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• Unable to boot: Missing Operating system

  - by Vivek S Panicker

  i had installed Ubuntu 11.10 along with the another Ubuntu 11.10 which already installed in my netbook. Later I formatted the partition I newly installed. Next time when I boot it went to Grub Rescue menu. I boot my system again with Ubuntu USB stick, Then I installed Boot repair package in USB and restored MBR and GRUB menu in hard disk. Now when I am restarting, I am getting a message Missing operating system, press any key to continue. Can somebody help me on this? Below is the output for sudo fdisk -l omitting empty partition (7) Disk /dev/sda: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00058a60 Device Boot Start End Blocks Id System /dev/sda1 * 2048 204072287 102035120 83 Linux /dev/sda2 204072958 312580095 54253569 5 Extended /dev/sda5 310507520 312580095 1036288 82 Linux swap / Solaris /dev/sda6 308432896 310503423 1035264 82 Linux swap / Solaris Partition table entries are not in disk order Disk /dev/sdb: 4006 MB, 4006608896 bytes 124 heads, 62 sectors/track, 1017 cylinders, total 7825408 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0004d3df Device Boot Start End Blocks Id System /dev/sdb1 * 62 7818695 3909317 b W95 FAT32 Below is the output for sudo blkid /dev/loop0: TYPE="squashfs" /dev/loop1: LABEL="casper-rw" UUID="533defb1-f073-254a-b46f-7ca0ac1f4e0c" TYPE="ext2" /dev/sda1: LABEL="Ubuntu" UUID="6a141040-3ba8-457a-9de5-ad06e6057084" TYPE="ext4" /dev/sda5: UUID="3a7f62d6-9c65-4d12-a3b6-5d62b9710f7d" TYPE="swap" /dev/sda6: UUID="274da115-cec2-4418-a1af-88fe921e3670" TYPE="swap" /dev/sdb1: LABEL="PENDRIVE" UUID="EC22-6BE4" TYPE="vfat" File /boot/grub/grub.cfg # # DO NOT EDIT THIS FILE # # It is automatically generated by grub-mkconfig using templates # from /etc/grub.d and settings from /etc/default/grub # ### BEGIN /etc/grub.d/00_header ### if [ -s $prefix/grubenv ]; then set have_grubenv=true load_env fi set default="0" if [ "${prev_saved_entry}" ]; then set saved_entry="${prev_saved_entry}" save_env saved_entry set prev_saved_entry= save_env prev_saved_entry set boot_once=true fi function savedefault { if [ -z "${boot_once}" ]; then saved_entry="${chosen}" save_env saved_entry fi } function recordfail { set recordfail=1 if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi } function load_video { insmod vbe insmod vga insmod video_bochs insmod video_cirrus } insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 6a141040-3ba8-457a-9de5-ad06e6057084 if loadfont /usr/share/grub/unicode.pf2 ; then set gfxmode=auto load_video insmod gfxterm insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 6a141040-3ba8-457a-9de5-ad06e6057084 set locale_dir=($root)/boot/grub/locale set lang=en_US insmod gettext fi terminal_output gfxterm if [ "${recordfail}" = 1 ]; then set timeout=10 else set timeout=10 fi ### END /etc/grub.d/00_header ### ### BEGIN /etc/grub.d/05_debian_theme ### set menu_color_normal=white/black set menu_color_highlight=black/light-gray if background_color 44,0,30; then clear fi ### END /etc/grub.d/05_debian_theme ### ### BEGIN /etc/grub.d/10_linux ### if [ ${recordfail} != 1 ]; then if [ -e ${prefix}/gfxblacklist.txt ]; then if hwmatch ${prefix}/gfxblacklist.txt 3; then if [ ${match} = 0 ]; then set linux_gfx_mode=keep else set linux_gfx_mode=text fi else set linux_gfx_mode=text fi else set linux_gfx_mode=keep fi else set linux_gfx_mode=text fi export linux_gfx_mode if [ "$linux_gfx_mode" != "text" ]; then load_video; fi menuentry 'Ubuntu, with Linux 3.0.0-12-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail set gfxpayload=$linux_gfx_mode insmod gzio insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 6a141040-3ba8-457a-9de5-ad06e6057084 linux /boot/vmlinuz-3.0.0-12-generic root=UUID=6a141040-3ba8-457a-9de5-ad06e6057084 ro quiet splash vt.handoff=7 initrd /boot/initrd.img-3.0.0-12-generic } menuentry 'Ubuntu, with Linux 3.0.0-12-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod gzio insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 6a141040-3ba8-457a-9de5-ad06e6057084 echo 'Loading Linux 3.0.0-12-generic ...' linux /boot/vmlinuz-3.0.0-12-generic root=UUID=6a141040-3ba8-457a-9de5-ad06e6057084 ro recovery nomodeset echo 'Loading initial ramdisk ...' initrd /boot/initrd.img-3.0.0-12-generic } ### END /etc/grub.d/10_linux ### ### BEGIN /etc/grub.d/20_linux_xen ### ### END /etc/grub.d/20_linux_xen ### ### BEGIN /etc/grub.d/20_memtest86+ ### menuentry "Memory test (memtest86+)" { insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 6a141040-3ba8-457a-9de5-ad06e6057084 linux16 /boot/memtest86+.bin } menuentry "Memory test (memtest86+, serial console 115200)" { insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 6a141040-3ba8-457a-9de5-ad06e6057084 linux16 /boot/memtest86+.bin console=ttyS0,115200n8 } ### END /etc/grub.d/20_memtest86+ ### ### BEGIN /etc/grub.d/30_os-prober ### ### END /etc/grub.d/30_os-prober ### ### BEGIN /etc/grub.d/40_custom ### # This file provides an easy way to add custom menu entries. Simply type the # menu entries you want to add after this comment. Be careful not to change # the 'exec tail' line above. ### END /etc/grub.d/40_custom ### ### BEGIN /etc/grub.d/41_custom ### if [ -f $prefix/custom.cfg ]; then source $prefix/custom.cfg; fi ### END /etc/grub.d/41_custom ###

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• Can't see my partitions after grub recovery

  - by dimbo

  I stupidly inserted the windows CD into my dual boot Ubuntu 11.10 / windows xp system. I just wanted to see if I could install windows on my external usb HD, but didn't actually go ahead with the install. It seems like the windows CD messed up my MBR and I had to use boot-repair and the ubuntu 11.10 live CD to gain access to ubuntu again. It seems to boot up a little differently (slower) but works. However, I now cant see any of my partitions in nautilus (there are 3). When I open gparted, it just shows my whole hard drive as unallocated (I know it has a windows partition that works and my ubuntu partition that I am using now). If I insert a usb pen, it is also not visible in nautilus but in gparted shows up as a FAT32 partition (which is correct although I cannot access it). sudo fdisk -l gives the following : demian@dimbo-TP:~$ sudo fdisk -l [sudo] password for demian: omitting empty partition (5) Disk /dev/sda: 320.1 GB, 320072933376 bytes 240 heads, 63 sectors/track, 41345 cylinders, total 625142448 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x877b877b Device Boot Start End Blocks Id System /dev/sda1 * 63 63842309 31921123+ 7 HPFS/NTFS/exFAT /dev/sda2 63844350 133484084 34819867+ 5 Extended /dev/sda3 127636488 133484084 2923798+ 82 Linux swap / Solaris /dev/sda4 133484085 625137344 245826630 83 Linux /dev/sda5 63844352 123445247 29800448 83 Linux /dev/sda6 123447296 127635455 2094080 82 Linux swap / Solaris Disk /dev/sdb: 8100 MB, 8100249600 bytes 12 heads, 40 sectors/track, 32960 cylinders, total 15820800 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xc3072e18 Device Boot Start End Blocks Id System /dev/sdb1 * 5992 15820799 7907404 c W95 FAT32 (LBA) Here is my grub.conf file. Like I said before, I had to use the 'boot-repair' utility with the live cd to get grub working again. I think that this utility maybe created a new grub for me because the startup is definitely not the same. The screen goes blank for a while, and then the ubuntu loading dots come up for a brief moment (instead of during the whole startup process) before the dektop is displayed. Anyway : # DO NOT EDIT THIS FILE # # It is automatically generated by grub-mkconfig using templates # from /etc/grub.d and settings from /etc/default/grub # ### BEGIN /etc/grub.d/00_header ### if [ -s $prefix/grubenv ]; then set have_grubenv=true load_env fi set default="0" if [ "${prev_saved_entry}" ]; then set saved_entry="${prev_saved_entry}" save_env saved_entry set prev_saved_entry= save_env prev_saved_entry set boot_once=true fi function savedefault { if [ -z "${boot_once}" ]; then saved_entry="${chosen}" save_env saved_entry fi } function recordfail { set recordfail=1 if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi } function load_video { insmod vbe insmod vga insmod video_bochs insmod video_cirrus } insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a if loadfont /usr/share/grub/unicode.pf2 ; then set gfxmode=auto load_video insmod gfxterm insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a set locale_dir=($root)/boot/grub/locale set lang=en_US insmod gettext fi terminal_output gfxterm if [ "${recordfail}" = 1 ]; then set timeout=10 else set timeout=10 fi ### END /etc/grub.d/00_header ### ### BEGIN /etc/grub.d/05_debian_theme ### set menu_color_normal=white/black set menu_color_highlight=black/light-gray if background_color 44,0,30; then clear fi ### END /etc/grub.d/05_debian_theme ### ### BEGIN /etc/grub.d/10_linux ### if [ ${recordfail} != 1 ]; then if [ -e ${prefix}/gfxblacklist.txt ]; then if hwmatch ${prefix}/gfxblacklist.txt 3; then if [ ${match} = 0 ]; then set linux_gfx_mode=keep else set linux_gfx_mode=text fi else set linux_gfx_mode=text fi else set linux_gfx_mode=keep fi else set linux_gfx_mode=text fi export linux_gfx_mode if [ "$linux_gfx_mode" != "text" ]; then load_video; fi menuentry 'Ubuntu, with Linux 3.0.0-12-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail set gfxpayload=$linux_gfx_mode insmod gzio insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a linux /boot/vmlinuz-3.0.0-12-generic root=UUID=5349ff67-b7b7-489f-a881-ae49c1dcd84a ro quiet splash vt.handoff=7 initrd /boot/initrd.img-3.0.0-12-generic } menuentry 'Ubuntu, with Linux 3.0.0-12-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod gzio insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a echo 'Loading Linux 3.0.0-12-generic ...' linux /boot/vmlinuz-3.0.0-12-generic root=UUID=5349ff67-b7b7-489f-a881-ae49c1dcd84a ro recovery nomodeset echo 'Loading initial ramdisk ...' initrd /boot/initrd.img-3.0.0-12-generic } ### END /etc/grub.d/10_linux ### ### BEGIN /etc/grub.d/20_linux_xen ### ### END /etc/grub.d/20_linux_xen ### ### BEGIN /etc/grub.d/20_memtest86+ ### menuentry "Memory test (memtest86+)" { insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a linux16 /boot/memtest86+.bin } menuentry "Memory test (memtest86+, serial console 115200)" { insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a linux16 /boot/memtest86+.bin console=ttyS0,115200n8 } ### END /etc/grub.d/20_memtest86+ ### ### BEGIN /etc/grub.d/30_os-prober ### menuentry "Microsoft Windows XP Professional (on /dev/sda1)" --class windows --class os { insmod part_msdos insmod ntfs set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 72A89361A89322A1 drivemap -s (hd0) ${root} chainloader +1 } ### END /etc/grub.d/30_os-prober ### ### BEGIN /etc/grub.d/40_custom ### # This file provides an easy way to add custom menu entries. Simply type the # menu entries you want to add after this comment. Be careful not to change # the 'exec tail' line above. ### END /etc/grub.d/40_custom ### ### BEGIN /etc/grub.d/41_custom ### if [ -f $prefix/custom.cfg ]; then source $prefix/custom.cfg; fi ### END /etc/grub.d/41_custom ### How can I get things back to normal. Thanks, Demian.

