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  • Changing the default installation path to a newly installed hard disk

    - by mgj
    Hi, I am currently working on a dual-booted PC. I am using Windows XP and Ubuntu 10.04 Lucid Lynx released in April 2010. The allocated partition to Ubuntu that I am making use of has almost exhausted. Current memory allocations on the PC wrt Ubuntu OS looks like this: bodhgaya@pc146724-desktop:~$ df -h Filesystem Size Used Avail Use% Mounted on /dev/sda2 8.6G 8.0G 113M 99% / none 998M 268K 998M 1% /dev none 1002M 580K 1002M 1% /dev/shm none 1002M 100K 1002M 1% /var/run none 1002M 0 1002M 0% /var/lock none 1002M 0 1002M 0% /lib/init/rw /dev/sda1 25G 16G 9.8G 62% /media/C /dev/sdb1 37G 214M 35G 1% /media/ubuntulinuxstore bodhgaya@pc146724-desktop:~$ cd /tmp I am trying to mount a 40GB(/dev/sdb1 - given below) new hard disk along with my existing Ubuntu system to overcome with hard disk space related issues. I referred to the following tutorial to mount a new hard disk onto the system:- http://www.smorgasbord.net/how-to-in...untu-linux%20/ I was able to successfully mount this hard disk for Ubuntu 0S. I have this new hard disk setup in /media/ubuntulinuxstore directory. The current partition in my system looks like this: bodhgaya@pc146724-desktop:/media/ubuntulinuxstore$ sudo fdisk -l [sudo] password for bodhgaya: Disk /dev/sda: 40.0 GB, 40000000000 bytes 255 heads, 63 sectors/track, 4863 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x446eceb5 Device Boot Start End Blocks Id System /dev/sda1 * 2 3264 26210047+ 7 HPFS/NTFS /dev/sda2 3265 4385 9004432+ 83 Linux /dev/sda3 4386 4863 3839535 82 Linux swap / Solaris Disk /dev/sdb: 40.0 GB, 40000000000 bytes 255 heads, 63 sectors/track, 4863 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xfa8afa8a Device Boot Start End Blocks Id System /dev/sdb1 1 4862 39053983+ 7 HPFS/NTFS bodhgaya@pc146724-desktop:/media/ubuntulinuxstore$ Now, I have a concern wrt the "location" where the new softwares will be installed. Generally softwares are installed via the terminal and by default a fixed path is used to where the post installation set up files can be found (I am talking in context of the drive). This is like the typical case of Windows, where softwares by default are installed in the C: drive. These days people customize their installations to a drive which they find apt to serve their purpose (generally based on availability of hard disk space). I am trying to figure out how to customize the same for Ubuntu. As we all know the most softwares are installed via commands given from the Terminal. My road block is how do I redirect the default path set on the terminal where files get installed to this new hard disk. This if done will help me overcome space constraints I am currently facing wrt the partition on which my Ubuntu is initially installed. I would also by this, save time on not formatting my system and reinstalling Ubuntu and other softwares all over again. Please help me with this, your suggestions are much appreciated.

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  • How to check if a Webcam is broken?

    - by user84812
    I just bought an Acer Aspire 3830TG, it comes with an integrated 1.3M HD Webcam. Before buying it i tried with a bootable Lubuntu usb stick, everything worked well except for the webcam, which i thought I had to tweak. The thing is that it seems the camera should work with no problems in ubuntu. The driver is detected, I try dmesg | grep uvcvideo and the output is [ 12.226174] uvcvideo: Found UVC 1.00 device 1.3M HD WebCam (058f:b002) [ 12.245553] usbcore: registered new interface driver uvcvideo I've also tried using different software (guvcview is black when camera output is MJPG and turns to funny colors when YU12 or YV12, cheese is always black, camorama is always with funny colors...). I should have checked that it was working properly with the default os (windows) but now it's too late for that. I even booted with a official Ubuntu Quantal distro from the usb pen, and the results are the same. so, my question is: is there any way to check that the camera is righmt or broken? So, if it's broken, at least i can go to the shop, show them that it's really broken and get an external webcam for free, or st like that. cheers. UPDATE 1 Thanks, jrp. I run sudo lsinput, and the output info about my video is the following: /dev/input/event6 bustype : BUS_USB vendor : 0x58f product : 0xb002 version : 2 name : "1.3M HD WebCam" phys : "usb-0000:00:1a.0-1.3/button" bits ev : EV_SYN EV_KEY /dev/input/event7 bustype : BUS_HOST vendor : 0x0 product : 0x6 version : 0 name : "Video Bus" phys : "LNXVIDEO/video/input0" bits ev : EV_SYN EV_KEY With this info, i'm not pretty sure about running the luvcview command. If I run luvcview -d /dev/video0 -L, the output is the following: SDL information: Video driver: x11 A window manager is available Device information: Device path: /dev/video0 { pixelformat = 'YUYV', description = 'YUV 4:2:2 (YUYV)' } { discrete: width = 640, height = 480 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 160, height = 120 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 176, height = 144 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 240 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 352, height = 288 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 720 } Time interval between frame: 1/7, 1/5, { discrete: width = 1280, height = 800 } Time interval between frame: 1/7, 1/5, { discrete: width = 1280, height = 960 } Time interval between frame: 1/7, 1/5, { discrete: width = 1280, height = 1024 } Time interval between frame: 1/7, 1/5, { pixelformat = 'MJPG', description = 'MJPEG' } { discrete: width = 640, height = 480 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 160, height = 120 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 176, height = 144 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 240 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 352, height = 288 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 720 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 800 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 960 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 1024 } Time interval between frame: 1/15, 1/10, 1/5, { pixelformat = 'RGB3', description = 'RGB3' } { discrete: width = 640, height = 480 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 160, height = 120 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 176, height = 144 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 240 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 352, height = 288 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 720 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 800 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 960 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 1024 } Time interval between frame: 1/15, 1/10, 1/5, { pixelformat = 'BGR3', description = 'BGR3' } { discrete: width = 640, height = 480 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 160, height = 120 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 176, height = 144 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 240 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 352, height = 288 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 720 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 800 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 960 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 1024 } Time interval between frame: 1/15, 1/10, 1/5, { pixelformat = 'YU12', description = 'YU12' } { discrete: width = 640, height = 480 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 160, height = 120 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 176, height = 144 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 240 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 352, height = 288 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 720 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 800 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 960 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 1024 } Time interval between frame: 1/15, 1/10, 1/5, { pixelformat = 'YV12', description = 'YV12' } { discrete: width = 640, height = 480 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 160, height = 120 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 176, height = 144 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 240 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 352, height = 288 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 720 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 800 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 960 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 1024 } Time interval between frame: 1/15, 1/10, 1/5, if i run luvcview by itself, the image is funny (blue and red colors, mainly, with myself in negative state). tx

