)handler).RouteData = requestContext.RouteData; return handler; Again this only works if you actually add a RouteData property to your handler explicitly as I did in my CallbackHandler implementation:/// <summary> /// Optionally store RouteData on this handler /// so we can access it internally /// </summary> public RouteData RouteData {get; set; } and the RouteHandler needs to set it when it creates the handler instance. Once you have the route data in your handler you can access Route Keys and Values and also the RouteHandler. Since my RouteHandler has a custom property for the MethodName to retrieve it from within the handler I can do something like this now to retrieve the MethodName (this example is actually not in the handler but target is an instance pass to the processor): // check for Route Data method name if (target is CallbackHandler) { var routeData = ((CallbackHandler)target).RouteData; if (routeData != null) methodToCall = ((CallbackHandlerRouteHandler)routeData.RouteHandler).MethodName; } When I need to access the dynamic values in the route ( symbol in StockQuote/{symbol}) I can retrieve it easily with the Values collection (RouteData.Values["symbol"]). In my CallbackHandler processing logic I’m basically looking for matching parameter names to Route parameters: // look for parameters in the routeif(routeData != null){    string parmString = routeData.Values[parameter.Name] as string;    adjustedParms[parmCounter] = ReflectionUtils.StringToTypedValue(parmString, parameter.ParameterType);} And with that we’ve come full circle. We’ve created a custom RouteHandler() that passes the RouteData to the handler it creates. We’ve registered our routes to use the RouteHandler, and we’ve utilized the route data in our handler. For completeness sake here’s the routine that executes a method call based on the parameters passed in and one of the options is to retrieve the inbound parameters off RouteData (as well as from POST data or QueryString parameters):internal object ExecuteMethod(string method, object target, string[] parameters, CallbackMethodParameterType paramType, ref CallbackMethodAttribute callbackMethodAttribute) { HttpRequest Request = HttpContext.Current.Request; object Result = null; // Stores parsed parameters (from string JSON or QUeryString Values) object[] adjustedParms = null; Type PageType = target.GetType(); MethodInfo MI = PageType.GetMethod(method, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic); if (MI == null) throw new InvalidOperationException("Invalid Server Method."); object[] methods = MI.GetCustomAttributes(typeof(CallbackMethodAttribute), false); if (methods.Length < 1) throw new InvalidOperationException("Server method is not accessible due to missing CallbackMethod attribute"); if (callbackMethodAttribute != null) callbackMethodAttribute = methods[0] as CallbackMethodAttribute; ParameterInfo[] parms = MI.GetParameters(); JSONSerializer serializer = new JSONSerializer(); RouteData routeData = null; if (target is CallbackHandler) routeData = ((CallbackHandler)target).RouteData; int parmCounter = 0; adjustedParms = new object[parms.Length]; foreach (ParameterInfo parameter in parms) { // Retrieve parameters out of QueryString or POST buffer if (parameters == null) { // look for parameters in the route if (routeData != null) { string parmString = routeData.Values[parameter.Name] as string; adjustedParms[parmCounter] = ReflectionUtils.StringToTypedValue(parmString, parameter.ParameterType); } // GET parameter are parsed as plain string values - no JSON encoding else if (HttpContext.Current.Request.HttpMethod == "GET") { // Look up the parameter by name string parmString = Request.QueryString[parameter.Name]; adjustedParms[parmCounter] = ReflectionUtils.StringToTypedValue(parmString, parameter.ParameterType); } // POST parameters are treated as methodParameters that are JSON encoded else if (paramType == CallbackMethodParameterType.Json) //string newVariable = methodParameters.GetValue(parmCounter) as string; adjustedParms[parmCounter] = serializer.Deserialize(Request.Params["parm" + (parmCounter + 1).ToString()], parameter.ParameterType); else adjustedParms[parmCounter] = SerializationUtils.DeSerializeObject( Request.Params["parm" + (parmCounter + 1).ToString()], parameter.ParameterType); } else if (paramType == CallbackMethodParameterType.Json) adjustedParms[parmCounter] = serializer.Deserialize(parameters[parmCounter], parameter.ParameterType); else adjustedParms[parmCounter] = SerializationUtils.DeSerializeObject(parameters[parmCounter], parameter.ParameterType); parmCounter++; } Result = MI.Invoke(target, adjustedParms); return Result; } The code basically uses Reflection to loop through all the parameters available on the method and tries to assign the parameters from RouteData, QueryString or POST variables. The parameters are converted into their appropriate types and then used to eventually make a Reflection based method call. What’s sweet is that the RouteData retrieval is just another option for dealing with the inbound data in this scenario and it adds exactly two lines of code plus the code to retrieve the MethodName I showed previously – a seriously low impact addition that adds a lot of extra value to this endpoint callback processing implementation. Debugging your Routes If you create a lot of routes it’s easy to run into Route conflicts where multiple routes have the same path and overlap with each other. This can be difficult to debug especially if you are using automatically generated routes like the routes created by CallbackHandlerRouteHandler.RegisterRoutes. Luckily there’s a tool that can help you out with this nicely. Phill Haack created a RouteDebugging tool you can download and add to your project. The easiest way to do this is to grab and add this to your project is to use NuGet (Add Library Package from your Project’s Reference Nodes):   which adds a RouteDebug assembly to your project. Once installed you can easily debug your routes with this simple line of code which needs to be installed at application startup:protected void Application_Start(object sender, EventArgs e) { CallbackHandlerRouteHandler.RegisterRoutes<StockService>(RouteTable.Routes); // Debug your routes RouteDebug.RouteDebugger.RewriteRoutesForTesting(RouteTable.Routes); } Any routed URL then displays something like this: The screen shows you your current route data and all the routes that are mapped along with a flag that displays which route was actually matched. This is useful – if you have any overlap of routes you will be able to see which routes are triggered – the first one in the sequence wins. This tool has saved my ass on a few occasions – and with NuGet now it’s easy to add it to your project in a few seconds and then remove it when you’re done. Routing Around Custom routing seems slightly complicated on first blush due to its disconnected components of RouteHandler, route registration and mapping of custom handlers. But once you understand the relationship between a RouteHandler, the RouteData and how to pass it to a handler, utilizing of Routing becomes a lot easier as you can easily pass context from the registration to the RouteHandler and through to the HttpHandler. The most important thing to understand when building custom routing solutions is to figure out how to map URLs in such a way that the handler can figure out all the pieces it needs to process the request. This can be via URL routing parameters and as I did in my example by passing additional context information as part of the RouteHandler instance that provides the proper execution context. In my case this ‘context’ was the method name, but it could be an actual static value like an enum identifying an operation or category in an application. Basically user supplied data comes in through the url and static application internal data can be passed via RouteHandler property values. Routing can make your application URLs easier to read by non-techie types regardless of whether you’re building Service type or REST applications, or full on Web interfaces. Routing in ASP.NET 4.0 makes it possible to create just about any extensionless URLs you can dream up and custom RouteHanmdler References Sample ProjectIncludes the sample CallbackHandler service discussed here along with compiled versionsof the Westwind.Web and Westwind.Utilities assemblies.  (requires .NET 4.0/VS 2010) West Wind Web Toolkit includes full implementation of CallbackHandler and the Routing Handler West Wind Web Toolkit Source CodeContains the full source code to the Westwind.Web and Westwind.Utilities assemblies usedin these samples. Includes the source described in the post.(Latest build in the Subversion Repository) CallbackHandler Source(Relevant code to this article tree in Westwind.Web assembly) JSONView FireFoxPluginA simple FireFox Plugin to easily view JSON data natively in FireFox.For IE you can use a registry hack to display JSON as raw text.© Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET  AJAX  HTTP  

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• Red Gate Coder interviews: Alex Davies

  - by Michael Williamson

  Alex Davies has been a software engineer at Red Gate since graduating from university, and is currently busy working on .NET Demon. We talked about tackling parallel programming with his actors framework, a scientific approach to debugging, and how JavaScript is going to affect the programming languages we use in years to come. So, if we start at the start, how did you get started in programming? When I was seven or eight, I was given a BBC Micro for Christmas. I had asked for a Game Boy, but my dad thought it would be better to give me a proper computer. For a year or so, I only played games on it, but then I found the user guide for writing programs in it. I gradually started doing more stuff on it and found it fun. I liked creating. As I went into senior school I continued to write stuff on there, trying to write games that weren’t very good. I got a real computer when I was fourteen and found ways to write BASIC on it. Visual Basic to start with, and then something more interesting than that. How did you learn to program? Was there someone helping you out? Absolutely not! I learnt out of a book, or by experimenting. I remember the first time I found a loop, I was like “Oh my God! I don’t have to write out the same line over and over and over again any more. It’s amazing!” When did you think this might be something that you actually wanted to do as a career? For a long time, I thought it wasn’t something that you would do as a career, because it was too much fun to be a career. I thought I’d do chemistry at university and some kind of career based on chemical engineering. And then I went to a careers fair at school when I was seventeen or eighteen, and it just didn’t interest me whatsoever. I thought “I could be a programmer, and there’s loads of money there, and I’m good at it, and it’s fun”, but also that I shouldn’t spoil my hobby. Now I don’t really program in my spare time any more, which is a bit of a shame, but I program all the rest of the time, so I can live with it. Do you think you learnt much about programming at university? Yes, definitely! I went into university knowing how to make computers do anything I wanted them to do. However, I didn’t have the language to talk about algorithms, so the algorithms course in my first year was massively important. Learning other language paradigms like functional programming was really good for breadth of understanding. Functional programming influences normal programming through design rather than actually using it all the time. I draw inspiration from it to write imperative programs which I think is actually becoming really fashionable now, but I’ve been doing it for ages. I did it first! There were also some courses on really odd programming languages, a bit of Prolog, a little bit of C. Having a little bit of each of those is something that I would have never done on my own, so it was important. And then there are knowledge-based courses which are about not programming itself but things that have been programmed like TCP. Those are really important for examples for how to approach things. Did you do any internships while you were at university? Yeah, I spent both of my summers at the same company. I thought I could code well before I went there. Looking back at the crap that I produced, it was only surpassed in its crappiness by all of the other code already in that company. I’m so much better at writing nice code now than I used to be back then. Was there just not a culture of looking after your code? There was, they just didn’t hire people for their abilities in that area. They hired people for raw IQ. The first indicator of it going wrong was that they didn’t have any computer scientists, which is a bit odd in a programming company. But even beyond that they didn’t have people who learnt architecture from anyone else. Most of them had started straight out of university, so never really had experience or mentors to learn from. There wasn’t the experience to draw from to teach each other. In the second half of my second internship, I was being given tasks like looking at new technologies and teaching people stuff. Interns shouldn’t be teaching people how to do their jobs! All interns are going to have little nuggets of things that you don’t know about, but they shouldn’t consistently be the ones who know the most. It’s not a good environment to learn. I was going to ask how you found working with people who were more experienced than you… When I reached Red Gate, I found some people who were more experienced programmers than me, and that was difficult. I’ve been coding since I was tiny. At university there were people who were cleverer than me, but there weren’t very many who were more experienced programmers than me. During my internship, I didn’t find anyone who I classed as being a noticeably more experienced programmer than me. So, it was a shock to the system to have valid criticisms rather than just formatting criticisms. However, Red Gate’s not so big on the actual code review, at least it wasn’t when I started. We did an entire product release and then somebody looked over all of the UI of that product which I’d written and say what they didn’t like. By that point, it was way too late and I’d disagree with them. Do you think the lack of code reviews was a bad thing? I think if there’s going to be any oversight of new people, then it should be continuous rather than chunky. For me I don’t mind too much, I could go out and get oversight if I wanted it, and in those situations I felt comfortable without it. If I was managing the new person, then maybe I’d be keener on oversight and then the right way to do it is continuously and in very, very small chunks. Have you had any significant projects you’ve worked on outside of a job? When I was a teenager I wrote all sorts of stuff. I used to write games, I derived how to do isomorphic projections myself once. I didn’t know what the word was so I couldn’t Google for it, so I worked it out myself. It was horrifically complicated. But it sort of tailed off when I started at university, and is now basically zero. If I do side-projects now, they tend to be work-related side projects like my actors framework, NAct, which I started in a down tools week. Could you explain a little more about NAct? It is a little C# framework for writing parallel code more easily. Parallel programming is difficult when you need to write to shared data. Sometimes parallel programming is easy because you don’t need to write to shared data. When you do need to access shared data, you could just have your threads pile in and do their work, but then you would screw up the data because the threads would trample on each other’s toes. You could lock, but locks are really dangerous if you’re using more than one of them. You get interactions like deadlocks, and that’s just nasty. Actors instead allows you to say this piece of data belongs to this thread of execution, and nobody else can read it. If you want to read it, then ask that thread of execution for a piece of it by sending a message, and it will send the data back by a message. And that avoids deadlocks as long as you follow some obvious rules about not making your actors sit around waiting for other actors to do something. There are lots of ways to write actors, NAct allows you to do it as if it was method calls on other objects, which means you get all the strong type-safety that C# programmers like. Do you think that this is suitable for the majority of parallel programming, or do you think it’s only suitable for specific cases? It’s suitable for most difficult parallel programming. If you’ve just got a hundred web requests which are all independent of each other, then I wouldn’t bother because it’s easier to just spin them up in separate threads and they can proceed independently of each other. But where you’ve got difficult parallel programming, where you’ve got multiple threads accessing multiple bits of data in multiple ways at different times, then actors is at least as good as all other ways, and is, I reckon, easier to think about. When you’re using actors, you presumably still have to write your code in a different way from you would otherwise using single-threaded code. You can’t use actors with any methods that have return types, because you’re not allowed to call into another actor and wait for it. If you want to get a piece of data out of another actor, then you’ve got to use tasks so that you can use “async” and “await” to await asynchronously for it. But other than that, you can still stick things in classes so it’s not too different really. Rather than having thousands of objects with mutable state, you can use component-orientated design, where there are only a few mutable classes which each have a small number of instances. Then there can be thousands of immutable objects. If you tend to do that anyway, then actors isn’t much of a jump. If I’ve already built my system without any parallelism, how hard is it to add actors to exploit all eight cores on my desktop? Usually pretty easy. If you can identify even one boundary where things look like messages and you have components where some objects live on one side and these other objects live on the other side, then you can have a granddaddy object on one side be an actor and it will parallelise as it goes across that boundary. Not too difficult. If we do get 1000-core desktop PCs, do you think actors will scale up? It’s hard. There are always in the order of twenty to fifty actors in my whole program because I tend to write each component as actors, and I tend to have one instance of each component. So this won’t scale to a thousand cores. What you can do is write data structures out of actors. I use dictionaries all over the place, and if you need a dictionary that is going to be accessed concurrently, then you could build one of those out of actors in no time. You can use queuing to marshal requests between different slices of the dictionary which are living on different threads. So it’s like a distributed hash table but all of the chunks of it are on the same machine. That means that each of these thousand processors has cached one small piece of the dictionary. I reckon it wouldn’t be too big a leap to start doing proper parallelism. Do you think it helps if actors get baked into the language, similarly to Erlang? Erlang is excellent in that it has thread-local garbage collection. C# doesn’t, so there’s a limit to how well C# actors can possibly scale because there’s a single garbage collected heap shared between all of them. When you do a global garbage collection, you’ve got to stop all of the actors, which is seriously expensive, whereas in Erlang garbage collections happen per-actor, so they’re insanely cheap. However, Erlang deviated from all the sensible language design that people have used recently and has just come up with crazy stuff. You can definitely retrofit thread-local garbage collection to .NET, and then it’s quite well-suited to support actors, even if it’s not baked into the language. Speaking of language design, do you have a favourite programming language? I’ll choose a language which I’ve never written before. I like the idea of Scala. It sounds like C#, only with some of the niggles gone. I enjoy writing static types. It means you don’t have to writing tests so much. When you say it doesn’t have some of the niggles? C# doesn’t allow the use of a property as a method group. It doesn’t have Scala case classes, or sum types, where you can do a switch statement and the compiler checks that you’ve checked all the cases, which is really useful in functional-style programming. Pattern-matching, in other words. That’s actually the major niggle. C# is pretty good, and I’m quite happy with C#. And what about going even further with the type system to remove the need for tests to something like Haskell? Or is that a step too far? I’m quite a pragmatist, I don’t think I could deal with trying to write big systems in languages with too few other users, especially when learning how to structure things. I just don’t know anyone who can teach me, and the Internet won’t teach me. That’s the main reason I wouldn’t use it. If I turned up at a company that writes big systems in Haskell, I would have no objection to that, but I wouldn’t instigate it. What about things in C#? For instance, there’s contracts in C#, so you can try to statically verify a bit more about your code. Do you think that’s useful, or just not worthwhile? I’ve not really tried it. My hunch is that it needs to be built into the language and be quite mathematical for it to work in real life, and that doesn’t seem to have ended up true for C# contracts. I don’t think anyone who’s tried them thinks they’re any good. I might be wrong. On a slightly different note, how do you like to debug code? I think I’m quite an odd debugger. I use guesswork extremely rarely, especially if something seems quite difficult to debug. I’ve been bitten spending hours and hours on guesswork and not being scientific about debugging in the past, so now I’m scientific to a fault. What I want is to see the bug happening in the debugger, to step through the bug happening. To watch the program going from a valid state to an invalid state. When there’s a bug and I can’t work out why it’s happening, I try to find some piece of evidence which places the bug in one section of the code. From that experiment, I binary chop on the possible causes of the bug. I suppose that means binary chopping on places in the code, or binary chopping on a stage through a processing cycle. Basically, I’m very stupid about how I debug. I won’t make any guesses, I won’t use any intuition, I will only identify the experiment that’s going to binary chop most effectively and repeat rather than trying to guess anything. I suppose it’s quite top-down. Is most of the time then spent in the debugger? Absolutely, if at all possible I will never debug using print statements or logs. I don’t really hold much stock in outputting logs. If there’s any bug which can be reproduced locally, I’d rather do it in the debugger than outputting logs. And with SmartAssembly error reporting, there’s not a lot that can’t be either observed in an error report and just fixed, or reproduced locally. And in those other situations, maybe I’ll use logs. But I hate using logs. You stare at the log, trying to guess what’s going on, and that’s exactly what I don’t like doing. You have to just look at it and see does this look right or wrong. We’ve covered how you get to grip with bugs. How do you get to grips with an entire codebase? I watch it in the debugger. I find little bugs and then try to fix them, and mostly do it by watching them in the debugger and gradually getting an understanding of how the code works using my process of binary chopping. I have to do a lot of reading and watching code to choose where my slicing-in-half experiment is going to be. The last time I did it was SmartAssembly. The old code was a complete mess, but at least it did things top to bottom. There wasn’t too much of some of the big abstractions where flow of control goes all over the place, into a base class and back again. Code’s really hard to understand when that happens. So I like to choose a little bug and try to fix it, and choose a bigger bug and try to fix it. Definitely learn by doing. I want to always have an aim so that I get a little achievement after every few hours of debugging. Once I’ve learnt the codebase I might be able to fix all the bugs in an hour, but I’d rather be using them as an aim while I’m learning the codebase. If I was a maintainer of a codebase, what should I do to make it as easy as possible for you to understand? Keep distinct concepts in different places. And name your stuff so that it’s obvious which concepts live there. You shouldn’t have some variable that gets set miles up the top of somewhere, and then is read miles down to choose some later behaviour. I’m talking from a very much SmartAssembly point of view because the old SmartAssembly codebase had tons and tons of these things, where it would read some property of the code and then deal with it later. Just thousands of variables in scope. Loads of things to think about. If you can keep concepts separate, then it aids me in my process of fixing bugs one at a time, because each bug is going to more or less be understandable in the one place where it is. And what about tests? Do you think they help at all? I’ve never had the opportunity to learn a codebase which has had tests, I don’t know what it’s like! What about when you’re actually developing? How useful do you find tests in finding bugs or regressions? Finding regressions, absolutely. Running bits of code that would be quite hard to run otherwise, definitely. It doesn’t happen very often that a test finds a bug in the first place. I don’t really buy nebulous promises like tests being a good way to think about the spec of the code. My thinking goes something like “This code works at the moment, great, ship it! Ah, there’s a way that this code doesn’t work. Okay, write a test, demonstrate that it doesn’t work, fix it, use the test to demonstrate that it’s now fixed, and keep the test for future regressions.” The most valuable tests are for bugs that have actually happened at some point, because bugs that have actually happened at some point, despite the fact that you think you’ve fixed them, are way more likely to appear again than new bugs are. Does that mean that when you write your code the first time, there are no tests? Often. The chance of there being a bug in a new feature is relatively unaffected by whether I’ve written a test for that new feature because I’m not good enough at writing tests to think of bugs that I would have written into the code. So not writing regression tests for all of your code hasn’t affected you too badly? There are different kinds of features. Some of them just always work, and are just not flaky, they just continue working whatever you throw at them. Maybe because the type-checker is particularly effective around them. Writing tests for those features which just tend to always work is a waste of time. And because it’s a waste of time I’ll tend to wait until a feature has demonstrated its flakiness by having bugs in it before I start trying to test it. You can get a feel for whether it’s going to be flaky code as you’re writing it. I try to write it to make it not flaky, but there are some things that are just inherently flaky. And very occasionally, I’ll think “this is going to be flaky” as I’m writing, and then maybe do a test, but not most of the time. How do you think your programming style has changed over time? I’ve got clearer about what the right way of doing things is. I used to flip-flop a lot between different ideas. Five years ago I came up with some really good ideas and some really terrible ideas. All of them seemed great when I thought of them, but they were quite diverse ideas, whereas now I have a smaller set of reliable ideas that are actually good for structuring code. So my code is probably more similar to itself than it used to be back in the day, when I was trying stuff out. I’ve got more disciplined about encapsulation, I think. There are operational things like I use actors more now than I used to, and that forces me to use immutability more than I used to. The first code that I wrote in Red Gate was the memory profiler UI, and that was an actor, I just didn’t know the name of it at the time. I don’t really use object-orientation. By object-orientation, I mean having n objects of the same type which are mutable. I want a constant number of objects that are mutable, and they should be different types. I stick stuff in dictionaries and then have one thing that owns the dictionary and puts stuff in and out of it. That’s definitely a pattern that I’ve seen recently. I think maybe I’m doing functional programming. Possibly. It’s plausible. If you had to summarise the essence of programming in a pithy sentence, how would you do it? Programming is the form of art that, without losing any of the beauty of architecture or fine art, allows you to produce things that people love and you make money from. So you think it’s an art rather than a science? It’s a little bit of engineering, a smidgeon of maths, but it’s not science. Like architecture, programming is on that boundary between art and engineering. If you want to do it really nicely, it’s mostly art. You can get away with doing architecture and programming entirely by having a good engineering mind, but you’re not going to produce anything nice. You’re not going to have joy doing it if you’re an engineering mind. Architects who are just engineering minds are not going to enjoy their job. I suppose engineering is the foundation on which you build the art. Exactly. How do you think programming is going to change over the next ten years? There will be an unfortunate shift towards dynamically-typed languages, because of JavaScript. JavaScript has an unfair advantage. JavaScript’s unfair advantage will cause more people to be exposed to dynamically-typed languages, which means other dynamically-typed languages crop up and the best features go into dynamically-typed languages. Then people conflate the good features with the fact that it’s dynamically-typed, and more investment goes into dynamically-typed languages. They end up better, so people use them. What about the idea of compiling other languages, possibly statically-typed, to JavaScript? It’s a reasonable idea. I would like to do it, but I don’t think enough people in the world are going to do it to make it pick up. The hordes of beginners are the lifeblood of a language community. They are what makes there be good tools and what makes there be vibrant community websites. And any particular thing which is the same as JavaScript only with extra stuff added to it, although it might be technically great, is not going to have the hordes of beginners. JavaScript is always to be quickest and easiest way for a beginner to start programming in the browser. And dynamically-typed languages are great for beginners. Compilers are pretty scary and beginners don’t write big code. And having your errors come up in the same place, whether they’re statically checkable errors or not, is quite nice for a beginner. If someone asked me to teach them some programming, I’d teach them JavaScript. If dynamically-typed languages are great for beginners, when do you think the benefits of static typing start to kick in? The value of having a statically typed program is in the tools that rely on the static types to produce a smooth IDE experience rather than actually telling me my compile errors. And only once you’re experienced enough a programmer that having a really smooth IDE experience makes a blind bit of difference, does static typing make a blind bit of difference. So it’s not really about size of codebase. If I go and write up a tiny program, I’m still going to get value out of writing it in C# using ReSharper because I’m experienced with C# and ReSharper enough to be able to write code five times faster if I have that help. Any other visions of the future? Nobody’s going to use actors. Because everyone’s going to be running on single-core VMs connected over network-ready protocols like JSON over HTTP. So, parallelism within one operating system is going to die. But until then, you should use actors. More Red Gater Coder interviews

