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• ZFS for Database Log Files

  - by user12620111

  I've been troubled by drop outs in CPU usage in my application server, characterized by the CPUs suddenly going from close to 90% CPU busy to almost completely CPU idle for a few seconds. Here is an example of a drop out as shown by a snippet of vmstat data taken while the application server is under a heavy workload. # vmstat 1  kthr      memory            page            disk          faults      cpu  r b w   swap  free  re  mf pi po fr de sr s3 s4 s5 s6   in   sy   cs us sy id  1 0 0 130160176 116381952 0 16 0 0 0 0  0  0  0  0  0 207377 117715 203884 70 21 9  12 0 0 130160160 116381936 0 25 0 0 0 0 0  0  0  0  0 200413 117162 197250 70 20 9  11 0 0 130160176 116381920 0 16 0 0 0 0 0  0  1  0  0 203150 119365 200249 72 21 7  8 0 0 130160176 116377808 0 19 0 0 0 0  0  0  0  0  0 169826 96144 165194 56 17 27  0 0 0 130160176 116377800 0 16 0 0 0 0  0  0  0  0  1 10245 9376 9164 2  1 97  0 0 0 130160176 116377792 0 16 0 0 0 0  0  0  0  0  2 15742 12401 14784 4 1 95  0 0 0 130160176 116377776 2 16 0 0 0 0  0  0  1  0  0 19972 17703 19612 6 2 92  14 0 0 130160176 116377696 0 16 0 0 0 0 0  0  0  0  0 202794 116793 199807 71 21 8  9 0 0 130160160 116373584 0 30 0 0 0 0  0  0 18  0  0 203123 117857 198825 69 20 11 This behavior occurred consistently while the application server was processing synthetic transactions: HTTP requests from JMeter running on an external machine. I explored many theories trying to explain the drop outs, including: Unexpected JMeter behavior Network contention Java Garbage Collection Application Server thread pool problems Connection pool problems Database transaction processing Database I/O contention Graphing the CPU %idle led to a breakthrough: Several of the drop outs were 30 seconds apart. With that insight, I went digging through the data again and looking for other outliers that were 30 seconds apart. In the database server statistics, I found spikes in the iostat "asvc_t" (average response time of disk transactions, in milliseconds) for the disk drive that was being used for the database log files. Here is an example:                     extended device statistics     r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 2053.6    0.0 8234.3  0.0  0.2    0.0    0.1   0  24 c3t60080E5...F4F6d0s0     0.0 2162.2    0.0 8652.8  0.0  0.3    0.0    0.1   0  28 c3t60080E5...F4F6d0s0     0.0 1102.5    0.0 10012.8  0.0  4.5    0.0    4.1   0  69 c3t60080E5...F4F6d0s0     0.0   74.0    0.0 7920.6  0.0 10.0    0.0  135.1   0 100 c3t60080E5...F4F6d0s0     0.0  568.7    0.0 6674.0  0.0  6.4    0.0   11.2   0  90 c3t60080E5...F4F6d0s0     0.0 1358.0    0.0 5456.0  0.0  0.6    0.0    0.4   0  55 c3t60080E5...F4F6d0s0     0.0 1314.3    0.0 5285.2  0.0  0.7    0.0    0.5   0  70 c3t60080E5...F4F6d0s0 Here is a little more information about my database configuration: The database and application server were running on two different SPARC servers. Storage for the database was on a storage array connected via 8 gigabit Fibre Channel Data storage and log file were on different physical disk drives Reliable low latency I/O is provided by battery backed NVRAM Highly available: Two Fibre Channel links accessed via MPxIO Two Mirrored cache controllers The log file physical disks were mirrored in the storage device Database log files on a ZFS Filesystem with cutting-edge technologies, such as copy-on-write and end-to-end checksumming Why would I be getting service time spikes in my high-end storage? First, I wanted to verify that the database log disk service time spikes aligned with the application server CPU drop outs, and they did: At first, I guessed that the disk service time spikes might be related to flushing the write through cache on the storage device, but I was unable to validate that theory. After searching the WWW for a while, I decided to try using a separate log device: # zpool add ZFS-db-41 log c3t60080E500017D55C000015C150A9F8A7d0 The ZFS log device is configured in a similar manner as described above: two physical disks mirrored in the storage array. This change to the database storage configuration eliminated the application server CPU drop outs: Here is the zpool configuration: # zpool status ZFS-db-41   pool: ZFS-db-41  state: ONLINE  scan: none requested config:         NAME                                     STATE         ZFS-db-41                                ONLINE           c3t60080E5...F4F6d0  ONLINE         logs           c3t60080E5...F8A7d0  ONLINE Now, the I/O spikes look like this:                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1053.5    0.0 4234.1  0.0  0.8    0.0    0.7   0  75 c3t60080E5...F8A7d0s0                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1131.8    0.0 4555.3  0.0  0.8    0.0    0.7   0  76 c3t60080E5...F8A7d0s0                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1167.6    0.0 4682.2  0.0  0.7    0.0    0.6   0  74 c3t60080E5...F8A7d0s0     0.0  162.2    0.0 19153.9  0.0  0.7    0.0    4.2   0  12 c3t60080E5...F4F6d0s0                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1247.2    0.0 4992.6  0.0  0.7    0.0    0.6   0  71 c3t60080E5...F8A7d0s0     0.0   41.0    0.0   70.0  0.0  0.1    0.0    1.6   0   2 c3t60080E5...F4F6d0s0                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1241.3    0.0 4989.3  0.0  0.8    0.0    0.6   0  75 c3t60080E5...F8A7d0s0                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1193.2    0.0 4772.9  0.0  0.7    0.0    0.6   0  71 c3t60080E5...F8A7d0s0 We can see the steady flow of 4k writes to the ZIL device from O_SYNC database log file writes. The spikes are from flushing the transaction group. Like almost all problems that I run into, once I thoroughly understand the problem, I find that other people have documented similar experiences. Thanks to all of you who have documented alternative approaches. Saved for another day: now that the problem is obvious, I should try "zfs:zfs_immediate_write_sz" as recommended in the ZFS Evil Tuning Guide. References: The ZFS Intent Log Solaris ZFS, Synchronous Writes and the ZIL Explained ZFS Evil Tuning Guide: Cache Flushes ZFS Evil Tuning Guide: Tuning ZFS for Database Performance

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• Is there an API for determining congressional districts?

  - by ardavis

  I'm looking to determine the congressional district based on an address my user is providing. This will avoid having the user to look it up themselves. Does an API of this sort exist? Note Through my attempts to find one, I've only come across these: http://www.govtrack.us/developers/api (not sure how to submit an an address or zip code however) The following resources are available in the API ...Bills and resolutions in the U.S. Congress since 1973 (the 93rd Congress). ...A (bill, person) pair indicating cosponsorship, with join and withdrawn dates. ...Members of Congress and U.S. Presidents since the founding of the nation. ...Terms held in office by Members of Congress and U.S. Presidents. Each term corresponds with an election, meaning each term in the House covers two years (one 'Congress'), as President four years, and in the Senate six years (three 'Congresses'). ...Roll call votes in the U.S. Congress since 1789. How people voted is accessed through the Vote_voter API. ...How people voted on roll call votes in the U.S. Congress since 1789. See the Vote API. Filter on the vote field to get the results of a particular vote... http://www.opencongress.org/api (seems to be a way to find congress information, but not districts) This API provides programmers with structured access to all the data on OpenCongress, everything from official bill info to news and blog coverage to user-generated votes on bills and much more... This API defaults to returning XML. All queries can also return JSON... https://groups.google.com/forum/?fromgroups=#!topic/opendems-discuss/CeKyi_aANaE (similar question, no resolution) I've been looking over Open Dems, and seeing what's exposed at this point and what isn't. I work with Democrats Abroad, and am interested in using stuff from the lab for their sites. I quickly looked over the Precinct API, which does both more and less than what I'd need. An ideal resource would be any way of translating addresses into CD at the very least (getting state district data would be good as well), since that would make it easier for DA's membership to make a difference in races like last month's NY26 race... Update I'm looking at the source for the govtrack.us website and the 'doGeoCode' function may be useful. view-source:http://www.govtrack.us/congress/members If no one has any suggestions, I will try to go off of what they are doing.