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  • Chunking a List - .NET vs Python

    - by Abhijeet Patel
    Chunking a List As I mentioned last time, I'm knee deep in python these days. I come from a statically typed background so it's definitely a mental adjustment. List comprehensions is BIG in Python and having worked with a few of them I can see why. Let's say we need to chunk a list into sublists of a specified size. Here is how we'd do it in C#  static class Extensions   {       public static IEnumerable<List<T>> Chunk<T>(this List<T> l, int chunkSize)       {           if (chunkSize <0)           {               throw new ArgumentException("chunkSize cannot be negative", "chunkSize");           }           for (int i = 0; i < l.Count; i += chunkSize)           {               yield return new List<T>(l.Skip(i).Take(chunkSize));           }       }    }    static void Main(string[] args)  {           var l = new List<string> { "a", "b", "c", "d", "e", "f","g" };             foreach (var list in l.Chunk(7))           {               string str = list.Aggregate((s1, s2) => s1 + "," + s2);               Console.WriteLine(str);           }   }   A little wordy but still pretty concise thanks to LINQ.We skip the iteration number plus chunkSize elements and yield out a new List of chunkSize elements on each iteration. The python implementation is a bit more terse. def chunkIterable(iter, chunkSize):      '''Chunks an iterable         object into a list of the specified chunkSize     '''        assert hasattr(iter, "__iter__"), "iter is not an iterable"      for i in xrange(0, len(iter), chunkSize):          yield iter[i:i + chunkSize]    if __name__ == '__main__':      l = ['a', 'b', 'c', 'd', 'e', 'f']      generator = chunkIterable(l,2)      try:          while(1):              print generator.next()      except StopIteration:          pass   xrange generates elements in the specified range taking in a seed and returning a generator. which can be used in a for loop(much like using a C# iterator in a foreach loop) Since chunkIterable has a yield statement, it turns this method into a generator as well. iter[i:i + chunkSize] essentially slices the list based on the current iteration index and chunksize and creates a new list that we yield out to the caller one at a time. A generator much like an iterator is a state machine and each subsequent call to it remembers the state at which the last call left off and resumes execution from that point. The caveat to keep in mind is that since variables are not explicitly typed we need to ensure that the object passed in is iterable using hasattr(iter, "__iter__").This way we can perform chunking on any object which is an "iterable", very similar to accepting an IEnumerable in the .NET land

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  • JSR 360 and JSR 361: A Big Leap for Java ME 8

    - by terrencebarr
    It might have gone unnoticed to some, but Java ME took a big leap forward a couple of weeks ago with the filing of two new JSRs: JSR 360: “Connected Limited Device Configuration 8″ (aka CLDC 8) JSR 361: “Java ME Embedded Profile” (aka ME EP) Together, these two JSRs will significantly update, enhance, and modernize the Java ME platform, and specifically small embedded Java, with a host of new features and functionality. JSR 360 – Connected Limited Device Configuration 8 CLDC 8 is based on JSR 139 (CLDC 1.1) and updates the core Java ME VM, language support, libraries, and features to be aligned with Java SE 8. This will include: VM updated to comply with the JVM language specification version 2 Support for SE 7/8 language features like Generics, Assertions, Annotations, Try-with-Resources, and more New libraries such as Collections, NIO subset, Logging API subset A consolidated and enhanced Generic Connection Framework for multi-protocol I/O With CLDC 8, Java ME and Java SE are entering their next phase of alignment – making Java the only technology today that truly scales application development, code re-use, and tooling across the whole range of IT platforms, from small embedded to large enterprise. JSR 361 – Java ME Embedded Profile ME EP is based on JSR 228 (IMP-NG) and updates the specification in key areas to provide a powerful and flexible application environment for small embedded Java platforms, building on the features of CLDC 8:  A new, lightweight component and services model Shared libraries Multi-application concurrency, inter-application communication, and event system Application management API optionality, to address low-footprint use cases With ME EP, application developers will have a modern application environment which allows development and deployment of  modular, robust, sophisticated, and footprint-optimized solutions for a wide range of embedded use cases and devices. Summary While these JSRs are still under development, it’s clear that there are exciting new times ahead for Java ME – turning into a serious application platform while maintaining the focus on resource-constrained devices to address the expected explosion of small, smart, and connected embedded platforms. To learn more, click on the above links for JSR 360 and JSR 361. Or review the JavaOne 2012 online presentations on the topic: CON11300: Expanding the reach of the Java ME Platform CON5943: Java ME 8 Service Platform And stay tuned for more in this space! Cheers, – Terrence Filed under: Mobile & Embedded Tagged: "jsr 360", "jsr 361", "me 8", embedded, Embedded Java, JCP

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  • JSR 360 and JSR 361: A Big Leap for Java ME 8

    - by terrencebarr
    It might have gone unnoticed to some, but Java ME took a big leap forward a couple of weeks ago with the filing of two new JSRs: JSR 360: “Connected Limited Device Configuration 8″ (aka CLDC 8) JSR 361: “Java ME Embedded Profile” (aka ME EP) Together, these two JSRs will significantly update, enhance, and modernize the Java ME platform, and specifically small embedded Java, with a host of new features and functionality. JSR 360 – Connected Limited Device Configuration 8 CLDC 8 is based on JSR 139 (CLDC 1.1) and updates the core Java ME VM, language support, libraries, and features to be aligned with Java SE 8. This will include: VM updated to comply with the JVM language specification version 2 Support for SE 7/8 language features like Generics, Assertions, Annotations, Try-with-Resources, and more New libraries such as Collections, NIO subset, Logging API subset A consolidated and enhanced Generic Connection Framework for multi-protocol I/O With CLDC 8, Java ME and Java SE are entering their next phase of alignment – making Java the only technology today that truly scales application development, code re-use, and tooling across the whole range of IT platforms, from small embedded to large enterprise. JSR 361 – Java ME Embedded Profile ME EP is based on JSR 228 (IMP-NG) and updates the specification in key areas to provide a powerful and flexible application environment for small embedded Java platforms, building on the features of CLDC 8:  A new, lightweight component and services model Shared libraries Multi-application concurrency, inter-application communication, and event system Application management API optionality, to address low-footprint use cases With ME EP, application developers will have a modern application environment which allows development and deployment of  modular, robust, sophisticated, and footprint-optimized solutions for a wide range of embedded use cases and devices. Summary While these JSRs are still under development, it’s clear that there are exciting new times ahead for Java ME – turning into a serious application platform while maintaining the focus on resource-constrained devices to address the expected explosion of small, smart, and connected embedded platforms. To learn more, click on the above links for JSR 360 and JSR 361. Or review the JavaOne 2012 online presentations on the topic: CON11300: Expanding the reach of the Java ME Platform CON5943: Java ME 8 Service Platform And stay tuned for more in this space! Cheers, – Terrence Filed under: Mobile & Embedded Tagged: "jsr 360", "jsr 361", "me 8", embedded, Embedded Java, JCP

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  • 2D animation example in pyglet (python) looping through 2 images/sprites every x seconds

    - by Bentley4
    Suppose you have two images: step1.png and step2.png . Can anyone show me a very simple example in pyglet how to loop through those 2 images say every 0.5 seconds? The character doesn't have to move, just a simple black screen with a fixed region wherein the two images continually change every 0.5 secs. I know how to make a character move, shoot projectiles etc. but I just can't figure out how to control the looping speed of the images.