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• problem in login in yahoo massanger

  - by khoyendra

  package session; import java.io.FileWriter; import java.text.DateFormat; import java.text.SimpleDateFormat; import javax.swing.JOptionPane; import org.openymsg.network.FireEvent; import org.openymsg.network.Session; import org.openymsg.network.SessionState; import org.openymsg.network.event.SessionListener; public class BotGUI extends javax.swing.JFrame implements SessionListener{ /** Creates new form BotGUI */ FileWriter fw; DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss"); public BotGUI() { initComponents(); } @SuppressWarnings("unchecked") // <editor-fold defaultstate="collapsed" desc="Generated Code"> private void initComponents() { jPanel1 = new javax.swing.JPanel(); jPanel2 = new javax.swing.JPanel(); jPanel3 = new javax.swing.JPanel(); jLabel1 = new javax.swing.JLabel(); jPanel4 = new javax.swing.JPanel(); jLabel2 = new javax.swing.JLabel(); jLabel3 = new javax.swing.JLabel(); uNameTextField = new javax.swing.JTextField(); uPassPasswordField = new javax.swing.JPasswordField(); jButton1 = new javax.swing.JButton(); jMenuBar1 = new javax.swing.JMenuBar(); jMenu1 = new javax.swing.JMenu(); jMenuItem1 = new javax.swing.JMenuItem(); jMenuItem2 = new javax.swing.JMenuItem(); jMenuItem3 = new javax.swing.JMenuItem(); jMenu2 = new javax.swing.JMenu(); setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); jPanel2.setLayout(new org.netbeans.lib.awtextra.AbsoluteLayout()); jPanel3.setBackground(new java.awt.Color(51, 51, 51)); jLabel1.setBackground(new java.awt.Color(0, 0, 255)); jLabel1.setFont(new java.awt.Font("Tahoma", 1, 12)); jLabel1.setForeground(new java.awt.Color(255, 255, 255)); jLabel1.setText("Yahoo Login Panel"); javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3); jPanel3.setLayout(jPanel3Layout); jPanel3Layout.setHorizontalGroup( jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(jPanel3Layout.createSequentialGroup() .addGap(38, 38, 38) .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 140, javax.swing.GroupLayout.PREFERRED_SIZE) .addContainerGap(532, Short.MAX_VALUE)) ); jPanel3Layout.setVerticalGroup( jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addComponent(jLabel1, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 30, Short.MAX_VALUE) ); jPanel2.add(jPanel3, new org.netbeans.lib.awtextra.AbsoluteConstraints(0, 0, 710, 30)); jPanel4.setLayout(new org.netbeans.lib.awtextra.AbsoluteLayout()); jLabel2.setText("Username"); jPanel4.add(jLabel2, new org.netbeans.lib.awtextra.AbsoluteConstraints(30, 20, 60, 20)); jLabel3.setText("Password"); jPanel4.add(jLabel3, new org.netbeans.lib.awtextra.AbsoluteConstraints(270, 20, 60, 20)); jPanel4.add(uNameTextField, new org.netbeans.lib.awtextra.AbsoluteConstraints(100, 20, 140, 20)); jPanel4.add(uPassPasswordField, new org.netbeans.lib.awtextra.AbsoluteConstraints(330, 20, 140, -1)); jButton1.setFont(new java.awt.Font("Tahoma", 1, 14)); // NOI18N jButton1.setText("Login"); jButton1.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(java.awt.event.ActionEvent evt) { jButton1ActionPerformed(evt); } }); jPanel4.add(jButton1, new org.netbeans.lib.awtextra.AbsoluteConstraints(490, 15, 90, -1)); jPanel2.add(jPanel4, new org.netbeans.lib.awtextra.AbsoluteConstraints(0, 30, 710, 60)); javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1); jPanel1.setLayout(jPanel1Layout); jPanel1Layout.setHorizontalGroup( jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addComponent(jPanel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) ); jPanel1Layout.setVerticalGroup( jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(jPanel1Layout.createSequentialGroup() .addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, 135, javax.swing.GroupLayout.PREFERRED_SIZE) .addContainerGap(293, Short.MAX_VALUE)) ); jMenu1.setText("Option"); jMenuItem1.setText("Logout"); jMenu1.add(jMenuItem1); jMenuItem2.setText("Load CSV"); jMenu1.add(jMenuItem2); jMenuItem3.setText("Exit"); jMenu1.add(jMenuItem3); jMenuBar1.add(jMenu1); jMenu2.setText("Help"); jMenuBar1.add(jMenu2); setJMenuBar(jMenuBar1); javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); getContentPane().setLayout(layout); layout.setHorizontalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) ); layout.setVerticalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) ); pack(); }// </editor-fold> public void handleConnectionClosed() { connectionClosed = true; loggedIn = false; } private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) { if(!uNameTextField.getText().equals("") && !uPassPasswordField.getText().equals("")){ Yahoo_login(uNameTextField.getText(),uPassPasswordField.getText()); }else{ JOptionPane.showMessageDialog(null, "Plese Enter User Id and Password"); } } Session yahooMessengerSession; MySessionListener mySessionListener; boolean loggedIn = false; boolean connectionClosed = false; public void Yahoo_login(String uName, String pass) { connectionClosed = false; if (loggedIn == false) { yahooMessengerSession = new Session(); mySessionListener = new MySessionListener(this); yahooMessengerSession.addSessionListener(mySessionListener); try { if ((uName.equals("")) || (pass.equals(""))) { System.out.println("User name/password is blank"); } else{ //initialized a file writer for log file System.out.println("Login start........"); yahooMessengerSession.login(uName, pass, true); //checks whether user was succesful in login in if (yahooMessengerSession!=null && yahooMessengerSession.getSessionStatus()== SessionState.LOGGED_ON) { //this loop is reached when the user has been successfully logined System.out.println("Login Success"); fw.write("User (" + uName + ") logged in at : " + dateFormat.format("09.05.10") + " \n"); fw.close(); } else { yahooMessengerSession.reset(); } } } catch(Exception e){ } } } public static void main(String args[]) { java.awt.EventQueue.invokeLater(new Runnable() { public void run() { new BotGUI().setVisible(true); } }); } // Variables declaration - do not modify private javax.swing.JButton jButton1; private javax.swing.JLabel jLabel1; private javax.swing.JLabel jLabel2; private javax.swing.JLabel jLabel3; private javax.swing.JMenu jMenu1; private javax.swing.JMenu jMenu2; private javax.swing.JMenuBar jMenuBar1; private javax.swing.JMenuItem jMenuItem1; private javax.swing.JMenuItem jMenuItem2; private javax.swing.JMenuItem jMenuItem3; private javax.swing.JPanel jPanel1; private javax.swing.JPanel jPanel2; private javax.swing.JPanel jPanel3; private javax.swing.JPanel jPanel4; private javax.swing.JTextField uNameTextField; private javax.swing.JPasswordField uPassPasswordField; // End of variables declaration public void dispatch(FireEvent fe) { throw new UnsupportedOperationException("Not supported yet."); } } i have to find the error SEVERE: error during the dispatch of event: FireEvent [org.openymsg.network.event.SessionListEvent to:null from:null message:null timestamp:0 status:0 list type:Friends size:2 LIST] java.lang.UnsupportedOperationException: Not supported yet. at yahoomessangerbot.MySessionListener.dispatch(MySessionListener.java:131) at org.openymsg.network.EventDispatcher.runEventNOW(EventDispatcher.java:133) at org.openymsg.network.EventDispatcher.run(EventDispatcher.java:114)

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• How to print PCL Directly to the printer? Vb.net VS 2010

  - by Justin

  Good day, I've been trying to upgrade an old Print Program that prints raw pcl directly to the printer. The print program takes a PCL Mask and a PCL Batch Spool File (just pcl with page turn commands, I think) merges them and sends them off to the printer. I'm able to send to the Printer a file stream of PCL but I get mixed results and i do not understand why printing is so difficult under .net. I mean yes there is the PrintDocument class, but to print PCL... Let's just say I'm ready to detach my printer from the network and burn it a live. Here is my class PrintDirect (rather a hybrid class) Imports System Imports System.Text Imports System.Runtime.InteropServices <StructLayout(LayoutKind.Sequential)> _ Public Structure DOCINFO <MarshalAs(UnmanagedType.LPWStr)> _ Public pDocName As String <MarshalAs(UnmanagedType.LPWStr)> _ Public pOutputFile As String <MarshalAs(UnmanagedType.LPWStr)> _ Public pDataType As String End Structure 'DOCINFO Public Class PrintDirect <DllImport("winspool.drv", CharSet:=CharSet.Unicode, ExactSpelling:=False, CallingConvention:=CallingConvention.StdCall)> _ Public Shared Function OpenPrinter(ByVal pPrinterName As String, ByRef phPrinter As IntPtr, ByVal pDefault As Integer) As Long End Function <DllImport("winspool.drv", CharSet:=CharSet.Unicode, ExactSpelling:=False, CallingConvention:=CallingConvention.StdCall)> _ Public Shared Function StartDocPrinter(ByVal hPrinter As IntPtr, ByVal Level As Integer, ByRef pDocInfo As DOCINFO) As Long End Function <DllImport("winspool.drv", CharSet:=CharSet.Unicode, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _ Public Shared Function StartPagePrinter(ByVal hPrinter As IntPtr) As Long End Function <DllImport("winspool.drv", CharSet:=CharSet.Ansi, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _ Public Shared Function WritePrinter(ByVal hPrinter As IntPtr, ByVal data As String, ByVal buf As Integer, ByRef pcWritten As Integer) As Long End Function <DllImport("winspool.drv", CharSet:=CharSet.Unicode, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _ Public Shared Function EndPagePrinter(ByVal hPrinter As IntPtr) As Long End Function <DllImport("winspool.drv", CharSet:=CharSet.Unicode, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _ Public Shared Function EndDocPrinter(ByVal hPrinter As IntPtr) As Long End Function <DllImport("winspool.drv", CharSet:=CharSet.Unicode, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _ Public Shared Function ClosePrinter(ByVal hPrinter As IntPtr) As Long End Function 'Helps uses to work with the printer Public Class PrintJob ''' <summary> ''' The address of the printer to print to. ''' </summary> ''' <remarks></remarks> Public PrinterName As String = "" Dim lhPrinter As New System.IntPtr() ''' <summary> ''' The object deriving from the Win32 API, Winspool.drv. ''' Use this object to overide the settings defined in the PrintJob Class. ''' </summary> ''' <remarks>Only use this when absolutly nessacary.</remarks> Public OverideDocInfo As New DOCINFO() ''' <summary> ''' The PCL Control Character or the ascii escape character. \x1b ''' </summary> ''' <remarks>ChrW(27)</remarks> Public Const PCL_Control_Character As Char = ChrW(27) ''' <summary> ''' Opens a connection to a printer, if false the connection could not be established. ''' </summary> ''' <returns></returns> ''' <remarks></remarks> Public Function OpenPrint() As Boolean Dim rtn_val As Boolean = False PrintDirect.OpenPrinter(PrinterName, lhPrinter, 0) If Not lhPrinter = 0 Then rtn_val = True End If Return rtn_val End Function ''' <summary> ''' The name of the Print Document. ''' </summary> ''' <value></value> ''' <returns></returns> ''' <remarks></remarks> Public Property DocumentName As String Get Return OverideDocInfo.pDocName End Get Set(ByVal value As String) OverideDocInfo.pDocName = value End Set End Property ''' <summary> ''' The type of Data that will be sent to the printer. ''' </summary> ''' <value>Send the print data type, usually "RAW" or "LPR". To overide use the OverideDocInfo Object</value> ''' <returns>The DataType as it was provided, if it is not part of the enumeration it is set to "UNKNOWN".</returns> ''' <remarks></remarks> Public Property DocumentDataType As PrintDataType Get Select Case OverideDocInfo.pDataType.ToUpper Case "RAW" Return PrintDataType.RAW Case "LPR" Return PrintDataType.LPR Case Else Return PrintDataType.UNKOWN End Select End Get Set(ByVal value As PrintDataType) OverideDocInfo.pDataType = [Enum].GetName(GetType(PrintDataType), value) End Set End Property Public Property DocumentOutputFile As String Get Return OverideDocInfo.pOutputFile End Get Set(ByVal value As String) OverideDocInfo.pOutputFile = value End Set End Property Enum PrintDataType UNKOWN = 0 RAW = 1 LPR = 2 End Enum ''' <summary> ''' Initializes the printing matrix ''' </summary> ''' <param name="PrintLevel">I have no idea what the hack this is...</param> ''' <remarks></remarks> Public Sub OpenDocument(Optional ByVal PrintLevel As Integer = 1) PrintDirect.StartDocPrinter(lhPrinter, PrintLevel, OverideDocInfo) End Sub ''' <summary> ''' Starts the next page. ''' </summary> ''' <remarks></remarks> Public Sub StartPage() PrintDirect.StartPagePrinter(lhPrinter) End Sub ''' <summary> ''' Writes a string to the printer, can be used to write out a section of the document at a time. ''' </summary> ''' <param name="data">The String to Send out to the Printer.</param> ''' <returns>The pcWritten as an integer, 0 may mean the writter did not write out anything.</returns> ''' <remarks>Warning the buffer is automatically created by the lenegth of the string.</remarks> Public Function WriteToPrinter(ByVal data As String) As Integer Dim pcWritten As Integer = 0 PrintDirect.WritePrinter(lhPrinter, data, data.Length - 1, pcWritten) Return pcWritten End Function Public Sub EndPage() PrintDirect.EndPagePrinter(lhPrinter) End Sub Public Sub CloseDocument() PrintDirect.EndDocPrinter(lhPrinter) End Sub Public Sub ClosePrint() PrintDirect.ClosePrinter(lhPrinter) End Sub ''' <summary> ''' Opens a connection to a printer and starts a new document. ''' </summary> ''' <returns>If false the connection could not be established. </returns> ''' <remarks></remarks> Public Function Open() As Boolean Dim rtn_val As Boolean = False rtn_val = OpenPrint() If rtn_val Then OpenDocument() End If Return rtn_val End Function ''' <summary> ''' Closes the document and closes the connection to the printer. ''' </summary> ''' <remarks></remarks> Public Sub Close() CloseDocument() ClosePrint() End Sub End Class End Class 'PrintDirect Here is how I print my file. I'm simple printing the PCL Masks, to show proof of concept. But I can't even do that. I can effectively create PCL and send it the printer without reading the file and it works fine... Plus I get mixed results with different stream reader text encoding as well. Dim pJob As New PrintDirect.PrintJob pJob.DocumentName = " test doc" pJob.DocumentDataType = PrintDirect.PrintJob.PrintDataType.RAW pJob.PrinterName = sPrinter.GetDevicePath '//This is where you'd stick your device name, sPrinter stands for Selected Printer from a dropdown (combobox). 'pJob.DocumentOutputFile = "C:\temp\test-spool.txt" If Not pJob.OpenPrint() Then MsgBox("Unable to connect to " & pJob.PrinterName, MsgBoxStyle.OkOnly, "Print Error") Exit Sub End If pJob.OpenDocument() pJob.StartPage() Dim sr As New IO.StreamReader(Me.txtFile.Text, Text.Encoding.ASCII) '//I've got best results with ASCII before, but only mized. Dim line As String = sr.ReadLine 'Fix for fly code on first run 'If line = 27 Then line = PrintDirect.PrintJob.PCL_Control_Character Do While (Not line Is Nothing) pJob.WriteToPrinter(line) line = sr.ReadLine Loop 'pJob.WriteToPrinter(ControlChars.FormFeed) pJob.EndPage() pJob.CloseDocument() sr.Close() sr.Dispose() sr = Nothing pJob.Close() I was able to get to print the mask, in the morning... now I'm getting strange printer characters scattered through 5 pages... I'm totally clueless. I must have changed something or the printer is at fault. You can access my test Check Mask, here http://kscserver.com/so/chk_mask.zip .