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• Why does switching users completely hang my system every time?

  - by Stéphane

  I have a fresh install of 11.04 64bit, with 2 administrator accounts and 4 normal accounts. The 4 normal accounts (the kids' accounts) don't have passwords, they can login simply by clicking on their names. When any of the users -- either admin or normal -- tries to switch to another account by clicking in the top-right corner of the screen and selecting another user, the screen goes black and the entire system locks up. Even CTRL+ALT+F1 through F7 does nothing. This is reproducible 100% of the time on this system. I can ssh into the box when the console locks up, and by running top, I see that Xorg is consuming about 100% of the CPU. Looking at the output of "ps axfu" in bash while the system is in this "locked up" state, here is the lightdm and X process tree: USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 1153 0.0 0.1 183508 4292 ? Ssl Dec26 0:00 lightdm root 2187 0.4 4.6 265976 164168 tty7 Ss+ 00:43 0:21 \_ /usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch stephane 2612 0.0 0.3 266400 10736 ? Ssl 01:52 0:00 \_ /usr/bin/gnome-session --session=ubuntu stephane 2650 0.0 0.0 12264 276 ? Ss 01:52 0:00 | \_ /usr/bin/ssh-agent /usr/bin/dbus-launch --exit-with-session /usr/bin/gnome-session --session=ubuntu stephane 2703 0.8 3.0 562068 106548 ? Sl 01:52 0:08 | \_ compiz stephane 2801 0.0 0.0 4264 584 ? Ss 01:52 0:00 | | \_ /bin/sh -c /usr/bin/compiz-decorator stephane 2802 0.0 0.3 265744 13772 ? Sl 01:52 0:00 | | \_ /usr/bin/unity-window-decorator ...cut... root 3024 80.6 0.3 107928 13088 tty8 Rs+ 01:53 12:34 \_ /usr/bin/X :1 -auth /var/run/lightdm/root/:1 -nolisten tcp vt8 -novtswitch That last process, pid #3024 in this case, is what has the CPU pegged. In case it matters (I suspect it might) here is what I think may be the relevant information for my video card, taken from /var/log/Xorg.0.log: [ 3392.653] (II) Loading /usr/lib/x86_64-linux-gnu/xorg/extra-modules/extra-modules.dpkg-tmp/modules/extensions/libglx.so [ 3392.653] (II) Module glx: vendor="FireGL - AMD Technologies Inc." [ 3392.653] compiled for 6.9.0, module version = 1.0.0 ... [ 3392.655] (II) LoadModule: "fglrx" [ 3392.655] (II) Loading /usr/lib/x86_64-linux-gnu/xorg/extra-modules/extra-modules.dpkg-tmp/modules/drivers/fglrx_drv.so [ 3392.672] (II) Module fglrx: vendor="FireGL - ATI Technologies Inc." [ 3392.672] compiled for 1.4.99.906, module version = 8.88.7 [ 3392.672] Module class: X.Org Video Driver ... [ 3392.759] (==) fglrx(0): ATI 2D Acceleration Architecture enabled [ 3392.759] (--) fglrx(0): Chipset: "AMD Radeon HD 6410D" (Chipset = 0x9644) Lastly: I did see this posting: Change user on 11.10 hangs system ...but I checked, and the libpam-smbpass package isn't installed on this system.

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• Visual Studio 2010 Launch Events

  - by Jim Duffy

  Don’t miss out on the opportunity to learn about the new features in Visual Studio 2010. Check out the MSDN Events page and find out when the talented folks of the Developer & Evangelism group will be visiting your city to prove to you that /*Life Runs On Code*/. I’ll be attending the Raleigh event June 2, 2010 from 1:00 - 5:00 PM. North Carolina State University, Jane S. McKimmon Conference Center 1101 Gorman St Raleigh North Carolina 27606 United States From the Raleigh Event page: Event Overview Learn about the rich application platforms that Microsoft® Visual Studio® 2010 supports, including Windows® 7, the Web, SharePoint®, Windows Azure™, SQL®, and Windows® Phone 7 Series. From tighter tester and dev collaboration to new ALM tools, there’s a lot that’s new. Here’s what you can expect: Windows Development with Visual Studio 2010 Visual Studio has always been the best way to build compelling visual solutions for Windows. Visual Studio 2010 continues this trend with great new tooling support for Silverlight 4, WPF, and native development. In this demo heavy session, you’ll see how you can build rich Windows applications with Silverlight 4 using new trusted application features including out-of-browser execution, saving to the file system, and even COM Automation. You’ll also see how you can use the new Task Parallel Library from within a WPF application to take advantage of all those cores in today’s modern computers. Web and Cloud Development with Visual Studio 2010 If you build solutions for the web, then this session is for you. Come see how your existing skills move forward with Visual Studio 2010 both for in-house ASP.NET development and the new frontier of the Cloud. In this session, you’ll see improved designers, new HTML and JavaScript snippets, Web Forms enhancements, and how you can quickly build great web sites using Dynamic Data. You’ll see the changes made to testable web sites with MVC 2.0 and how we’ve integrated JQuery support into the platform. You’ll then see how easy it is to leverage your existing code and move to the cloud with Windows Azure. Windows Phone 7 Developer Tools and Platform Overview This session provides an overview of Visual Studio® 2010 for Windows Phone. Learn about the powerful capabilities of this new application platform and the developer tools experience including basic IDE usage, debugging, packaging, and deployment. This session also shows how you can use Microsoft Expression® Blend™ for Windows Phone to build great Silverlight applications. Have a day. :-|

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• 2D Animation Smoothness - Delta time vs. Kinematics

  - by viperld002

  I'm animating a sprite in 2D with key frames of rotation and xy-positions. I've recently had a discussion with someone saying that when the device (happens to be an iPad using cocos2D) hits a performance bump due to whatever else the user may be doing, lag will arise and that the best way to fight it is to not use actual positions, but velocities, accelerations and torques with kinematics. His message is to evaluate the positions and rotations from these speeds at the current point in time. I've never experienced a situation where I've heard of using kinematics to stem lag in 2D animations and am not sure of how effective it could be. Also, it seems to be overkill. The application is not networked so it's all running on a local device. The desired effect is that the animation always plays as closely as it can to the target frame rate. Wouldn't the technique suffer the same problems as just using the time since the last frame or a fixed time step since the kinematics would also require some time value to perform the calculation? What techniques could you suggest to best achieve the desired effect? EDIT 1 Thank you for your responses, they are very illuminating. I want to clarify my question before choosing an answer however, to make sure that this post really serves it's purpose. I have a sprite of a ball, and a text file with 3 arrays worth of information (rotation,translations x, translations y) with each unit of information existing as a key frame to be stepped through (0 to 49 and back to 0 to replay it again). I have this playing by interpolating from the current key frame to the next, every n-units of time. The animation is visibly correct when compared to a video I was given of it, and it is smooth because of the interpolations between the key frames. This is the existing state of the project. There are no physics simulated, only a static animation of a ball moving in a way an artist specifically designed. Should I, instead of rotation in degrees and translations by positions in space, derive velocities, accelerations and torques to express this static animation as a function of time? As in, position now = foo(time now), where foo uses kinematics.

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• How can I make a universal construction more efficient?