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  • Apple iPad 2 In April, iPhone 5 in June With New Hardware[Rumours]

    - by Gopinath
    Blogs and news sites are buzzing with the rumours of Apple’s next generation iPad and iPhone devices. These rumours interests the bloggers, geeks and end users of Apple devices as Apple maintains very tight lip on the new features of their upcoming products. The gadget blog Engadget has some very interesting rumours on the release of iPad 2 & iPhone 5 as well the new hardware they are going to have. Lets get into the details if you love to read the rumours of high profile blogs iPad 2 Release Date and Specs Apple seems to be all set to release iPad 2 in April, that is almost an year after the release of first iPad. It’s common for Apple to enjoy an one year long time to release a new version of their products. So if at all the rumours are to be believed, I can place an order of iPad 2 in April. Just like many of you out there, I’m also holding my iPad buying instinct and waiting for iPad 2 as it’s going to have at the minimum retina display,  Facetime features and few game changing features in Apple’s style. The report claims, iPad 2 will have a front and back cameras retina display SD Card slot (seems to be no USB) a dual GSM / CDMA chipset, that lets you use it with both GSM(AT &T, Airte) and CDMA(Verizon, Reliance) telecom providers iPhone 5 Release Date and Specs When it comes to iPhone 5 information, the rumour claims that the new iPhone is a completed redesigned device and it’s slated to release in summer of United States(i.e. June 2011). The device is also being tested by senior Apple executives right inside the campus and strictly not allowed to carry it outside. This restriction is to make sure that iPhone 5 will not land land up in a bar and then in the hands of geek blogs like how it happened with iPhone 4 last year. When it comes to the hardware of iPhone 5 Apple’s new A5 CPU (a Cortex A9-based, multi-core chip) a dual GSM / CDMA chipset, that lets you use it with both GSM(AT &T, Airte) and CDMA(Verizon, Reliance) telecom providers via Engadget and cc image credit flickr/mr-blixt This article titled,Apple iPad 2 In April, iPhone 5 in June With New Hardware[Rumours], was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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  • How to Easily Put a Windows PC into Kiosk Mode With Assigned Access

    - by Chris Hoffman
    Windows 8.1′s Assigned Access feature allows you to easily lock a Windows PC to a single application, such as a web browser. This feature makes it easy for anyone to configure Windows 8.1 devices as point-of-sale or other kiosk systems. In the past, setting up a Windows PC in kiosk mode involved much more work, requiring the use of third-party software, group policy, or Linux distributions designed around kiosk mode. Assigned Access is available on Windows 8.1 RT, Windows 8.1 Professional, and Windows 8.1 Enterprise. The standard edition of Windows 8.1 doesn’t support Assigned Access. Create a User Account for Assigned Access Rather than turn your entire computer into a locked-down kiosk system, Assigned Access allows you to create a separate user account that can only launch a single app — such as a web browser. To set this up, you must be logged into Windows as a user with administrator permissions. First, open the PC settings app — swipe in from the right or press Windows Key + C to open the charms bar, tap Settings, and tap Change PC settings. In the PC settings app, select Accounts and select Other accounts. Use the Add an account button to create a new Windows account. Select  the “Sign in without a Microsoft account” option and select Local account to create a local user account. You could also create a Microsoft account, but you may not want to do this if you just want a locked-down account with only browser access. If you need to install apps from the Windows Store to use in Assigned Access mode, you’ll have to set up a Microsoft account instead of a local account. A local account will still allow you access to the preinstalled apps, such as Internet Explorer. You may want to create a user account with a blank password. This would make it simple for anyone to access kiosk mode, even if the system becomes locked or needs to be rebooted. The account will be created as a standard user account with limited permissions. Leave it as a standard user account — don’t make it an administrator account. Set Up Assigned Access Once you’ve created an account, you’ll first need to sign into it. If you don’t, you’ll see a “This account has no apps” message when trying to enable Assigned Access. Go back to the welcome screen, log in to the new account you created, and allow Windows to go through the first-time account setup process. If you want to use a non-default app in kiosk mode, install it while logged in as that user account. Once you’re done, log out of the other account, log back in as your administrator account, and go back to the Other accounts screen. Click the Set up an account for assigned access option to continue. Select the user account you created and select the app you want to limit the account to. For a web-based kiosk, this can be a web browser such as the Modern version of Internet Explorer. Businesses can also create their own Modern apps and set them to run in kiosk mode in this way. Note that Microsoft’s documentation says “web browsers are not good choices for assigned access” because they require more permissions than average Modern (or “Windows Store”) apps. However, if you want to provide a kiosk for web-browsing, using Assigned Access is a much better option than using Guest Mode and offering up a full Windows desktop. When you’re done, restart your PC and log in as the Assigned Access account. Windows will automatically open the app you chose and won’t allow a user to leave that app. Standard Windows 8 features like the charms bar, app switcher, and Start screen won’t appear. Pressing the Windows key once will do nothing. To sign out of Assigned Access mode, press the Windows key five times — quickly — while signed in. You’ll be sent back to the standard login screen. The account will actually still be logged in and the app will remain running — this method just “locks” the screen and allows another user to log in. Automatically Log Into Assigned Access Whenever your Windows device boots, you can log into the Assigned Access account and turn it into a kiosk system. While this isn’t ideal for all kiosk systems, you may want the device to automatically launch the specific app when it boots without requiring any login process. To do so, you’ll just need to have Windows automatically log into the Assigned Access account when it boots. This option is hidden and not available in the standard Control Panel. You’ll need to use the hidden netplwiz Control Panel tool to set up automatic login on boot. If you didn’t create a password for the user account, leave the Password field empty while configuring this. Security Considerations If you’re using this feature to turn a Windows 8.1 system into a kiosk and leaving it open to the public, remember to consider security. Anyone could come up to the system, press the Windows key five times, and try to log into your standard administrator user account. Ensure the administrator user account has a strong password so people won’t be able to get past the kiosk system’s limitations and tamper with the system. Even Windows 8′s detractors have to admit that it’s an ideal system for a touch-screen kiosk device, running either a browser or another specific application. Assigned Access finally makes this easy to set up on Windows systems in the real world — no IT experience, third-party software, or Linux distributions necessary.     