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• JavaNullPointerException/Layout Error when working with lists and ListView on Android

  - by psyhclo

  Hey, I'm trying to implement a ListView on Android, which will print the data retrieved from the SQLite Database. So I want to retrieve a lot of columns from the table and add this to a list, so I will print this list as a ListView. For this I created a method that will select all the columns from the table in a separate class, and I will print the ListView in a ListActivity. I want to retrieve 6 columns of the table, which is represented by the ids 2, 4, 5, 6, 7, 9. But it shows a lot of errors: 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): FATAL EXCEPTION: main 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): java.lang.NullPointerException 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:355) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.ArrayAdapter.getView(ArrayAdapter.java:323) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.AbsListView.obtainView(AbsListView.java:1418) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.ListView.makeAndAddView(ListView.java:1745) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.ListView.fillDown(ListView.java:670) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.ListView.fillFromTop(ListView.java:727) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.ListView.layoutChildren(ListView.java:1598) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.AbsListView.onLayout(AbsListView.java:1248) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.view.View.layout(View.java:7175) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.FrameLayout.onLayout(FrameLayout.java:338) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.view.View.layout(View.java:7175) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.FrameLayout.onLayout(FrameLayout.java:338) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.view.View.layout(View.java:7175) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.FrameLayout.onLayout(FrameLayout.java:338) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.view.View.layout(View.java:7175) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1254) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1130) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.LinearLayout.onLayout(LinearLayout.java:1047) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.view.View.layout(View.java:7175) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.FrameLayout.onLayout(FrameLayout.java:338) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.view.View.layout(View.java:7175) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.FrameLayout.onLayout(FrameLayout.java:338) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.view.View.layout(View.java:7175) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1254) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1130) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.LinearLayout.onLayout(LinearLayout.java:1047) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.view.View.layout(View.java:7175) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.widget.FrameLayout.onLayout(FrameLayout.java:338) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.view.View.layout(View.java:7175) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.view.ViewRoot.performTraversals(ViewRoot.java:1140) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.view.ViewRoot.handleMessage(ViewRoot.java:1859) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.os.Handler.dispatchMessage(Handler.java:99) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.os.Looper.loop(Looper.java:123) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at android.app.ActivityThread.main(ActivityThread.java:3647) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at java.lang.reflect.Method.invokeNative(Native Method) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at java.lang.reflect.Method.invoke(Method.java:507) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 12-24 19:19:04.066: ERROR/AndroidRuntime(22630): at dalvik.system.NativeStart.main(Native Method) Here is the code of the method that select the data. public List<String> selectAll() { List<String> list1 = new ArrayList<String>(); List<String> list2 = new ArrayList<String>(); List<String> list3 = new ArrayList<String>(); List<String> list4 = new ArrayList<String>(); List<String> list5 = new ArrayList<String>(); List<String> list6 = new ArrayList<String>(); Cursor cursor = this.db.query(TABLE_NAME, null, null, null, null, null, "duration desc"); if (cursor.moveToFirst()) { do { list1.add(cursor.getString(2)); list2.add(cursor.getString(4)); list3.add(cursor.getString(5)); list4.add(cursor.getString(6)); list5.add(cursor.getString(7)); list6.add(cursor.getString(9)); list1.addAll(list2); list1.addAll(list3); list1.addAll(list4); list1.addAll(list5); list1.addAll(list6); } while (cursor.moveToNext()); Log.i(TAG, "After cursor.moveToNext()"); } if (cursor != null && !cursor.isClosed()) { cursor.close(); } Log.i(TAG, "Before selectAll returnment"); return list1; } And here is the code of the ListActivity class: public class RatedCalls extends ListActivity { private static final String LOG_TAG = "RatedCallsActivity"; private CallDataHelper cdh; StringBuilder sb = new StringBuilder(); OpenHelper openHelper = new OpenHelper(RatedCalls.this); @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Log.i(LOG_TAG, "calling from onCreate()"); cdh = new CallDataHelper(this); Log.i(LOG_TAG, "--->>> before calling the service"); startService(new Intent(this, RatedCallsService.class)); Log.i(LOG_TAG, "Service called."); Log.i(LOG_TAG, "--->>> after calling the service"); fillList(); } public void fillList() { List<String> ratedCalls = this.cdh.selectAll(); setListAdapter(new ArrayAdapter<String>(this, R.layout.listitem, ratedCalls)); ListView lv = getListView(); lv.setTextFilterEnabled(true); lv.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView<?> parent, View view, int position, long id) { // When clicked, show a toast with the TextView text Toast.makeText(getApplicationContext(), ((TextView) view).getText(), Toast.LENGTH_SHORT).show(); } }); } }

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• Silverlight 4 + WCF RIA - Data Service Design Best Practices

  - by Chadd Nervig

  Hey all. I realize this is a rather long question, but I'd really appreciate any help from anyone experienced with RIA services. Thanks! I'm working on a Silverlight 4 app that views data from the server. I'm relatively inexperienced with RIA Services, so have been working through the tasks of getting the data I need down to the client, but every new piece I add to the puzzle seems to be more and more problematic. I feel like I'm missing some basic concepts here, and it seems like I'm just 'hacking' pieces on, in time-consuming ways, each one breaking the previous ones as I try to add them. I'd love to get the feedback of developers experienced with RIA services, to figure out the intended way to do what I'm trying to do. Let me lay out what I'm trying to do: First, the data. The source of this data is a variety of sources, primarily created by a shared library which reads data from our database, and exposes it as POCOs (Plain Old CLR Objects). I'm creating my own POCOs to represent the different types of data I need to pass between server and client. DataA - This app is for viewing a certain type of data, lets call DataA, in near-realtime. Every 3 minutes, the client should pull data down from the server, of all the new DataA since the last time it requested data. DataB - Users can view the DataA objects in the app, and may select one of them from the list, which displays additional details about that DataA. I'm bringing these extra details down from the server as DataB. DataC - One of the things that DataB contains is a history of a couple important values over time. I'm calling each data point of this history a DataC object, and each DataB object contains many DataCs. The Data Model - On the server side, I have a single DomainService: [EnableClientAccess] public class MyDomainService : DomainService { public IEnumerable<DataA> GetDataA(DateTime? startDate) { /*Pieces together the DataAs that have been created since startDate, and returns them*/ } public DataB GetDataB(int dataAID) { /*Looks up the extended info for that dataAID, constructs a new DataB with that DataA's data, plus the extended info (with multiple DataCs in a List<DataC> property on the DataB), and returns it*/ } //Not exactly sure why these are here, but I think it //wouldn't compile without them for some reason? The data //is entirely read-only, so I don't need to update. public void UpdateDataA(DataA dataA) { throw new NotSupportedException(); } public void UpdateDataB(DataB dataB) { throw new NotSupportedException(); } } The classes for DataA/B/C look like this: [KnownType(typeof(DataB))] public partial class DataA { [Key] [DataMember] public int DataAID { get; set; } [DataMember] public decimal MyDecimalA { get; set; } [DataMember] public string MyStringA { get; set; } [DataMember] public DataTime MyDateTimeA { get; set; } } public partial class DataB : DataA { [Key] [DataMember] public int DataAID { get; set; } [DataMember] public decimal MyDecimalB { get; set; } [DataMember] public string MyStringB { get; set; } [Include] //I don't know which of these, if any, I need? [Composition] [Association("DataAToC","DataAID","DataAID")] public List<DataC> DataCs { get; set; } } public partial class DataC { [Key] [DataMember] public int DataAID { get; set; } [Key] [DataMember] public DateTime Timestamp { get; set; } [DataMember] public decimal MyHistoricDecimal { get; set; } } I guess a big question I have here is... Should I be using Entities instead of POCOs? Are my classes constructed correctly to be able to pass the data down correctly? Should I be using Invoke methods instead of Query (Get) methods on the DomainService? On the client side, I'm having a number of issues. Surprisingly, one of my biggest ones has been threading. I didn't expect there to be so many threading issues with MyDomainContext. What I've learned is that you only seem to be able to create MyDomainContextObjects on the UI thread, all of the queries you can make are done asynchronously only, and that if you try to fake doing it synchronously by blocking the calling thread until the LoadOperation finishes, you have to do so on a background thread, since it uses the UI thread to make the query. So here's what I've got so far. The app should display a stream of the DataA objects, spreading each 3min chunk of them over the next 3min (so they end up displayed 3min after the occurred, looking like a continuous stream, but only have to be downloaded in 3min bursts). To do this, the main form initializes, creates a private MyDomainContext, and starts up a background worker, which continuously loops in a while(true). On each loop, it checks if it has any DataAs left over to display. If so, it displays that Data, and Thread.Sleep()s until the next DataA is scheduled to be displayed. If it's out of data, it queries for more, using the following methods: public DataA[] GetDataAs(DateTime? startDate) { _loadOperationGetDataACompletion = new AutoResetEvent(false); LoadOperation<DataA> loadOperationGetDataA = null; loadOperationGetDataA = _context.Load(_context.GetDataAQuery(startDate), System.ServiceModel.DomainServices.Client.LoadBehavior.RefreshCurrent, false); loadOperationGetDataA.Completed += new EventHandler(loadOperationGetDataA_Completed); _loadOperationGetDataACompletion.WaitOne(); List<DataA> dataAs = new List<DataA>(); foreach (var dataA in loadOperationGetDataA.Entities) dataAs.Add(dataA); return dataAs.ToArray(); } private static AutoResetEvent _loadOperationGetDataACompletion; private static void loadOperationGetDataA_Completed(object sender, EventArgs e) { _loadOperationGetDataACompletion.Set(); } Seems kind of clunky trying to force it into being synchronous, but since this already is on a background thread, I think this is OK? So far, everything actually works, as much of a hack as it seems like it may be. It's important to note that if I try to run that code on the UI thread, it locks, because it waits on the WaitOne() forever, locking the thread, so it can't make the Load request to the server. So once the data is displayed, users can click on one as it goes by to fill a details pane with the full DataB data about that object. To do that, I have the the details pane user control subscribing to a selection event I have setup, which gets fired when the selection changes (on the UI thread). I use a similar technique there, to get the DataB object: void SelectionService_SelectedDataAChanged(object sender, EventArgs e) { DataA dataA = /*Get the selected DataA*/; MyDomainContext context = new MyDomainContext(); var loadOperationGetDataB = context.Load(context.GetDataBQuery(dataA.DataAID), System.ServiceModel.DomainServices.Client.LoadBehavior.RefreshCurrent, false); loadOperationGetDataB.Completed += new EventHandler(loadOperationGetDataB_Completed); } private void loadOperationGetDataB_Completed(object sender, EventArgs e) { this.DataContext = ((LoadOperation<DataB>)sender).Entities.SingleOrDefault(); } Again, it seems kinda hacky, but it works... except on the DataB that it loads, the DataCs list is empty. I've tried all kinds of things there, and I don't see what I'm doing wrong to allow the DataCs to come down with the DataB. I'm about ready to make a 3rd query for the DataCs, but that's screaming even more hackiness to me. It really feels like I'm fighting against the grain here, like I'm doing this in an entirely unintended way. If anyone could offer any assistance, and point out what I'm doing wrong here, I'd very much appreciate it! Thanks!

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• Records not being saved to core data sqlite file

  - by esd100

  I'm a complete newbie when it comes to iOS programming and much less Core Data. It's rather non-intuitive for me, as I really came into my own with programming with MATLAB, which I guess is more of a 'scripting' language. At any rate, my problem is that I had no idea what I had to do to create a database for my application. So I read a little bit and thought I had to create a SQL database of my stuff and then import it. Long story short, I created a SQLite db and I want to use the work I have already done to import stuff into my CoreData database. I tried exporting to comma-delimited files and xml files and reading those in, but I didn't like it and it seemed like an extra step that I shouldn't need to do. So, I imported the SQLite database into my resources and added the sqlite framework. I have my core data model setup and it is setting up the SQLite database for the model correctly in the background. When I run through my program to add objects to my entities, it seems to work and I can even fetch results afterward. However, when I inspect the Core Data Database SQLite file, no records have been saved. How is it possible for it to fetch results but not save them to the database? - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{ //load in the path for resources NSString *paths = [[NSBundle mainBundle] resourcePath]; NSString *databaseName = @"histology.sqlite"; NSString *databasePath = [paths stringByAppendingPathComponent:databaseName]; [self createDatabase:databasePath ]; NSError *error; if ([[self managedObjectContext] save:&error]) { NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]); } // Test listing all CELLS from the store NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entityMO = [NSEntityDescription entityForName:@"CELL" inManagedObjectContext:[self managedObjectContext]]; [fetchRequest setEntity:entityMO]; NSArray *fetchedObjects = [[self managedObjectContext] executeFetchRequest:fetchRequest error:&error]; for (CELL *cellName in fetchedObjects) { //NSLog(@"cellName: %@", cellName); } -(void) createDatabase:databasePath { NSLog(@"The createDatabase function was entered."); NSLog(@"The databasePath is %@ ",[databasePath description]); // Setup the database object sqlite3 *histoDatabase; // Open the database from filessytem if(sqlite3_open([databasePath UTF8String], &histoDatabase) == SQLITE_OK) { NSLog(@"The database was opened"); // Setup the SQL Statement and compile it for faster access const char *sqlStatement = "SELECT * FROM CELL"; sqlite3_stmt *compiledStatement; if(sqlite3_prepare_v2(histoDatabase, sqlStatement, -1, &compiledStatement, NULL) != SQLITE_OK) { NSAssert1(0, @"Error while creating add statement. '%s'", sqlite3_errmsg(histoDatabase)); } if(sqlite3_prepare_v2(histoDatabase, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) { // Loop through the results and add them to cell MO array while(sqlite3_step(compiledStatement) == SQLITE_ROW) { CELL *cellMO = [NSEntityDescription insertNewObjectForEntityForName:@"CELL" inManagedObjectContext:[self managedObjectContext]]; if (sqlite3_column_type(compiledStatement, 0) != SQLITE_NULL) { cellMO.cellName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 0)]; } else { cellMO.cellName = @"undefined"; } if (sqlite3_column_type(compiledStatement, 1) != SQLITE_NULL) { cellMO.cellDescription = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 1)]; } else { cellMO.cellDescription = @"undefined"; } NSLog(@"The contents of NSString *cellName = %@",[cellMO.cellName description]); } } // Release the compiled statement from memory sqlite3_finalize(compiledStatement); } sqlite3_close(histoDatabase); } I have a feeling that it has something to do with the timing of opening/closing both of the databases? Attached I have some SQL debugging output to the terminal 2012-05-28 16:03:39.556 MedPix[34751:fb03] The createDatabase function was entered. 2012-05-28 16:03:39.557 MedPix[34751:fb03] The databasePath is /Users/jack/Library/Application Support/iPhone Simulator/5.1/Applications/A6B2A79D-BA93-4E24-9291-5B7948A3CDF4/MedPix.app/histology.sqlite 2012-05-28 16:03:39.559 MedPix[34751:fb03] The database was opened 2012-05-28 16:03:39.560 MedPix[34751:fb03] The database was prepared 2012-05-28 16:03:39.575 MedPix[34751:fb03] CoreData: annotation: Connecting to sqlite database file at "/Users/jack/Library/Application Support/iPhone Simulator/5.1/Applications/A6B2A79D-BA93-4E24-9291-5B7948A3CDF4/Documents/MedPix.sqlite" 2012-05-28 16:03:39.576 MedPix[34751:fb03] CoreData: annotation: creating schema. 2012-05-28 16:03:39.577 MedPix[34751:fb03] CoreData: sql: pragma page_size=4096 2012-05-28 16:03:39.578 MedPix[34751:fb03] CoreData: sql: pragma auto_vacuum=2 2012-05-28 16:03:39.630 MedPix[34751:fb03] CoreData: sql: BEGIN EXCLUSIVE 2012-05-28 16:03:39.631 MedPix[34751:fb03] CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA' 2012-05-28 16:03:39.632 MedPix[34751:fb03] CoreData: sql: CREATE TABLE ZCELL ( Z_PK INTEGER PRIMARY KEY, Z_ENT INTEGER, Z_OPT INTEGER, ZCELLDESCRIPTION VARCHAR, ZCELLNAME VARCHAR ) ... 2012-05-28 16:03:39.669 MedPix[34751:fb03] CoreData: annotation: Creating primary key table. 2012-05-28 16:03:39.671 MedPix[34751:fb03] CoreData: sql: CREATE TABLE Z_PRIMARYKEY (Z_ENT INTEGER PRIMARY KEY, Z_NAME VARCHAR, Z_SUPER INTEGER, Z_MAX INTEGER) 2012-05-28 16:03:39.672 MedPix[34751:fb03] CoreData: sql: INSERT INTO Z_PRIMARYKEY(Z_ENT, Z_NAME, Z_SUPER, Z_MAX) VALUES(1, 'CELL', 0, 0) ... 2012-05-28 16:03:39.701 MedPix[34751:fb03] CoreData: sql: CREATE TABLE Z_METADATA (Z_VERSION INTEGER PRIMARY KEY, Z_UUID VARCHAR(255), Z_PLIST BLOB) 2012-05-28 16:03:39.702 MedPix[34751:fb03] CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA' 2012-05-28 16:03:39.703 MedPix[34751:fb03] CoreData: sql: DELETE FROM Z_METADATA WHERE Z_VERSION = ? 2012-05-28 16:03:39.704 MedPix[34751:fb03] CoreData: sql: INSERT INTO Z_METADATA (Z_VERSION, Z_UUID, Z_PLIST) VALUES (?, ?, ?) 2012-05-28 16:03:39.705 MedPix[34751:fb03] CoreData: sql: COMMIT 2012-05-28 16:03:39.710 MedPix[34751:fb03] CoreData: sql: pragma cache_size=200 2012-05-28 16:03:39.711 MedPix[34751:fb03] CoreData: sql: SELECT Z_VERSION, Z_UUID, Z_PLIST FROM Z_METADATA 2012-05-28 16:03:39.712 MedPix[34751:fb03] The contents of NSString *cellName = Beta Cell 2012-05-28 16:03:39.712 MedPix[34751:fb03] The contents of NSString *cellName = Gastric Chief Cell ... 2012-05-28 16:03:39.714 MedPix[34751:fb03] The database was prepared 2012-05-28 16:03:39.764 MedPix[34751:fb03] The createDatabase function has finished. Now fetching. 2012-05-28 16:03:39.765 MedPix[34751:fb03] CoreData: sql: SELECT 0, t0.Z_PK, t0.Z_OPT, t0.ZCELLDESCRIPTION, t0.ZCELLNAME FROM ZCELL t0 2012-05-28 16:03:39.766 MedPix[34751:fb03] CoreData: annotation: sql connection fetch time: 0.0008s 2012-05-28 16:03:39.767 MedPix[34751:fb03] CoreData: annotation: total fetch execution time: 0.0016s for 0 rows. 2012-05-28 16:03:39.768 MedPix[34751:fb03] cellName: <CELL: 0x6bbc120> (entity: CELL; id: 0x6bbc160 <x-coredata:///CELL/t57D10DDD-74E2-474F-97EE-E3BD0FF684DA34> ; data: { cellDescription = "S cells are cells which release secretin, found in the jejunum and duodenum. They are stimulated by a drop in pH to 4 or below in the small intestine's lumen. The released secretin will increase the s"; cellName = "S Cell"; organs = ( ); specimens = ( ); systems = ( ); tissues = ( ); }) ... Sections were cut short to abbreviate. But note that the fetch results contain information, but it says that total fetch execution was for "0" rows? How can that be? Any help will be greatly appreciated, especially detailed explanations. :) Thanks.