  - by VF1

  A "universal construction" is a wrapper class for a sequential object that enables it to be linearized (a strong consistency condition for concurrent objects). For instance, here's an adapted wait-free construction, in Java, from [1], which presumes the existence of a wait-free queue that satisfies the interface WFQ (which only requires one-time consensus between threads) and assumes a Sequential interface: public interface WFQ<T> // "FIFO" iteration { int enqueue(T t); // returns the sequence number of t Iterable<T> iterateUntil(int max); // iterates until sequence max } public interface Sequential { // Apply an invocation (method + arguments) // and get a response (return value + state) Response apply(Invocation i); } public interface Factory<T> { T generate(); } // generate new default object public interface Universal extends Sequential {} public class SlowUniversal implements Universal { Factory<? extends Sequential> generator; WFQ<Invocation> wfq = new WFQ<Invocation>(); Universal(Factory<? extends Sequential> g) { generator = g; } public Response apply(Invocation i) { int max = wfq.enqueue(i); Sequential s = generator.generate(); for(Invocation invoc : wfq.iterateUntil(max)) s.apply(invoc); return s.apply(i); } } This implementation isn't very satisfying, however, since it presumes determinism of a Sequential and is really slow. I attempted to add memory recycling: public interface WFQD<T> extends WFQ<T> { T dequeue(int n); } // dequeues only when n is the tail, else assists other threads public interface CopyableSequential extends Sequential { CopyableSequential copy(); } public class RecyclingUniversal implements Universal { WFQD<CopyableSequential> wfqd = new WFQD<CopyableSequential>(); Universal(CopyableSequential init) { wfqd.enqueue(init); } public Response apply(Invocation i) { int max = wfqd.enqueue(i); CopyableSequential cs = null; int ctr = max; for(CopyableSequential csq : wfq.iterateUntil(max)) if(--max == 0) cs = csq.copy(); wfqd.dequeue(max); return cs.apply(i); } } Here are my specific questions regarding the extension: Does my implementation create a linearizable multi-threaded version of a CopyableSequential? Is it possible extend memory recycling without extending the interface (perhaps my new methods trivialize the problem)? My implementation only reduces memory when a thread returns, so can this be strengthened? [1] provided an implementation for WFQ<T>, not WFQD<T> - one does exist, though, correct? [1] Herlihy and Shavit, The Art of Multiprocessor Programming.

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• Real-Time Multi-User Gaming Platform

  - by Victor Engel

  I asked this question at Stack Overflow but was told it's more appropriate here, so I'm posting it again here. I'm considering developing a real-time multi-user game, and I want to gather some information about possibilities before I do some real development. I've thought about how best to ask the question, and for simplicity, the best way that occurred to me was to make an analogy to the field (or playground) game darebase. In the field game of darebase, there are two or more bases. To start, there is one team on each base. The game is a fancy game of tag. When two people meet out in the field, the person who left his base most recently timewise captures the other person. They then return to that person's base. Play continues until everyone is part of the same team. So, analogizing this to an online computer game, let's suppose there are an indefinite number of bases. When a person starts up the game, he has a team that is located at, for example, his current GPS coordinates. It could be a virtual world, but for sake of argument, let's suppose the virtual world corresponds to the player's actual GPS coordinates. The game software then consults the database to see where the closest other base is that is online, and the two teams play their game of virtual tag. Note that the user of the other base could have a different base than the one run by the current user as the closest base to him, in which case, he would be in two simultaneous battles, one with each base. When they go offline, the state of their players is saved on a server somewhere. Game logic calls for the players to have some automaton-logic of some sort, so they can fend for themselves in a limited way using basic rules, until their user goes online again. The user doesn't control the players' movements directly, but issues general directives that influence the players' movement logic. I think this analogy is good enough to frame my question. What sort of platforms are available to develop this sort of game? I've been looking at smartfoxserver, but I'm not convinced yet that it is the best option or even that it will work at all. One possibility, of course, would be to roll out my own web server, but I'd rather not do that if there is an existing service out there already that I could tap into. I will be developing for iOS devices at first. So any suggestions would be greatly appreciated. I think I need to establish the architecture first before proceeding with this project. Note that darbase is not the game I intend to implement, but, upon reflection, that might not be a bad idea either.

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• Wrong statistics in AUX_STATS$ might puzzle the optimizer

  - by Mike Dietrich

  We do recommend the creation of System Statistics for quite a long time. Since Oracle 9i the optimizer works with a CPU and IO cost based model. And in order to give the optimizer some knowledge about the IO subsystem's performance and throughput - once System Statistics are collected - they'll get stored in AUX_STATS$. For this purpose in the old Oracle 9i days some default values had been defined - and you'll still find those defaults in Oracle Database 11g Release 2 in AUX_STATS$. But these old values don't reflect the performance of modern IO systems. So it might be a good best practice post upgrade to create fresh System Statistics if you haven't done this before.  You can collect System Statistics with: exec DBMS_STATS.GATHER_SYSTEM_STATS('start'); and end it later by executing: exec DBMS_STATS.GATHER_SYSTEM_STATS('stop'); You could also run DBMS_STATS.GATHER_SYSTEM_STATS('interval', interval=>N) instead where N is the number of minutes when statistics gathering is stopped automatically. Please make sure you'll do this on a real workload period. It won't make sense to gather these values while the database is in an idle state. You should do this ideally for several hours. It doesn't affect performance in a negative way as the values are anyway collected in V$SYSSTAT and V$SESSTAT. And in case you'd like to delete the stats and revert to the old default values you'd simply execute:exec DBMS_STATS.DELETE_SYSTEM_STATS; The tricky thing in Oracle Database 11.2 - and that's why I'm actually writing this blog post today - is bug9842771. This leads to wrong values in AUX_STATS$ for SREADTIM and MREADTIM by factor 1000 guiding the optimizer sometimes into the totally wrong directon. The workaround is to overwrite these values manually and divide them by 1000. Use the DBMS_STATS.SET_SYSTEM_STATS procedure. See this MOS Note:9842771.8 for the above bug for some further information. This issue is fixed in Oracle Database 11.2.0.3 and above. To get some background information about the statistics collected in please read this section in the Oracle Database 11.2 Performance Tuning Guide. And gathering System Statistics might have some implication if you have mixed workloads - and interacts with DB_FILE_MULTIBLOCK_READ_COUNT. For more information please read section 13.4.1.2.

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• 2D game - Missile shooting problem on Android

  - by Niksa

  Hello, I have to make a tank that sits still but moves his turret and shoots missiles. As this is my first Android application ever and I haven't done any game development either, I've come across a few problems... Now, I did the tank and the moving turret once I read the Android tutorial for the LunarLander sample code. So this code is based on the LunarLander code. But I'm having trouble doing the missile firing then SPACE button is being pressed. private void doDraw(Canvas canvas) { canvas.drawBitmap(backgroundImage, 0, 0, null); // draws the tank canvas.drawBitmap(tank, x_tank, y_tank, new Paint()); // draws and rotates the tank turret canvas.rotate((float) mHeading, (float) x_turret + mTurretWidth, y_turret); canvas.drawBitmap(turret, x_turret, y_turret, new Paint()); // draws the grenade that is a regular circle from ShapeDrawable class bullet.setBounds(x_bullet, y_bullet, x_bullet + width, y_bullet + height); bullet.draw(canvas); } UPDATE GAME method private void updateGame() throws InterruptedException { long now = System.currentTimeMillis(); if (mLastTime > now) return; double elapsed = (now - mLastTime) / 1000.0; mLastTime = now; // dUP and dDown, rotates the turret from 0 to 75 degrees. if (dUp) mHeading += 1 * (PHYS_SLEW_SEC * elapsed); if (mHeading >= 75) mHeading = 75; if (dDown) mHeading += (-1) * (PHYS_SLEW_SEC * elapsed); if (mHeading < 0) mHeading = 0; if (dSpace){ // missile Logic, a straight trajectorie for now x_bullet -= 1; y_bullet -= 1; //doesn't work, has to be updated every pixel or what? } boolean doKeyDown(int keyCode, KeyEvent msg) { boolean handled = false; synchronized (mSurfaceHolder) { if (keyCode == KeyEvent.KEYCODE_SPACE){ dSpace = true; handled = true; } if (keyCode == KeyEvent.KEYCODE_DPAD_UP){ dUp = true; handled = true; } if (keyCode == KeyEvent.KEYCODE_DPAD_DOWN){ dDown = true; handled = true; } return handled; } } } a method run that runs the game... public void run() { while (mRun) { Canvas c = null; try { c = mSurfaceHolder.lockCanvas(null); synchronized (mSurfaceHolder) { if (mMode == STATE_RUNNING) updateGame(); doDraw(c); } } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { // do this in a finally so that if an exception is thrown // during the above, we don't leave the Surface in an // inconsistent state if (c != null) { mSurfaceHolder.unlockCanvasAndPost(c); } } } } So the question would be, how do I make that the bullet is fired on a single SPACE key press from the turret to the end of the screen? Could you help me out here, I seem to be in the dark here... Thanks, Niksa

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• How do I maintain a really poorly written code base?