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• How do I write a bash script to replace words in files and then rename files?

  - by Jason

  Hi All, I have a folder structure, as shown below: I need to create a bash script that does 4 things: It searches all the files in the generic directory and finds the string 'generic' and makes it into 'something' As above, but changes "GENERIC" to "SOMETHING" As above, but changes "Generic" to "Something" Renames any filename that has "generic" in it with "something" Right now I am doing this process manually by using the search and replace in net beans. I dont know much about bash scripting, but i'm sure this can be done. I'm thinking of something that I would run and it would take "Something" as the input. Where would I start? what functions should I use? overall guidance would be great. thanks. I am using Ubuntu 10.5 desktop edition.

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• Context Issue in ASP.NET MVC 3 Unobtrusive Ajax

  - by imran_ku07

      Introduction:          One of the coolest feature you can find in ASP.NET MVC 3 is Unobtrusive Ajax and Unobtrusive Client Validation which separates the javaScript behavior and functionality from the contents of a web page. If you are migrating your ASP.NET MVC 2 (or 1) application to ASP.NET MVC 3 and leveraging the Unobtrusive Ajax feature then you will find that the this context in the callback function is not the same as in ASP.NET MVC 2(or 1). In this article, I will show you the issue and a simple solution.       Description:           The easiest way to understand the issue is to start with an example. Create an ASP.NET MVC 3 application. Then add the following javascript file references inside your page,   <script src="@Url.Content("~/Scripts/MicrosoftAjax.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/MicrosoftMvcAjax.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/jquery-1.4.4.min.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.js")" type="text/javascript"></script>             Then add the following lines into your view,   @Ajax.ActionLink("About", "About", new AjaxOptions { OnSuccess = "Success" }) <script type="text/javascript"> function Success(data) { alert(this.innerHTML) } </script>              Next, disable Unobtrusive Ajax feature from web.config,   <add key="UnobtrusiveJavaScriptEnabled" value="false"/>              Then run your application and click the About link, you will see the alert window with "About" message on the screen. This shows that the this context in the callback function is the element which is clicked. Now, let's see what will happen when we leverage Unobtrusive Ajax feature. Now enable Unobtrusive Ajax feature from web.config,     <add key="UnobtrusiveJavaScriptEnabled" value="true"/>              Then run your application again and click the About link again, this time you will see the alert window with "undefined" message on the screen. This shows that the this context in the callback function is not the element which is clicked. Here, this context in the callback function is the Ajax settings object provided by jQuery. This may not be desirable because your callback function may need the this context as the element which triggers the Ajax request. The easiest way to make the this context as the element which triggers the Ajax request is to add this line in jquery.unobtrusive-ajax.js file just before $.ajax(options) line,   options.context = element;              Then run your application again and click the About link again, you will find that the this context in the callback function remains same whether you use Unobtrusive Ajax or not.       Summary:          In this article I showed you a breaking change and a simple workaround in ASP.NET MVC 3. If you are migrating your application from ASP.NET MVC 2(or 1) to ASP.NET MVC 3 and leveraging Unobtrusive Ajax feature then you need to consider this breaking change. Hopefully you will enjoy this article too.     SyntaxHighlighter.all()

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• What's the best practice for async APIs that return futures on Scala?

  - by Maurício Linhares

  I have started a project to write an async PostgreSQL driver on Scala and to be async, I need to accept callbacks and use futures, but then accepting a callback and a future makes the code cumbersome because you always have to send a callback even if it is useless. Here's a test: "insert a row in the database" in { withHandler { (handler, future) => future.get(5, TimeUnit.SECONDS) handler.sendQuery( this.create ){ query => }.get( 5, TimeUnit.SECONDS ) handler.sendQuery( this.insert ){ query => }.get( 5, TimeUnit.SECONDS ).rowsAffected === 1 } } Sending the empty callback is horrible but I couldn't find a way to make it optional or anything like that, so right now I don't have a lot of ideas on how this external API should look like. It could be something like: handler.sendQuery( this.create ).addListener { query => println(query) } But then again, I'm not sure how people are organizing API's in this regard. Providing examples in other projects would also be great.

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• Best way to prevent UIPanGestureRecognizer from firing when moving sprites in cocos2d

  - by cjroebuck

  Im using UIPanGestureRecognizer in my cocos2d game to do drag and drop of sprites. I have a row of sprites and when I drag a sprite on top of another one, the sprite underneath it and any other sprites between should shift left or right out of the way to allow space to drop the currently selected sprite. This is working ok, however, if I am too quick at dragging the sprite around the screen, this triggers another round of the UIPanGestureRecognizer's callback method, and screws up the logic, as the sprites are in-between shifting. I need a way to freeze the callback from firing, whilst the other sprites are shifting, then once they have finished moving, re-enable the callback to fire. Whats the best way to do this?

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• Callbacks: when to return value, and when to modify parameter?

  - by MarkN

  When writing a callback, when is best to have the callback return a value, and when is it best to have the callback modify a parameter? Is there a difference? For example, if we wanted to grab a list of dependencies, when would you do this: function GetDependencies(){ return [{"Dep1" : 1.1}, {"Dept2": 1.2}, {"Dep3" : 1.3}]; } And when would you do this? function RegisterDependencies(register){ register.add("Dep1", 1.1); register.add("Dep2", 1.2); register.add("Dep3", 1.3); }

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• Java Swing MVC question

  - by juFo

  I'm following this MVC model: http://java.sun.com/developer/technicalArticles/javase/mvc/ In my model I have an "ArrayList shapes" field and I need the shapes in my view. Is the only way of getting my shapes by getting them in the modelPropertyChange method? public void modelPropertyChange(PropertyChangeEvent evt) { if (evt.getPropertyName().equals(MyController.PROPERTY_TEXT)) { ArrayList<Shape> shapes = (ArrayList<Shape>) evt.getNewValue(); } } or should I also create a generic getter method in my controller? like this generic setter method: protected void setModelProperty(String propertyName, Object newValue) { for (AbstractModel model: registeredModels) { try { Method method = model.getClass(). getMethod("set"+propertyName, new Class[] { newValue.getClass() } ); method.invoke(model, newValue); } catch (Exception ex) { // Handle exception. } } } If I need such a generic getter method, I have no clue how to transform this generic setter above to a generic getter method. If I don't need such a generic getter method to retreive my data from the model, if I only need the modelPropertyChange method from my View. How would I get my data from the model the first time the application starts? :o Pfft I need to get my arraylist of shapes from my model in my view :( (and later I need to get some other data also) So confusing :(

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• A Django form for entering a 0 to n email addresses

  - by Erik

  I have a Django application with some fairly common models in it: UserProfile and Organization. A UserProfile or an Organization can both have 0 to n emails, so I have an Email model that has a GenericForeignKey. UserProfile and Organization Models both have a GenericRelation called emails that points back to the Email model (summary code provided below). The question: what is the best way to provide an Organization form that allows a user to enter organization details including 0 to n email addresses? My Organization create view is a Django class-based view. I'm leading towards creating a dynamic form and an enabling it with Javascript to allow the user to add as many email addresses as necessary. I will render the form with django-crispy-forms. I've thought about doing this with a formset embedded within the form, but this seems like overkill for email addresses. Embedding a formset in a form delivered by a class-based view is cumbersome too. Note that the same issue occurs with the Organization fields phone_numbers and locations. emails.py: from django.db import models from parent_mixins import Parent_Mixin class Email(Parent_Mixin,models.Model): email_type = models.CharField(blank=True,max_length=100,null=True,default=None,verbose_name='Email Type') email = models.EmailField() class Meta: app_label = 'core' organizations.py: from emails import Email from locations import Location from phone_numbers import Phone_Number from django.contrib.contenttypes import generic from django.db import models class Organization(models.Model): active = models.BooleanField() duns_number = models.CharField(blank=True,default=None,null=True,max_length=9) # need to validate this emails = generic.GenericRelation(Email,content_type_field='parent_type',object_id_field='parent_id') legal_name = models.CharField(blank=True,default=None,null=True,max_length=200) locations = generic.GenericRelation(Location,content_type_field='parent_type',object_id_field='parent_id') name = models.CharField(blank=True,default=None,null=True,max_length=200) organization_group = models.CharField(blank=True,default=None,null=True,max_length=200) organization_type = models.CharField(blank=True,default=None,null=True,max_length=200) phone_numbers = generic.GenericRelation(Phone_Number,content_type_field='parent_type',object_id_field='parent_id') taxpayer_id_number = models.CharField(blank=True,default=None,null=True,max_length=9) # need to validate this class Meta: app_label = 'core' parent_mixins.py from django.contrib.contenttypes.models import ContentType from django.contrib.contenttypes import generic from django.db import models class Parent_Mixin(models.Model): parent_type = models.ForeignKey(ContentType,blank=True,null=True) parent_id = models.PositiveIntegerField(blank=True,null=True) parent = generic.GenericForeignKey('parent_type', 'parent_id') class Meta: abstract = True app_label = 'core'