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• Handling TclErrors in Python

  - by anteater7171

  In the following code I'll get the following error if I right click the window that pops up. Then go down to the very bottom entry widget then delete it's contents. It seems to be giving me a TclError. How do I go about handeling such an error? The Error Exception in Tkinter callback Traceback (most recent call last): File "C:\Python26\Lib\lib-tk\Tkinter.py", line 1410, in __call__ return self.func(*args) File "C:\Python26\CPUDEMO.py", line 503, in I TL.sclS.set(S1) File "C:\Python26\Lib\lib-tk\Tkinter.py", line 2765, in set self.tk.call(self._w, 'set', value) TclError: expected floating-point number but got "" The Code #F #PIthon.py # Import/Setup import Tkinter import psutil,time import re from PIL import Image, ImageTk from time import sleep class simpleapp_tk(Tkinter.Tk): def __init__(self,parent): Tkinter.Tk.__init__(self,parent) self.parent = parent self.initialize() def initialize(self): Widgets self.menu = Tkinter.Menu(self, tearoff = 0 ) M = [ "Options...", "Exit"] self.selectedM = Tkinter.StringVar() self.menu.add_radiobutton( label = 'Hide', variable = self.selectedM, command = self.E ) self.menu.add_radiobutton( label = 'Bump', variable = self.selectedM, command = self.E ) self.menu.add_separator() self.menu.add_radiobutton( label = 'Options...', variable = self.selectedM, command = self.E ) self.menu.add_separator() self.menu.add_radiobutton( label = 'Exit', variable = self.selectedM, command = self.E ) self.frame1 = Tkinter.Frame(self,bg='grey15',relief='ridge',borderwidth=4,width=185, height=39) self.frame1.grid() self.frame1.grid_propagate(0) self.frame1.bind( "<Button-3><ButtonRelease-3>", self.D ) self.frame1.bind( "<Button-2><ButtonRelease-2>", self.C ) self.frame1.bind( "<Double-Button-1>", self.C ) self.labelVariable = Tkinter.StringVar() self.label = Tkinter.Label(self.frame1,textvariable=self.labelVariable,fg="lightgreen",bg="grey15",borderwidth=1,font=('arial', 10, 'bold')) self.label.grid(column=1,row=0,columnspan=1,sticky='nsew') self.label.bind( "<Button-3><ButtonRelease-3>", self.D ) self.label.bind( "<Button-2><ButtonRelease-2>", self.C ) self.label.bind( "<Double-Button-1>", self.C ) self.F() self.overrideredirect(1) self.wm_attributes("-topmost", 1) global TL1 TL1 = Tkinter.Toplevel(self) TL1.wm_geometry("+0+5000") TL1.overrideredirect(1) TL1.button = Tkinter.Button(TL1,text="? CPU",fg="lightgreen",bg="grey15",activeforeground="lightgreen", activebackground='grey15',borderwidth=4,font=('Arial', 8, 'bold'),command=self.J) TL1.button.pack(ipadx=1) Events def Reset(self): self.label.configure(font=('arial', 10, 'bold'),fg='Lightgreen',bg='grey15',borderwidth=0) self.labela.configure(font=('arial', 8, 'bold'),fg='Lightgreen',bg='grey15',borderwidth=0) self.frame1.configure(bg='grey15',relief='ridge',borderwidth=4,width=224, height=50) self.label.pack(ipadx=38) def helpmenu(self): t2 = Tkinter.Toplevel(self) Tkinter.Label(t2, text='This is a help menu', anchor="w",justify="left",fg="darkgreen",bg="grey90",relief="ridge",borderwidth=5,font=('Arial', 10)).pack(fill='both', expand=1) t2.resizable(False,False) t2.title('Help') menu = Tkinter.Menu(self) t2.config(menu=menu) filemenu = Tkinter.Menu(menu) menu.add_cascade(label="| Exit |", menu=filemenu) filemenu.add_command(label="Exit", command=t2.destroy) def aboutmenu(self): t1 = Tkinter.Toplevel(self) Tkinter.Label(t1, text=' About:\n\n CPU Usage v1.0\n\n Publisher: Drew French\n Date: 05/09/10\n Email: [email protected] \n\n\n\n\n\n\n Written in Python 2.6.4', anchor="w",justify="left",fg="darkgreen",bg="grey90",relief="sunken",borderwidth=5,font=('Arial', 10)).pack(fill='both', expand=1) t1.resizable(False,False) t1.title('About') menu = Tkinter.Menu(self) t1.config(menu=menu) filemenu = Tkinter.Menu(menu) menu.add_cascade(label="| Exit |", menu=filemenu) filemenu.add_command(label="Exit", command=t1.destroy) def A (self,event): TL.entryVariable1.set(TL.sclY.get()) TL.entryVariable2.set(TL.sclX.get()) Y = TL.sclY.get() X = TL.sclX.get() self.wm_geometry("+" + str(X) + "+" + str(Y)) def B(self,event): Y1 = TL.entryVariable1.get() X1 = TL.entryVariable2.get() self.wm_geometry("+" + str(X1) + "+" + str(Y1)) TL.sclY.set(Y1) TL.sclX.set(X1) def C(self,event): s = self.wm_geometry() geomPatt = re.compile(r"(\d+)?x?(\d+)?([+-])(\d+)([+-])(\d+)") m = geomPatt.search(s) X3 = m.group(4) Y3 = m.group(6) M = int(Y3) - 150 P = M + 150 while Y3 > M: sleep(0.0009) Y3 = int(Y3) - 1 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(Y3)) sleep(2.00) while Y3 < P: sleep(0.0009) Y3 = int(Y3) + 1 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(Y3)) def D(self, event=None): self.menu.post( event.x_root, event.y_root ) def E(self): if self.selectedM.get() =='Options...': Setup global TL TL = Tkinter.Toplevel(self) menu = Tkinter.Menu(TL) TL.config(menu=menu) filemenu = Tkinter.Menu(menu) menu.add_cascade(label="| Menu |", menu=filemenu) filemenu.add_command(label="Instruction Manual...", command=self.helpmenu) filemenu.add_command(label="About...", command=self.aboutmenu) filemenu.add_separator() filemenu.add_command(label="Exit Options", command=TL.destroy) filemenu.add_command(label="Exit", command=self.destroy) helpmenu = Tkinter.Menu(menu) menu.add_cascade(label="| Help |", menu=helpmenu) helpmenu.add_command(label="Instruction Manual...", command=self.helpmenu) helpmenu.add_separator() helpmenu.add_command(label="Quick Help...", command=self.helpmenu) Title TL.label5 = Tkinter.Label(TL,text="CPU Usage: Options",anchor="center",fg="black",bg="lightgreen",relief="ridge",borderwidth=5,font=('Arial', 18, 'bold')) TL.label5.pack(padx=15,ipadx=5) X Y scale TL.separator = Tkinter.Frame(TL,height=7, bd=1, relief='ridge', bg='grey95') TL.separator.pack(pady=5,padx=5) # TL.sclX = Tkinter.Scale(TL.separator, from_=0, to=1500, orient='horizontal', resolution=1, command=self.A) TL.sclX.grid(column=1,row=0,ipadx=27, sticky='w') TL.label1 = Tkinter.Label(TL.separator,text="X",anchor="s",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label1.grid(column=0,row=0, pady=1, sticky='S') TL.sclY = Tkinter.Scale(TL.separator, from_=0, to=1500, resolution=1, command=self.A) TL.sclY.grid(column=2,row=1,rowspan=2,sticky='e', padx=4) TL.label3 = Tkinter.Label(TL.separator,text="Y",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label3.grid(column=2,row=0, padx=10, sticky='e') TL.entryVariable2 = Tkinter.StringVar() TL.entry2 = Tkinter.Entry(TL.separator,textvariable=TL.entryVariable2, fg="grey15",bg="grey90",relief="sunken",insertbackground="black",borderwidth=5,font=('Arial', 10)) TL.entry2.grid(column=1,row=1,ipadx=20, pady=10,sticky='EW') TL.entry2.bind("<Return>", self.B) TL.label2 = Tkinter.Label(TL.separator,text="X:",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label2.grid(column=0,row=1, ipadx=4, sticky='W') TL.entryVariable1 = Tkinter.StringVar() TL.entry1 = Tkinter.Entry(TL.separator,textvariable=TL.entryVariable1, fg="grey15",bg="grey90",relief="sunken",insertbackground="black",borderwidth=5,font=('Arial', 10)) TL.entry1.grid(column=1,row=2,sticky='EW') TL.entry1.bind("<Return>", self.B) TL.label4 = Tkinter.Label(TL.separator,text="Y:", anchor="center",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label4.grid(column=0,row=2, ipadx=4, sticky='W') TL.label7 = Tkinter.Label(TL.separator,text="Text Colour:",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label7.grid(column=1,row=3,stick="W",ipady=10) TL.selectedP = Tkinter.StringVar() TL.opt1 = Tkinter.OptionMenu(TL.separator, TL.selectedP,'Normal', 'White','Black', 'Blue', 'Steel Blue','Green','Light Green','Yellow','Orange' ,'Red',command=self.G) TL.opt1.config(fg="black",bg="grey90",activebackground="grey90",activeforeground="black", anchor="center",relief="raised",direction='right',font=('Arial', 10)) TL.opt1.grid(column=1,row=4,sticky='EW',padx=20,ipadx=20) TL.selectedP.set('Normal') TL.label7 = Tkinter.Label(TL.separator,text="Refresh Rate:",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label7.grid(column=1,row=5,stick="W",ipady=10) TL.sclS = Tkinter.Scale(TL.separator, from_=10, to=2000, orient='horizontal', resolution=10, command=self.H) TL.sclS.grid(column=1,row=6,ipadx=27, sticky='w') TL.sclS.set(650) TL.entryVariableS = Tkinter.StringVar() TL.entryS = Tkinter.Entry(TL.separator,textvariable=TL.entryVariableS, fg="grey15",bg="grey90",relief="sunken",insertbackground="black",borderwidth=5,font=('Arial', 10)) TL.entryS.grid(column=1,row=7,ipadx=20, pady=10,sticky='EW') TL.entryS.bind("<Return>", self.I) TL.entryVariableS.set(650) # TL.resizable(False,False) TL.title('Options') geomPatt = re.compile(r"(\d+)?x?(\d+)?([+-])(\d+)([+-])(\d+)") s = self.wm_geometry() m = geomPatt.search(s) X = m.group(4) Y = m.group(6) TL.sclY.set(Y) TL.sclX.set(X) if self.selectedM.get() == 'Exit': self.destroy() if self.selectedM.get() == 'Bump': s = self.wm_geometry() geomPatt = re.compile(r"(\d+)?x?(\d+)?([+-])(\d+)([+-])(\d+)") m = geomPatt.search(s) X3 = m.group(4) Y3 = m.group(6) M = int(Y3) - 150 P = M + 150 while Y3 > M: sleep(0.0009) Y3 = int(Y3) - 1 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(Y3)) sleep(2.00) while Y3 < P: sleep(0.0009) Y3 = int(Y3) + 1 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(Y3)) if self.selectedM.get() == 'Hide': s = self.wm_geometry() geomPatt = re.compile(r"(\d+)?x?(\d+)?([+-])(\d+)([+-])(\d+)") m = geomPatt.search(s) X3 = m.group(4) Y3 = m.group(6) M = int(Y3) + 5000 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(M)) TL1.wm_geometry("+0+190") def F (self): G = round(psutil.cpu_percent(), 1) G1 = str(G) + '%' self.labelVariable.set(G1) try: S2 = TL.entryVariableS.get() except ValueError, e: S2 = 650 except NameError: S2 = 650 self.after(int(S2), self.F) def G (self,event): if TL.selectedP.get() =='Normal': self.label.config( fg = 'lightgreen' ) TL1.button.config( fg = 'lightgreen',activeforeground='lightgreen') if TL.selectedP.get() =='Red': self.label.config( fg = 'red' ) TL1.button.config( fg = 'red',activeforeground='red') if TL.selectedP.get() =='Orange': self.label.config( fg = 'orange') TL1.button.config( fg = 'orange',activeforeground='orange') if TL.selectedP.get() =='Yellow': self.label.config( fg = 'yellow') TL1.button.config( fg = 'yellow',activeforeground='yellow') if TL.selectedP.get() =='Light Green': self.label.config( fg = 'lightgreen' ) TL1.button.config( fg = 'lightgreen',activeforeground='lightgreen') if TL.selectedP.get() =='Normal': self.label.config( fg = 'lightgreen' ) TL1.button.config( fg = 'lightgreen',activeforeground='lightgreen') if TL.selectedP.get() =='Steel Blue': self.label.config( fg = 'steelblue1' ) TL1.button.config( fg = 'steelblue1',activeforeground='steelblue1') if TL.selectedP.get() =='Blue': self.label.config( fg = 'blue') TL1.button.config( fg = 'blue',activeforeground='blue') if TL.selectedP.get() =='Green': self.label.config( fg = 'darkgreen' ) TL1.button.config( fg = 'darkgreen',activeforeground='darkgreen') if TL.selectedP.get() =='White': self.label.config( fg = 'white' ) TL1.button.config( fg = 'white',activeforeground='white') if TL.selectedP.get() =='Black': self.label.config( fg = 'black') TL1.button.config( fg = 'black',activeforeground='black') def H (self,event): TL.entryVariableS.set(TL.sclS.get()) S = TL.sclS.get() def I (self,event): S1 = TL.entryVariableS.get() TL.sclS.set(S1) TL.sclS.set(TL.sclS.get()) S1 = TL.entryVariableS.get() TL.sclS.set(S1) def J (self): s = self.wm_geometry() geomPatt = re.compile(r"(\d+)?x?(\d+)?([+-])(\d+)([+-])(\d+)") m = geomPatt.search(s) X3 = m.group(4) Y3 = m.group(6) M = int(Y3) - 5000 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(M)) TL1.wm_geometry("+0+5000") Loop if name == "main": app = simpleapp_tk(None) app.mainloop()

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• Confusing Java syntax...

  - by posfan12

  I'm trying to convert the following code (from Wikipedia) from Java to JavaScript: /* * 3 June 2003, [[:en:User:Cyp]]: * Maze, generated by my algorithm * 24 October 2006, [[:en:User:quin]]: * Source edited for clarity * 25 January 2009, [[:en:User:DebateG]]: * Source edited again for clarity and reusability * 1 June 2009, [[:en:User:Nandhp]]: * Source edited to produce SVG file when run from the command-line * * This program was originally written by [[:en:User:Cyp]], who * attached it to the image description page for an image generated by * it on en.wikipedia. The image was licensed under CC-BY-SA-3.0/GFDL. */ import java.awt.*; import java.applet.*; import java.util.Random; /* Define the bit masks */ class Constants { public static final int WALL_ABOVE = 1; public static final int WALL_BELOW = 2; public static final int WALL_LEFT = 4; public static final int WALL_RIGHT = 8; public static final int QUEUED = 16; public static final int IN_MAZE = 32; } public class Maze extends java.applet.Applet { /* The width and height (in cells) of the maze */ private int width; private int height; private int maze[][]; private static final Random rnd = new Random(); /* The width in pixels of each cell */ private int cell_width; /* Construct a Maze with the default width, height, and cell_width */ public Maze() { this(20,20,10); } /* Construct a Maze with specified width, height, and cell_width */ public Maze(int width, int height, int cell_width) { this.width = width; this.height = height; this.cell_width = cell_width; } /* Initialization method that will be called when the program is * run from the command-line. Maze will be written as SVG file. */ public static void main(String[] args) { Maze m = new Maze(); m.createMaze(); m.printSVG(); } /* Initialization method that will be called when the program is * run as an applet. Maze will be displayed on-screen. */ public void init() { createMaze(); } /* The maze generation algorithm. */ private void createMaze(){ int x, y, n, d; int dx[] = { 0, 0, -1, 1 }; int dy[] = { -1, 1, 0, 0 }; int todo[] = new int[height * width], todonum = 0; /* We want to create a maze on a grid. */ maze = new int[width][height]; /* We start with a grid full of walls. */ for (x = 0; x < width; ++x) { for (y = 0; y < height; ++y) { if (x == 0 || x == width - 1 || y == 0 || y == height - 1) { maze[x][y] = Constants.IN_MAZE; } else { maze[x][y] = 63; } } } /* Select any square of the grid, to start with. */ x = 1 + rnd.nextInt (width - 2); y = 1 + rnd.nextInt (height - 2); /* Mark this square as connected to the maze. */ maze[x][y] &= ~48; /* Remember the surrounding squares, as we will */ for (d = 0; d < 4; ++d) { if ((maze[][d][][d] & Constants.QUEUED) != 0) { /* want to connect them to the maze. */ todo[todonum++] = ((x + dx[d]) << Constants.QUEUED) | (y + dy[d]); maze[][d][][d] &= ~Constants.QUEUED; } } /* We won't be finished until all is connected. */ while (todonum > 0) { /* We select one of the squares next to the maze. */ n = rnd.nextInt (todonum); x = todo[n] >> 16; /* the top 2 bytes of the data */ y = todo[n] & 65535; /* the bottom 2 bytes of the data */ /* We will connect it, so remove it from the queue. */ todo[n] = todo[--todonum]; /* Select a direction, which leads to the maze. */ do { d = rnd.nextInt (4); } while ((maze[][d][][d] & Constants.IN_MAZE) != 0); /* Connect this square to the maze. */ maze[x][y] &= ~((1 << d) | Constants.IN_MAZE); maze[][d][][d] &= ~(1 << (d ^ 1)); /* Remember the surrounding squares, which aren't */ for (d = 0; d < 4; ++d) { if ((maze[][d][][d] & Constants.QUEUED) != 0) { /* connected to the maze, and aren't yet queued to be. */ todo[todonum++] = ((x + dx[d]) << Constants.QUEUED) | (y + dy[d]); maze[][d][][d] &= ~Constants.QUEUED; } } /* Repeat until finished. */ } /* Add an entrance and exit. */ maze[1][1] &= ~Constants.WALL_ABOVE; maze[width - 2][height - 2] &= ~Constants.WALL_BELOW; } /* Called by the applet infrastructure to display the maze on-screen. */ public void paint(Graphics g) { drawMaze(g); } /* Called to write the maze to an SVG file. */ public void printSVG() { System.out.format("<svg width=\"%d\" height=\"%d\" version=\"1.1\"" + " xmlns=\"http://www.w3.org/2000/svg\">\n", width*cell_width, height*cell_width); System.out.println(" <g stroke=\"black\" stroke-width=\"1\"" + " stroke-linecap=\"round\">"); drawMaze(null); System.out.println(" </g>\n</svg>"); } /* Main maze-drawing loop. */ public void drawMaze(Graphics g) { int x, y; for (x = 1; x < width - 1; ++x) { for (y = 1; y < height - 1; ++y) { if ((maze[x][y] & Constants.WALL_ABOVE) != 0) drawLine( x * cell_width, y * cell_width, (x + 1) * cell_width, y * cell_width, g); if ((maze[x][y] & Constants.WALL_BELOW) != 0) drawLine( x * cell_width, (y + 1) * cell_width, (x + 1) * cell_width, (y + 1) * cell_width, g); if ((maze[x][y] & Constants.WALL_LEFT) != 0) drawLine( x * cell_width, y * cell_width, x * cell_width, (y + 1) * cell_width, g); if ((maze[x][y] & Constants.WALL_RIGHT) != 0) drawLine((x + 1) * cell_width, y * cell_width, (x + 1) * cell_width, (y + 1) * cell_width, g); } } } /* Draw a line, either in the SVG file or on the screen. */ public void drawLine(int x1, int y1, int x2, int y2, Graphics g) { if ( g != null ) g.drawLine(x1, y1, x2, y2); else System.out.format(" <line x1=\"%d\" y1=\"%d\"" + " x2=\"%d\" y2=\"%d\" />\n", x1, y1, x2, y2); } } Anyway, I was chugging along fairly quickly when I came to a bit that I just don't understand: /* Remember the surrounding squares, as we will */ for (var d = 0; d < 4; ++d) { if ((maze[][d][][d] & Constants.QUEUED) != 0) { /* want to connect them to the maze. */ todo[todonum++] = ((x + dx[d]) << Constants.QUEUED) | (y + dy[d]); maze[][d][][d] &= ~Constants.QUEUED; } } What I don't get is why there are four sets of brackets following the "maze" parameter instead of just two, since "maze" is a two dimensional array, not a four dimensional array. I'm sure there's a good reason for this. Problem is, I just don't get it. Thanks!