  - by onlineapplab.com

  Recently I got hired to work on existing web application because of NDA I'm not at liberty to disclose any details but this application is working online in sort of a beta testing stage before official launch. We have a few hundred users right now but this number is supposed to significantly increase after official launch. The application is written in PHP (but it is irrelevant to my question) and is running on a dual xeon processor standalone server with severe performance problems. I have seen a lot of bad PHP code but this really sets new standards, especially knowing how much time and money was invested in developing it. it is as badly coded as possible there is PHP, HTML, SQL mixed together and code is repeated whenever it is necessary (especially SQL queries). there are not any functions used, not mentioning any OOP there are four versions of the app (desktop, iPhone, Android + other mobile) each version has pretty much the same functionality but was created by copying the whole code base, so now there are some differences between each version and it is really hard to maintain the database is really badly designed, which is causing severe performance problems also for fixing some errors in PHP code there is a lot of database triggers used which are updating data on SELECT and on INSERT so any testing is a nightmare Basically, any sin of a bad programming you can imagine is there for example it is not only possible to use SQL injections in literally every place but you can log into app if you use a login which doesn't exist and an empty password. The team which created this app is not working on it any more and there is an outsourced team which suggested that there are some problems but was never willing to deal with the elephant in the room partially because they've got a very comfortable contract and partially due to lack of skills (just my opinion). My job was supposed to be fixing some performance problems and extending existing functionality but first thing I was asked to do was a review of the existing code base. I've made my review and it was quite a shock for the management but my conclusions were after some time finally confirmed by other programmers. Management made it clear that it is not possible to start rewriting this app from scratch (which in my opinion should be done). We have to maintain its operable state and at the same time fix performance errors and extend the functionality. My question is, as I don't want just to patch the existing code, how to transform this into properly written app while keeping the existing code working at the same time? My plan is: Unify four existing versions into common code base (fixing only most obvious errors). Redesign db and use triggers to populate it with data (so data will be maintained in two formats at the same time) All new functionality will be written as separate project. Step by step transfer existing functionality into the new project After some time everything will be in the new project Some explanation about #2, right now it is practically impossible to make any updates in existing db any change requires reviewing whole code and making changes in many places. Is such plan feasible at all? Another solution is to walk away and leave the headache to someone else.

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• Critical Patch Updates During EBS 11i Exception to Sustaining Support Period

  - by Elke Phelps (Oracle Development)

  As previously blogged in the EBS 11i and 12.1 Support Timeline Changes entry, two important changes to the Oracle Lifetime Support policies were announced at Oracle OpenWorld 2012 - San Francisco.  These changes affect E-Business Suite Releases 11i and 12.1. Critical Patch Updates for EBS 11i during the Exception to Sustaining Support Period You may be wondering about the availability of Critical Patch Updates (CPU) for EBS 11i during the Exception to Sustaining Support period.  The following details the E-Business Suite Critical Patch Update support policy for EBS 11i during the Exception to Sustaining Support period: Oracle will continue to provide CPUs containing critical security fixes for E-Business Suite 11i.  CPUs will be packaged and released as as cumulative patches for both ATG RUP 6 and ATG RUP 7. As always, we try to minimize the number of patches and dependencies required for uptake of a CPU; however, there have been quite a few changes to the 11i baseline since its release.  For dependency reasons the 11i CPUs may require a higher number of files in order to bring them up to a consistent, stable, and well tested level. EBS 11i customer will continue to receive CPUs up to and including the October 2014 CPU. Where can I learn more? There are two interlocking policies that affect the E-Business Suite:  Oracle's Lifetime Support policies for each EBS release (timelines which were updated by this announcement), and the Error Correction Support policies (which state the minimum baselines for new patches). For more information about how these policies interact, see: Understanding Support Windows for E-Business Suite Releases What about E-Business Suite technology stack components? Things get more complicated when one considers individual techstack components such as Oracle Forms or the Oracle Database.  To learn more about the interlocking EBS+techstack component support windows, see these two articles: On Apps Tier Patching and Support: A Primer for E-Business Suite Users On Database Patching and Support: A Primer for E-Business Suite Users Where can I learn more about Critical Patch Updates?The Critical Patch Update Advisory is the starting point for relevant information. It includes a list of products affected, pointers to obtain the patches, a summary of the security vulnerabilities, and links to other important documents.  Related Articles EBS 11i and 12.1 Support Timeline Changes Frequently Asked Questions about Latest EBS Support Changes Extended Support Fees Waived for E-Business Suite 11i and 12.0

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• How Do I Do Alpha Transparency Properly In XNA 4.0?

  - by Soshimo

  Okay, I've read several articles, tutorials, and questions regarding this. Most point to the same technique which doesn't solve my problem. I need the ability to create semi-transparent sprites (texture2D's really) and have them overlay another sprite. I can achieve that somewhat with the code samples I've found but I'm not satisfied with the results and I know there is a way to do this. In mobile programming (BREW) we did it old school and actually checked each pixel for transparency before rendering. In this case it seems to render the sprite below it blended with the alpha above it. This may be an artifact of how I'm rendering the texture but, as I said before, all examples point to this one technique. Before I go any further I'll go ahead and paste my example code. public void Draw(SpriteBatch batch, Camera camera, float alpha) { int tileMapWidth = Width; int tileMapHeight = Height; batch.Begin(SpriteSortMode.Texture, BlendState.AlphaBlend, SamplerState.PointWrap, DepthStencilState.Default, RasterizerState.CullNone, null, camera.TransformMatrix); for (int x = 0; x < tileMapWidth; x++) { for (int y = 0; y < tileMapHeight; y++) { int tileIndex = _map[y, x]; if (tileIndex != -1) { Texture2D texture = _tileTextures[tileIndex]; batch.Draw( texture, new Rectangle( (x * Engine.TileWidth), (y * Engine.TileHeight), Engine.TileWidth, Engine.TileHeight), new Color(new Vector4(1f, 1f, 1f, alpha ))); } } } batch.End(); } As you can see, in this code I'm using the overloaded SpriteBatch.Begin method which takes, among other things, a blend state. I'm almost positive that's my problem. I don't want to BLEND the sprites, I want them to be transparent when alpha is 0. In this example I can set alpha to 0 but it still renders both tiles, with the lower z ordered sprite showing through, discolored because of the blending. This is not a desired effect, I want the higher z-ordered sprite to fade out and not effect the color beneath it in such a manner. I might be way off here as I'm fairly new to XNA development so feel free to steer me in the correct direction in the event I'm going down the wrong rabbit hole. TIA

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• New Version 3.1 Endeca Information Discovery Now Available