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  • Site Studio Mobile Example - WCM Reuse

    - by john.brunswick
    Mobile internet usage is growing by leaps and bounds and it is theorized that in the not-to-distant future it will eclipse traditional access via desktop browsers. Mary Meeker, a managing director at Morgan Stanley and head of their global technology research team, recently predicted that mobile usage will eclipse desktop usage within the next 5 years in an Events@Google series presentation. In order for organizations to reach their prospects, customers and business partners, they will need to make their content readily available on mobile devices. A few years ago it was fairly challenging to provide a special, separate, site to cater to mobile users using technologies like WML (Wireless Markup Language). Modern mobile browsers have rendered the need for this as irrelevant and now the focus has moved toward providing a browsing experience that works well on small screen sizes and is highly performant. What does all of this mean for Oracle UCM? Taking site content from an existing Site Studio site and targeting it for consumption for mobile devices is a very straightforward process that is aided by a number of native capabilities in the product. The example highlighted in this post takes advantage of dynamic conversion capabilities in Oracle UCM to enable site content to be created and updated via MS Office documents. These documents are then converted to a simple, clean HTML format for consumption in the desktop and mobile browsing experiences. To help better understand how this is possible the example below shows a fictional .COM and its mobile site counterpart that both leverage the same underlying content. The scenario is not complete or production ready, but highlights that a mobile experience may be best delivered by omitting portions of a site that would be present within the version served to desktop clients. If you have browsed CNet (news.com) on a mobile device it becomes quickly apparent that they are serving an optimized version for your mobile device. An iPhone style version can be accessed at http://iphone.cnet.com/. In order to do that they leveraged some work done for the iPhone iUi project developed by Joe Hewitt that provides mobile browsers an experience that is similar to what users may find in a native iPhone application. For our example parts of this framework are used (the CSS) and this approach provides a page that will degrade nicely over a wide range of mobile browsers, since it is comprised of lightweight HTML markup and CSS. The iPhone iUi framework also provides some nice JavaScript to enable animated transitions between pages, but for the widest range of mobile browser compatibility we will only incorporate the CSS and HTML DIV / UL based page markup in our example.

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  • Global Webcast: Increase Pharmaceutical Sales Effectiveness

    - by charles.knapp
    See a next-generation approach to Pharmaceutical sales challenges! • Increase the quality of sales interactions with enhanced call planning and eDetailing • Improve sample management with electronic signature storage and inventory tracking on the go • Increase marketing effectiveness with closed loop marketing and personalized content delivery Watch as senior vice president of CRM, Anthony Lye, and director of life sciences product strategy, Piers Evans, provide the first public look at Oracle's new Pharmaceutical Sales On The Go solution, powered by Oracle CRM On Demand Release 17 -- Life Sciences Edition. Register now for this informative GLOBAL webcast on March 31, 9 AM PDT/4 PM GMT.

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  • Issues running commands

    - by Joel
    Every time I run a command I get this back. E: Could not open lock file /var/lib/apt/lists/lock - open (13: Permission denied) E: Unable to lock directory /var/lib/apt/lists/ E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied) E: Unable to lock the administration directory (/var/lib/dpkg/), are you root? christopher@christopher:~$ This didn't start happening until I changed my device name.

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  • Problem booting Windows after failed installation Ubuntu 12.04 alongside Windows 7

    - by Tassos
    I tried to install in my laptop Ubuntu 12.04 so that I can dual-boot with Windows 7. I made some mistakes during this process and I didn't manage to install Ubuntu. But my real problem now is that I'm afraid that I also destroyed the installation of Windows 7. Your help would be precious for me. Here are the details of what I did: 1) I followed these instructions to dual boot Ubuntu 12.04 and Windows 7: http://www.linuxbsdos.com/2012/05/17/how-to-dual-boot-ubuntu-12-04-and-windows-7/ The only difference from what is described above, is that in my case the device names where: /dev/mapper/isw_fdjdhbadc_Volume0* instead of: /dev/sda* Note that I had created a bootable USB stick to do that. 2) The installation proceeded normally, but in the end I got a fatal error because the grub-install failed. 3) Then, after googling this problem, I runned ubuntu from the USB stick and run this command: sudo grub-install --root-directory=/home/ubuntu/temp /dev/mapper/isw_fdjdhbadc_Volume0p5 (/isw_fdjdhbadc_Volume0p5 was the partition that I had made for /boot) but this command also failed. 4) Then, I did something stupid (I think): I run the above command as: sudo grub-install --root-directory=/home/ubuntu/temp /dev/mapper/isw_fdjdhbadc_Volume0 namely I tried to install grub in the device isw_fdjdhbadc_Volume0 instead of the boot partition isw_fdjdhbadc_Volume0p5 The above command did not fail and was executed ok. 5) After that, I tried to boot my laptop, but it seemed that I had no operation system. Not even windows were detected. 6) I thought that I should uninstall grub from isw_fdjdhbadc_Volume0. So following some online instructions that I found, I booted again Ubuntu from the USB stick and run the following command (this was stupid since the instructions were for a totally different case than mine): sudo dd if=/dev/zero of=/dev/mapper/isw_fdjdhbadc_Volume0 bs=446 count=1 Afte that, I was still unable to boot Windows. I realize that I deleted something that I shouldn't, but I'm hope that this is not crucial and I can recover somehow. When I boot Ubuntu from the USB, I can see that the partition with Windows is still there, with all the directories, Windows files, my data etc. So, my question is: Is there a way to undo the mistakes that I desribed above and recover Windows 7? This is my major question. After solving that, I'd also like to know what I did wrong with the installation of Ubuntu. Thanks in advance for you valuable help!