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• Creating a dynamic proxy generator with c# – Part 3 – Creating the constructors

  - by SeanMcAlinden

  Creating a dynamic proxy generator with c# – Part 1 – Creating the Assembly builder, Module builder and caching mechanism Creating a dynamic proxy generator with c# – Part 2 – Interceptor Design For the latest code go to http://rapidioc.codeplex.com/ When building our proxy type, the first thing we need to do is build the constructors. There needs to be a corresponding constructor for each constructor on the passed in base type. We also want to create a field to store the interceptors and construct this list within each constructor. So assuming the passed in base type is a User<int, IRepository> class, were looking to generate constructor code like the following:   Default Constructor public User`2_RapidDynamicBaseProxy() {     this.interceptors = new List<IInterceptor<User<int, IRepository>>>();     DefaultInterceptor<User<int, IRepository>> item = new DefaultInterceptor<User<int, IRepository>>();     this.interceptors.Add(item); }     Parameterised Constructor public User`2_RapidDynamicBaseProxy(IRepository repository1) : base(repository1) {     this.interceptors = new List<IInterceptor<User<int, IRepository>>>();     DefaultInterceptor<User<int, IRepository>> item = new DefaultInterceptor<User<int, IRepository>>();     this.interceptors.Add(item); }   As you can see, we first populate a field on the class with a new list of the passed in base type. Construct our DefaultInterceptor class. Add the DefaultInterceptor instance to our interceptor collection. Although this seems like a relatively small task, there is a fair amount of work require to get this going. Instead of going through every line of code – please download the latest from http://rapidioc.codeplex.com/ and debug through. In this post I’m going to concentrate on explaining how it works. TypeBuilder The TypeBuilder class is the main class used to create the type. You instantiate a new TypeBuilder using the assembly module we created in part 1. /// <summary> /// Creates a type builder. /// </summary> /// <typeparam name="TBase">The type of the base class to be proxied.</typeparam> public static TypeBuilder CreateTypeBuilder<TBase>() where TBase : class {     TypeBuilder typeBuilder = DynamicModuleCache.Get.DefineType         (             CreateTypeName<TBase>(),             TypeAttributes.Class | TypeAttributes.Public,             typeof(TBase),             new Type[] { typeof(IProxy) }         );       if (typeof(TBase).IsGenericType)     {         GenericsHelper.MakeGenericType(typeof(TBase), typeBuilder);     }       return typeBuilder; }   private static string CreateTypeName<TBase>() where TBase : class {     return string.Format("{0}_RapidDynamicBaseProxy", typeof(TBase).Name); } As you can see, I’ve create a new public class derived from TBase which also implements my IProxy interface, this is used later for adding interceptors. If the base type is generic, the following GenericsHelper.MakeGenericType method is called. GenericsHelper using System; using System.Reflection.Emit; namespace Rapid.DynamicProxy.Types.Helpers {     /// <summary>     /// Helper class for generic types and methods.     /// </summary>     internal static class GenericsHelper     {         /// <summary>         /// Makes the typeBuilder a generic.         /// </summary>         /// <param name="concrete">The concrete.</param>         /// <param name="typeBuilder">The type builder.</param>         public static void MakeGenericType(Type baseType, TypeBuilder typeBuilder)         {             Type[] genericArguments = baseType.GetGenericArguments();               string[] genericArgumentNames = GetArgumentNames(genericArguments);               GenericTypeParameterBuilder[] genericTypeParameterBuilder                 = typeBuilder.DefineGenericParameters(genericArgumentNames);               typeBuilder.MakeGenericType(genericTypeParameterBuilder);         }           /// <summary>         /// Gets the argument names from an array of generic argument types.         /// </summary>         /// <param name="genericArguments">The generic arguments.</param>         public static string[] GetArgumentNames(Type[] genericArguments)         {             string[] genericArgumentNames = new string[genericArguments.Length];               for (int i = 0; i < genericArguments.Length; i++)             {                 genericArgumentNames[i] = genericArguments[i].Name;             }               return genericArgumentNames;         }     } }       As you can see, I’m getting all of the generic argument types and names, creating a GenericTypeParameterBuilder and then using the typeBuilder to make the new type generic. InterceptorsField The interceptors field will store a List<IInterceptor<TBase>>. Fields are simple made using the FieldBuilder class. The following code demonstrates how to create the interceptor field. FieldBuilder interceptorsField = typeBuilder.DefineField(     "interceptors",     typeof(System.Collections.Generic.List<>).MakeGenericType(typeof(IInterceptor<TBase>)),       FieldAttributes.Private     ); The field will now exist with the new Type although it currently has no data – we’ll deal with this in the constructor. Add method for interceptorsField To enable us to add to the interceptorsField list, we are going to utilise the Add method that already exists within the System.Collections.Generic.List class. We still however have to create the methodInfo necessary to call the add method. This can be done similar to the following: Add Interceptor Field MethodInfo addInterceptor = typeof(List<>)     .MakeGenericType(new Type[] { typeof(IInterceptor<>).MakeGenericType(typeof(TBase)) })     .GetMethod     (        "Add",        BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic,        null,        new Type[] { typeof(IInterceptor<>).MakeGenericType(typeof(TBase)) },        null     ); So we’ve create a List<IInterceptor<TBase>> type, then using the type created a method info called Add which accepts an IInterceptor<TBase>. Now in our constructor we can use this to call this.interceptors.Add(// interceptor); Building the Constructors This will be the first hard-core part of the proxy building process so I’m going to show the class and then try to explain what everything is doing. For a clear view, download the source from http://rapidioc.codeplex.com/, go to the test project and debug through the constructor building section. Anyway, here it is: DynamicConstructorBuilder using System; using System.Collections.Generic; using System.Reflection; using System.Reflection.Emit; using Rapid.DynamicProxy.Interception; using Rapid.DynamicProxy.Types.Helpers; namespace Rapid.DynamicProxy.Types.Constructors {     /// <summary>     /// Class for creating the proxy constructors.     /// </summary>     internal static class DynamicConstructorBuilder     {         /// <summary>         /// Builds the constructors.         /// </summary>         /// <typeparam name="TBase">The base type.</typeparam>         /// <param name="typeBuilder">The type builder.</param>         /// <param name="interceptorsField">The interceptors field.</param>         public static void BuildConstructors<TBase>             (                 TypeBuilder typeBuilder,                 FieldBuilder interceptorsField,                 MethodInfo addInterceptor             )             where TBase : class         {             ConstructorInfo interceptorsFieldConstructor = CreateInterceptorsFieldConstructor<TBase>();               ConstructorInfo defaultInterceptorConstructor = CreateDefaultInterceptorConstructor<TBase>();               ConstructorInfo[] constructors = typeof(TBase).GetConstructors();               foreach (ConstructorInfo constructorInfo in constructors)             {                 CreateConstructor<TBase>                     (                         typeBuilder,                         interceptorsField,                         interceptorsFieldConstructor,                         defaultInterceptorConstructor,                         addInterceptor,                         constructorInfo                     );             }         }           #region Private Methods           private static void CreateConstructor<TBase>             (                 TypeBuilder typeBuilder,                 FieldBuilder interceptorsField,                 ConstructorInfo interceptorsFieldConstructor,                 ConstructorInfo defaultInterceptorConstructor,                 MethodInfo AddDefaultInterceptor,                 ConstructorInfo constructorInfo             ) where TBase : class         {             Type[] parameterTypes = GetParameterTypes(constructorInfo);               ConstructorBuilder constructorBuilder = CreateConstructorBuilder(typeBuilder, parameterTypes);               ILGenerator cIL = constructorBuilder.GetILGenerator();               LocalBuilder defaultInterceptorMethodVariable =                 cIL.DeclareLocal(typeof(DefaultInterceptor<>).MakeGenericType(typeof(TBase)));               ConstructInterceptorsField(interceptorsField, interceptorsFieldConstructor, cIL);               ConstructDefaultInterceptor(defaultInterceptorConstructor, cIL, defaultInterceptorMethodVariable);               AddDefaultInterceptorToInterceptorsList                 (                     interceptorsField,                     AddDefaultInterceptor,                     cIL,                     defaultInterceptorMethodVariable                 );               CreateConstructor(constructorInfo, parameterTypes, cIL);         }           private static void CreateConstructor(ConstructorInfo constructorInfo, Type[] parameterTypes, ILGenerator cIL)         {             cIL.Emit(OpCodes.Ldarg_0);               if (parameterTypes.Length > 0)             {                 LoadParameterTypes(parameterTypes, cIL);             }               