  - by Mike.Hallett(at)Oracle-BI&EPM

  Normal 0 false false false EN-GB X-NONE X-NONE MicrosoftInternetExplorer4 Business User Self-Service Data Mash-up Analysis and Discovery integrated with OBI11g and Hadoop Oracle Endeca Information Discovery 3.1 (OEID) is a major release that incorporates significant new self-service discovery capabilities for business users, including agile data mashup, extended support for unstructured analytics, and an even tighter integration with Oracle BI.  · Self-Service Data Mashup and Discovery Dashboards: business users can combine information from multiple sources, including their own up-loaded spreadsheets, to conduct analysis on the complete set.  Creating discovery dashboards has been made even easier by intuitive drag-and drop layouts and wizard-based configuration.  Business users can now build new discovery applications in minutes, without depending on IT. · Enhanced Integration with Oracle BI: OEID 3.1 enhances its’ native integration with Oracle Business Intelligence Foundation. Business users can now incorporate information from trusted BI warehouses, leveraging dimensions and attributes defined in Oracle’s Common Enterprise Information Model, but evolve them based on the varying day-to-day demands and requirements that they personally manage. · Deep Unstructured Analysis: business users can gain new insights from a wide variety of enterprise and public sources, helping companies to build an actionable Big Data strategy.  With OEID’s long-standing differentiation in correlating unstructured information with structured data, business users can now perform their own text mining to identify hidden concepts, without having to request support from IT. They can augment these insights with best in class keyword search and pattern matching, all in the context of rich, interactive visualizations and analytic summaries. · Enterprise-Class Self-Service Discovery:  OEID 3.1 enables IT to provide a powerful self-service platform to the business as part of a broader Business Analytics strategy, preserving the value of existing investments in data quality, governance, and security.  Business users can take advantage of IT-curated information to drive discovery across high volumes and varieties of data, and share insights with colleagues at a moment’s notice. · Harvest Content from the Web with the Endeca Web Acquisition Toolkit:  Oracle now provides best-of-breed data access to website content through the Oracle Endeca Web Acquisition Toolkit.  This provides an agile, graphical interface for developers to rapidly access and integrate any information exposed through a web front-end.  Organizations can now cost-effectively include content from consumer sites, industry forums, government or supplier portals, cloud applications, and myriad other web sources as part of their overall strategy for data discovery and unstructured analytics. For more information: OEID 3.1 OTN Software and Documentation Download And Endeca available for download on Software Delivery Cloud (eDelivery) New OEID 3.1 Videos on YouTube Oracle.com Endeca Site /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;}

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• Using elapsed time for SlowMo in XNA

  - by Dave Voyles

  I'm trying to create a slow-mo effect in my pong game so that when a player is a button the paddles and ball will suddenly move at a far slower speed. I believe my understanding of the concepts of adjusting the timing in XNA are done, but I'm not sure of how to incorporate it into my design exactly. The updates for my bats (paddles) are done in my Bat.cs class: /// Controls the bat moving up the screen /// </summary> public void MoveUp() { SetPosition(Position + new Vector2(0, -moveSpeed)); } /// <summary> /// Controls the bat moving down the screen /// </summary> public void MoveDown() { SetPosition(Position + new Vector2(0, moveSpeed)); } /// <summary> /// Updates the position of the AI bat, in order to track the ball /// </summary> /// <param name="ball"></param> public virtual void UpdatePosition(Ball ball) { size.X = (int)Position.X; size.Y = (int)Position.Y; } While the rest of my game updates are done in my GameplayScreen.cs class (I'm using the XNA game state management sample) Class GameplayScreen { ........... bool slow; .......... public override void Update(GameTime gameTime, bool otherScreenHasFocus, bool coveredByOtherScreen) base.Update(gameTime, otherScreenHasFocus, false); if (IsActive) { // SlowMo Stuff Elapsed = (float)gameTime.ElapsedGameTime.TotalSeconds; if (Slowmo) Elapsed *= .8f; MoveTimer += Elapsed; double elapsedTime = gameTime.ElapsedGameTime.TotalMilliseconds; if (Keyboard.GetState().IsKeyDown(Keys.Up)) slow = true; else if (Keyboard.GetState().IsKeyDown(Keys.Down)) slow = false; if (slow == true) elapsedTime *= .1f; // Updating bat position leftBat.UpdatePosition(ball); rightBat.UpdatePosition(ball); // Updating the ball position ball.UpdatePosition(); and finally my fixed time step is declared in the constructor of my Game1.cs Class: /// <summary> /// The main game constructor. /// </summary> public Game1() { IsFixedTimeStep = slow = false; } So my question is: Where do I place the MoveTimer or elapsedTime, so that my bat will slow down accordingly?

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• Randomely loosing wireless connexion with Cubuntu 12.04

  - by statquant

  I am presently experiencing random disconnections from my wireless network. It looks like it is more and more frequent (however I have not seen any clear pattern). This is killing me... Here is some information that should help (from ubuntu forums). Thanks for reading Machine : Acer Aspire S3 statquant@euclide:~$ lsb_release -d Description: Ubuntu 12.04.1 LTS statquant@euclide:~$ uname -mr 3.2.0-33-generic x86_64 statquant@euclide:~$ sudo /etc/init.d/networking restart * Running /etc/init.d/networking restart is deprecated because it may not enable again some interfaces * Reconfiguring network interfaces... statquant@euclide:~$ lspci 02:00.0 Network controller: Atheros Communications Inc. AR9485 Wireless Network Adapter (rev 01) statquant@euclide:~$ lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 001 Device 004: ID 064e:c321 Suyin Corp. Bus 002 Device 003: ID 0bda:0129 Realtek Semiconductor Corp. statquant@euclide:~$ ifconfig wlan0 Link encap:Ethernet HWaddr 74:de:2b:dd:c4:78 inet addr:192.168.1.3 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::76de:2bff:fedd:c478/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:913 errors:0 dropped:0 overruns:0 frame:0 TX packets:802 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:873218 (873.2 KB) TX bytes:125826 (125.8 KB) statquant@euclide:~$ iwconfig wlan0 IEEE 802.11bgn ESSID:"Bbox-D646D1" Mode:Managed Frequency:2.437 GHz Access Point: 00:19:70:80:01:6C Bit Rate=65 Mb/s Tx-Power=16 dBm Retry long limit:7 RTS thr:off Fragment thr:off Power Management:on Link Quality=56/70 Signal level=-54 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:71 Missed beacon:0 statquant@euclide:~$ dmesg | grep "wlan" [ 17.495866] ADDRCONF(NETDEV_UP): wlan0: link is not ready [ 17.498950] ADDRCONF(NETDEV_UP): wlan0: link is not ready [ 20.072015] wlan0: authenticate with 00:19:70:80:01:6c (try 1) [ 20.269853] wlan0: authenticate with 00:19:70:80:01:6c (try 2) [ 20.272386] wlan0: authenticated [ 20.298682] wlan0: associate with 00:19:70:80:01:6c (try 1) [ 20.302321] wlan0: RX AssocResp from 00:19:70:80:01:6c (capab=0x431 status=0 aid=1) [ 20.302325] wlan0: associated [ 20.307307] ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready [ 30.402292] wlan0: no IPv6 routers present statquant@euclide:~$ sudo lshw -C network [sudo] password for statquant: *-network description: Wireless interface product: AR9485 Wireless Network Adapter vendor: Atheros Communications Inc. physical id: 0 bus info: pci@0000:02:00.0 logical name: wlan0 version: 01 serial: 74:de:2b:dd:c4:78 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list rom ethernet physical wireless configuration: broadcast=yes driver=ath9k driverversion=3.2.0-33-generic firmware=N/A ip=192.168.1.3 latency=0 link=yes multicast=yes wireless=IEEE 802.11bgn resources: irq:17 memory:c0400000-c047ffff memory:afb00000-afb0ffff statquant@euclide:~$ iwlist scan wlan0 Scan completed : Cell 01 - Address: 00:19:70:80:01:6C Channel:6 Frequency:2.437 GHz (Channel 6) Quality=56/70 Signal level=-54 dBm Encryption key:on ESSID:"Bbox-D646D1" Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s 9 Mb/s; 12 Mb/s; 18 Mb/s Bit Rates:24 Mb/s; 36 Mb/s; 48 Mb/s; 54 Mb/s Mode:Master Extra:tsf=000000125fb152bb Extra: Last beacon: 40020ms ago IE: Unknown: 000B42626F782D443634364431 IE: Unknown: 010882848B960C121824 IE: Unknown: 030106 IE: IEEE 802.11i/WPA2 Version 1 Group Cipher : TKIP Pairwise Ciphers (2) : CCMP TKIP Authentication Suites (1) : PSK IE: WPA Version 1 Group Cipher : TKIP Pairwise Ciphers (2) : CCMP TKIP Authentication Suites (1) : PSK IE: Unknown: 2A0100 IE: Unknown: 32043048606C IE: Unknown: DD180050F2020101820003A4000027A4000042435E0062322F00 IE: Unknown: 2D1A4C101BFF00000000000000000000000000000000000000000000 IE: Unknown: 3D1606080800000000000000000000000000000000000000 IE: Unknown: DD0900037F01010000FF7F IE: Unknown: DD0A00037F04010000000000 And... finally, please note that I did the following (after looking for fixes of similar problems), but unfortunately it did not work sudo modprobe -r iwlwifi sudo modprobe iwlwifi 11n_disable=1