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  • DevConnections VS 2010 Issue

    - by guybarrette
    The latest issue of DevConnections is focused around the Visual Studio 2010 launch. One of the ads is a brand new Visual Studio ad (click to expand).  Looks like the infinite loop is everywhere. var addthis_pub="guybarrette";

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  • DevConnections VS 2010 Issue

    The latest issue of DevConnections is focused around the Visual Studio 2010 launch. One of the ads is a brand new Visual Studio ad (click to expand).  Looks like the infinite loop is everywhere. var addthis_pub="guybarrette";...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Angry Bird Makers: Developers Love iOS Over Android To Make Money

    - by Gopinath
    These days web is buzzing with Apple iOS vs Google Android debates. Recently Fortune predicted that Android is going to explode in 2011 and it will surpass Apple’s iOS market share. Yes Android is set to spread its wings across all the devices – smartphones, TVs, set top boxes, in car entertainment devices, what not. Think of any device that requires operating system, Android can be used. On the other than iOS is only available on very selective Apple devices – iPods, iPhones and iPads. When it comes to the count of devices running on a specific OS, Android will be far ahead of iOS but when you consider a quality of devices and providing an eco system for business to make money iOS seems to be the winner. That is what experts and analysts are saysing. Here is an excerpt from Peter Vesterbacka, maker of the popular Angry Birds game, interview to Tech N Marketing site.  He says Apple will be the number one platform for a long time from a developer perspective, they have gotten so many things right. And they know what they are doing and they call the shots. Android is growing, but it’s also growing complexity at the same time. Device fragmentation not the issue, but rather the fragmentation of the ecosystem. So many different shops, so many different models. The carriers messing with the experience again. Open but not really open, a very Google centric ecosystem. And paid content just doesn’t work on Android. Peter says developer prefer iOS over Android as it’s not very easy to make money on Android market. That’s why they released a free version of Angry Birds game with ads support for Android devices. Free is the way to go with Android. Nobody has been successful selling content on Android. We will offer a way to remove the ads by paying for the app, but we don’t expect that to be a huge revenue stream. You can read full interview here. cc image credit: flickr/johanl This article titled,Angry Bird Makers: Developers Love iOS Over Android To Make Money, was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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  • Looking into ASP.Net MVC 4.0 Mobile Development - part 2

    - by nikolaosk
    In this post I will be continuing my discussion on ASP.Net MVC 4.0 mobile development. You can have a look at my first post on the subject here . Make sure you read it and understand it well before you move one reading the remaining of this post. I will not be writing any code in this post. I will try to explain a few concepts related to the MVC 4.0 mobile functionality. In this post I will be looking into the Browser Overriding feature in ASP.Net MVC 4.0. By that I mean that we override the user agent for a given user session. This is very useful feature for people who visit a site through a device and they experience the mobile version of the site, but what they really want is the option to be able to switch to the desktop view. "Why they might want to do that?", you might wonder.Well first of all the users of our ASP.Net MVC 4.0 application will appreciate that they have the option to switch views while some others will think that they will enjoy more the contents of our website with the "desktop view" since the mobile device they view our site has a quite large display.  Obviously this is only one site. These are just different views that are rendered.To put it simply, browser overriding lets our application treat requests as if they were coming from a different browser rather than the one they are actually from. In order to do that programmatically we must have a look at the System.Web.WebPages namespace and the classes in it. Most specifically the class BrowserHelpers. Have a look at the picture below   In this class we see some extension methods for HttpContext class.These methods are called extensions-helpers methods and we use them to switch to one browser from another thus overriding the current/actual browser. These APIs have effect on layout,views and partial views and will not affect any other ASP.Net Request.Browser related functionality.The overridden browser is stored in a cookie. Let me explain what some of these methods do. SetOverriddenBrowser() -  let us set the user agent string to specific value GetOverriddenBrowser() -  let us get the overridden value ClearOverriddenBrowser() -  let us remove any overridden user agent for the current request   To recap, in our ASP.Net MVC 4.0 applications when our application is viewed in our mobile devices, we can have a link like "Desktop View" for all those who desperately want to see the site with in full desktop-browser version.We then can specify a browser type override. My controller class (snippet of code) that is responsible for handling the switching could be something like that. public class SwitchViewController : Controller{ public RedirectResult SwitchView(bool mobile, string returnUrl){if (Request.Browser.IsMobileDevice == mobile)HttpContext.ClearOverriddenBrowser();elseHttpContext.SetOverriddenBrowser(mobile ? BrowserOverride.Mobile : BrowserOverride.Desktop);return Redirect(returnUrl);}} Hope it helps!!!!

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  • Web Development Services - Contribution of Programming and Testing

    Web Development Services include development of basic websites to highly complex and structured websites. Earlier local personal computer revolutionized the market and started offering application to cater all user needs but their mission and vision lacked the flexibility. Hence loop was filled after World Wide Web invented.

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  • Rendering another screen on top of main game screen in fullscreen mode

    - by wolf
    my game runs in fullscreen mode and uses active rendering. The graphics are drawn on the fullscreen window in each game loop: public void render() { Window w = screen.getFullScreenWindow(); Graphics2D g = screen.getGraphics(); renderer.render(g, level, w.getWidth(), w.getHeight()); g.dispose(); screen.update(); } This is the screen.update() method: public void update(){ Window w = device.getFullScreenWindow(); if(w != null){ BufferStrategy s = w.getBufferStrategy(); if(!s.contentsLost()){ s.show(); } } } I want to display another screen on my main game screen (menu, inventory etc). Lets say I have a JPanel inventory, which has a grid of inventory cells (manually drawn) and some Swing components like JPopupMenu. So i tried adding that to my window and repainting it in the game loop, which worked okay most of the time... but sometimes the panel wouldn't get displayed. Blindly moving things around in the inventory worked, but it just didn't display. When i alt-tabbed out and back again, it displayed properly. I also tried drawing the rest of the inventory on my full screen window and using a JPanel to display only the buttons and popupmenus. The inventory displayed properly, but the Swing components keep flickering. I'm guessing this is because I don't know how to combine active and passive rendering. public void render() { Graphics2D g = screen.getGraphics(); invManager.render(g); g.dispose(); screen.update(); invPanel.repaint(); } Should i use something else instead of a JPanel? I don't really need active rendering for these screens, but I don't understand why they sometimes just don't display. Or maybe I should just make my own custom components instead of using Swing? I also read somewhere that using multiple panels/frames in a game is bad practice so should I draw everything on one window/frame/panel? If I CAN use JPanels for this, should I add and remove them every time the inventory is toggled? Or just change their visibility?