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• Moving items from one tableView to another tableView with extra's

  - by Totumus Maximus

  Let's say I have 2 UITableViews next to eachother on an ipad in landscape-mode. Now I want to move multiple items from one tableView to the other. They are allowed to be inserted on the bottom of the other tableView. Both have multiSelection activated. Now the movement itself is no problem with normal cells. But in my program each cell has an object which contains the consolidationState of the cell. There are 4 states a cell can have: Basic, Holding, Parent, Child. Basic = an ordinary cell. Holding = a cell which contains multiple childs but which wont be shown in this state. Parent = a cell which contains multiple childs and are shown directly below this cell. Child = a cell created by the Parent cell. The object in each cell also has some array which contains its children. The object also holds a quantityValue, which is displayed on the cell itself. Now the movement gets tricky. Holding and Parent cells can't move at all. Basic cells can move freely. Child cells can move freely but based on how many Child cells are left in the Parent. The parent will change or be deleted all together. If a Parent cell has more then 1 Child cell left it will stay a Parent cell. Else the Parent has no or 1 Child cell left and is useless. It will then be deleted. The items that are moved will always be of the same state. They will all be Basic cells. This is how I programmed the movement: *First I determine which of the tableViews is the sender and which is the receiver. *Second I ask all indexPathsForSelectedRows and sort them from highest row to lowest. *Then I build the data to be transferred. This I do by looping through the selectedRows and ask their object from the sender's listOfItems. *When I saved all the data I need I delete all the items from the sender TableView. This is why I sorted the selectedRows so I can start at the highest indexPath.row and delete without screwing up the other indexPaths. *When I loop through the selectedRows I check whether I found a cell with state Basic or Child. *If its a Basic cell I do nothing and just delete the cell. (this works fine with all Basic Cells) *If its a Child cell I go and check it's Parent cell immidiately. Since all Child cells are directly below the Parent cell and no other the the Parent's Childs are below that Parent I can safely get the path of the selected Childcell and move upwards and find it's Parent cell. When this Parent cell is found (this will always happen, no exceptions) it has to change accordingly. *The Parent cell will either be deleted or the object inside will have its quantity and children reduced. *After the Parent cell has changed accordingly the Child cell is deleted similarly like the Basic cells *After the deletion of the cells the receiver tableView will build new indexPaths so the movedObjects will have a place to go. *I then insert the objects into the listOfItems of the receiver TableView. The code works in the following ways: Only Basic cells are moved. Basic cells and just 1 child for each parent is moved. A single Basic/Child cell is moved. The code doesn't work when: I select more then 1 or all childs of some parent cell. The problem happens somewhere into updating the parent cells. I'm staring blindly at the code now so maybe a fresh look will help fix things. Any help will be appreciated. Here is the method that should do the movement: -(void)moveSelectedItems { UITableView *senderTableView = //retrieves the table with the data here. UITableView *receiverTableView = //retrieves the table which gets the data here. NSArray *selectedRows = senderTableView.indexPathsForSelectedRows; //sort selected rows from lowest indexPath.row to highest selectedRows = [selectedRows sortedArrayUsingSelector:@selector(compare:)]; //build up target rows (all objects to be moved) NSMutableArray *targetRows = [[NSMutableArray alloc] init]; for (int i = 0; i<selectedRows.count; i++) { NSIndexPath *path = [selectedRows objectAtIndex:i]; [targetRows addObject:[senderTableView.listOfItems objectAtIndex:path.row]]; } //delete rows at active for (int i = selectedRows.count-1; i >= 0; i--) { NSIndexPath *path = [selectedRows objectAtIndex:i]; //check what item you are deleting. act upon the status. Parent- and HoldingCells cant be selected so only check for basic and childs MyCellObject *item = [senderTableView.listOfItems objectAtIndex:path.row]; if (item.consolidatedState == ConsolidationTypeChild) { for (int j = path.row; j >= 0; j--) { MyCellObject *consolidatedItem = [senderTableView.listOfItems objectAtIndex:j]; if (consolidatedItem.consolidatedState == ConsolidationTypeParent) { //copy the consolidated item but with 1 less quantity MyCellObject *newItem = [consolidatedItem copyWithOneLessQuantity]; //creates a copy of the object with 1 less quantity. if (newItem.quantity > 1) { newItem.consolidatedState = ConsolidationTypeParent; [senderTableView.listOfItems replaceObjectAtIndex:j withObject:newItem]; } else if (newItem.quantity == 1) { newItem.consolidatedState = ConsolidationTypeBasic; [senderTableView.listOfItems removeObjectAtIndex:j]; MyCellObject *child = [senderTableView.listOfItems objectAtIndex:j+1]; child.consolidatedState = ConsolidationTypeBasic; [senderTableView.listOfItems replaceObjectAtIndex:j+1 withObject:child]; } else { [senderTableView.listOfItems removeObject:consolidatedItem]; } [senderTableView reloadData]; } } } [senderTableView.listOfItems removeObjectAtIndex:path.row]; } [senderTableView deleteRowsAtIndexPaths:selectedRows withRowAnimation:UITableViewRowAnimationTop]; //make new indexpaths for row animation NSMutableArray *newRows = [[NSMutableArray alloc] init]; for (int i = 0; i < targetRows.count; i++) { NSIndexPath *newPath = [NSIndexPath indexPathForRow:i+receiverTableView.listOfItems.count inSection:0]; [newRows addObject:newPath]; DLog(@"%i", i); //scroll to newest items [receiverTableView setContentOffset:CGPointMake(0, fmaxf(receiverTableView.contentSize.height - recieverTableView.frame.size.height, 0.0)) animated:YES]; } //add rows at target for (int i = 0; i < targetRows.count; i++) { MyCellObject *insertedItem = [targetRows objectAtIndex:i]; //all moved items will be brought into the standard (basic) consolidationType insertedItem.consolidatedState = ConsolidationTypeBasic; [receiverTableView.ListOfItems insertObject:insertedItem atIndex:receiverTableView.ListOfItems.count]; } [receiverTableView insertRowsAtIndexPaths:newRows withRowAnimation:UITableViewRowAnimationNone]; } If anyone has some fresh ideas of why the movement is bugging out let me know. If you feel like you need some extra information I'll be happy to add it. Again the problem is in the movement of ChildCells and updating the ParentCells properly. I could use some fresh looks and outsider ideas on this. Thanks in advance. *updated based on comments

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• Why does fprintf start printing out of order or not at all?

  - by Steve Melvin

  This code should take an integer, create pipes, spawn two children, wait until they are dead, and start all over again. However, around the third time around the loop I lose my prompt to enter a number and it no longer prints the number I've entered. Any ideas? #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #define WRITE 1 #define READ 0 int main (int argc, const char * argv[]) { //Pipe file-descriptor array unsigned int isChildA = 0; int pipeA[2]; int pipeB[2]; int num = 0; while(1){ fprintf(stderr,"Enter an integer: "); scanf("%i", &num); if(num == 0){ fprintf(stderr,"You entered zero, exiting...\n"); exit(0); } //Open Pipes if(pipe(pipeA) < 0){ fprintf(stderr,"Could not create pipe A.\n"); exit(1); } if(pipe(pipeB) < 0){ fprintf(stderr,"Could not create pipe B.\n"); exit(1); } fprintf(stderr,"Value read: %i \n", num); fprintf(stderr,"Parent PID: %i\n", getpid()); pid_t procID = fork(); switch (procID) { case -1: fprintf(stderr,"Fork error, quitting...\n"); exit(1); break; case 0: isChildA = 1; break; default: procID = fork(); if (procID<0) { fprintf(stderr,"Fork error, quitting...\n"); exit(1); } else if(procID == 0){ isChildA = 0; } else { write(pipeA[WRITE], &num, sizeof(int)); close(pipeA[WRITE]); close(pipeA[READ]); close(pipeB[WRITE]); close(pipeB[READ]); pid_t pid; while (pid = waitpid(-1, NULL, 0)) { if (errno == ECHILD) { break; } } } break; } if (procID == 0) { //We're a child, do kid-stuff. ssize_t bytesRead = 0; int response; while (1) { while (bytesRead == 0) { bytesRead = read((isChildA?pipeA[READ]:pipeB[READ]), &response, sizeof(int)); } if (response < 2) { //Kill other child and self fprintf(stderr, "Terminating PROCID: %i\n", getpid()); write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int)); close(pipeA[WRITE]); close(pipeA[READ]); close(pipeB[WRITE]); close(pipeB[READ]); return 0; } else if(!(response%2)){ //Even response/=2; fprintf(stderr,"PROCID: %i, VALUE: %i\n", getpid(), response); write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int)); bytesRead = 0; } else { //Odd response*=3; response++; fprintf(stderr,"PROCID: %i, VALUE: %i\n", getpid(), response); write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int)); bytesRead = 0; } } } } return 0; } This is the output I am getting... bash-3.00$ ./proj2 Enter an integer: 101 Value read: 101 Parent PID: 9379 PROCID: 9380, VALUE: 304 PROCID: 9381, VALUE: 152 PROCID: 9380, VALUE: 76 PROCID: 9381, VALUE: 38 PROCID: 9380, VALUE: 19 PROCID: 9381, VALUE: 58 PROCID: 9380, VALUE: 29 PROCID: 9381, VALUE: 88 PROCID: 9380, VALUE: 44 PROCID: 9381, VALUE: 22 PROCID: 9380, VALUE: 11 PROCID: 9381, VALUE: 34 PROCID: 9380, VALUE: 17 PROCID: 9381, VALUE: 52 PROCID: 9380, VALUE: 26 PROCID: 9381, VALUE: 13 PROCID: 9380, VALUE: 40 PROCID: 9381, VALUE: 20 PROCID: 9380, VALUE: 10 PROCID: 9381, VALUE: 5 PROCID: 9380, VALUE: 16 PROCID: 9381, VALUE: 8 PROCID: 9380, VALUE: 4 PROCID: 9381, VALUE: 2 PROCID: 9380, VALUE: 1 Terminating PROCID: 9381 Terminating PROCID: 9380 Enter an integer: 102 Value read: 102 Parent PID: 9379 PROCID: 9386, VALUE: 51 PROCID: 9387, VALUE: 154 PROCID: 9386, VALUE: 77 PROCID: 9387, VALUE: 232 PROCID: 9386, VALUE: 116 PROCID: 9387, VALUE: 58 PROCID: 9386, VALUE: 29 PROCID: 9387, VALUE: 88 PROCID: 9386, VALUE: 44 PROCID: 9387, VALUE: 22 PROCID: 9386, VALUE: 11 PROCID: 9387, VALUE: 34 PROCID: 9386, VALUE: 17 PROCID: 9387, VALUE: 52 PROCID: 9386, VALUE: 26 PROCID: 9387, VALUE: 13 PROCID: 9386, VALUE: 40 PROCID: 9387, VALUE: 20 PROCID: 9386, VALUE: 10 PROCID: 9387, VALUE: 5 PROCID: 9386, VALUE: 16 PROCID: 9387, VALUE: 8 PROCID: 9386, VALUE: 4 PROCID: 9387, VALUE: 2 PROCID: 9386, VALUE: 1 Terminating PROCID: 9387 Terminating PROCID: 9386 Enter an integer: 104 Value read: 104 Parent PID: 9379 Enter an integer: PROCID: 9388, VALUE: 52 PROCID: 9389, VALUE: 26 PROCID: 9388, VALUE: 13 PROCID: 9389, VALUE: 40 PROCID: 9388, VALUE: 20 PROCID: 9389, VALUE: 10 PROCID: 9388, VALUE: 5 PROCID: 9389, VALUE: 16 PROCID: 9388, VALUE: 8 PROCID: 9389, VALUE: 4 PROCID: 9388, VALUE: 2 PROCID: 9389, VALUE: 1 Terminating PROCID: 9388 Terminating PROCID: 9389 105 Value read: 105 Parent PID: 9379 Enter an integer: PROCID: 9395, VALUE: 316 PROCID: 9396, VALUE: 158 PROCID: 9395, VALUE: 79 PROCID: 9396, VALUE: 238 PROCID: 9395, VALUE: 119 PROCID: 9396, VALUE: 358 PROCID: 9395, VALUE: 179 PROCID: 9396, VALUE: 538 PROCID: 9395, VALUE: 269 PROCID: 9396, VALUE: 808 PROCID: 9395, VALUE: 404 PROCID: 9396, VALUE: 202 PROCID: 9395, VALUE: 101 PROCID: 9396, VALUE: 304 PROCID: 9395, VALUE: 152 PROCID: 9396, VALUE: 76 PROCID: 9395, VALUE: 38 PROCID: 9396, VALUE: 19 PROCID: 9395, VALUE: 58 PROCID: 9396, VALUE: 29 PROCID: 9395, VALUE: 88 PROCID: 9396, VALUE: 44 PROCID: 9395, VALUE: 22 PROCID: 9396, VALUE: 11 PROCID: 9395, VALUE: 34 PROCID: 9396, VALUE: 17 PROCID: 9395, VALUE: 52 PROCID: 9396, VALUE: 26 PROCID: 9395, VALUE: 13 PROCID: 9396, VALUE: 40 PROCID: 9395, VALUE: 20 PROCID: 9396, VALUE: 10 PROCID: 9395, VALUE: 5 PROCID: 9396, VALUE: 16 PROCID: 9395, VALUE: 8 PROCID: 9396, VALUE: 4 PROCID: 9395, VALUE: 2 PROCID: 9396, VALUE: 1 Terminating PROCID: 9395 Terminating PROCID: 9396 105 Value read: 105 Parent PID: 9379 Enter an integer: PROCID: 9397, VALUE: 316 PROCID: 9398, VALUE: 158 PROCID: 9397, VALUE: 79 PROCID: 9398, VALUE: 238 PROCID: 9397, VALUE: 119 PROCID: 9398, VALUE: 358 PROCID: 9397, VALUE: 179 PROCID: 9398, VALUE: 538 PROCID: 9397, VALUE: 269 PROCID: 9398, VALUE: 808 PROCID: 9397, VALUE: 404 PROCID: 9398, VALUE: 202 PROCID: 9397, VALUE: 101 PROCID: 9398, VALUE: 304 PROCID: 9397, VALUE: 152 PROCID: 9398, VALUE: 76 PROCID: 9397, VALUE: 38 PROCID: 9398, VALUE: 19 PROCID: 9397, VALUE: 58 PROCID: 9398, VALUE: 29 PROCID: 9397, VALUE: 88 PROCID: 9398, VALUE: 44 PROCID: 9397, VALUE: 22 PROCID: 9398, VALUE: 11 PROCID: 9397, VALUE: 34 PROCID: 9398, VALUE: 17 PROCID: 9397, VALUE: 52 PROCID: 9398, VALUE: 26 PROCID: 9397, VALUE: 13 PROCID: 9398, VALUE: 40 PROCID: 9397, VALUE: 20 PROCID: 9398, VALUE: 10 PROCID: 9397, VALUE: 5 PROCID: 9398, VALUE: 16 PROCID: 9397, VALUE: 8 PROCID: 9398, VALUE: 4 PROCID: 9397, VALUE: 2 PROCID: 9398, VALUE: 1 Terminating PROCID: 9397 Terminating PROCID: 9398 106 Value read: 106 Parent PID: 9379 Enter an integer: PROCID: 9399, VALUE: 53 PROCID: 9400, VALUE: 160 PROCID: 9399, VALUE: 80 PROCID: 9400, VALUE: 40 PROCID: 9399, VALUE: 20 PROCID: 9400, VALUE: 10 PROCID: 9399, VALUE: 5 PROCID: 9400, VALUE: 16 PROCID: 9399, VALUE: 8 PROCID: 9400, VALUE: 4 PROCID: 9399, VALUE: 2 PROCID: 9400, VALUE: 1 Terminating PROCID: 9399 Terminating PROCID: 9400 ^C Another thing that's strange, when ran from within XCode it behaves normally. However, when ran from bash on Solaris or OSX it acts up.

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• Delphi - Proper way to page though data.