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• Suggestions for Summer Intern Application Assignments

  - by orangepips

  As part of our application process we want prospective college interns to complete an assignment on their own - either programming or analytical - to give us something tangible to evaluate such as code or a flowchart. I have two ideas for these assignments, one programming and one analytical, I am interested in gathering feedback about these. Programming Assignment Generate an a month's calendar for a given date. The first row should indicate the days of the week (e.g. Sunday - Saturday). Each subsequent row should contain a week's days. The date supplied should be highlighted (e.g. bolded). I am thinking we'll probably proscribe the output format even more strictly - probably down to what the HTML source should look like including CSS classes. Thinking is this forces answerers to actually do some work if they merely copy a solution from the internet. Analytical Assignment Diagram or describe in prose a system for managing a set of traffic lights for traffic at a four way intersection. Each direction (i.e. North, South, East and West) has two lanes (i.e. right and left). The left lane is turn only and has green arrow light to indicate right of way. The system is able to detect if lanes have cars in them and change the lights accordingly. I would expect a flow chart or some prose describing a finite state machine that deals with each contingency. This would hopefully provide some indication of the applicant's ability to reason through a logic problem of sorts and articulate an approach for solving. Areas Seeking Feedback Is it unreasonable to ask this of applicants? If not, is it better to request before or after a phone screen? Are these questions too hard or easy for a collegiate audience? Any suggestions for alternate questions? Do these seem like good tools for analyzing people who would part of a software development life cycle? Programming language suggestions - I'm thinking Java, Python and/or C# (we're actually a ColdFusion shop).

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• Understanding exceptional cases

  - by Justin

  I've been studying the use of exceptions in various php projects (such as Doctrine and Zend Framework). Exceptions seem to be thrown when unordinary input/state occurs. A perfect example is Doctrine throwing an exception when you try to use a invalid query string. I think the creators of the doctrine api understood that first, you can't query data by using an invalid DQL statement, and a developer should immediately be warned that an error has occurred, rather then letting execution continue with the possibility of an error code going un-checked. I also bet that this simplifies reading the code. I can't think of a situation where you would want to use an invalid DQL statement, except unit testing. Since this is true, it's better to avoid plaguing a bunch of code with null/error checks and use exceptions. I've read in books that exceptions shouldn't be thrown when validating dating user input. I've seen examples where of where the guideline is broken. One example is the Zend framework. If supplying an invalid controller or action name, an exception is thrown. Unlike doctrine, the user has more direct control over this sort of input. I know you can configure an error controller and set up a 404 message or what have you, but I'm curious why they have used an exception in this scenario? I guess you can argue the Zend Framework does not know how to continue processing the quest. One last example Is I wrote a function to return some html based on a given resource type. This resource type is hard-coded and sent when a user interacts with a web site (such as clicking a button to display the form to input data). I don't expect users to be mucking around with the request type. Under normal operating conditions, the resource type should be valid. To clean up some logic, I was going to throw an exception if a particular form wasn't found. This is mainly to find the correct form associated with a resource type so proper validation can occur. Does this sound like a valid use case for an exception? Right now it's pretty trivial, but I do plan to implement a restful consumer and re-using a function to map resources to their validation services would be very useful. I can then catch the exception and based on the consumer, return an error message suitable for the request type...

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• Big-name School for Undergrad Students

  - by itaiferber

  As a soon-to-be graduating high school senior in the U.S., I'm going to be facing a tough decision in a few months: which college should I go to? Will it be worth it to go to Cornell or Stanford or Carnegie Mellon (assuming I get in, of course) to get a big-name computer science degree, internships, and connections with professors, while taking on massive debt; or am I better off going to SUNY Binghamton (probably the best state school in New York) and still get a pretty decent education while saving myself from over a hundred-thousand dollars worth of debt? Yes, I know questions like this has been asked before (namely here and here), but please bear with me because I haven't found an answer that fits my particular situation. I've read the two linked questions above in depth, but they haven't answered what I want to know: Yes, I understand that going to a big-name college can potentially get me connected with some wonderful professors and leaders in the field, but on average, how does that translate financially? I mean, will good connections pay off so well that I'd be easily getting rid of over a hundred-thousand dollars of debt? And how does the fact that I can get a fifth-years master's degree at Carnegie Mellon play into the equation? Will the higher degree right off the bat help me get a better-paying job just out of college, or will the extra year only put me further into debt? Not having to go to graduate school to get a comparable degree will, of course, be a great financial relief, but will getting it so early give it any greater worth? And if I go to SUNY Binghamton, which is far lesser-known than what I've considered (although if there are any alumni out there who want to share their experience, I would greatly appreciate it), would I be closing off doors that would potentially offset my short-term economic gain with long-term benefits? Essentially, is the short-term benefit overweighed by a potential long-term loss? The answers to these questions all tie in to my final college decision (again, permitting I make it to these schools), so I hope that asking the skilled and knowledgeable people of the field will help me make the right choice (if there is such a thing). Also, please note: I'm in a rather peculiar situation where I can't pay for college without taking out a bunch of loans, but will be getting little to no financial aid (likely federal or otherwise). I don't want to elaborate on this too much (so take it at face value), but this is mainly the reason I'm asking the question. Thanks a lot! It means a lot to me.

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• C# 5 Async, Part 3: Preparing Existing code For Await

  - by Reed

  While the Visual Studio Async CTP provides a fantastic model for asynchronous programming, it requires code to be implemented in terms of Task and Task<T>.  The CTP adds support for Task-based asynchrony to the .NET Framework methods, and promises to have these implemented directly in the framework in the future.  However, existing code outside the framework will need to be converted to using the Task class prior to being usable via the CTP. Wrapping existing asynchronous code into a Task or Task<T> is, thankfully, fairly straightforward.  There are two main approaches to this. Code written using the Asynchronous Programming Model (APM) is very easy to convert to using Task<T>.  The TaskFactory class provides the tools to directly convert APM code into a method returning a Task<T>.  This is done via the FromAsync method.  This method takes the BeginOperation and EndOperation methods, as well as any parameters and state objects as arguments, and returns a Task<T> directly. For example, we could easily convert the WebRequest BeginGetResponse and EndGetResponse methods into a method which returns a Task<WebResponse> via: Task<WebResponse> task = Task.Factory .FromAsync<WebResponse>( request.BeginGetResponse, request.EndGetResponse, null); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Event-based Asynchronous Pattern (EAP) code can also be wrapped into a Task<T>, though this requires a bit more effort than the one line of code above.  This is handled via the TaskCompletionSource<T> class.  MSDN provides a detailed example of using this to wrap an EAP operation into a method returning Task<T>.  It demonstrates handling cancellation and exception handling as well as the basic operation of the asynchronous method itself. The basic form of this operation is typically: Task<YourResult> GetResultAsync() { var tcs = new TaskCompletionSource<YourResult>(); // Handle the event, and setup the task results... this.GetResultCompleted += (o,e) => { if (e.Error != null) tcs.TrySetException(e.Error); else if (e.Cancelled) tcs.TrySetCanceled(); else tcs.TrySetResult(e.Result); }; // Call the asynchronous method this.GetResult(); // Return the task from the TaskCompletionSource return tcs.Task; } We can easily use these methods to wrap our own code into a method that returns a Task<T>.  Existing libraries which cannot be edited can be extended via Extension methods.  The CTP uses this technique to add appropriate methods throughout the framework. The suggested naming for these methods is to define these methods as “Task<YourResult> YourClass.YourOperationAsync(…)”.  However, this naming often conflicts with the default naming of the EAP.  If this is the case, the CTP has standardized on using “Task<YourResult> YourClass.YourOperationTaskAsync(…)”. Once we’ve wrapped all of our existing code into operations that return Task<T>, we can begin investigating how the Async CTP can be used with our own code.