cIL.Emit(OpCodes.Call, constructorInfo);             cIL.Emit(OpCodes.Ret);         }           private static void LoadParameterTypes(Type[] parameterTypes, ILGenerator cIL)         {             for (int i = 1; i <= parameterTypes.Length; i++)             {                 cIL.Emit(OpCodes.Ldarg_S, i);             }         }           private static void AddDefaultInterceptorToInterceptorsList             (                 FieldBuilder interceptorsField,                 MethodInfo AddDefaultInterceptor,                 ILGenerator cIL,                 LocalBuilder defaultInterceptorMethodVariable             )         {             cIL.Emit(OpCodes.Ldarg_0);             cIL.Emit(OpCodes.Ldfld, interceptorsField);             cIL.Emit(OpCodes.Ldloc, defaultInterceptorMethodVariable);             cIL.Emit(OpCodes.Callvirt, AddDefaultInterceptor);         }           private static void ConstructDefaultInterceptor             (                 ConstructorInfo defaultInterceptorConstructor,                 ILGenerator cIL,                 LocalBuilder defaultInterceptorMethodVariable             )         {             cIL.Emit(OpCodes.Newobj, defaultInterceptorConstructor);             cIL.Emit(OpCodes.Stloc, defaultInterceptorMethodVariable);         }           private static void ConstructInterceptorsField             (                 FieldBuilder interceptorsField,                 ConstructorInfo interceptorsFieldConstructor,                 ILGenerator cIL             )         {             cIL.Emit(OpCodes.Ldarg_0);             cIL.Emit(OpCodes.Newobj, interceptorsFieldConstructor);             cIL.Emit(OpCodes.Stfld, interceptorsField);         }           private static ConstructorBuilder CreateConstructorBuilder(TypeBuilder typeBuilder, Type[] parameterTypes)         {             return typeBuilder.DefineConstructor                 (                     MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.RTSpecialName                     | MethodAttributes.HideBySig, CallingConventions.Standard, parameterTypes                 );         }           private static Type[] GetParameterTypes(ConstructorInfo constructorInfo)         {             ParameterInfo[] parameterInfoArray = constructorInfo.GetParameters();               Type[] parameterTypes = new Type[parameterInfoArray.Length];               for (int p = 0; p < parameterInfoArray.Length; p++)             {                 parameterTypes[p] = parameterInfoArray[p].ParameterType;             }               return parameterTypes;         }           private static ConstructorInfo CreateInterceptorsFieldConstructor<TBase>() where TBase : class         {             return ConstructorHelper.CreateGenericConstructorInfo                 (                     typeof(List<>),                     new Type[] { typeof(IInterceptor<TBase>) },                     BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic                 );         }           private static ConstructorInfo CreateDefaultInterceptorConstructor<TBase>() where TBase : class         {             return ConstructorHelper.CreateGenericConstructorInfo                 (                     typeof(DefaultInterceptor<>),                     new Type[] { typeof(TBase) },                     BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic                 );         }           #endregion     } } So, the first two tasks within the class should be fairly clear, we are creating a ConstructorInfo for the interceptorField list and a ConstructorInfo for the DefaultConstructor, this is for instantiating them in each contructor. We then using Reflection get an array of all of the constructors in the base class, we then loop through the array and create a corresponding proxy contructor. Hopefully, the code is fairly easy to follow other than some new types and the dreaded Opcodes. ConstructorBuilder This class defines a new constructor on the type. ILGenerator The ILGenerator allows the use of Reflection.Emit to create the method body. LocalBuilder The local builder allows the storage of data in local variables within a method, in this case it’s the constructed DefaultInterceptor. Constructing the interceptors field The first bit of IL you’ll come across as you follow through the code is the following private method used for constructing the field list of interceptors. private static void ConstructInterceptorsField             (                 FieldBuilder interceptorsField,                 ConstructorInfo interceptorsFieldConstructor,                 ILGenerator cIL             )         {             cIL.Emit(OpCodes.Ldarg_0);             cIL.Emit(OpCodes.Newobj, interceptorsFieldConstructor);             cIL.Emit(OpCodes.Stfld, interceptorsField);         } The first thing to know about generating code using IL is that you are using a stack, if you want to use something, you need to push it up the stack etc. etc. OpCodes.ldArg_0 This opcode is a really interesting one, basically each method has a hidden first argument of the containing class instance (apart from static classes), constructors are no different. This is the reason you can use syntax like this.myField. So back to the method, as we want to instantiate the List in the interceptorsField, first we need to load the class instance onto the stack, we then load the new object (new List<TBase>) and finally we store it in the interceptorsField. Hopefully, that should follow easily enough in the method. In each constructor you would now have this.interceptors = new List<User<int, IRepository>>(); Constructing and storing the DefaultInterceptor The next bit of code we need to create is the constructed DefaultInterceptor. Firstly, we create a local builder to store the constructed type. Create a local builder LocalBuilder defaultInterceptorMethodVariable =     cIL.DeclareLocal(typeof(DefaultInterceptor<>).MakeGenericType(typeof(TBase))); Once our local builder is ready, we then need to construct the DefaultInterceptor<TBase> and store it in the variable. Connstruct DefaultInterceptor private static void ConstructDefaultInterceptor     (         ConstructorInfo defaultInterceptorConstructor,         ILGenerator cIL,         LocalBuilder defaultInterceptorMethodVariable     ) {     cIL.Emit(OpCodes.Newobj, defaultInterceptorConstructor);     cIL.Emit(OpCodes.Stloc, defaultInterceptorMethodVariable); } As you can see, using the ConstructorInfo named defaultInterceptorConstructor, we load the new object onto the stack. Then using the store local opcode (OpCodes.Stloc), we store the new object in the local builder named defaultInterceptorMethodVariable. Add the constructed DefaultInterceptor to the interceptors field collection Using the add method created earlier in this post, we are going to add the new DefaultInterceptor object to the interceptors field collection. Add Default Interceptor private static void AddDefaultInterceptorToInterceptorsList     (         FieldBuilder interceptorsField,         MethodInfo AddDefaultInterceptor,         ILGenerator cIL,         LocalBuilder defaultInterceptorMethodVariable     ) {     cIL.Emit(OpCodes.Ldarg_0);     cIL.Emit(OpCodes.Ldfld, interceptorsField);     cIL.Emit(OpCodes.Ldloc, defaultInterceptorMethodVariable);     cIL.Emit(OpCodes.Callvirt, AddDefaultInterceptor); } So, here’s whats going on. The class instance is first loaded onto the stack using the load argument at index 0 opcode (OpCodes.Ldarg_0) (remember the first arg is the hidden class instance). The interceptorsField is then loaded onto the stack using the load field opcode (OpCodes.Ldfld). We then load the DefaultInterceptor object we stored locally using the load local opcode (OpCodes.Ldloc). Then finally we call the AddDefaultInterceptor method using the call virtual opcode (Opcodes.Callvirt). Completing the constructor The last thing we need to do is complete the constructor. Complete the constructor private static void CreateConstructor(ConstructorInfo constructorInfo, Type[] parameterTypes, ILGenerator cIL)         {             cIL.Emit(OpCodes.Ldarg_0);               if (parameterTypes.Length > 0)             {                 LoadParameterTypes(parameterTypes, cIL);             }               cIL.Emit(OpCodes.Call, constructorInfo);             cIL.Emit(OpCodes.Ret);         }           private static void LoadParameterTypes(Type[] parameterTypes, ILGenerator cIL)         {             for (int i = 1; i <= parameterTypes.Length; i++)             {                 cIL.Emit(OpCodes.Ldarg_S, i);             }         } So, the first thing we do again is load the class instance using the load argument at index 0 opcode (OpCodes.Ldarg_0). We then load each parameter using OpCode.Ldarg_S, this opcode allows us to specify an index position for each argument. We then setup calling the base constructor using OpCodes.Call and the base constructors ConstructorInfo. Finally, all methods are required to return, even when they have a void return. As there are no values on the stack after the OpCodes.Call line, we can safely call the OpCode.Ret to give the constructor a void return. If there was a value, we would have to pop the value of the stack before calling return otherwise, the method would try and return a value. Conclusion This was a slightly hardcore post but hopefully it hasn’t been too hard to follow. The main thing is that a number of the really useful opcodes have been used and now the dynamic proxy is capable of being constructed. If you download the code and debug through the tests at http://rapidioc.codeplex.com/, you’ll be able to create proxies at this point, they cannon do anything in terms of interception but you can happily run the tests, call base methods and properties and also take a look at the created assembly in Reflector. Hope this is useful. The next post should be up soon, it will be covering creating the private methods for calling the base class methods and properties. Kind Regards, Sean.