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  • Very very slow transfer speeds between Windows 7 and samba server running on Ubuntu 11.10/12.04 minimal

    - by kuzyt
    As mentioned in the title I tried transferring files between Windows 7 and the samba server running on both Ubuntu 11.10 and 12.04 but both showed very slow transfer speeds. Can someone please guide me in the right direction to debug this problem ? wget --output-document=/dev/null http://tokyo1.linode.com/100MB-tokyo.bin --2012-08-21 22:02:17-- http://tokyo1.linode.com/100MB-tokyo.bin Resolving tokyo1.linode.com (tokyo1.linode.com)... 106.187.33.12 Connecting to tokyo1.linode.com (tokyo1.linode.com)|106.187.33.12|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 104857600 (100M) [application/octet-stream] Saving to: `/dev/null' 8% [=============> ] 8,923,980 64.8K/s eta 15m 0s wlan0 IEEE 802.11abgn ESSID:"TNET" Mode:Managed Frequency:2.462 GHz Access Point: 58:6D:8F:26:20:7A Bit Rate=117 Mb/s Tx-Power=20 dBm Retry long limit:7 RTS thr:off Fragment thr:off Power Management:off Link Quality=57/70 Signal level=-53 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:101 Invalid misc:2448 Missed beacon:0 03:00.0 Network controller: Atheros Communications Inc. AR9300 Wireless LAN adaptor (rev 01) Subsystem: Atheros Communications Inc. Device 3112 Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx+ Latency: 0, Cache Line Size: 64 bytes Interrupt: pin A routed to IRQ 16 Region 0: Memory at fea00000 (64-bit, non-prefetchable) [size=128K] Expansion ROM at fea20000 [disabled] [size=64K] Capabilities: [40] Power Management version 3 Flags: PMEClk- DSI- D1+ D2- AuxCurrent=375mA PME(D0+,D1+,D2-,D3hot+,D3cold-) Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME- Capabilities: [50] MSI: Enable- Count=1/4 Maskable+ 64bit+ Address: 0000000000000000 Data: 0000 Masking: 00000000 Pending: 00000000 Capabilities: [70] Express (v2) Endpoint, MSI 00 DevCap: MaxPayload 128 bytes, PhantFunc 0, Latency L0s <1us, L1 <8us ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset- DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported- RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop- MaxPayload 128 bytes, MaxReadReq 512 bytes DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr- TransPend- LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s L1, Latency L0 <2us, L1 <64us ClockPM- Surprise- LLActRep- BwNot- LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- Retrain- CommClk+ ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt- LnkSta: Speed 2.5GT/s, Width x1, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt- DevCap2: Completion Timeout: Not Supported, TimeoutDis+ DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis- LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-, Selectable De-emphasis: -6dB Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS- Compliance De-emphasis: -6dB LnkSta2: Current De-emphasis Level: -6dB Capabilities: [100 v1] Advanced Error Reporting UESta: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol- UEMsk: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol- UESvrt: DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol- CESta: RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr- CEMsk: RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr+ AERCap: First Error Pointer: 00, GenCap- CGenEn- ChkCap- ChkEn- Capabilities: [140 v1] Virtual Channel Caps: LPEVC=0 RefClk=100ns PATEntryBits=1 Arb: Fixed- WRR32- WRR64- WRR128- Ctrl: ArbSelect=Fixed Status: InProgress- VC0: Caps: PATOffset=00 MaxTimeSlots=1 RejSnoopTrans- Arb: Fixed- WRR32- WRR64- WRR128- TWRR128- WRR256- Ctrl: Enable+ ID=0 ArbSelect=Fixed TC/VC=01 Status: NegoPending- InProgress- Capabilities: [300 v1] Device Serial Number 00-00-00-00-00-00-00-00 Kernel driver in use: ath9k Kernel modules: ath9k

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  • Broadcom BCM4331 not working on new Mac Mini 5,1

    - by Jon
    I can't seem to get my wireless card working on my Mac Mini 5,1. Lspci returns: 03:00.0 Network controller: Broadcom Corporation BCM4331 802.11a/b/g/n (rev 02) But running "additional drivers" doesn't detect anything. The nm-applet menu reads "device not ready--firmware missing." What can I do to get this to work? Note, this is with 12.04.1, so many of the previous discussions (for 11.10, etc) probably don't apply here.

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  • PTLQueue : a scalable bounded-capacity MPMC queue