  - by Brad

  I have a string list (TStrings) that has a couple thousand items in it. I need to process them in groups of 100. I basically want to know what the best way to do the loop is in Delphi. I'm hitting a brick wall when I'm trying to figure it out. Thanks unit Unit2; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls; type TForm2 = class(TForm) Memo1: TMemo; Memo2: TMemo; Button1: TButton; procedure Button1Click(Sender: TObject); private { Private declarations } public { Public declarations } end; var Form2: TForm2; implementation Uses math; {$R *.dfm} procedure TForm2.Button1Click(Sender: TObject); var I:Integer; pages:Integer; str:string; begin pages:= ceil(memo1.Lines.Count/100) ; memo2.Lines.add('Total Pages: '+inttostr(pages)); memo2.Lines.add('Total Items: '+inttostr(memo1.Lines.Count)); // Should just do in batches of 100 VS entire list for I := 0 to memo1.lines.Count - 1 do begin if str '' then str:= str+#10+ memo1.Lines.Strings[i] else str:= memo1.Lines.Strings[i]; end; //I need to stop here every 100 items, then process the items. memo2.Lines.Add(str); end; end. Example form object Form2: TForm2 Left = 0 Top = 0 Caption = 'Form2' ClientHeight = 245 ClientWidth = 527 Color = clBtnFace Font.Charset = DEFAULT_CHARSET Font.Color = clWindowText Font.Height = -11 Font.Name = 'Tahoma' Font.Style = [] OldCreateOrder = False PixelsPerInch = 96 TextHeight = 13 object Memo1: TMemo Left = 16 Top = 8 Width = 209 Height = 175 Lines.Strings = ( '4xlt columbia thunder storm jacket' '5 things about thunder storms' 'a thunder storm with a lot of thunder ' 'and lighting sccreensaver' 'a thunder storm with a lot of thunder ' 'and lighting screensaver with no nag ' 'screens' 'all about thunder storms' 'all about thunderstorms for kids' 'amazing tornado videos and ' 'thunderstorm videos' 'are thunder storms louder in ohio?' 'bad thunder storms' 'bathing in thunder storm' 'best thunderstorm pictures' 'cartoon thunder storms' 'celtic thunder storm' 'central valley thunder storm' 'chicago thunderstorm pictures' 'cool thunderstorm pictures' 'current thunderstorm warnings' 'does thunder storms in december mean ' 'snow will be coming' 'facts about thunderstorms for kids' 'facts on thunderstorms for kids' 'fedex thunderstorm video' 'florida thunderstorms facts' 'free relaxing thunderstorm music' 'free soothing thunderstorm sounds ' 'online' 'free thunderstorm mp3' 'free thunderstorm mp3 download' 'free thunderstorm mp3 downloads' 'free thunderstorm mp3s' 'free thunderstorm music' 'free thunderstorm pictures' 'free thunderstorm sound effects' 'free thunderstorm sounds' 'free thunderstorm sounds cd' 'free thunderstorm sounds mp3' 'free thunderstorm sounds online' 'free thunderstorm soundscape' 'free thunderstorm video' 'free thunderstorm video download' 'free thunderstorm videos' 'god of storm and thunder' 'horses storm thunder rain' 'how do thunder storms form' 'how far away is a thunder storm' 'how long do thunder storms last' 'ice cube in a thunder storm' 'indoor thunderstorm safety tips' 'information about thunderstorms for kids' 'interesting thunderstorm facts' 'is it dangerous to shower during thunder ' 'storm' 'is there frequently thunder during snow ' 'storms' 'isolated thunderstorms' 'it'#39's just a thunder storm baby there is ' 'nothing you should fear lyrics' 'lightning & thunder storm safety' 'lightning and thunderstorm facts' 'lightning and thunderstorms facts' 'lightning and thunderstorms for kids' 'listen to thunderstorm sounds online' 'mississauga thunder storm' 'nature sounds free mp3 thunder storm' 'only about thunderstorms facts' 'original storm deep thunderstick' 'phone use during thunder storms' 'pictures of thunderstorms' 'pocono thunder storm' 'posters of thunder storms' 'power rangers ninja storm' 'power rangers thunder storm' 'power rangers thunder storm cast' 'power rangers thunder storm games' 'power rangers thunder storm morphers' 'power rangers thunder storm part 1' 'power rangers thunder storm part 2' 'power rangers thunderstorm' 'power rangers thunderstorm cannon' 'power rangers thunderstorm deluxe ' 'megazord' 'power rangers thunderstorm games' 'power rangers thunderstorm megazord' 'power rangers thunderstorm part 2' 'power rangers thunderstorm pictures' 'power rnager ninja storm thunder staff' 'powerful thunder and lightning storms' 'precambrian thunder storms' 'rain thunderstorm mp3' 'rain thunderstorm pictures' 'relaxing thunderstorm music' 'reminds me of ohio river thunder lighten ' 'storms' 'sacramento thunder storm' 'safety tips for when your caught in a ' 'thunder storm' 'scattered thunderstorms' 'schemer puts his head in the thunder ' 'storm' 'sedative thunder storm' 'server thunder storms' 'severe supercell thunderstorm pictures' 'severe thunder storm pictures' 'severe thunder storms' 'severe thunderstorm facts' 'severe thunderstorm pictures' 'severe thunderstorm pictures hail' 'severe thunderstorm pictures in alberta' 'severe thunderstorm pictures tornado' 'severe thunderstorm safety' 'severe thunderstorm safety tips' 'severe thunderstorm videos' 'severe thunderstorm warning' 'severe thunderstorm warning los ' 'angeles' 'severe thunderstorm warning signs' 'severe thunderstorm warnings' 'severe thunderstorms' 'severe thunderstorms facts' 'shakespeare use thunder storm for ' 'cosmic disorder julius caesar' 'soothing thunderstorm sounds online' 'sound effects of severe thunder storm' 'sound of rain storm finger snapping ' 'thunder chorus' 'split thunder storm' 'storm 3d thunder power' 'storm dark thunder' 'storm dark thunder bowling ball' 'storm dark thunder bowling ball sale' 'storm dark thunder for sale' 'storm dark thunder pearl' 'storm dark thunder pearl bowling ball' 'storm dark thunder review' 'storm dark thunder shirt' 'storm dark thunderball' 'storm deep thunder' 'storm deep thunder 11' 'storm deep thunder 15' 'storm deep thunder 15 lure' 'storm deep thunder 2' 'storm deep thunder lures' 'storm deep thunderstick' 'storm deep thunderstick crankbaits' 'storm deep thunderstick dts09' 'storm deep thunderstick jr' 'storm deep thunderstick lures' 'storm deep thundersticks' 'storm rolling thunder 3 ball roller' 'storm rolling thunder bowling bag' 'storm rolling thunder three ball bowling ' 'bag' 'storm shallow thunder' 'storm shallow thunder 15' 'storm thunder claw' 'storm thunder craw' 'storm watches thunder' 'storms with constant lightning and ' 'thunder non-stop' 'supercell thunder storms' 'supercell thunderstorm pictures' 'supercell thunderstorms' 'swimming pools thunder storms' 'tampa + lightning strikes + thunder ' 'storms' 'texas thunderstorm pictures' 'texas thunderstorm warnings' 'thunder and lightning storm' 'thunder and lighting storms' 'thunder and lightning storms' 'thunder bay snow storm video' 'thunder storm' 'thunder storm and windmill' 'thunder storm cd' 'thunder storm cloud' 'thunder storm clouds' 'thunder storm dog peppermint oil' 'thunder storm in winter' 'thunder storm in winter and weather ' 'prediction' 'thunder storm lx-3 & road blaster psx ' 'download' 'thunder storm occurances' 'thunder storm photos' 'thunder storm poems' 'thunder storm safety' 'thunder storm sign' 'thunder storm sounds' 'thunder storms' 'thunder storms and deaths' 'thunder storms and ilghting' 'thunder storms and lighting' 'thunder storms cd' 'thunder storms in the arctic arctic ' 'weather' 'thunder storms in winter' 'thunder storms on you tub' 'thunder storms pics' 'thunder storms with rain' 'thunderstorm' 'thunderstorm backgrounds' 'thunderstorm capital' 'thunderstorm capital 2008 dorfman' 'thunderstorm capital in boston' 'thunderstorm capital llc' 'thunderstorm capital of canada' 'thunderstorm capital of the us' 'thunderstorm capital of the world' 'thunderstorm facts' 'thunderstorm facts for kids' 'thunderstorm facts hail' 'thunderstorm facts tornadoes' 'thunderstorm mp3' 'thunderstorm mp3 download' 'thunderstorm mp3 download free' 'thunderstorm mp3 downloads' 'thunderstorm mp3 downloads free' 'thunderstorm mp3 files' 'thunderstorm mp3 free' 'thunderstorm mp3 free download' 'thunderstorm mp3 free downloads' 'thunderstorm mp3 torrent' 'thunderstorm mp3s' 'thunderstorm music' 'thunderstorm music cd' 'thunderstorm music downloads' 'thunderstorm music free' 'thunderstorm music playlists' 'thunderstorm music rain' 'thunderstorm pics' 'thunderstorm pictures' 'thunderstorm pictures for kids' 'thunderstorm safety' 'thunderstorm safety for kids' 'thunderstorm safety precautions' 'thunderstorm safety procedures' 'thunderstorm safety rules' 'thunderstorm safety tips' 'thunderstorm safety tips for kids' 'thunderstorm safety tips shelter' 'thunderstorm safety tips trees' 'thunderstorm sound effects' 'thunderstorm sound effects cd' 'thunderstorm sound effects download' 'thunderstorm sound effects free' 'thunderstorm sound effects free ' 'download' 'thunderstorm sound effects free music ' 'feature audio' 'thunderstorm sound effects mp3' 'thunderstorm sound effects rain' 'thunderstorm sounds' 'thunderstorm sounds cd' 'thunderstorm sounds download' 'thunderstorm sounds for sleep' 'thunderstorm sounds for sleeping' 'thunderstorm sounds free' 'thunderstorm sounds free download' 'thunderstorm sounds free downloads' 'thunderstorm sounds mp3' 'thunderstorm sounds mp3 download' 'thunderstorm sounds mp3 free' 'thunderstorm sounds online' 'thunderstorm sounds online for free' 'thunderstorm sounds online free' 'thunderstorm sounds sleep' 'thunderstorm sounds streaming' 'thunderstorm sounds torrent' 'thunderstorm soundscape' 'thunderstorm soundscapes' 'thunderstorm video' 'thunderstorm video clips' 'thunderstorm video download' 'thunderstorm video downloads' 'thunderstorm videos' 'thunderstorm videos for kids' 'thunderstorm videos lightning' 'thunderstorm videos online' 'thunderstorm wallpaper' 'thunderstorm warning' 'thunderstorm warning brisbane' 'thunderstorm warning definition' 'thunderstorm warning los angeles' 'thunderstorm warning san diego' 'thunderstorm warning san mateo county' 'thunderstorm warning santa barbara' 'thunderstorm warning santa clara' 'thunderstorm warning santa clara ' 'county' 'thunderstorm warning signal' 'thunderstorm warning signs' 'thunderstorm warning vs watch' 'thunderstorm warnings' 'thunderstorm warnings and watches' 'thunderstorm warnings for nj' 'thunderstorm warnings qld' 'thunderstorms' 'thunderstorms facts' 'thunderstorms facts for kids' 'thunderstorms for kids' 'tornados and thunder storms animated' 'understanding thunderstorms for kids' 'watch thunderstorm videos' 'weather underground forecast ' 'thunderstorms' 'what causes thunder storms' 'what is a thunder storm' 'where d thunder storms occur') TabOrder = 0 end object Memo2: TMemo Left = 240 Top = 8 Width = 265 Height = 129 Lines.Strings = ( 'Memo2') TabOrder = 1 end object Button1: TButton Left = 384 Top = 184 Width = 75 Height = 25 Caption = 'Button1' TabOrder = 2 OnClick = Button1Click end end

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• XSL Template outputting massive chunk of text, rather than HTML. But only on one section

  - by Throlkim

  I'm having a slightly odd situation with an XSL template. Most of it outputs fine, but a certain for-each loop is causing me problems. Here's the XML: <area> <feature type="Hall"> <Heading><![CDATA[Hall]]></Heading> <Para><![CDATA[Communal gardens, pathway leading to PVCu double glazed communal front door to]]></Para> </feature> <feature type="Entrance Hall"> <Heading><![CDATA[Communal Entrance Hall]]></Heading> <Para><![CDATA[Plain ceiling, centre light fitting, fire door through to inner hallway, wood and glazed panelled front door to]]></Para> </feature> <feature type="Inner Hall"> <Heading><![CDATA[Inner Hall]]></Heading> <Para><![CDATA[Plain ceiling with pendant light fitting and covings, security telephone, airing cupboard housing gas boiler serving domestic hot water and central heating, telephone point, storage cupboard housing gas and electric meters, wooden panelled doors off to all rooms.]]></Para> </feature> <feature type="Lounge (Reception)" width="3.05" length="4.57" units="metre"> <Heading><![CDATA[Lounge (Reception)]]></Heading> <Para><![CDATA[15' 6" x 10' 7" (4.72m x 3.23m) Window to the side and rear elevation, papered ceiling with pendant light fitting and covings, two double panelled radiators, power points, wall mounted security entry phone, TV aerial point.]]></Para> </feature> <feature type="Kitchen" width="3.05" length="3.66" units="metre"> <Heading><![CDATA[Kitchen]]></Heading> <Para><![CDATA[12' x 10' (3.66m x 3.05m) Double glazed window to the rear elevation, textured ceiling with strip lighting, range of base and wall units in Beech with brushed aluminium handles, co-ordinated working surfaces with inset stainless steel sink with mixer taps over, co-ordinated tiled splashbacks, gas and electric cooker points, large storage cupboard with shelving, power points.]]></Para> </feature> <feature type="Entrance Porch"> <Heading><![CDATA[Balcony]]></Heading> <Para><![CDATA[Views across the communal South facing garden, wrought iron balustrade.]]></Para> </feature> <feature type="Bedroom" width="3.35" length="3.96" units="metre"> <Heading><![CDATA[Bedroom One]]></Heading> <Para><![CDATA[13' 6" x 11' 5" (4.11m x 3.48m) Double glazed windows to the front and side elevations, papered ceiling with pendant light fittings and covings, single panelled radiator, power points, telephone point, security entry phone.]]></Para> </feature> <feature type="Bedroom" width="3.05" length="3.35" units="metre"> <Heading><![CDATA[Bedroom Two]]></Heading> <Para><![CDATA[11' 4" x 10' 1" (3.45m x 3.07m) Double glazed window to the front elevation, plain ceiling with centre light fitting and covings, power points.]]></Para> </feature> <feature type="bathroom"> <Heading><![CDATA[Bathroom]]></Heading> <Para><![CDATA[Obscure double glazed window to the rear elevation, textured ceiling with centre light fitting and extractor fan, suite in white comprising of low level WC, wall mounted wash hand basin and walk in shower housing 'Triton T80' electric shower, co-ordinated tiled splashbacks.]]></Para> </feature> </area> And here's the section of my template that processes it: <xsl:for-each select="area"> <li> <xsl:for-each select="feature"> <li> <h5> <xsl:value-of select="Heading"/> </h5> <xsl:value-of select="Para"/> </li> </xsl:for-each> </li> </xsl:for-each> And here's the output: Hall Communal gardens, pathway leading to PVCu double glazed communal front door to Communal Entrance Hall Plain ceiling, centre light fitting, fire door through to inner hallway, wood and glazed panelled front door to Inner Hall Plain ceiling with pendant light fitting and covings, security telephone, airing cupboard housing gas boiler serving domestic hot water and central heating, telephone point, storage cupboard housing gas and electric meters, wooden panelled doors off to all rooms. Lounge (Reception) 15' 6" x 10' 7" (4.72m x 3.23m) Window to the side and rear elevation, papered ceiling with pendant light fitting and covings, two double panelled radiators, power points, wall mounted security entry phone, TV aerial point. Kitchen 12' x 10' (3.66m x 3.05m) Double glazed window to the rear elevation, textured ceiling with strip lighting, range of base and wall units in Beech with brushed aluminium handles, co-ordinated working surfaces with inset stainless steel sink with mixer taps over, co-ordinated tiled splashbacks, gas and electric cooker points, large storage cupboard with shelving, power points. Balcony Views across the communal South facing garden, wrought iron balustrade. Bedroom One 13' 6" x 11' 5" (4.11m x 3.48m) Double glazed windows to the front and side elevations, papered ceiling with pendant light fittings and covings, single panelled radiator, power points, telephone point, security entry phone. Bedroom Two 11' 4" x 10' 1" (3.45m x 3.07m) Double glazed window to the front elevation, plain ceiling with centre light fitting and covings, power points. Bathroom Obscure double glazed window to the rear elevation, textured ceiling with centre light fitting and extractor fan, suite in white comprising of low level WC, wall mounted wash hand basin and walk in shower housing 'Triton T80' electric shower, co-ordinated tiled splashbacks. For reference, here's the entire XSLT: http://pastie.org/private/eq4gjvqoc1amg9ynyf6wzg The rest of it all outputs fine - what am I missing from the above section?

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• Issues passing values to shader

  - by numerical25

  I am having issues passing values to my shader. My application compiles fine, but my cube object won't shade. Below is majority of my code. Most of my code for communicating with my shader is in createObject method myGame.cpp #include "MyGame.h" #include "OneColorCube.h" /* This code sets a projection and shows a turning cube. What has been added is the project, rotation and a rasterizer to change the rasterization of the cube. The issue that was going on was something with the effect file which was causing the vertices not to be rendered correctly.*/ typedef struct { ID3D10Effect* pEffect; ID3D10EffectTechnique* pTechnique; //vertex information ID3D10Buffer* pVertexBuffer; ID3D10Buffer* pIndicesBuffer; ID3D10InputLayout* pVertexLayout; UINT numVertices; UINT numIndices; }ModelObject; ModelObject modelObject; // World Matrix D3DXMATRIX WorldMatrix; // View Matrix D3DXMATRIX ViewMatrix; // Projection Matrix D3DXMATRIX ProjectionMatrix; ID3D10EffectMatrixVariable* pProjectionMatrixVariable = NULL; ID3D10EffectVectorVariable* pLightVarible = NULL; bool MyGame::InitDirect3D() { if(!DX3dApp::InitDirect3D()) { return false; } D3D10_RASTERIZER_DESC rastDesc; rastDesc.FillMode = D3D10_FILL_WIREFRAME; rastDesc.CullMode = D3D10_CULL_FRONT; rastDesc.FrontCounterClockwise = true; rastDesc.DepthBias = false; rastDesc.DepthBiasClamp = 0; rastDesc.SlopeScaledDepthBias = 0; rastDesc.DepthClipEnable = false; rastDesc.ScissorEnable = false; rastDesc.MultisampleEnable = false; rastDesc.AntialiasedLineEnable = false; ID3D10RasterizerState *g_pRasterizerState; mpD3DDevice->CreateRasterizerState(&rastDesc, &g_pRasterizerState); //mpD3DDevice->RSSetState(g_pRasterizerState); // Set up the World Matrix D3DXMatrixIdentity(&WorldMatrix); D3DXMatrixLookAtLH(&ViewMatrix, new D3DXVECTOR3(0.0f, 10.0f, -20.0f), new D3DXVECTOR3(0.0f, 0.0f, 0.0f), new D3DXVECTOR3(0.0f, 1.0f, 0.0f)); // Set up the projection matrix D3DXMatrixPerspectiveFovLH(&ProjectionMatrix, (float)D3DX_PI * 0.5f, (float)mWidth/(float)mHeight, 0.1f, 100.0f); if(!CreateObject()) { return false; } return true; } //These are actions that take place after the clearing of the buffer and before the present void MyGame::GameDraw() { static float rotationAngleY = 15.0f; static float rotationAngleX = 0.0f; static D3DXMATRIX rotationXMatrix; static D3DXMATRIX rotationYMatrix; // create the rotation matrix using the rotation angle D3DXMatrixRotationY(&rotationYMatrix, rotationAngleY); D3DXMatrixRotationX(&rotationXMatrix, rotationAngleX); //rotationAngleY += (float)D3DX_PI * 0.002f; //rotationAngleX += (float)D3DX_PI * 0.001f; WorldMatrix = rotationYMatrix * rotationXMatrix; // Set the input layout mpD3DDevice->IASetInputLayout(modelObject.pVertexLayout); // Set vertex buffer UINT stride = sizeof(VertexPos); UINT offset = 0; mpD3DDevice->IASetVertexBuffers(0, 1, &modelObject.pVertexBuffer, &stride, &offset); // Set primitive topology mpD3DDevice->IASetPrimitiveTopology(D3D10_PRIMITIVE_TOPOLOGY_TRIANGLELIST); //ViewMatrix._43 += 0.005f; // Combine and send the final matrix to the shader D3DXMATRIX finalMatrix = (WorldMatrix * ViewMatrix * ProjectionMatrix); pProjectionMatrixVariable->SetMatrix((float*)&finalMatrix); // make sure modelObject is valid // Render a model object D3D10_TECHNIQUE_DESC techniqueDescription; modelObject.pTechnique->GetDesc(&techniqueDescription); // Loop through the technique passes for(UINT p=0; p < techniqueDescription.Passes; ++p) { modelObject.pTechnique->GetPassByIndex(p)->Apply(0); // draw the cube using all 36 vertices and 12 triangles mpD3DDevice->Draw(36,0); } } //Render actually incapsulates Gamedraw, so you can call data before you actually clear the buffer or after you //present data void MyGame::Render() { DX3dApp::Render(); } bool MyGame::CreateObject() { //Create Layout D3D10_INPUT_ELEMENT_DESC layout[] = { {"POSITION",0,DXGI_FORMAT_R32G32B32_FLOAT, 0 , 0, D3D10_INPUT_PER_VERTEX_DATA, 0}, {"COLOR",0,DXGI_FORMAT_R32G32B32A32_FLOAT, 0 , 12, D3D10_INPUT_PER_VERTEX_DATA, 0}, {"NORMAL",0,DXGI_FORMAT_R32G32B32A32_FLOAT, 0 , 24, D3D10_INPUT_PER_VERTEX_DATA, 0} }; UINT numElements = (sizeof(layout)/sizeof(layout[0])); modelObject.numVertices = sizeof(vertices)/sizeof(VertexPos); for(int i = 0; i < modelObject.numVertices; i += 3) { D3DXVECTOR3 out; D3DXVECTOR3 v1 = vertices[0 + i].pos; D3DXVECTOR3 v2 = vertices[1 + i].pos; D3DXVECTOR3 v3 = vertices[2 + i].pos; D3DXVECTOR3 u = v2 - v1; D3DXVECTOR3 v = v3 - v1; D3DXVec3Cross(&out, &u, &v); D3DXVec3Normalize(&out, &out); vertices[0 + i].normal = out; vertices[1 + i].normal = out; vertices[2 + i].normal = out; } //Create buffer desc D3D10_BUFFER_DESC bufferDesc; bufferDesc.Usage = D3D10_USAGE_DEFAULT; bufferDesc.ByteWidth = sizeof(VertexPos) * modelObject.numVertices; bufferDesc.BindFlags = D3D10_BIND_VERTEX_BUFFER; bufferDesc.CPUAccessFlags = 0; bufferDesc.MiscFlags = 0; D3D10_SUBRESOURCE_DATA initData; initData.pSysMem = vertices; //Create the buffer HRESULT hr = mpD3DDevice->CreateBuffer(&bufferDesc, &initData, &modelObject.pVertexBuffer); if(FAILED(hr)) return false; /* //Create indices DWORD indices[] = { 0,1,3, 1,2,3 }; ModelObject.numIndices = sizeof(indices)/sizeof(DWORD); bufferDesc.ByteWidth = sizeof(DWORD) * ModelObject.numIndices; bufferDesc.BindFlags = D3D10_BIND_INDEX_BUFFER; initData.pSysMem = indices; hr = mpD3DDevice->CreateBuffer(&bufferDesc, &initData, &ModelObject.pIndicesBuffer); if(FAILED(hr)) return false;*/ ///////////////////////////////////////////////////////////////////////////// //Set up fx files LPCWSTR effectFilename = L"effect.fx"; modelObject.pEffect = NULL; hr = D3DX10CreateEffectFromFile(effectFilename, NULL, NULL, "fx_4_0", D3D10_SHADER_ENABLE_STRICTNESS, 0, mpD3DDevice, NULL, NULL, &modelObject.pEffect, NULL, NULL); if(FAILED(hr)) return false; pProjectionMatrixVariable = modelObject.pEffect->GetVariableByName("Projection")->AsMatrix(); pLightVarible = modelObject.pEffect->GetVariableByName("lightSource")->AsVector(); //Dont sweat the technique. Get it! LPCSTR effectTechniqueName = "Render"; D3DXVECTOR3 vLight(10.0f, 10.0f, 10.0f); pLightVarible->SetFloatVector(vLight); modelObject.pTechnique = modelObject.pEffect->GetTechniqueByName(effectTechniqueName); if(modelObject.pTechnique == NULL) return false; //Create Vertex layout D3D10_PASS_DESC passDesc; modelObject.pTechnique->GetPassByIndex(0)->GetDesc(&passDesc); hr = mpD3DDevice->CreateInputLayout(layout, numElements, passDesc.pIAInputSignature, passDesc.IAInputSignatureSize, &modelObject.pVertexLayout); if(FAILED(hr)) return false; return true; } And below is my shader effect.fx matrix Projection; float3 lightSource; float4 lightColor = {0.5, 0.5, 0.5, 0.5}; // PS_INPUT - input variables to the pixel shader // This struct is created and fill in by the // vertex shader struct PS_INPUT { float4 Pos : SV_POSITION; float4 Color : COLOR0; float4 Normal : NORMAL; }; //////////////////////////////////////////////// // Vertex Shader - Main Function /////////////////////////////////////////////// PS_INPUT VS(float4 Pos : POSITION, float4 Color : COLOR, float4 Normal : NORMAL) { PS_INPUT psInput; // Pass through both the position and the color psInput.Pos = mul( Pos, Projection ); psInput.Color = Color; psInput.Normal = Normal; return psInput; } /////////////////////////////////////////////// // Pixel Shader /////////////////////////////////////////////// float4 PS(PS_INPUT psInput) : SV_Target { float4 finalColor = 0; finalColor = saturate(dot(lightSource, psInput.Normal) * lightColor); return finalColor; } // Define the technique technique10 Render { pass P0 { SetVertexShader( CompileShader( vs_4_0, VS() ) ); SetGeometryShader( NULL ); SetPixelShader( CompileShader( ps_4_0, PS() ) ); } }

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• What is the fastest cyclic synchronization in Java (ExecutorService vs. CyclicBarrier vs. X)?