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• How to use DoDirect/Paypal Pro in asp.net?

  - by ptahiliani

  using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using System.Net;using System.IO;using System.Collections;public partial class Default2 : System.Web.UI.Page{    protected void Page_Load(object sender, EventArgs e)    {    }    protected void Button1_Click(object sender, EventArgs e)    {        //API Credentials (3-token)        string strUsername = "<<enter your sandbox username here>>";        string strPassword = "<<enter your sandbox password here>>";        string strSignature = "<<enter your signature here>>";        string strCredentials = "USER=" + strUsername + "&PWD=" + strPassword + "&SIGNATURE=" + strSignature;        string strNVPSandboxServer = "https://api-3t.sandbox.paypal.com/nvp";        string strAPIVersion = "2.3";        string strNVP = strCredentials + "&METHOD=DoDirectPayment" +        "&CREDITCARDTYPE=" + "Visa" +        "&ACCT=" + "4710496235600346" +        "&EXPDATE=" + "10" + "2017" +        "&CVV2=" + "123" +        "&AMT=" + "12.34" +        "&FIRSTNAME=" + "Demo" +        "&LASTNAME=" + "User" +        "&IPADDRESS=192.168.2.236" +        "&STREET=" + "Lorem-1" +        "&CITY=" + "Lipsum-1" +        "&STATE=" + "Lorem" +        "&COUNTRY=" + "INDIA" +        "&ZIP=" + "302004" +        "&COUNTRYCODE=IN" +        "&PAYMENTACTION=Sale" +        "&VERSION=" + strAPIVersion;        try        {            //Create web request and web response objects, make sure you using the correct server (sandbox/live)            HttpWebRequest wrWebRequest = (HttpWebRequest)WebRequest.Create(strNVPSandboxServer);            wrWebRequest.Method = "POST";            StreamWriter requestWriter = new StreamWriter(wrWebRequest.GetRequestStream());            requestWriter.Write(strNVP);            requestWriter.Close();            // Get the response.            HttpWebResponse hwrWebResponse = (HttpWebResponse)wrWebRequest.GetResponse();            StreamReader responseReader = new StreamReader(wrWebRequest.GetResponse().GetResponseStream());            //and read the response            string responseData = responseReader.ReadToEnd();            responseReader.Close();            string result = Server.UrlDecode(responseData);            string[] arrResult = result.Split('&');            Hashtable htResponse = new Hashtable();            string[] responseItemArray;            foreach (string responseItem in arrResult)            {                responseItemArray = responseItem.Split('=');                htResponse.Add(responseItemArray[0], responseItemArray[1]);            }            string strAck = htResponse["ACK"].ToString();            if (strAck == "Success" || strAck == "SuccessWithWarning")            {                string strAmt = htResponse["AMT"].ToString();                string strCcy = htResponse["CURRENCYCODE"].ToString();                string strTransactionID = htResponse["TRANSACTIONID"].ToString();                //ordersDataSource.InsertParameters["TransactionID"].DefaultValue = strTransactionID;                string strSuccess = "Thank you, your order for: $" + strAmt + " " + strCcy + " has been processed.";                //successLabel.Text = strSuccess;                Response.Write(strSuccess.ToString());            }            else            {                string strErr = "Error: " + htResponse["L_LONGMESSAGE0"].ToString();                string strErrcode = "Error code: " + htResponse["L_ERRORCODE0"].ToString();                //errLabel.Text = strErr;                //errcodeLabel.Text = strErrcode;                Response.Write(strErr.ToString() + "<br/>" + strErrcode.ToString());                return;            }        }        catch (Exception ex)        {            // do something to catch the error, like write to a log file.            Response.Write("error processing");        }    }}

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• Brocken package manager due to incorrect Banshee package

  - by user54974

  Sup, so, I'm not familiar with linux at all so help is much appreciated. I've been trying to boot my pc up from a live CD unsuccessfully. I get to the stage at which there are the options to test without installing or install or so on where I select 'Install Ubuntu.' Here it relays through some fast DOS commands until it reaches 'end trace' and then, eventually, 'Killed.' I have already got a functional 11.10 version installed, could this be a problem? The reason I am attempting a reinstall is because the package system is damaged inside 11.10, a problem I can't seem to solve. If I try to install any new software from within the software centre it tells me that two banshee extensions must be removed. I try to remove these from inside the terminal, using apt-get remove, which results in:** You might want to run apt-get -f install to correct these: The following packages have unmet dependencies. banshee-extension-ubuntuonemusicstore : Depends: banshee (>= 2.2.1) but 2.2.0-1ubuntu2 is to be installed E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution). The software centre suggests that I disable all third party repositories and run apt-get install -f I have done so but the package system remains damaged and apt-get install -fattempts to install banshee 2.2.1 but returns: Errors were encountered while processing: /var/cache/apt/archives/banshee_2.2.1-1ubuntu3_i386.deb E: Sub-process /usr/bin/dpkg returned an error code (1) I have also tried apt-get update (runs fine) and apt-get upgrade. The upgrade command apt-get upgrade results in: Reading package lists... Done Building dependency tree Reading state information... Done You might want to run ‘apt-get -f install’ to correct these. The following packages have unmet dependencies. banshee-extension-soundmenu : Depends: banshee (>= 2.2.1) but 2.2.0-1ubuntu2 is installed banshee-extension-ubuntuonemusicstore : Depends: banshee (>= 2.2.1) but 2.2.0-1ubuntu2 is installed E: Unmet dependencies. Try using -f. I seem to be going round and round in circles here! If only I could reinstall successfully. Only proposed updates (oneiric proposed) is not enabled.

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• Bios Memory settings and Virtualization + Ubuntu (Unofficial Answers Welcome) [closed]

  - by TardisGuy

  Attempting to optimize my (Main Windowless) Ubuntu system for my uses I will detail questions below, I understand this might be the wrong place to ask these questions. If so, my apologies and I thank you so much for your patience. Thanks to all the volenteers that have helped me learn ubuntu over the years (Since 5.10) This is a "short" list of questions I have been trying to figure out for some time. If you feel you can answer one but not another, that's already more than I could ask for. I have wrote this up in a format for easy navigation to important points Hopefully to less annoy your eyes. You're welcome :) or i'm sorry i annoy you. :( If you would be so kind, Please format answers as follows: question 1: _ _ _ _ _ or question 1-a: _ _ _ _ _ If you want to simply link me to relevant information, rather than type up something really detailed; that would be more than awesome! Memory Specific Questions Goal: Maximizing memory bandwith to better perform in Virtualization, and Large file compression. (Possible conflict?) Ganged vs Unganged "which is better?"** is relative, i know. But what about ganged vs unganged - With or without Bank/channel interleaving? a: Speculation - If i understand correctly, "channel interleaving has something to do with using both channels to read or write in a kind of "striping" pattern, as opposed to a standard half duplex operation.(probably wrong) but wouldn't ganged channels make this irrelevant? Memory Interleaving(bank). Does it have a down side? Does it require a ratio of clocks? (If I run 4x4gig ddr3) a. If im reading correctly(trying to learn), this is designed to spread operations between latency cycles to work around the higher latency of "normal" operation. b. However it seems to me that it has to be: divisible by fractions of a master clock? So if i run memory at 1333mhz, then the mean between 2 (physical) banks would operate every (roughly) 600Mhz? Warning! Possibly utter nonsense: (1333/2 interleaving to act like 1 memory module per 2 sticks of a total of 4 sticks, meaning 2x channels@4) c. which makes me wonder if there would be left over clock cycles the system would have to... "truncate/balance" or something? But I'm certain theres a feature somewhere i don't understand. Virtualization Questions AMD-V - Option of IOMMU Turned it on, why do i have extra option of "64MB"? If IOMMU is on, but "64MB" is "disabled", Is it on? (have scoured google, I still dont know) a. I think i understand that its supposed to (kind of) "set aside" a part of ram to act as a faster interactive zone for "stuff" (usb, Graphics, and... what?) b. I am using Nvidia graphics on AMD (Used kernel option "iommu=pt iommu=1, pt "passthrough"? No idea what they do, found it on google to solve boot up issue) c. Will this option help me use low latency sound hardware, like my midi keyboard? Can you recommend any additional tweaks? a. sysctl settings? b. swap settings? Grats, youve reached the end. Thanks for Reading.