    - by Dave
    Title: Fast concurrent MPMC queue -- I've used the following concurrent queue algorithm enough that it warrants a blog entry. I'll sketch out the design of a fast and scalable multiple-producer multiple-consumer (MPSC) concurrent queue called PTLQueue. The queue has bounded capacity and is implemented via a circular array. Bounded capacity can be a useful property if there's a mismatch between producer rates and consumer rates where an unbounded queue might otherwise result in excessive memory consumption by virtue of the container nodes that -- in some queue implementations -- are used to hold values. A bounded-capacity queue can provide flow control between components. Beware, however, that bounded collections can also result in resource deadlock if abused. The put() and take() operators are partial and wait for the collection to become non-full or non-empty, respectively. Put() and take() do not allocate memory, and are not vulnerable to the ABA pathologies. The PTLQueue algorithm can be implemented equally well in C/C++ and Java. Partial operators are often more convenient than total methods. In many use cases if the preconditions aren't met, there's nothing else useful the thread can do, so it may as well wait via a partial method. An exception is in the case of work-stealing queues where a thief might scan a set of queues from which it could potentially steal. Total methods return ASAP with a success-failure indication. (It's tempting to describe a queue or API as blocking or non-blocking instead of partial or total, but non-blocking is already an overloaded concurrency term. Perhaps waiting/non-waiting or patient/impatient might be better terms). It's also trivial to construct partial operators by busy-waiting via total operators, but such constructs may be less efficient than an operator explicitly and intentionally designed to wait. A PTLQueue instance contains an array of slots, where each slot has volatile Turn and MailBox fields. The array has power-of-two length allowing mod/div operations to be replaced by masking. We assume sensible padding and alignment to reduce the impact of false sharing. (On x86 I recommend 128-byte alignment and padding because of the adjacent-sector prefetch facility). Each queue also has PutCursor and TakeCursor cursor variables, each of which should be sequestered as the sole occupant of a cache line or sector. You can opt to use 64-bit integers if concerned about wrap-around aliasing in the cursor variables. Put(null) is considered illegal, but the caller or implementation can easily check for and convert null to a distinguished non-null proxy value if null happens to be a value you'd like to pass. Take() will accordingly convert the proxy value back to null. An advantage of PTLQueue is that you can use atomic fetch-and-increment for the partial methods. We initialize each slot at index I with (Turn=I, MailBox=null). Both cursors are initially 0. All shared variables are considered "volatile" and atomics such as CAS and AtomicFetchAndIncrement are presumed to have bidirectional fence semantics. Finally T is the templated type. I've sketched out a total tryTake() method below that allows the caller to poll the queue. tryPut() has an analogous construction. Zebra stripping : alternating row colors for nice-looking code listings. See also google code "prettify" : https://code.google.com/p/google-code-prettify/ Prettify is a javascript module that yields the HTML/CSS/JS equivalent of pretty-print. -- pre:nth-child(odd) { background-color:#ff0000; } pre:nth-child(even) { background-color:#0000ff; } border-left: 11px solid #ccc; margin: 1.7em 0 1.7em 0.3em; background-color:#BFB; font-size:12px; line-height:65%; " // PTLQueue : Put(v) : // producer : partial method - waits as necessary assert v != null assert Mask = 1 && (Mask & (Mask+1)) == 0 // Document invariants // doorway step // Obtain a sequence number -- ticket // As a practical concern the ticket value is temporally unique // The ticket also identifies and selects a slot auto tkt = AtomicFetchIncrement (&PutCursor, 1) slot * s = &Slots[tkt & Mask] // waiting phase : // wait for slot's generation to match the tkt value assigned to this put() invocation. // The "generation" is implicitly encoded as the upper bits in the cursor // above those used to specify the index : tkt div (Mask+1) // The generation serves as an epoch number to identify a cohort of threads // accessing disjoint slots while s-Turn != tkt : Pause assert s-MailBox == null s-MailBox = v // deposit and pass message Take() : // consumer : partial method - waits as necessary auto tkt = AtomicFetchIncrement (&TakeCursor,1) slot * s = &Slots[tkt & Mask] // 2-stage waiting : // First wait for turn for our generation // Acquire exclusive "take" access to slot's MailBox field // Then wait for the slot to become occupied while s-Turn != tkt : Pause // Concurrency in this section of code is now reduced to just 1 producer thread // vs 1 consumer thread. // For a given queue and slot, there will be most one Take() operation running // in this section. // Consumer waits for producer to arrive and make slot non-empty // Extract message; clear mailbox; advance Turn indicator // We have an obvious happens-before relation : // Put(m) happens-before corresponding Take() that returns that same "m" for T v = s-MailBox if v != null : s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 // unlock slot to admit next producer and consumer return v Pause tryTake() : // total method - returns ASAP with failure indication for auto tkt = TakeCursor slot * s = &Slots[tkt & Mask] if s-Turn != tkt : return null T v = s-MailBox // presumptive return value if v == null : return null // ratify tkt and v values and commit by advancing cursor if CAS (&TakeCursor, tkt, tkt+1) != tkt : continue s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 return v The basic idea derives from the Partitioned Ticket Lock "PTL" (US20120240126-A1) and the MultiLane Concurrent Bag (US8689237). The latter is essentially a circular ring-buffer where the elements themselves are queues or concurrent collections. You can think of the PTLQueue as a partitioned ticket lock "PTL" augmented to pass values from lock to unlock via the slots. Alternatively, you could conceptualize of PTLQueue as a degenerate MultiLane bag where each slot or "lane" consists of a simple single-word MailBox instead of a general queue. Each lane in PTLQueue also has a private Turn field which acts like the Turn (Grant) variables found in PTL. Turn enforces strict FIFO ordering and restricts concurrency on the slot mailbox field to at most one simultaneous put() and take() operation. PTL uses a single "ticket" variable and per-slot Turn (grant) fields while MultiLane has distinct PutCursor and TakeCursor cursors and abstract per-slot sub-queues. Both PTL and MultiLane advance their cursor and ticket variables with atomic fetch-and-increment. PTLQueue borrows from both PTL and MultiLane and has distinct put and take cursors and per-slot Turn fields. Instead of a per-slot queues, PTLQueue uses a simple single-word MailBox field. PutCursor and TakeCursor act like a pair of ticket locks, conferring "put" and "take" access to a given slot. PutCursor, for instance, assigns an incoming put() request to a slot and serves as a PTL "Ticket" to acquire "put" permission to that slot's MailBox field. To better explain the operation of PTLQueue we deconstruct the operation of put() and take() as follows. Put() first increments PutCursor obtaining a new unique ticket. That ticket value also identifies a slot. Put() next waits for that slot's Turn field to match that ticket value. This is tantamount to using a PTL to acquire "put" permission on the slot's MailBox field. Finally, having obtained exclusive "put" permission on the slot, put() stores the message value into the slot's MailBox. Take() similarly advances TakeCursor, identifying a slot, and then acquires and secures "take" permission on a slot by waiting for Turn. Take() then waits for the slot's MailBox to become non-empty, extracts the message, and clears MailBox. Finally, take() advances the slot's Turn field, which releases both "put" and "take" access to the slot's MailBox. Note the asymmetry : put() acquires "put" access to the slot, but take() releases that lock. At any given time, for a given slot in a PTLQueue, at most one thread has "put" access and at most one thread has "take" access. This restricts concurrency from general MPMC to 1-vs-1. We have 2 ticket locks -- one for put() and one for take() -- each with its own "ticket" variable in the form of the corresponding cursor, but they share a single "Grant" egress variable in the form of the slot's Turn variable. Advancing the PutCursor, for instance, serves two purposes. First, we obtain a unique ticket which identifies a slot. Second, incrementing the cursor is the doorway protocol step to acquire the per-slot mutual exclusion "put" lock. The cursors and operations to increment those cursors serve double-duty : slot-selection and ticket assignment for locking the slot's MailBox field. At any given time a slot MailBox field can be in one of the following states: empty with no pending operations -- neutral state; empty with one or more waiting take() operations pending -- deficit; occupied with no pending operations; occupied with one or more waiting put() operations -- surplus; empty with a pending put() or pending put() and take() operations -- transitional; or occupied with a pending