  - by Alex Dunlop

  Which Java synchronization construct is likely to provide the best performance for a concurrent, iterative processing scenario with a fixed number of threads like the one outlined below? After experimenting on my own for a while (using ExecutorService and CyclicBarrier) and being somewhat surprised by the results, I would be grateful for some expert advice and maybe some new ideas. Existing questions here do not seem to focus primarily on performance, hence this new one. Thanks in advance! The core of the app is a simple iterative data processing algorithm, parallelized to the spread the computational load across 8 cores on a Mac Pro, running OS X 10.6 and Java 1.6.0_07. The data to be processed is split into 8 blocks and each block is fed to a Runnable to be executed by one of a fixed number of threads. Parallelizing the algorithm was fairly straightforward, and it functionally works as desired, but its performance is not yet what I think it could be. The app seems to spend a lot of time in system calls synchronizing, so after some profiling I wonder whether I selected the most appropriate synchronization mechanism(s). A key requirement of the algorithm is that it needs to proceed in stages, so the threads need to sync up at the end of each stage. The main thread prepares the work (very low overhead), passes it to the threads, lets them work on it, then proceeds when all threads are done, rearranges the work (again very low overhead) and repeats the cycle. The machine is dedicated to this task, Garbage Collection is minimized by using per-thread pools of pre-allocated items, and the number of threads can be fixed (no incoming requests or the like, just one thread per CPU core). V1 - ExecutorService My first implementation used an ExecutorService with 8 worker threads. The program creates 8 tasks holding the work and then lets them work on it, roughly like this: // create one thread per CPU executorService = Executors.newFixedThreadPool( 8 ); ... // now process data in cycles while( ...) { // package data into 8 work items ... // create one Callable task per work item ... // submit the Callables to the worker threads executorService.invokeAll( taskList ); } This works well functionally (it does what it should), and for very large work items indeed all 8 CPUs become highly loaded, as much as the processing algorithm would be expected to allow (some work items will finish faster than others, then idle). However, as the work items become smaller (and this is not really under the program's control), the user CPU load shrinks dramatically: blocksize | system | user | cycles/sec 256k 1.8% 85% 1.30 64k 2.5% 77% 5.6 16k 4% 64% 22.5 4096 8% 56% 86 1024 13% 38% 227 256 17% 19% 420 64 19% 17% 948 16 19% 13% 1626 Legend: - block size = size of the work item (= computational steps) - system = system load, as shown in OS X Activity Monitor (red bar) - user = user load, as shown in OS X Activity Monitor (green bar) - cycles/sec = iterations through the main while loop, more is better The primary area of concern here is the high percentage of time spent in the system, which appears to be driven by thread synchronization calls. As expected, for smaller work items, ExecutorService.invokeAll() will require relatively more effort to sync up the threads versus the amount of work being performed in each thread. But since ExecutorService is more generic than it would need to be for this use case (it can queue tasks for threads if there are more tasks than cores), I though maybe there would be a leaner synchronization construct. V2 - CyclicBarrier The next implementation used a CyclicBarrier to sync up the threads before receiving work and after completing it, roughly as follows: main() { // create the barrier barrier = new CyclicBarrier( 8 + 1 ); // create Runable for thread, tell it about the barrier Runnable task = new WorkerThreadRunnable( barrier ); // start the threads for( int i = 0; i < 8; i++ ) { // create one thread per core new Thread( task ).start(); } while( ... ) { // tell threads about the work ... // N threads + this will call await(), then system proceeds barrier.await(); // ... now worker threads work on the work... // wait for worker threads to finish barrier.await(); } } class WorkerThreadRunnable implements Runnable { CyclicBarrier barrier; WorkerThreadRunnable( CyclicBarrier barrier ) { this.barrier = barrier; } public void run() { while( true ) { // wait for work barrier.await(); // do the work ... // wait for everyone else to finish barrier.await(); } } } Again, this works well functionally (it does what it should), and for very large work items indeed all 8 CPUs become highly loaded, as before. However, as the work items become smaller, the load still shrinks dramatically: blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.7% 78% 6.1 16k 5.5% 52% 25 4096 9% 29% 64 1024 11% 15% 117 256 12% 8% 169 64 12% 6.5% 285 16 12% 6% 377 For large work items, synchronization is negligible and the performance is identical to V1. But unexpectedly, the results of the (highly specialized) CyclicBarrier seem MUCH WORSE than those for the (generic) ExecutorService: throughput (cycles/sec) is only about 1/4th of V1. A preliminary conclusion would be that even though this seems to be the advertised ideal use case for CyclicBarrier, it performs much worse than the generic ExecutorService. V3 - Wait/Notify + CyclicBarrier It seemed worth a try to replace the first cyclic barrier await() with a simple wait/notify mechanism: main() { // create the barrier // create Runable for thread, tell it about the barrier // start the threads while( ... ) { // tell threads about the work // for each: workerThreadRunnable.setWorkItem( ... ); // ... now worker threads work on the work... // wait for worker threads to finish barrier.await(); } } class WorkerThreadRunnable implements Runnable { CyclicBarrier barrier; @NotNull volatile private Callable<Integer> workItem; WorkerThreadRunnable( CyclicBarrier barrier ) { this.barrier = barrier; this.workItem = NO_WORK; } final protected void setWorkItem( @NotNull final Callable<Integer> callable ) { synchronized( this ) { workItem = callable; notify(); } } public void run() { while( true ) { // wait for work while( true ) { synchronized( this ) { if( workItem != NO_WORK ) break; try { wait(); } catch( InterruptedException e ) { e.printStackTrace(); } } } // do the work ... // wait for everyone else to finish barrier.await(); } } } Again, this works well functionally (it does what it should). blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.4% 80% 6.3 16k 4.6% 60% 30.1 4096 8.6% 41% 98.5 1024 12% 23% 202 256 14% 11.6% 299 64 14% 10.0% 518 16 14.8% 8.7% 679 The throughput for small work items is still much worse than that of the ExecutorService, but about 2x that of the CyclicBarrier. Eliminating one CyclicBarrier eliminates half of the gap. V4 - Busy wait instead of wait/notify Since this app is the primary one running on the system and the cores idle anyway if they're not busy with a work item, why not try a busy wait for work items in each thread, even if that spins the CPU needlessly. The worker thread code changes as follows: class WorkerThreadRunnable implements Runnable { // as before final protected void setWorkItem( @NotNull final Callable<Integer> callable ) { workItem = callable; } public void run() { while( true ) { // busy-wait for work while( true ) { if( workItem != NO_WORK ) break; } // do the work ... // wait for everyone else to finish barrier.await(); } } } Also works well functionally (it does what it should). blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.2% 81% 6.3 16k 4.2% 62% 33 4096 7.5% 40% 107 1024 10.4% 23% 210 256 12.0% 12.0% 310 64 11.9% 10.2% 550 16 12.2% 8.6% 741 For small work items, this increases throughput by a further 10% over the CyclicBarrier + wait/notify variant, which is not insignificant. But it is still much lower-throughput than V1 with the ExecutorService. V5 - ? So what is the best synchronization mechanism for such a (presumably not uncommon) problem? I am weary of writing my own sync mechanism to completely replace ExecutorService (assuming that it is too generic and there has to be something that can still be taken out to make it more efficient). It is not my area of expertise and I'm concerned that I'd spend a lot of time debugging it (since I'm not even sure my wait/notify and busy wait variants are correct) for uncertain gain. Any advice would be greatly appreciated.

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• Optimizing a lot of Scanner.findWithinHorizon(pattern, 0) calls

  - by darvids0n

  I'm building a process which extracts data from 6 csv-style files and two poorly laid out .txt reports and builds output CSVs, and I'm fully aware that there's going to be some overhead searching through all that whitespace thousands of times, but I never anticipated converting about about 50,000 records would take 12 hours. Excerpt of my manual matching code (I know it's horrible that I use lists of tokens like that, but it was the best thing I could think of): public static String lookup(List<String> tokensBefore, List<String> tokensAfter) { String result = null; while(_match(tokensBefore)) { // block until all input is read if(id.hasNext()) { result = id.next(); // capture the next token that matches if(_matchImmediate(tokensAfter)) // try to match tokensAfter to this result return result; } else return null; // end of file; no match } return null; // no matches } private static boolean _match(List<String> tokens) { return _match(tokens, true); } private static boolean _match(List<String> tokens, boolean block) { if(tokens != null && !tokens.isEmpty()) { if(id.findWithinHorizon(tokens.get(0), 0) == null) return false; for(int i = 1; i <= tokens.size(); i++) { if (i == tokens.size()) { // matches all tokens return true; } else if(id.hasNext() && !id.next().matches(tokens.get(i))) { break; // break to blocking behaviour } } } else { return true; // empty list always matches } if(block) return _match(tokens); // loop until we find something or nothing else return false; // return after just one attempted match } private static boolean _matchImmediate(List<String> tokens) { if(tokens != null) { for(int i = 0; i <= tokens.size(); i++) { if (i == tokens.size()) { // matches all tokens return true; } else if(!id.hasNext() || !id.next().matches(tokens.get(i))) { return false; // doesn't match, or end of file } } return false; // we have some serious problems if this ever gets called } else { return true; // empty list always matches } } Basically wondering how I would work in an efficient string search (Boyer-Moore or similar). My Scanner id is scanning a java.util.String, figured buffering it to memory would reduce I/O since the search here is being performed thousands of times on a relatively small file. The performance increase compared to scanning a BufferedReader(FileReader(File)) was probably less than 1%, the process still looks to be taking a LONG time. I've also traced execution and the slowness of my overall conversion process is definitely between the first and last like of the lookup method. In fact, so much so that I ran a shortcut process to count the number of occurrences of various identifiers in the .csv-style files (I use 2 lookup methods, this is just one of them) and the process completed indexing approx 4 different identifiers for 50,000 records in less than a minute. Compared to 12 hours, that's instant. Some notes (updated): I don't necessarily need the pattern-matching behaviour, I only get the first field of a line of text so I need to match line breaks or use Scanner.nextLine(). All ID numbers I need start at position 0 of a line and run through til the first block of whitespace, after which is the name of the corresponding object. I would ideally want to return a String, not an int locating the line number or start position of the result, but if it's faster then it will still work just fine. If an int is being returned, however, then I would now have to seek to that line again just to get the ID; storing the ID of every line that is searched sounds like a way around that. Anything to help me out, even if it saves 1ms per search, will help, so all input is appreciated. Thankyou! Usage scenario 1: I have a list of objects in file A, who in the old-style system have an id number which is not in file A. It is, however, POSSIBLY in another csv-style file (file B) or possibly still in a .txt report (file C) which each also contain a bunch of other information which is not useful here, and so file B needs to be searched through for the object's full name (1 token since it would reside within the second column of any given line), and then the first column should be the ID number. If that doesn't work, we then have to split the search token by whitespace into separate tokens before doing a search of file C for those tokens as well. Generalised code: String field; for (/* each record in file A */) { /* construct the rest of this object from file A info */ // now to find the ID, if we can List<String> objectName = new ArrayList<String>(1); objectName.add(Pattern.quote(thisObject.fullName)); field = lookup(objectSearchToken, objectName); // search file B if(field == null) // not found in file B { lookupReset(false); // initialise scanner to check file C objectName.clear(); // not using the full name String[] tokens = thisObject.fullName.split(id.delimiter().pattern()); for(String s : tokens) objectName.add(Pattern.quote(s)); field = lookup(objectSearchToken, objectName); // search file C lookupReset(true); // back to file B } else { /* found it, file B specific processing here */ } if(field != null) // found it in B or C thisObject.ID = field; } The objectName tokens are all uppercase words with possible hyphens or apostrophes in them, separated by spaces. Much like a person's name. As per a comment, I will pre-compile the regex for my objectSearchToken, which is just [\r\n]+. What's ending up happening in file C is, every single line is being checked, even the 95% of lines which don't contain an ID number and object name at the start. Would it be quicker to use ^[\r\n]+.*(objectname) instead of two separate regexes? It may reduce the number of _match executions. The more general case of that would be, concatenate all tokensBefore with all tokensAfter, and put a .* in the middle. It would need to be matching backwards through the file though, otherwise it would match the correct line but with a huge .* block in the middle with lots of lines. The above situation could be resolved if I could get java.util.Scanner to return the token previous to the current one after a call to findWithinHorizon. I have another usage scenario. Will put it up asap.

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• How to implement Google Maps new version of API v2

  - by bapatla

  Hi every one I came to know that google maps has deprecated its previous version API v1 and introduced a new version of google maps API v2. I tried out one example by following some links in google any how i am pretty sure that i got the api key correctly by providing the exact hash key code and managed to get the correct api key. Now i managed to write some code as well but when i tried to execute the code i am getting the errors please help me to solve this here is my code and i even tried the sample codes provided by google play services an i got the same problem this is the sample that i have done by referring some links in google main activity package com.example.apv; import com.google.android.gms.maps.CameraUpdateFactory; import com.google.android.gms.maps.GoogleMap; import com.google.android.gms.maps.MapFragment; import com.google.android.gms.maps.model.BitmapDescriptorFactory; import com.google.android.gms.maps.model.LatLng; import com.google.android.gms.maps.model.MarkerOptions; import android.os.Bundle; import android.app.Activity; import android.app.FragmentManager; public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); FragmentManager fragmentManager = getFragmentManager(); MapFragment mapFragment = (MapFragment) fragmentManager.findFragmentById(R.id.map); GoogleMap googleMap = mapFragment.getMap(); LatLng sfLatLng = new LatLng(37.7750, -122.4183); googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL); googleMap.addMarker(new MarkerOptions() .position(sfLatLng) .title("San Francisco") .snippet("Population: 776733") .icon(BitmapDescriptorFactory.defaultMarker( BitmapDescriptorFactory.HUE_AZURE))); googleMap.getUiSettings().setCompassEnabled(true); googleMap.getUiSettings().setZoomControlsEnabled(true); googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(sfLatLng, 10)); } } main.xml <?xml version="1.0" encoding="utf-8"?> <fragment xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/map" android:layout_width="match_parent" android:layout_height="match_parent" class="com.google.android.gms.maps.MapFragment"/> and finally my manifest file <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.apv" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="8" android:targetSdkVersion="17"/> <permission android:name="com.codebybrian.mapsample.permission.MAPS_RECEIVE" android:protectionLevel="signature"/> <!--Required permissions--> permission oid:name="com.codebybrian.mapsample.permission.MAPS_RECEIVE"/> <!--Used by the API to download map tiles from Google Maps servers: --> <uses-permission android:name="android.permission.INTERNET"/> <!--Allows the API to access Google web-based services: --> <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"/> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> <!--Optional permissions--> <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/> <!--Version 2 of the Google Maps Android API requires OpenGL ES version 2 --> <uses-feature android:glEsVersion="0x00020000" android:required="true"/> application android:label="@string/app_name" android:icon="@drawable/ic_launcher"> <activity android:name=".MyMapActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN"/> <category android:name="android.intent.category.LAUNCHER"/> </intent-filter> </activity> <meta-data android:name="com.google.android.maps.v2.API_KEY" android:value="AZzaSSsBmhi4dXoKSylGGmjkQ5Jev9UdAJBjk"/> </application> </manifest> i run my application in emulator of version 4.2 and api level of 17 i got following error 12-17 10:06:52.590: E/Trace(826): error opening trace file: No such file or directory (2) 12-17 10:06:52.590: W/Trace(826): Unexpected value from nativeGetEnabledTags: 0 12-17 10:06:52.590: W/Trace(826): Unexpected value from nativeGetEnabledTags: 0 12-17 10:06:52.590: W/Trace(826): Unexpected value from nativeGetEnabledTags: 0 12-17 10:06:52.680: I/ActivityThread(826): Pub com.google.android.gms.plus;com.google.android.gms.plus.action: com.google.android.gms.plus.provider.PlusProvider 12-17 10:06:52.740: W/Trace(826): Unexpected value from nativeGetEnabledTags: 0 12-17 10:06:52.740: W/Trace(826): Unexpected value from nativeGetEnabledTags: 0 12-17 10:06:52.760: W/Trace(826): Unexpected value from nativeGetEnabledTags: 0 later i came to know that these version cant execute in emulator so i tried executing it with two devices one is Sony xperia u of android version 2.3.7 and Samsung galaxy tab of android version 4.1.1 and these are my outputs 12-17 14:37:02.468: D/AndroidRuntime(7636): Shutting down VM 12-17 14:37:02.468: W/dalvikvm(7636): threadid=1: thread exiting with uncaught exception (group=0x41f672a0) 12-17 14:37:02.476: E/AndroidRuntime(7636): FATAL EXCEPTION: main 12-17 14:37:02.476: E/AndroidRuntime(7636): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.apv/com.example.apv.MyMapActivity}: java.lang.ClassNotFoundException: com.example.apv.MyMapActivity 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2021) 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2122) 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.app.ActivityThread.access$600(ActivityThread.java:140) 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1228) 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.os.Handler.dispatchMessage(Handler.java:99) 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.os.Looper.loop(Looper.java:137) 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.app.ActivityThread.main(ActivityThread.java:4895) 12-17 14:37:02.476: E/AndroidRuntime(7636): at java.lang.reflect.Method.invokeNative(Native Method) 12-17 14:37:02.476: E/AndroidRuntime(7636): at java.lang.reflect.Method.invoke(Method.java:511) 12-17 14:37:02.476: E/AndroidRuntime(7636): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller .run(ZygoteInit.java:994) 12-17 14:37:02.476: E/AndroidRuntime(7636): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761) 12-17 14:37:02.476: E/AndroidRuntime(7636): at dalvik.system.NativeStart.main(Native Method) 12-17 14:37:02.476: E/AndroidRuntime(7636): Caused by: java.lang.ClassNotFoundException: com.example.apv.MyMapActivity 12-17 14:37:02.476: E/AndroidRuntime(7636): at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61) 12-17 14:37:02.476: E/AndroidRuntime(7636): at java.lang.ClassLoader.loadClass(ClassLoader.java:501) 12-17 14:37:02.476: E/AndroidRuntime(7636): at java.lang.ClassLoader.loadClass(ClassLoader.java:461) 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.app.Instrumentation.newActivity(Instrumentation.java:1068) 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2012) 12-17 14:37:02.476: E/AndroidRuntime(7636): ... 11 more could any one please suggest me to how to get this done and give me some links of new version API v2 tutorials of google maps and some examples links please help me