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• What actions does Ubuntu trigger when battery is low?

  - by blueyed

  When the battery is low, the screen gets dimmed after a few seconds already. This appears to be some special power-saving mode, and might be related to the time in org.gnome.settings-daemon.plugins.power.time-low (1200 seconds (20 minutes) the default). While this seems to get triggered by gnome-settings-daemon, I wonder what else Ubuntu does when this happens (e.g. via DBus listeners), or other event listeners that look for a "low battery" state. It seems like something in this regard causes Ubuntu / X / the system to behave more sluggish afterwards (when the laptop is on AC again), and I would like to look into what might be causing this. I could not find anything related via dconf-editor, e.g. in org.gnome.settings-daemon.plugins.power. It appears to get setup via idle_configure in plugins/power/gsd-power-manager.c, but it's probably something more related to something that listens on the DBus interface, which gets notified via e.g.: if (!g_dbus_connection_emit_signal (manager->priv->connection, NULL, GSD_POWER_DBUS_PATH, "org.freedesktop.DBus.Properties", "PropertiesChanged", props_changed, &error)) I could imagine that some "power saving" property gets set, but not unset when AC is available anymore and/or the battery is not low anymore. I have looked at the CPU governor setting (/sys/devices/system/cpu/cpu*/cpufreq/scaling_governor), but it was ondemand. I am using gnome-settings-daemon with awesomeWM on Ubuntu 14.04. gnome-settings-daemon=3.8.6.1-0ubuntu11.1 I've also compared gsd's plugins/power/gsd-power-manager.c with the one from Debian's gnome-settings-daemon-3.12.1, but could not find anything obvious that might have been fixed/changed in this regard. I have managed to trigger the gnome-power-manager's gnome-settings plugin (which dims the screen etc), by patching upower and use it after killing the system's upower daemon. (note that it's probably only energy that is being used by gpm to calculate it by itself). It does not make the system become sluggish.. OTOH I have not heard the speaker's beeping, which might come from the BIOS, which might be involved here, too - or other programs using the kernel's interface on /sys/class/power_supply/BAT0/. --- src/linux/up-device-supply.c.orig 2014-06-07 16:48:32.735920661 +0200 +++ src/linux/up-device-supply.c 2014-06-07 16:48:39.391920525 +0200 @@ -821,6 +821,9 @@ supply->priv->energy_old_first = 0; } + percentage = 3.1f; + time_to_empty = 3*60; + energy = 5; g_object_set (device, "energy", energy, "energy-full", energy_full,

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• ConcurrentDictionary<TKey,TValue> used with Lazy<T>

  - by Reed

  In a recent thread on the MSDN forum for the TPL, Stephen Toub suggested mixing ConcurrentDictionary<T,U> with Lazy<T>.  This provides a fantastic model for creating a thread safe dictionary of values where the construction of the value type is expensive.  This is an incredibly useful pattern for many operations, such as value caches. The ConcurrentDictionary<TKey, TValue> class was added in .NET 4, and provides a thread-safe, lock free collection of key value pairs.  While this is a fantastic replacement for Dictionary<TKey, TValue>, it has a potential flaw when used with values where construction of the value class is expensive. The typical way this is used is to call a method such as GetOrAdd to fetch or add a value to the dictionary.  It handles all of the thread safety for you, but as a result, if two threads call this simultaneously, two instances of TValue can easily be constructed. If TValue is very expensive to construct, or worse, has side effects if constructed too often, this is less than desirable.  While you can easily work around this with locking, Stephen Toub provided a very clever alternative – using Lazy<TValue> as the value in the dictionary instead. This looks like the following.  Instead of calling: MyValue value = dictionary.GetOrAdd( key, () => new MyValue(key)); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } We would instead use a ConcurrentDictionary<TKey, Lazy<TValue>>, and write: MyValue value = dictionary.GetOrAdd( key, () => new Lazy<MyValue>( () => new MyValue(key))) .Value; This simple change dramatically changes how the operation works.  Now, if two threads call this simultaneously, instead of constructing two MyValue instances, we construct two Lazy<MyValue> instances. However, the Lazy<T> class is very cheap to construct.  Unlike “MyValue”, we can safely afford to construct this twice and “throw away” one of the instances. We then call Lazy<T>.Value at the end to fetch our “MyValue” instance.  At this point, GetOrAdd will always return the same instance of Lazy<MyValue>.  Since Lazy<T> doesn’t construct the MyValue instance until requested, the actual MyClass instance returned is only constructed once.

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• Ubuntu 12.04 updates fail recently - Please help

  - by user74152

  I upgraded Ubuntu 11.10 to 12.04 LTS immediately after its release (april 2012). Since then updates (new kernels and others) succeeded regularly, but recently, suddenly, updates fail consistently. What causes the problem and how can it be solved? Terminal information after the last update attempt: ariel@ariel-MS-7592:~$ sudo apt-get upgrade Reading package lists... Done Building dependency tree Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. 3 not fully installed or removed. After this operation, 0 B of additional disk space will be used. Do you want to continue [Y/n]? y Setting up linux-image-3.2.0-26-generic (3.2.0-26.41) ... Running depmod. update-initramfs: deferring update (hook will be called later) Examining /etc/kernel/postinst.d. run-parts: executing /etc/kernel/postinst.d/dkms 3.2.0-26-generic /boot/vmlinuz-3.2.0-26-generic run-parts: executing /etc/kernel/postinst.d/initramfs-tools 3.2.0-26-generic /boot/vmlinuz-3.2.0-26-generic update-initramfs: Generating /boot/initrd.img-3.2.0-26-generic run-parts: executing /etc/kernel/postinst.d/pm-utils 3.2.0-26-generic /boot/vmlinuz-3.2.0-26-generic run-parts: executing /etc/kernel/postinst.d/update-notifier 3.2.0-26-generic /boot/vmlinuz-3.2.0-26-generic run-parts: executing /etc/kernel/postinst.d/zz-update-grub 3.2.0-26-generic /boot/vmlinuz-3.2.0-26-generic /usr/sbin/grub-mkconfig: 11: /etc/default/grub: splash”: not found run-parts: /etc/kernel/postinst.d/zz-update-grub exited with return code 127 Failed to process /etc/kernel/postinst.d at /var/lib/dpkg/info/linux-image-3.2.0-26-generic.postinst line 1010. dpkg: error processing linux-image-3.2.0-26-generic (--configure): subprocess installed post-installation script returned error exit status 2 No apport report written because MaxReports is reached already dpkg: dependency problems prevent configuration of linux-image-generic: linux-image-generic depends on linux-image-3.2.0-26-generic; however: Package linux-image-3.2.0-26-generic is not configured yet. dpkg: error processing linux-image-generic (--configure): dependency problems - leaving unconfigured dpkg: dependency problems prevent configuration of linux-generic: linux-generic depends on linux-image-generic (= 3.2.0.26.28); however: Package linux-image-generic is not configured yet. dpkg: error processing linux-generic (--configure): dependency problems - leaving unconfiguredNo apport report written because MaxReports is reached already No apport report written because MaxReports is reached already Errors were encountered while processing: linux-image-3.2.0-26-generic linux-image-generic linux-generic E: Sub-process /usr/bin/dpkg returned an error code (1)

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