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• Another "Windows 7 entry missing from Grub2" Question

  - by 4x10

  Like many before me had the following problem that after installing Ubuntu (with windows 7 already installed), the grub boot loader wouldnt show windows 7 as a boot option, though i can boot fine if I use the "Choose Boot Device" options on the x220. The difference is that I try using UEFI only so many answers didn't really fit my problem, though i tried several stuffs: after running boot repair it destroyed the ubuntu boot loader custom entry in /etc/grub.d/40_custom for windows which doesnt show up many update-grub and reboots trying windows repair recovery thing while being there i also did bootrec.exe /FixBoot and update-grub and reboot again and finaly because it was so much fun, i installed linux all over again, while formatting and deleting everything linux related before that. Now that i think of it, Ubuntu also didn't notice Windows being there during the Setup and it still doesnt according to the Boot Info from Boot Repair. Boot Info Script 0.61-git-patched [23 April 2012] ============================= Boot Info Summary: =============================== => No boot loader is installed in the MBR of /dev/sda. sda1: __________________________________________________________________________ File system: vfat Boot sector type: Windows 7: FAT32 Boot sector info: No errors found in the Boot Parameter Block. Operating System: Boot files: /efi/Boot/bootx64.efi /efi/ubuntu/grubx64.efi sda2: __________________________________________________________________________ File system: Boot sector type: - Boot sector info: Mounting failed: mount: unknown filesystem type '' sda3: __________________________________________________________________________ File system: ntfs Boot sector type: Windows Vista/7: NTFS Boot sector info: No errors found in the Boot Parameter Block. Operating System: Windows 7 Boot files: /Windows/System32/winload.exe sda4: __________________________________________________________________________ File system: ext4 Boot sector type: - Boot sector info: Operating System: Ubuntu precise (development branch) Boot files: /boot/grub/grub.cfg /etc/fstab sda5: __________________________________________________________________________ File system: ext4 Boot sector type: - Boot sector info: Operating System: Boot files: sda6: __________________________________________________________________________ File system: swap Boot sector type: - Boot sector info: ============================ Drive/Partition Info: ============================= Drive: sda _____________________________________________________________________ Disk /dev/sda: 320.1 GB, 320072933376 bytes 255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes Partition Boot Start Sector End Sector # of Sectors Id System /dev/sda1 1 625,142,447 625,142,447 ee GPT GUID Partition Table detected. Partition Start Sector End Sector # of Sectors System /dev/sda1 2,048 206,847 204,800 EFI System partition /dev/sda2 206,848 468,991 262,144 Microsoft Reserved Partition (Windows) /dev/sda3 468,992 170,338,303 169,869,312 Data partition (Windows/Linux) /dev/sda4 170,338,304 330,338,304 160,000,001 Data partition (Windows/Linux) /dev/sda5 330,338,305 617,141,039 286,802,735 Data partition (Windows/Linux) /dev/sda6 617,141,040 625,141,040 8,000,001 Swap partition (Linux) "blkid" output: ________________________________________________________________ Device UUID TYPE LABEL /dev/sda1 885C-ED1B vfat /dev/sda3 EE06CC0506CBCCB1 ntfs /dev/sda4 604dd3b2-64ca-4200-b8fb-820e8d0ca899 ext4 /dev/sda5 d62515fd-8120-4a74-b17b-0bdf244124a3 ext4 /dev/sda6 7078b649-fb2a-4c59-bd03-fd31ef440d37 swap ================================ Mount points: ================================= Device Mount_Point Type Options /dev/sda1 /boot/efi vfat (rw) /dev/sda4 / ext4 (rw,errors=remount-ro) /dev/sda5 /home ext4 (rw) =========================== sda4/boot/grub/grub.cfg: =========================== -------------------------------------------------------------------------------- # # DO NOT EDIT THIS FILE # # It is automatically generated by grub-mkconfig using templates # from /etc/grub.d and settings from /etc/default/grub # ### BEGIN /etc/grub.d/00_header ### if [ -s $prefix/grubenv ]; then set have_grubenv=true load_env fi set default="0" if [ "${prev_saved_entry}" ]; then set saved_entry="${prev_saved_entry}" save_env saved_entry set prev_saved_entry= save_env prev_saved_entry set boot_once=true fi function savedefault { if [ -z "${boot_once}" ]; then saved_entry="${chosen}" save_env saved_entry fi } function recordfail { set recordfail=1 if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi } function load_video { insmod efi_gop insmod efi_uga insmod video_bochs insmod video_cirrus } insmod part_gpt insmod ext2 set root='(hd0,gpt4)' search --no-floppy --fs-uuid --set=root 604dd3b2-64ca-4200-b8fb-820e8d0ca899 if loadfont /usr/share/grub/unicode.pf2 ; then set gfxmode=auto load_video insmod gfxterm insmod part_gpt insmod ext2 set root='(hd0,gpt4)' search --no-floppy --fs-uuid --set=root 604dd3b2-64ca-4200-b8fb-820e8d0ca899 set locale_dir=($root)/boot/grub/locale set lang=en_US insmod gettext fi terminal_output gfxterm if [ "${recordfail}" = 1 ]; then set timeout=-1 else set timeout=10 fi ### END /etc/grub.d/00_header ### ### BEGIN /etc/grub.d/05_debian_theme ### set menu_color_normal=white/black set menu_color_highlight=black/light-gray if background_color 44,0,30; then clear fi ### END /etc/grub.d/05_debian_theme ### ### BEGIN /etc/grub.d/10_linux ### function gfxmode { set gfxpayload="$1" if [ "$1" = "keep" ]; then set vt_handoff=vt.handoff=7 else set vt_handoff= fi } if [ ${recordfail} != 1 ]; then if [ -e ${prefix}/gfxblacklist.txt ]; then if hwmatch ${prefix}/gfxblacklist.txt 3; then if [ ${match} = 0 ]; then set linux_gfx_mode=keep else set linux_gfx_mode=text fi else set linux_gfx_mode=text fi else set linux_gfx_mode=keep fi else set linux_gfx_mode=text fi export linux_gfx_mode if [ "$linux_gfx_mode" != "text" ]; then load_video; fi menuentry 'Ubuntu, with Linux 3.2.0-20-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail gfxmode $linux_gfx_mode insmod gzio insmod part_gpt insmod ext2 set root='(hd0,gpt4)' search --no-floppy --fs-uuid --set=root 604dd3b2-64ca-4200-b8fb-820e8d0ca899 linux /boot/vmlinuz-3.2.0-20-generic root=UUID=604dd3b2-64ca-4200-b8fb-820e8d0ca899 ro quiet splash $vt_handoff initrd /boot/initrd.img-3.2.0-20-generic } menuentry 'Ubuntu, with Linux 3.2.0-20-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod gzio insmod part_gpt insmod ext2 set root='(hd0,gpt4)' search --no-floppy --fs-uuid --set=root 604dd3b2-64ca-4200-b8fb-820e8d0ca899 echo 'Loading Linux 3.2.0-20-generic ...' linux /boot/vmlinuz-3.2.0-20-generic root=UUID=604dd3b2-64ca-4200-b8fb-820e8d0ca899 ro recovery nomodeset echo 'Loading initial ramdisk ...' initrd /boot/initrd.img-3.2.0-20-generic } ### END /etc/grub.d/10_linux ### ### BEGIN /etc/grub.d/20_linux_xen ### ### END /etc/grub.d/20_linux_xen ### ### BEGIN /etc/grub.d/20_memtest86+ ### menuentry "Memory test (memtest86+)" { insmod part_gpt insmod ext2 set root='(hd0,gpt4)' search --no-floppy --fs-uuid --set=root 604dd3b2-64ca-4200-b8fb-820e8d0ca899 linux16 /boot/memtest86+.bin } menuentry "Memory test (memtest86+, serial console 115200)" { insmod part_gpt insmod ext2 set root='(hd0,gpt4)' search --no-floppy --fs-uuid --set=root 604dd3b2-64ca-4200-b8fb-820e8d0ca899 linux16 /boot/memtest86+.bin console=ttyS0,115200n8 } ### END /etc/grub.d/20_memtest86+ ### ### BEGIN /etc/grub.d/30_os-prober ### ### END /etc/grub.d/30_os-prober ### ### BEGIN /etc/grub.d/40_custom ### # This file provides an easy way to add custom menu entries. Simply type the # menu entries you want to add after this comment. Be careful not to change # the 'exec tail' line above. ### END /etc/grub.d/40_custom ### ### BEGIN /etc/grub.d/41_custom ### if [ -f $prefix/custom.cfg ]; then source $prefix/custom.cfg; fi ### END /etc/grub.d/41_custom ### -------------------------------------------------------------------------------- =============================== sda4/etc/fstab: ================================ -------------------------------------------------------------------------------- # /etc/fstab: static file system information. # # Use 'blkid' to print the universally unique identifier for a # device; this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc nodev,noexec,nosuid 0 0 # / was on /dev/sda4 during installation UUID=604dd3b2-64ca-4200-b8fb-820e8d0ca899 / ext4 errors=remount-ro 0 1 # /boot/efi was on /dev/sda1 during installation UUID=885C-ED1B /boot/efi vfat defaults 0 1 # /home was on /dev/sda5 during installation UUID=d62515fd-8120-4a74-b17b-0bdf244124a3 /home ext4 defaults 0 2 # swap was on /dev/sda6 during installation UUID=7078b649-fb2a-4c59-bd03-fd31ef440d37 none swap sw 0 0 -------------------------------------------------------------------------------- =================== sda4: Location of files loaded by Grub: ==================== GiB - GB File Fragment(s) 129.422874451 = 138.966753280 boot/grub/grub.cfg 1 83.059570312 = 89.184534528 boot/initrd.img-3.2.0-20-generic 2 101.393131256 = 108.870045696 boot/vmlinuz-3.2.0-20-generic 1 83.059570312 = 89.184534528 initrd.img 2 101.393131256 = 108.870045696 vmlinuz 1 ADDITIONAL INFORMATION : =================== log of boot-repair 2012-04-25__23h40 =================== boot-repair version : 3.18-0ppa3~precise boot-sav version : 3.18-0ppa4~precise glade2script version : 0.3.2.1-0ppa7~precise internet: connected python-software-properties version : 0.82.7 0 upgraded, 0 newly installed, 1 reinstalled, 0 to remove and 591 not upgraded. dpkg-preconfigure: unable to re-open stdin: No such file or directory boot-repair is executed in installed-session (Ubuntu precise (development branch) , precise , Ubuntu , x86_64) WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted. =================== OSPROBER: /dev/sda4:The OS now in use - Ubuntu precise (development branch) CurrentSession:linux =================== BLKID: /dev/sda3: UUID="EE06CC0506CBCCB1" TYPE="ntfs" /dev/sda1: UUID="885C-ED1B" TYPE="vfat" /dev/sda4: UUID="604dd3b2-64ca-4200-b8fb-820e8d0ca899" TYPE="ext4" /dev/sda5: UUID="d62515fd-8120-4a74-b17b-0bdf244124a3" TYPE="ext4" /dev/sda6: UUID="7078b649-fb2a-4c59-bd03-fd31ef440d37" TYPE="swap" 1 disks with OS, 1 OS : 1 Linux, 0 MacOS, 0 Windows, 0 unknown type OS. WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util sfdisk doesn't support GPT. Use GNU Parted. =================== /etc/default/grub : # If you change this file, run 'update-grub' afterwards to update # /boot/grub/grub.cfg. # For full documentation of the options in this file, see: # info -f grub -n 'Simple configuration' GRUB_DEFAULT=0 #GRUB_HIDDEN_TIMEOUT=0 #GRUB_HIDDEN_TIMEOUT_QUIET=true GRUB_TIMEOUT=10 GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian` GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" GRUB_CMDLINE_LINUX="" # Uncomment to enable BadRAM filtering, modify to suit your needs # This works with Linux (no patch required) and with any kernel that obtains # the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...) #GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef" # Uncomment to disable graphical terminal (grub-pc only) #GRUB_TERMINAL=console # The resolution used on graphical terminal # note that you can use only modes which your graphic card supports via VBE # you can see them in real GRUB with the command `vbeinfo' #GRUB_GFXMODE=640x480 # Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux #GRUB_DISABLE_LINUX_UUID=true # Uncomment to disable generation of recovery mode menu entries #GRUB_DISABLE_RECOVERY="true" # Uncomment to get a beep at grub start #GRUB_INIT_TUNE="480 440 1" EFI_OF_PART[1] (, ) =================== dmesg | grep EFI : [ 0.000000] EFI v2.00 by Lenovo [ 0.000000] Kernel-defined memdesc doesn't match the one from EFI! [ 0.000000] EFI: mem00: type=3, attr=0xf, range=[0x0000000000000000-0x0000000000001000) (0MB) [ 0.000000] EFI: mem01: type=7, attr=0xf, range=[0x0000000000001000-0x000000000004e000) (0MB) [ 0.000000] EFI: mem02: type=3, attr=0xf, range=[0x000000000004e000-0x0000000000058000) (0MB) [ 0.000000] EFI: mem03: type=10, attr=0xf, range=[0x0000000000058000-0x0000000000059000) (0MB) [ 0.000000] EFI: mem04: type=7, attr=0xf, range=[0x0000000000059000-0x000000000005e000) (0MB) [ 0.000000] EFI: mem05: type=4, attr=0xf, range=[0x000000000005e000-0x000000000005f000) (0MB) [ 0.000000] EFI: mem06: type=3, attr=0xf, range=[0x000000000005f000-0x00000000000a0000) (0MB) [ 0.000000] EFI: mem07: type=2, attr=0xf, range=[0x0000000000100000-0x00000000005b9000) (4MB) [ 0.000000] EFI: mem08: type=7, attr=0xf, range=[0x00000000005b9000-0x0000000020000000) (506MB) [ 0.000000] EFI: mem09: type=0, attr=0xf, range=[0x0000000020000000-0x0000000020200000) (2MB) [ 0.000000] EFI: mem10: type=7, attr=0xf, range=[0x0000000020200000-0x00000000364e4000) (354MB) [ 0.000000] EFI: mem11: type=2, attr=0xf, range=[0x00000000364e4000-0x000000003726a000) (13MB) [ 0.000000] EFI: mem12: type=7, attr=0xf, range=[0x000000003726a000-0x0000000040000000) (141MB) [ 0.000000] EFI: mem13: type=0, attr=0xf, range=[0x0000000040000000-0x0000000040200000) (2MB) [ 0.000000] EFI: mem14: type=7, attr=0xf, range=[0x0000000040200000-0x000000009df35000) (1501MB) [ 0.000000] EFI: mem15: type=2, attr=0xf, range=[0x000000009df35000-0x00000000d39a0000) (858MB) [ 0.000000] EFI: mem16: type=4, attr=0xf, range=[0x00000000d39a0000-0x00000000d39c0000) (0MB) [ 0.000000] EFI: mem17: type=7, attr=0xf, range=[0x00000000d39c0000-0x00000000d5df5000) (36MB) [ 0.000000] EFI: mem18: type=4, attr=0xf, range=[0x00000000d5df5000-0x00000000d6990000) (11MB) [ 0.000000] EFI: mem19: type=7, attr=0xf, range=[0x00000000d6990000-0x00000000d6b82000) (1MB) [ 0.000000] EFI: mem20: type=1, attr=0xf, range=[0x00000000d6b82000-0x00000000d6b9f000) (0MB) [ 0.000000] EFI: mem21: type=7, attr=0xf, range=[0x00000000d6b9f000-0x00000000d77b0000) (12MB) [ 0.000000] EFI: mem22: type=4, attr=0xf, range=[0x00000000d77b0000-0x00000000d780a000) (0MB) [ 0.000000] EFI: mem23: type=7, attr=0xf, range=[0x00000000d780a000-0x00000000d7826000) (0MB) [ 0.000000] EFI: mem24: type=4, attr=0xf, range=[0x00000000d7826000-0x00000000d7868000) (0MB) [ 0.000000] EFI: mem25: type=7, attr=0xf, range=[0x00000000d7868000-0x00000000d7869000) (0MB) [ 0.000000] EFI: mem26: type=4, attr=0xf, range=[0x00000000d7869000-0x00000000d786a000) (0MB) [ 0.000000] EFI: mem27: type=7, attr=0xf, range=[0x00000000d786a000-0x00000000d786b000) (0MB) [ 0.000000] EFI: mem28: type=4, attr=0xf, range=[0x00000000d786b000-0x00000000d786c000) (0MB) [ 0.000000] EFI: mem29: type=7, attr=0xf, range=[0x00000000d786c000-0x00000000d786d000) (0MB) [ 0.000000] EFI: mem30: type=4, attr=0xf, range=[0x00000000d786d000-0x00000000d825f000) (9MB) [ 0.000000] EFI: mem31: type=7, attr=0xf, range=[0x00000000d825f000-0x00000000d8261000) (0MB) [ 0.000000] EFI: mem32: type=4, attr=0xf, range=[0x00000000d8261000-0x00000000d82f7000) (0MB) [ 0.000000] EFI: mem33: type=7, attr=0xf, range=[0x00000000d82f7000-0x00000000d82f8000) (0MB) [ 0.000000] EFI: mem34: type=4, attr=0xf, range=[0x00000000d82f8000-0x00000000d8705000) (4MB) [ 0.000000] EFI: mem35: type=7, attr=0xf, range=[0x00000000d8705000-0x00000000d8706000) (0MB) [ 0.000000] EFI: mem36: type=4, attr=0xf, range=[0x00000000d8706000-0x00000000d8761000) (0MB) [ 0.000000] EFI: mem37: type=7, attr=0xf, range=[0x00000000d8761000-0x00000000d8768000) (0MB) [ 0.000000] EFI: mem38: type=4, attr=0xf, range=[0x00000000d8768000-0x00000000d9b9f000) (20MB) [ 0.000000] EFI: mem39: type=7, attr=0xf, range=[0x00000000d9b9f000-0x00000000d9e4c000) (2MB) [ 0.000000] EFI: mem40: type=2, attr=0xf, range=[0x00000000d9e4c000-0x00000000d9e52000) (0MB) [ 0.000000] EFI: mem41: type=3, attr=0xf, range=[0x00000000d9e52000-0x00000000da59f000) (7MB) [ 0.000000] EFI: mem42: type=5, attr=0x800000000000000f, range=[0x00000000da59f000-0x00000000da6c3000) (1MB) [ 