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• Android Uncaught Exception

  - by Agrim Asthana

  09-30 02:32:31.474: D/ddm-heap(214): Got feature list request 09-30 02:32:31.634: D/AndroidRuntime(214): Shutting down VM 09-30 02:32:31.634: W/dalvikvm(214): threadid=3: thread exiting with uncaught exception (group=0x4001b188) 09-30 02:32:31.634: E/AndroidRuntime(214): Uncaught handler: thread main exiting due to uncaught exception 09-30 02:32:31.654: E/AndroidRuntime(214): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.mjcet.mjcet/com.mjcet.mjcet.MJCET}: java.lang.ClassNotFoundException: com.mjcet.mjcet.MJCET in loader dalvik.system.PathClassLoader@44e8c820 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread.access$2200(ActivityThread.java:119) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.os.Handler.dispatchMessage(Handler.java:99) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.os.Looper.loop(Looper.java:123) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread.main(ActivityThread.java:4363) 09-30 02:32:31.654: E/AndroidRuntime(214): at java.lang.reflect.Method.invokeNative(Native Method) 09-30 02:32:31.654: E/AndroidRuntime(214): at java.lang.reflect.Method.invoke(Method.java:521) 09-30 02:32:31.654: E/AndroidRuntime(214): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 09-30 02:32:31.654: E/AndroidRuntime(214): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 09-30 02:32:31.654: E/AndroidRuntime(214): at dalvik.system.NativeStart.main(Native Method) 09-30 02:32:31.654: E/AndroidRuntime(214): Caused by: java.lang.ClassNotFoundException: com.mjcet.mjcet.MJCET in loader dalvik.system.PathClassLoader@44e8c820 09-30 02:32:31.654: E/AndroidRuntime(214): at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:243) 09-30 02:32:31.654: E/AndroidRuntime(214): at java.lang.ClassLoader.loadClass(ClassLoader.java:573) 09-30 02:32:31.654: E/AndroidRuntime(214): at java.lang.ClassLoader.loadClass(ClassLoader.java:532) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.Instrumentation.newActivity(Instrumentation.java:1021) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2409) 09-30 02:32:31.654: E/AndroidRuntime(214): ... 11 more 09-30 02:32:31.684: I/dalvikvm(214): threadid=7: reacting to signal 3 09-30 02:32:31.684: E/dalvikvm(214): Unable to open stack trace file '/data/anr/traces.txt': Permission denied the above is my debugging output for the below activities LOGINACTIVITY.java package com.agrim.mjcet; import com.agrim.mjcet.R; import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.view.View; //import android.widget.TextView; import android.widget.Button; import android.widget.EditText; import android.view.View.OnClickListener; public class LoginActivity extends Activity { EditText txtUserName; EditText txtPassword; Button btnLogin; Button btnCancel; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // setting default screen to login.xml setContentView(R.layout.main); txtUserName=(EditText)this.findViewById(R.id.txtUname); txtPassword=(EditText)this.findViewById(R.id.txtPwd); btnLogin=(Button)this.findViewById(R.id.btnLogin); btnLogin=(Button)this.findViewById(R.id.btnLogin); btnLogin.setOnClickListener(new OnClickListener() { public void onClick(View v) { // Switching to Register screen if((txtUserName.getText().toString()).equals(txtPassword.getText().toString())) { Intent myIntent = new Intent(getApplicationContext(),SampleActivity.class); startActivityForResult(myIntent, 0); } } } ); } } SAMPLE ACTIVITY.java package com.agrim.mjcet; import com.agrim.mjcet.R; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.widget.TextView; public class SampleActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Set View to register.xml setContentView(R.layout.lol); TextView HomeScreen = (TextView) findViewById(R.id.back); HomeScreen.setOnClickListener(new View.OnClickListener() { public void onClick(View arg0) { // Closing registration screen // Switching to Login Screen/closing register screen finish(); } }); } } and here are my 2 layouts MAIN.XML <TableLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:background="#000000" android:stretchColumns="1"> <TableRow> <TextView android:text="@string/user_name" android:textColor="#347235" android:id="@+id/TextView01" android:layout_width="wrap_content" android:layout_marginLeft="25dip" android:layout_height="wrap_content"> </TextView> <EditText android:text="" android:inputType="text" android:id="@+id/txtUname" android:layout_weight="0.75" android:layout_width="wrap_content" android:layout_marginRight="10dip" android:layout_marginBottom="5dip" android:background="#FFFFFF" android:layout_height="wrap_content"> </EditText> </TableRow> <TableRow> <TextView android:text="@string/password" android:textColor="#347235" android:id="@+id/TextView02" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="25dip"> </TextView> <EditText android:text="" android:inputType="textPassword" android:id="@+id/txtPwd" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginRight="10dip" android:layout_weight="1" android:background="#FFFFFF" android:gravity="center"> </EditText> </TableRow> <TableRow> <Button android:id="@+id/btnLogin" android:layout_width="fill_parent" android:layout_height="wrap_content" android:background="#FFFFFF" android:layout_marginTop="25dip" android:layout_marginLeft="50dip" android:onClick="onClickMyButton" android:text="@string/login" /> <Button android:id="@+id/btnCancel" android:layout_width="fill_parent" android:layout_height="wrap_content" android:background="#FFFFFF" android:layout_marginTop="25dip" android:layout_marginLeft="100dip" android:layout_marginRight="50dip" android:text="@string/cancel" /> </TableRow> <FrameLayout android:layout_width="wrap_content" android:layout_height="match_parent" > <ImageView android:layout_width="fill_parent" android:layout_height="match_parent" android:scaleType="centerInside" android:src="@drawable/logo_invert" android:contentDescription="@drawable/logo_invert"/> </FrameLayout> </TableLayout> and finally LOL.xml <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:background="#000000" android:layout_height="fill_parent" > <ImageView android:layout_width="fill_parent" android:id="@+id/back" android:layout_height="match_parent" android:scaleType="centerInside" android:src="@drawable/lol" android:contentDescription="@drawable/lol"> </ImageView> <RelativeLayout android:layout_width="match_parent" android:layout_height="138dp" android:orientation="vertical" android:gravity="bottom" > <TextView android:id="@+id/TextView02" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:layout_centerHorizontal="true" android:text="@string/coming_soon" android:textColor="#347235" /> </RelativeLayout> </FrameLayout> I get a force close upon initialization.. and yes this is my first android app :)

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• Questions related to writing your own file downloader using multiple threads java

  - by Shekhar

  Hello In my current company, i am doing a PoC on how we can write a file downloader utility. We have to use socket programming(TCP/IP) for downloading the files. One of the requirements of the client is that a file(which will be large in size) should be transfered in chunks for example if we have a file of 5Mb size then we can have 5 threads which transfer 1 Mb each. I have written a small application which downloads a file. You can download the eclipe project from http://www.fileflyer.com/view/QM1JSC0 A brief explanation of my classes FileSender.java This class provides the bytes of file. It has a method called sendBytesOfFile(long start,long end, long sequenceNo) which gives the number of bytes. import java.io.File; import java.io.IOException; import java.util.zip.CRC32; import org.apache.commons.io.FileUtils; public class FileSender { private static final String FILE_NAME = "C:\\shared\\test.pdf"; public ByteArrayWrapper sendBytesOfFile(long start,long end, long sequenceNo){ try { File file = new File(FILE_NAME); byte[] fileBytes = FileUtils.readFileToByteArray(file); System.out.println("Size of file is " +fileBytes.length); System.out.println(); System.out.println("Start "+start +" end "+end); byte[] bytes = getByteArray(fileBytes, start, end); ByteArrayWrapper wrapper = new ByteArrayWrapper(bytes, sequenceNo); return wrapper; } catch (IOException e) { throw new RuntimeException(e); } } private byte[] getByteArray(byte[] bytes, long start, long end){ long arrayLength = end-start; System.out.println("Start : "+start +" end : "+end + " Arraylength : "+arrayLength +" length of source array : "+bytes.length); byte[] arr = new byte[(int)arrayLength]; for(int i = (int)start, j =0; i < end;i++,j++){ arr[j] = bytes[i]; } return arr; } public static long fileSize(){ File file = new File(FILE_NAME); return file.length(); } } Second Class is FileReceiver.java - This class receives the file. Small Explanation what this file does This class finds the size of the file to be fetched from Sender Depending upon the size of the file it finds the start and end position till the bytes needs to be read. It starts n number of threads giving each thread start,end, sequence number and a list which all the threads share. Each thread reads the number of bytes and creates a ByteArrayWrapper. ByteArrayWrapper objects are added to the list Then i have while loop which basically make sure that all threads have done their work finally it sorts the list based on the sequence number. then the bytes are joined, and a complete byte array is formed which is converted to a file. Code of File Receiver package com.filedownloader; import java.io.File; import java.io.IOException; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.List; import java.util.zip.CRC32; import org.apache.commons.io.FileUtils; public class FileReceiver { public static void main(String[] args) { FileReceiver receiver = new FileReceiver(); receiver.receiveFile(); } public void receiveFile(){ long startTime = System.currentTimeMillis(); long numberOfThreads = 10; long filesize = FileSender.fileSize(); System.out.println("File size received "+filesize); long start = filesize/numberOfThreads; List<ByteArrayWrapper> list = new ArrayList<ByteArrayWrapper>(); for(long threadCount =0; threadCount<numberOfThreads ;threadCount++){ FileDownloaderTask task = new FileDownloaderTask(threadCount*start,(threadCount+1)*start,threadCount,list); new Thread(task).start(); } while(list.size() != numberOfThreads){ // this is done so that all the threads should complete their work before processing further. //System.out.println("Waiting for threads to complete. List size "+list.size()); } if(list.size() == numberOfThreads){ System.out.println("All bytes received "+list); Collections.sort(list, new Comparator<ByteArrayWrapper>() { @Override public int compare(ByteArrayWrapper o1, ByteArrayWrapper o2) { long sequence1 = o1.getSequence(); long sequence2 = o2.getSequence(); if(sequence1 < sequence2){ return -1; }else if(sequence1 > sequence2){ return 1; } else{ return 0; } } }); byte[] totalBytes = list.get(0).getBytes(); byte[] firstArr = null; byte[] secondArr = null; for(int i = 1;i<list.size();i++){ firstArr = totalBytes; secondArr = list.get(i).getBytes(); totalBytes = concat(firstArr, secondArr); } System.out.println(totalBytes.length); convertToFile(totalBytes,"c:\\tmp\\test.pdf"); long endTime = System.currentTimeMillis(); System.out.println("Total time taken with "+numberOfThreads +" threads is "+(endTime-startTime)+" ms" ); } } private byte[] concat(byte[] A, byte[] B) { byte[] C= new byte[A.length+B.length]; System.arraycopy(A, 0, C, 0, A.length); System.arraycopy(B, 0, C, A.length, B.length); return C; } private void convertToFile(byte[] totalBytes,String name) { try { FileUtils.writeByteArrayToFile(new File(name), totalBytes); } catch (IOException e) { throw new RuntimeException(e); } } } Code of ByteArrayWrapper package com.filedownloader; import java.io.Serializable; public class ByteArrayWrapper implements Serializable{ private static final long serialVersionUID = 3499562855188457886L; private byte[] bytes; private long sequence; public ByteArrayWrapper(byte[] bytes, long sequenceNo) { this.bytes = bytes; this.sequence = sequenceNo; } public byte[] getBytes() { return bytes; } public long getSequence() { return sequence; } } Code of FileDownloaderTask import java.util.List; public class FileDownloaderTask implements Runnable { private List<ByteArrayWrapper> list; private long start; private long end; private long sequenceNo; public FileDownloaderTask(long start,long end,long sequenceNo,List<ByteArrayWrapper> list) { this.list = list; this.start = start; this.end = end; this.sequenceNo = sequenceNo; } @Override public void run() { ByteArrayWrapper wrapper = new FileSender().sendBytesOfFile(start, end, sequenceNo); list.add(wrapper); } } Questions related to this code 1) Does file downloading becomes fast when multiple threads is used? In this code i am not able to see the benefit. 2) How should i decide how many threads should i create ? 3) Are their any opensource libraries which does that 4) The file which file receiver receives is valid and not corrupted but checksum (i used FileUtils of common-io) does not match. Whats the problem? 5) This code gives out of memory when used with large file(above 100 Mb) i.e. because byte array which is created. How can i avoid? I know this is a very bad code but i have to write this in one day -:). Please suggest any other good way to do this? Thanks Shekhar

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• SocketChannel in Java sends data, but it doesn't get to destination application

  - by Peterson

  Hi Everybody, I'm suffering a lot to create a simple ChatServer in Java, using the NIO libraries. Wonder if someone could help me. I am doing that by using SocketChannel and Selector to handle multiple clients in a single thread. The problem is: I am able to accept new connections and get it's data, but when I try to send data back, the SocketChannel simply doesn't work. In the method write(), it returns a integer that is the same size of the data i'm passing to it, but the client never receives that data. Strangely, when I close the server application, the client receives the data. It's like the socketchannel maintains a buffer, and it only get flushed when I close the application. Here are some more details, to give you more information to help. I'm handling the events in this piece of code: private void run() throws IOException { ServerSocketChannel ssc = ServerSocketChannel.open(); // Set it to non-blocking, so we can use select ssc.configureBlocking( false ); // Get the Socket connected to this channel, and bind it // to the listening port this.serverSocket = ssc.socket(); InetSocketAddress isa = new InetSocketAddress( this.port ); serverSocket.bind( isa ); // Create a new Selector for selecting this.masterSelector = Selector.open(); // Register the ServerSocketChannel, so we can // listen for incoming connections ssc.register( masterSelector, SelectionKey.OP_ACCEPT ); while (true) { // See if we've had any activity -- either // an incoming connection, or incoming data on an // existing connection int num = masterSelector.select(); // If we don't have any activity, loop around and wait // again if (num == 0) { continue; } // Get the keys corresponding to the activity // that has been detected, and process them // one by one Set keys = masterSelector.selectedKeys(); Iterator it = keys.iterator(); while (it.hasNext()) { // Get a key representing one of bits of I/O // activity SelectionKey key = (SelectionKey)it.next(); // What kind of activity is it? if ((key.readyOps() & SelectionKey.OP_ACCEPT) == SelectionKey.OP_ACCEPT) { // Aceita a conexão Socket s = serverSocket.accept(); System.out.println( "LOG: Conexao TCP aceita de " + s.getInetAddress() + ":" + s.getPort() ); // Make sure to make it non-blocking, so we can // use a selector on it. SocketChannel sc = s.getChannel(); sc.configureBlocking( false ); // Registra a conexao no seletor, apenas para leitura sc.register( masterSelector, SelectionKey.OP_READ ); } else if ( key.isReadable() ) { SocketChannel sc = null; // It's incoming data on a connection, so // process it sc = (SocketChannel)key.channel(); // Verifica se a conexão corresponde a um cliente já existente if((clientsMap.getClient(key)) != null){ boolean closedConnection = !processIncomingClientData(key); if(closedConnection){ int id = clientsMap.getClient(key); closeClient(id); } } else { boolean clientAccepted = processIncomingDataFromNewClient(key); if(!clientAccepted){ // Se o cliente não foi aceito, sua conexão é simplesmente fechada sc.socket().close(); sc.close(); key.cancel(); } } } } // We remove the selected keys, because we've dealt // with them. keys.clear(); } } This piece of code is simply handles new clients that wants to connect to the chat. So, a client makes a TCP connection to the server, and once it gets accepted, it sends data to the server following a simply text protocol, informing his id and asking to get registrated to the server. I handle this in the method processIncomingDataFromNewClient(key). I'm also keeping a map of clients and its connections in a data structure similar to a hashtable. I? doing that because I need to recover a client Id from a connection and a connection from a client Id. This is can be shown in: clientsMap.getClient(key). But the problem itself resides in the method processIncomingDataFromNewClient(key). There, I simply read the data that the client sent to me, validate it, and if it's ok, I send a message back to the client to tell that it is connected to the chat server. Here is a similar piece of code: private boolean processIncomingDataFromNewClient(SelectionKey key){ SocketChannel sc = (SocketChannel) key.channel(); String connectionOrigin = sc.socket().getInetAddress() + ":" + sc.socket().getPort(); int id = 0; //id of the client buf.clear(); int bytesRead = 0; try { bytesRead = sc.read(buf); if(bytesRead<=0){ System.out.println("Conexão fechada pelo: " + connectionOrigin); return false; } System.out.println("LOG: " + bytesRead + " bytes lidos de " + connectionOrigin); String msg = new String(buf.array(),0,bytesRead); // Do validations with the client sent me here // gets the client id }catch (Exception e) { e.printStackTrace(); System.out.println("LOG: Oops. Cliente não conhece o protocolo. Fechando a conexão: " + connectionOrigin); System.out.println("LOG: Primeiros 10 caracteres enviados pelo cliente: " + msg); return false; } } } catch (IOException e) { System.out.println("LOG: Erro ao ler dados da conexao: " + connectionOrigin); System.out.println("LOG: "+ e.getLocalizedMessage()); System.out.println("LOG: Fechando a conexão..."); return false; } // If it gets to here, the protocol is ok and we can add the client boolean inserted = clientsMap.addClient(key, id); if(!inserted){ System.out.println("LOG: Não foi possível adicionar o cliente. Ou ele já está conectado ou já têm clientes demais. Id: " + id); System.out.println("LOG: Fechando a conexão: " + connectionOrigin); return false; } System.out.println("LOG: Novo cliente conectado! Enviando mesnsagem de confirmação. Id: " + id + " Conexao: " + connectionOrigin); /* Here is the error */ sendMessage(id, "Servidor pet: connection accepted"); System.out.println("LOG: Novo cliente conectado! Id: " + id + " Conexao: " + connectionOrigin); return true; } And finally, the method sendMessage(SelectionKey key) looks like this: private void sendMessage(int destId, String msg) { Charset charset = Charset.forName("ISO-8859-1"); CharBuffer charBuffer = CharBuffer.wrap(msg, 0, msg.length()); ByteBuffer bf = charset.encode(charBuffer); //bf.flip(); int bytesSent = 0; SelectionKey key = clientsMap.getClient(destId); SocketChannel sc = (SocketChannel) key.channel(); try { / int total_bytes_sent = 0; while(total_bytes_sent < msg.length()){ bytesSent = sc.write(bf); total_bytes_sent += bytesSent; } System.out.println("LOG: Bytes enviados para o cliente " + destId + ": "+ total_bytes_sent + " Tamanho da mensagem: " + msg.length()); } catch (IOException e) { System.out.println("LOG: Erro ao mandar mensagem para: " + destId); System.out.println("LOG: " + e.getLocalizedMessage()); } } So, what is happening is that the server, when send a message, prints something like this: LOG: Bytes sent to the client: 28 Size of the message: 28 So, it tells that it sent the data, but the chat client keeps blocking, waiting in the recv() method. So, the data never gets to it. When I close the server application, though, all the data appears in the client. I wonder why. It is important to say that the client is in C and the server JAVA, and I'm running both in the same machine, an Ubuntu Guest in virtualbox under windows. I also run both under windows host and under linuxes hosts, and keep getting the same strange problem. I'm sorry for the great lenght of this question, but I already searched a lot of places for an answer, found a lot of tutorials and questions, including here at StackOverflow, but coundn't find a reasonable explanation. I am really not liking this Java NIO, and i saw a lot of people complaining about it too. I am thinking that if I had done that in C it would have been a lot easier :-D So, if someone could help me and even discuss this behavor, it would be great! :-) Thanks everybody in advance, Péterson

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