take() or pending put() and take() operations -- transitional. The partial put() and take() operators can be implemented with an atomic fetch-and-increment operation, which may confer a performance advantage over a CAS-based loop. In addition we have independent PutCursor and TakeCursor cursors. Critically, a put() operation modifies PutCursor but does not access the TakeCursor and a take() operation modifies the TakeCursor cursor but does not access the PutCursor. This acts to reduce coherence traffic relative to some other queue designs. It's worth noting that slow threads or obstruction in one slot (or "lane") does not impede or obstruct operations in other slots -- this gives us some degree of obstruction isolation. PTLQueue is not lock-free, however. The implementation above is expressed with polite busy-waiting (Pause) but it's trivial to implement per-slot parking and unparking to deschedule waiting threads. It's also easy to convert the queue to a more general deque by replacing the PutCursor and TakeCursor cursors with Left/Front and Right/Back cursors that can move either direction. Specifically, to push and pop from the "left" side of the deque we would decrement and increment the Left cursor, respectively, and to push and pop from the "right" side of the deque we would increment and decrement the Right cursor, respectively. We used a variation of PTLQueue for message passing in our recent OPODIS 2013 paper. ul { list-style:none; padding-left:0; padding:0; margin:0; margin-left:0; } ul#myTagID { padding: 0px; margin: 0px; list-style:none; margin-left:0;} -- -- There's quite a bit of related literature in this area. I'll call out a few relevant references: Wilson's NYU Courant Institute UltraComputer dissertation from 1988 is classic and the canonical starting point : Operating System Data Structures for Shared-Memory MIMD Machines with Fetch-and-Add. Regarding provenance and priority, I think PTLQueue or queues effectively equivalent to PTLQueue have been independently rediscovered a number of times. See CB-Queue and BNPBV, below, for instance. But Wilson's dissertation anticipates the basic idea and seems to predate all the others. Gottlieb et al : Basic Techniques for the Efficient Coordination of Very Large Numbers of Cooperating Sequential Processors Orozco et al : CB-Queue in Toward high-throughput algorithms on many-core architectures which appeared in TACO 2012. Meneghin et al : BNPVB family in Performance evaluation of inter-thread communication mechanisms on multicore/multithreaded architecture Dmitry Vyukov : bounded MPMC queue (highly recommended) Alex Otenko : US8607249 (highly related). John Mellor-Crummey : Concurrent queues: Practical fetch-and-phi algorithms. Technical Report 229, Department of Computer Science, University of Rochester Thomasson : FIFO Distributed Bakery Algorithm (very similar to PTLQueue). Scott and Scherer : Dual Data Structures I'll propose an optimization left as an exercise for the reader. Say we wanted to reduce memory usage by eliminating inter-slot padding. Such padding is usually "dark" memory and otherwise unused and wasted. But eliminating the padding leaves us at risk of increased false sharing. Furthermore lets say it was usually the case that the PutCursor and TakeCursor were numerically close to each other. (That's true in some use cases). We might still reduce false sharing by incrementing the cursors by some value other than 1 that is not trivially small and is coprime with the number of slots. Alternatively, we might increment the cursor by one and mask as usual, resulting in a logical index. We then use that logical index value to index into a permutation table, yielding an effective index for use in the slot array. The permutation table would be constructed so that nearby logical indices would map to more distant effective indices. (Open question: what should that permutation look like? Possibly some perversion of a Gray code or De Bruijn sequence might be suitable). As an aside, say we need to busy-wait for some condition as follows : "while C == 0 : Pause". Lets say that C is usually non-zero, so we typically don't wait. But when C happens to be 0 we'll have to spin for some period, possibly brief. We can arrange for the code to be more machine-friendly with respect to the branch predictors by transforming the loop into : "if C == 0 : for { Pause; if C != 0 : break; }". Critically, we want to restructure the loop so there's one branch that controls entry and another that controls loop exit. A concern is that your compiler or JIT might be clever enough to transform this back to "while C == 0 : Pause". You can sometimes avoid this by inserting a call to a some type of very cheap "opaque" method that the compiler can't elide or reorder. On Solaris, for instance, you could use :"if C == 0 : { gethrtime(); for { Pause; if C != 0 : break; }}". It's worth noting the obvious duality between locks and queues. If you have strict FIFO lock implementation with local spinning and succession by direct handoff such as MCS or CLH,then you can usually transform that lock into a queue. Hidden commentary and annotations - invisible : * And of course there's a well-known duality between queues and locks, but I'll leave that topic for another blog post. * Compare and contrast : PTLQ vs PTL and MultiLane * Equivalent : Turn; seq; sequence; pos; position; ticket * Put = Lock; Deposit Take = identify and reserve slot; wait; extract & clear; unlock * conceptualize : Distinct PutLock and TakeLock implemented as ticket lock or PTL Distinct arrival cursors but share per-slot "Turn" variable provides exclusive role-based access to slot's mailbox field put() acquires exclusive access to a slot for purposes of "deposit" assigns slot round-robin and then acquires deposit access rights/perms to that slot take() acquires exclusive access to slot for purposes of "withdrawal" assigns slot round-robin and then acquires withdrawal access rights/perms to that slot At any given time, only one thread can have withdrawal access to a slot at any given time, only one thread can have deposit access to a slot Permissible for T1 to have deposit access and T2 to simultaneously have withdrawal access * round-robin for the purposes of; role-based; access mode; access role mailslot; mailbox; allocate/assign/identify slot rights; permission; license; access permission; * PTL/Ticket hybrid Asymmetric usage ; owner oblivious lock-unlock pairing K-exclusion add Grant cursor pass message m from lock to unlock via Slots[] array Cursor performs 2 functions : + PTL ticket + Assigns request to slot in round-robin fashion Deconstruct protocol : explication put() : allocate slot in round-robin fashion acquire PTL for "put" access store message into slot associated with PTL index take() : Acquire PTL for "take" access // doorway step seq = fetchAdd (&Grant, 1) s = &Slots[seq & Mask] // waiting phase while s-Turn != seq : pause Extract : wait for s-mailbox to be full v = s-mailbox s-mailbox = null Release PTL for both "put" and "take" access s-Turn = seq + Mask + 1 * Slot round-robin assignment and lock "doorway" protocol leverage the same cursor and FetchAdd operation on that cursor FetchAdd (&Cursor,1) + round-robin slot assignment and dispersal + PTL/ticket lock "doorway" step waiting phase is via "Turn" field in slot * PTLQueue uses 2 cursors -- put and take. Acquire "put" access to slot via PTL-like lock Acquire "take" access to slot via PTL-like lock 2 locks : put and take -- at most one thread can access slot's mailbox Both locks use same "turn" field Like multilane : 2 cursors : put and take slot is simple 1-capacity mailbox instead of queue Borrow per-slot turn/grant from PTL Provides strict FIFO Lock slot : put-vs-put take-vs-take at most one put accesses slot at any one time at most one put accesses take at any one time reduction to 1-vs-1 instead of N-vs-M concurrency Per slot locks for put/take Release put/take by advancing turn * is instrumental in ... * P-V Semaphore vs lock vs K-exclusion * See also : FastQueues-excerpt.java dice-etc/queue-mpmc-bounded-blocking-circular-xadd/ * PTLQueue is the same as PTLQB - identical * Expedient return; ASAP; prompt; immediately * Lamport's Bakery algorithm : doorway step then waiting phase Threads arriving at doorway obtain a unique ticket number Threads enter in ticket order * In the terminology of Reed and Kanodia a ticket lock corresponds to the busy-wait implementation of a semaphore using an eventcount and a sequencer It can also be thought of as an optimization of Lamport's bakery lock was designed for fault-tolerance rather than performance Instead of spinning on the release counter, processors using a bakery lock repeatedly examine the tickets of their peers --

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  • Android 4 Fragments with Mono for Android

    - by Wallym
    With the release of Android 3.0, Google added support for larger displays and attention-grabbing UI designs and layouts. On a tablet screen, UI components can be used to present better information. How does Android do this? It has a technology called Fragments, and I'll look at its implementation in the currently shipping operating system, Android 4. (Let's get past all the jokes about Android and fragmentation on its device platform.)For more information on this, check out my article at Visual Studio Magazine - http://visualstudiomagazine.com/articles/2012/12/13/android-4-and-fragments.aspx

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