0.000000] EFI: mem43: type=5, attr=0x800000000000000f, range=[0x00000000da6c3000-0x00000000da79f000) (0MB) [ 0.000000] EFI: mem44: type=6, attr=0x800000000000000f, range=[0x00000000da79f000-0x00000000da8b1000) (1MB) [ 0.000000] EFI: mem45: type=6, attr=0x800000000000000f, range=[0x00000000da8b1000-0x00000000da99f000) (0MB) [ 0.000000] EFI: mem46: type=0, attr=0xf, range=[0x00000000da99f000-0x00000000daa22000) (0MB) [ 0.000000] EFI: mem47: type=0, attr=0xf, range=[0x00000000daa22000-0x00000000daa9b000) (0MB) [ 0.000000] EFI: mem48: type=0, attr=0xf, range=[0x00000000daa9b000-0x00000000daa9c000) (0MB) [ 0.000000] EFI: mem49: type=0, attr=0xf, range=[0x00000000daa9c000-0x00000000daa9f000) (0MB) [ 0.000000] EFI: mem50: type=10, attr=0xf, range=[0x00000000daa9f000-0x00000000daadd000) (0MB) [ 0.000000] EFI: mem51: type=10, attr=0xf, range=[0x00000000daadd000-0x00000000dab9f000) (0MB) [ 0.000000] EFI: mem52: type=9, attr=0xf, range=[0x00000000dab9f000-0x00000000dabdc000) (0MB) [ 0.000000] EFI: mem53: type=9, attr=0xf, range=[0x00000000dabdc000-0x00000000dabff000) (0MB) [ 0.000000] EFI: mem54: type=4, attr=0xf, range=[0x00000000dabff000-0x00000000dac00000) (0MB) [ 0.000000] EFI: mem55: type=7, attr=0xf, range=[0x0000000100000000-0x000000021e600000) (4582MB) [ 0.000000] EFI: mem56: type=11, attr=0x8000000000000001, range=[0x00000000f80f8000-0x00000000f80f9000) (0MB) [ 0.000000] EFI: mem57: type=11, attr=0x8000000000000001, range=[0x00000000fed1c000-0x00000000fed20000) (0MB) [ 0.000000] ACPI: UEFI 00000000dabde000 0003E (v01 LENOVO TP-8D 00001280 PTL 00000002) [ 0.000000] ACPI: UEFI 00000000dabdd000 00042 (v01 PTL COMBUF 00000001 PTL 00000001) [ 0.000000] ACPI: UEFI 00000000dabdc000 00292 (v01 LENOVO TP-8D 00001280 PTL 00000002) [ 0.795807] fb0: EFI VGA frame buffer device [ 1.057243] EFI Variables Facility v0.08 2004-May-17 [ 9.122104] fb: conflicting fb hw usage inteldrmfb vs EFI VGA - removing generic driver ReadEFI: /dev/sda , N 128 , 0 , , PRStart 1024 , PRSize 128 WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted. =================== PARTITIONS & DISKS: sda4 : sda, not-sepboot, grubenv-ok grub2, grub-efi, update-grub, 64, with-boot, is-os, gpt-but-not-EFI, fstab-has-bad-efi, no-nt, no-winload, no-recov-nor-hid, no-bmgr, no-grldr, no-b-bcd, apt-get, grub-install, . sda3 : sda, maybesepboot, no-grubenv nogrub, no-docgrub, no-update-grub, 32, no-boot, no-os, gpt-but-not-EFI, part-has-no-fstab, no-nt, haswinload, no-recov-nor-hid, no-bmgr, no-grldr, no-b-bcd, nopakmgr, nogrubinstall, /mnt/boot-sav/sda3. sda1 : sda, maybesepboot, no-grubenv nogrub, no-docgrub, no-update-grub, 32, no-boot, no-os, is-correct-EFI, part-has-no-fstab, no-nt, no-winload, no-recov-nor-hid, no-bmgr, no-grldr, no-b-bcd, nopakmgr, nogrubinstall, /boot/efi. sda5 : sda, maybesepboot, no-grubenv nogrub, no-docgrub, no-update-grub, 32, no-boot, no-os, gpt-but-not-EFI, part-has-no-fstab, no-nt, no-winload, no-recov-nor-hid, no-bmgr, no-grldr, no-b-bcd, nopakmgr, nogrubinstall, /home. sda : GPT-BIS, GPT, no-BIOS_boot, has-correctEFI, 2048 sectors * 512 bytes =================== PARTED: Model: ATA HITACHI HTS72323 (scsi) Disk /dev/sda: 320GB Sector size (logical/physical): 512B/512B Partition Table: gpt Number Start End Size File system Name Flags 1 1049kB 106MB 105MB fat32 EFI system partition boot 2 106MB 240MB 134MB Microsoft reserved partition msftres 3 240MB 87.2GB 87.0GB ntfs Basic data partition 4 87.2GB 169GB 81.9GB ext4 5 169GB 316GB 147GB ext4 6 316GB 320GB 4096MB linux-swap(v1) =================== MOUNT: /dev/sda4 on / type ext4 (rw,errors=remount-ro) proc on /proc type proc (rw,noexec,nosuid,nodev) sysfs on /sys type sysfs (rw,noexec,nosuid,nodev) none on /sys/fs/fuse/connections type fusectl (rw) none on /sys/kernel/debug type debugfs (rw) none on /sys/kernel/security type securityfs (rw) udev on /dev type devtmpfs (rw,mode=0755) devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620) tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755) none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880) none on /run/shm type tmpfs (rw,nosuid,nodev) /dev/sda1 on /boot/efi type vfat (rw) /dev/sda5 on /home type ext4 (rw) gvfs-fuse-daemon on /home/vierlex/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=vierlex) /dev/sda3 on /mnt/boot-sav/sda3 type fuseblk (rw,nosuid,nodev,allow_other,blksize=4096) /sys/block/sda: alignment_offset bdi capability dev device discard_alignment events events_async events_poll_msecs ext_range holders inflight power queue range removable ro sda1 sda2 sda3 sda4 sda5 sda6 size slaves stat subsystem trace uevent /dev: agpgart autofs block bsg btrfs-control bus char console core cpu cpu_dma_latency disk dri ecryptfs fb0 fd full fuse hpet input kmsg log mapper mcelog mei mem net network_latency network_throughput null oldmem port ppp psaux ptmx pts random rfkill rtc rtc0 sda sda1 sda2 sda3 sda4 sda5 sda6 sg0 shm snapshot snd stderr stdin stdout tpm0 uinput urandom usbmon0 usbmon1 usbmon2 v4l vga_arbiter video0 watchdog zero /dev/mapper: control /boot/efi: EFI /boot/efi/EFI: Boot Microsoft ubuntu /boot/efi/efi: Boot Microsoft ubuntu /boot/efi/efi/Boot: bootx64.efi /boot/efi/efi/ubuntu: grubx64.efi WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted. =================== DF: Filesystem Type Size Used Avail Use% Mounted on /dev/sda4 ext4 77G 4.1G 69G 6% / udev devtmpfs 3.9G 12K 3.9G 1% /dev tmpfs tmpfs 1.6G 864K 1.6G 1% /run none tmpfs 5.0M 0 5.0M 0% /run/lock none tmpfs 3.9G 152K 3.9G 1% /run/shm /dev/sda1 vfat 96M 18M 79M 19% /boot/efi /dev/sda5 ext4 137G 2.2G 128G 2% /home /dev/sda3 fuseblk 81G 30G 52G 37% /mnt/boot-sav/sda3 =================== FDISK: Disk /dev/sda: 320.1 GB, 320072933376 bytes 255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xf34fe538 Device Boot Start End Blocks Id System /dev/sda1 1 625142447 312571223+ ee GPT =================== Before mainwindow FSCK no PASTEBIN yes WUBI no WINBOOT yes recommendedrepair, purge, QTY_OF_PART_FOR_REINSTAL 1 no-kernel-purge UNHIDEBOOT_ACTION yes (10s), noflag () PART_TO_REINSTALL_GRUB sda4, FORCE_GRUB no (sda) REMOVABLEDISK no USE_SEPARATEBOOTPART no (sda3) grub2 () UNCOMMENT_GFXMODE no ATA ADD_KERNEL_OPTION no (acpi=off) MBR_TO_RESTORE ( ) EFI detected. Please check the options. =================== Actions FSCK no PASTEBIN yes WUBI no WINBOOT no bootinfo, nombraction, QTY_OF_PART_FOR_REINSTAL 1 no-kernel-purge UNHIDEBOOT_ACTION no (10s), noflag () PART_TO_REINSTALL_GRUB sda4, FORCE_GRUB no (sda) REMOVABLEDISK no USE_SEPARATEBOOTPART no (sda3) grub2 () UNCOMMENT_GFXMODE no ATA ADD_KERNEL_OPTION no (acpi=off) MBR_TO_RESTORE ( ) No change has been performed on your computer. See you soon! internet: connected Thanks for your time and attention. EDIT: additional Info Request =No boot loader is installed in the MBR of /dev/sda. But maybe this is how it is supposed to work? yea this is ok. boot stuff seems to be on a seperate partition, in my case sda1. I'm very new to this UEFI thing too. missing files like bootmgr i don't really have a clue :D but yea, maybe thats how it suppose to be? Instead and whats not shown in the log for some reason: There is additional microsoft bootfiles on sda1 under /efi/microsoft/ [much stuff] I remember also doing some kind of hack to make a UEFI windows 7 usb stick. http://jake.io/b/2011/installing-windows-7-with-uefi-boot-on-an-x220-from-usb/ In short: creating and placing bootx64.efi on the stick so it can be booted in UEFI mode. boot order i decide that in my BIOS. i read somwhere that the thinkpad x220 (essential part of the serial number: 4921 http://www.lenovo.com/shop/americas/content/user_guides/x220_x220i_x220tablet_x220itablet_ug_en.pdf) doesnt really have UEFI interface or something, still, these 2 options are listed with all the other usual devices you can give a boot priority to. Right now it looks like this: Boot Priority Order 1. ubuntu 2. Windows Boot Manager 3. USB FDD 4. USB HDD 5. ATA HDD0 HITACHI [random string]

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• C#/.NET Little Wonders: The Concurrent Collections (1 of 3)

  - by James Michael Hare

  Once again we consider some of the lesser known classes and keywords of C#.  In the next few weeks, we will discuss the concurrent collections and how they have changed the face of concurrent programming. This week’s post will begin with a general introduction and discuss the ConcurrentStack<T> and ConcurrentQueue<T>.  Then in the following post we’ll discuss the ConcurrentDictionary<T> and ConcurrentBag<T>.  Finally, we shall close on the third post with a discussion of the BlockingCollection<T>. For more of the "Little Wonders" posts, see the index here. A brief history of collections In the beginning was the .NET 1.0 Framework.  And out of this framework emerged the System.Collections namespace, and it was good.  It contained all the basic things a growing programming language needs like the ArrayList and Hashtable collections.  The main problem, of course, with these original collections is that they held items of type object which means you had to be disciplined enough to use them correctly or you could end up with runtime errors if you got an object of a type you weren't expecting. Then came .NET 2.0 and generics and our world changed forever!  With generics the C# language finally got an equivalent of the very powerful C++ templates.  As such, the System.Collections.Generic was born and we got type-safe versions of all are favorite collections.  The List<T> succeeded the ArrayList and the Dictionary<TKey,TValue> succeeded the Hashtable and so on.  The new versions of the library were not only safer because they checked types at compile-time, in many cases they were more performant as well.  So much so that it's Microsoft's recommendation that the System.Collections original collections only be used for backwards compatibility. So we as developers came to know and love the generic collections and took them into our hearts and embraced them.  The problem is, thread safety in both the original collections and the generic collections can be problematic, for very different reasons. Now, if you are only doing single-threaded development you may not care – after all, no locking is required.  Even if you do have multiple threads, if a collection is “load-once, read-many” you don’t need to do anything to protect that container from multi-threaded access, as illustrated below: 1: public static class OrderTypeTranslator 2: { 3: // because this dictionary is loaded once before it is ever accessed, we don't need to synchronize 4: // multi-threaded read access 5: private static readonly Dictionary<string, char> _translator = new Dictionary<string, char> 6: { 7: {"New", 'N'}, 8: {"Update", 'U'}, 9: {"Cancel", 'X'} 10: }; 11:  12: // the only public interface into the dictionary is for reading, so inherently thread-safe 13: public static char? Translate(string orderType) 14: { 15: char charValue; 16: if (_translator.TryGetValue(orderType, out charValue)) 17: { 18: return charValue; 19: } 20:  21: return null; 22: } 23: } Unfortunately, most of our computer science problems cannot get by with just single-threaded applications or with multi-threading in a load-once manner.  Looking at  today's trends, it's clear to see that computers are not so much getting faster because of faster processor speeds -- we've nearly reached the limits we can push through with today's technologies -- but more because we're adding more cores to the boxes.  With this new hardware paradigm, it is even more important to use multi-threaded applications to take full advantage of parallel processing to achieve higher application speeds. So let's look at how to use collections in a thread-safe manner. Using historical collections in a concurrent fashion The early .NET collections (System.Collections) had a Synchronized() static method that could be used to wrap the early collections to make them completely thread-safe.  This paradigm was dropped in the generic collections (System.Collections.Generic) because having a synchronized wrapper resulted in atomic locks for all operations, which could prove overkill in many multithreading situations.  Thus the paradigm shifted to having the user of the collection specify their own locking, usually with an external object: 1: public class OrderAggregator 2: { 3: private static readonly Dictionary<string, List<Order>> _orders = new Dictionary<string, List<Order>>(); 4: private static readonly _orderLock = new object(); 5:  6: public void Add(string accountNumber, Order newOrder) 7: { 8: List<Order> ordersForAccount; 9:  10: // a complex operation like this should all be protected 11: lock (_orderLock) 12: { 13: if (!_orders.TryGetValue(accountNumber, out ordersForAccount)) 14: { 15: _orders.Add(accountNumber, ordersForAccount = new List<Order>()); 16: } 17:  18: ordersForAccount.Add(newOrder); 19: } 20: } 21: } Notice how we’re performing several operations on the dictionary under one lock.  With the Synchronized() static methods of the early collections, you wouldn’t be able to specify this level of locking (a more macro-level).  So in the generic collections, it was decided that if a user needed synchronization, they could implement their own locking scheme instead so that they could provide synchronization as needed. The need for better concurrent access to collections Here’s the problem: it’s relatively easy to write a collection that locks itself down completely for access, but anything more complex than that can be difficult and error-prone to write, and much less to make it perform efficiently!  For example, what if you have a Dictionary that has frequent reads but in-frequent updates?  Do you want to lock down the entire Dictionary for every access?  This would be overkill and would prevent concurrent reads.  In such cases you could use something like a ReaderWriterLockSlim which allows for multiple readers in a lock, and then once a writer grabs the lock it blocks all further readers until the writer is done (in a nutshell).  This is all very complex stuff to consider. Fortunately, this is where the Concurrent Collections come in.  The Parallel Computing Platform team at Microsoft went through great pains to determine how to make a set of concurrent collections that would have the best performance characteristics for general case multi-threaded use. Now, as in all things involving threading, you should always make sure you evaluate all your container options based on the particular usage scenario and the degree of parallelism you wish to acheive. This article should not be taken to understand that these collections are always supperior to the generic collections. Each fills a particular need for a particular situation. Understanding what each container is optimized for is key to the success of your application whether it be single-threaded or multi-threaded. General points to consider with the concurrent collections The MSDN points out that the concurrent collections all support the ICollection interface. However, since the collections are already synchronized, the IsSynchronized property always returns false, and SyncRoot always returns null.  Thus you should not attempt to use these properties for synchronization purposes. Note that since the concurrent collections also may have different operations than the traditional data structures you may be used to.  Now you may ask why they did this, but it was done out of necessity to keep operations safe and atomic.  For example, in order to do a Pop() on a stack you have to know the stack is non-empty, but between the time you check the stack’s IsEmpty property and then do the Pop() another thread may have come in and made the stack empty!  This is why some of the traditional operations have been changed to make them safe for concurrent use. In addition, some properties and methods in the concurrent collections achieve concurrency by creating a snapshot of the collection, which means that some operations that were traditionally O(1) may now be O(n) in the concurrent models.  I’ll try to point these out as we talk about each collection so you can be aware of any potential performance impacts.  Finally, all the concurrent containers are safe for enumeration even while being modified, but some of the containers support this in different ways (snapshot vs. dirty iteration).  Once again I’ll highlight how thread-safe enumeration works for each collection. ConcurrentStack<T>: The thread-safe LIFO container The ConcurrentStack<T> is the thread-safe counterpart to the System.Collections.Generic.Stack<T>, which as you may remember is your standard last-in-first-out container.  If you think of algorithms that favor stack usage (for example, depth-first searches of graphs and trees) then you can see how using a thread-safe stack would be of benefit. The ConcurrentStack<T> achieves thread-safe access by using System.Threading.Interlocked operations.  This means that the multi-threaded access to the stack requires no traditional locking and is very, very fast! For the most part, the ConcurrentStack<T> behaves like it’s Stack<T> counterpart with a few differences: Pop() was removed in favor of TryPop() Returns true if an item existed and was popped and false if empty. PushRange() and TryPopRange() were added Allows you to push multiple items and pop multiple items atomically. Count takes a snapshot of the stack and then counts the items. This means it is a O(n) operation, if you just want to check for an empty stack, call IsEmpty instead which is O(1). ToArray() and GetEnumerator() both also take snapshots. This means that iteration over a stack will give you a static view at the time of the call and will not reflect updates. Pushing on a ConcurrentStack<T> works just like you’d expect except for the aforementioned PushRange() method that was added to allow you to push a range of items concurrently. 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: // but you can also push multiple items in one atomic operation (no interleaves) 7: stack.PushRange(new [] { "Second", "Third", "Fourth" }); For looking at the top item of the stack (without removing it) the Peek() method has been removed in favor of a TryPeek().  This is because in order to do a peek the stack must be non-empty, but between the time you check for empty and the time you execute the peek the stack contents may have changed.  Thus the TryPeek() was created to be an atomic check for empty, and then peek if not empty: 1: // to look at top item of stack without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (stack.TryPeek(out item)) 5: { 6: Console.WriteLine("Top item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Stack was empty."); 11: } Finally, to remove items from the stack, we have the TryPop() for single, and TryPopRange() for multiple items.  Just like the TryPeek(), these operations replace Pop() since we need to ensure atomically that the stack is non-empty before we pop from it: 1: // to remove items, use TryPop or TryPopRange to get multiple items atomically (no interleaves) 2: if (stack.TryPop(out item)) 3: { 4: Console.WriteLine("Popped " + item); 5: } 6:  7: // TryPopRange will only pop up to the number of spaces in the array, the actual number popped is returned. 8: var poppedItems = new string[2]; 9: int numPopped = stack.TryPopRange(poppedItems); 10:  11: foreach (var theItem in poppedItems.Take(numPopped)) 12: { 13: Console.WriteLine("Popped " + theItem); 14: } Finally, note that as stated before, GetEnumerator() and ToArray() gets a snapshot of the data at the time of the call.  That means if you are enumerating the stack you will get a snapshot of the stack at the time of the call.  This is illustrated below: 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: var results = stack.GetEnumerator(); 7:  8: // but you can also push multiple items in one atomic operation (no interleaves) 9: stack.PushRange(new [] { "Second", "Third", "Fourth" }); 10:  11: while(results.MoveNext()) 12: { 13: Console.WriteLine("Stack only has: " + results.Current); 14: } The only item that will be printed out in the above code is "First" because the snapshot was taken before the other items were added. This may sound like an issue, but it’s really for safety and is more correct.  You don’t want to enumerate a stack and have half a view of the stack before an update and half a view of the stack after an update, after all.  In addition, note that this is still thread-safe, whereas iterating through a non-concurrent collection while updating it in the old collections would cause an exception. ConcurrentQueue<T>: The thread-safe FIFO container The ConcurrentQueue<T> is the thread-safe counterpart of the System.Collections.Generic.Queue<T> class.  The concurrent queue uses an underlying list of small arrays and lock-free System.Threading.Interlocked operations on the head and tail arrays.  Once again, this allows us to do thread-safe operations without the need for heavy locks! The ConcurrentQueue<T> (like the ConcurrentStack<T>) has some departures from the non-concurrent counterpart.  Most notably: Dequeue() was removed in favor of TryDequeue(). Returns true if an item existed and was dequeued and false if empty. Count does not take a snapshot It subtracts the head and tail index to get the count.  This results overall in a O(1) complexity which is quite good.  It’s still recommended, however, that for empty checks you call IsEmpty instead of comparing Count to zero. ToArray() and GetEnumerator() both take snapshots. This means that iteration over a queue will give you a static view at the time of the call and will not reflect updates. The Enqueue() method on the ConcurrentQueue<T> works much the same as the generic Queue<T>: 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5: queue.Enqueue("Second"); 6: queue.Enqueue("Third"); For front item access, the TryPeek() method must be used to attempt to see the first item if the queue.  There is no Peek() method since, as you’ll remember, we can only peek on a non-empty queue, so we must have an atomic TryPeek() that checks for empty and then returns the first item if the queue is non-empty. 1: // to look at first item in queue without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (queue.TryPeek(out item)) 5: { 6: Console.WriteLine("First item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Queue was empty."); 11: } Then, to remove items you use TryDequeue().  Once again this is for the same reason we have TryPeek() and not Peek(): 1: // to remove items, use TryDequeue. If queue is empty returns false. 2: if (queue.TryDequeue(out item)) 3: { 4: Console.WriteLine("Dequeued first item " + item); 5: } Just like the concurrent stack, the ConcurrentQueue<T> takes a snapshot when you call ToArray() or GetEnumerator() which means that subsequent updates to the queue will not be seen when you iterate over the results.  Thus once again the code below will only show the first item, since the other items were added after the snapshot. 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5:  6: var iterator = queue.GetEnumerator(); 7:  8: queue.Enqueue("Second"); 9: queue.Enqueue("Third"); 10:  11: // only shows First 12: while (iterator.MoveNext()) 13: { 14: Console.WriteLine("Dequeued item " + iterator.Current); 15: } Using collections concurrently You’ll notice in the examples above I stuck to using single-threaded examples so as to make them deterministic and the results obvious.  Of course, if we used these collections in a truly multi-threaded way the results would be less deterministic, but would still be thread-safe and with no locking on your part required! For example, say you have an order processor that takes an IEnumerable<Order> and handles each other in a multi-threaded fashion, then groups the responses together in a concurrent collection for aggregation.  This can be done easily with the TPL’s Parallel.ForEach(): 1: public static IEnumerable<OrderResult> ProcessOrders(IEnumerable<Order> orderList) 2: { 3: var proxy = new OrderProxy(); 4: var results = new ConcurrentQueue<OrderResult>(); 5:  6: // notice that we can process all these in parallel and put the results 7: // into our concurrent collection without needing any external locking! 8: Parallel.ForEach(orderList, 9: order => 10: { 11: var result = proxy.PlaceOrder(order); 12:  13: results.Enqueue(result); 14: }); 15:  16: return results; 17: } Summary Obviously, if you do not need multi-threaded safety, you don’t need to use these collections, but when you do need multi-threaded collections these are just the ticket! The plethora of features (I always think of the movie The Three Amigos when I say plethora) built into these containers and the amazing way they acheive thread-safe access in an efficient manner is wonderful to behold. Stay tuned next week where we’ll continue our discussion with the ConcurrentBag<T> and the ConcurrentDictionary<TKey,TValue>. For some excellent information on the performance of the concurrent collections and how they perform compared to a traditional brute-force locking strategy, see this wonderful whitepaper by the Microsoft Parallel Computing Platform team here.   Tweet Technorati Tags: C#,.NET,Concurrent Collections,Collections,Multi-Threading,Little Wonders,BlackRabbitCoder,James Michael Hare

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• Understanding C# async / await (1) Compilation

  - by Dixin

  Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is named MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine, MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been refactored, so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# language level syntax sugar. There is no difference to await a async method or a normal method. As long as a method returns Task, it is awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } Once again, the above state machine code is already refactored, but it still has a lot of things. More clean up can be done if we only keep the core logic, and the state machine can become very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> public void MoveNext() // IAsyncStateMachine member. { try { switch (this.State) { // Original code is split by "await"s into "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; MultiCallMethodAsyncStateMachine that1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => that1.MoveNext()); break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; MultiCallMethodAsyncStateMachine that2 = this; this.currentTaskToAwait.ContinueWith(_ => that2.MoveNext()); break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] public void SetStateMachine(IAsyncStateMachine stateMachine) // IAsyncStateMachine member. { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; multiCallMethodAsyncStateMachine.MoveNext(); // Original code are moved into this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clean - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback If we focus on the point of callback, the simplification  can go even further – the entire state machine can be completely purged, and we can just keep the code inside MoveNext(). Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is not to wait. In a await expression, a Task object will be return immediately so that execution is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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• Grub 'Read Error' - Only Loads with LiveCD

  - by Ryan Sharp

  Problem After installing Ubuntu to complete my Windows 7/Ubuntu 12.04 dual-boot setup, Grub just wouldn't load at all unless I boot from the LiveCD. Afterwards, everything works completely normal. However, this workaround isn't a solution and I'd like to be able to boot without the aid of a disc. Fdisk -l Using the fdisk -l command, I am given the following: Disk /dev/sda: 64.0 GB, 64023257088 bytes 255 heads, 63 sectors/track, 7783 cylinders, total 125045424 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x324971d1 Device Boot Start End Blocks Id System /dev/sda1 2048 206847 102400 7 HPFS/NTFS/exFAT /dev/sda2 208896 48957439 24374272 7 HPFS/NTFS/exFAT /dev/sda3 * 48959486 124067839 37554177 5 Extended /dev/sda5 48959488 124067839 37554176 83 Linux Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xc0ee6a69 Device Boot Start End Blocks Id System /dev/sdb1 1024208894 1953523711 464657409 5 Extended /dev/sdb3 * 2048 1024206847 512102400 7 HPFS/NTFS/exFAT /dev/sdb5 1024208896 1937897471 456844288 83 Linux /dev/sdb6 1937899520 1953523711 7812096 82 Linux swap / Solaris Partition table entries are not in disk order Disk /dev/sdc: 320.1 GB, 320072933376 bytes 255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x292eee23 Device Boot Start End Blocks Id System /dev/sdc1 2048 625141759 312569856 7 HPFS/NTFS/exFAT Bootinfoscript I've used the BootInfoScript, and received the following output: Boot Info Script 0.61 [1 April 2012] ============================= Boot Info Summary: =============================== => Grub2 (v1.99) is installed in the MBR of /dev/sda and looks at sector 1 of the same hard drive for core.img. core.img is at this location and looks for (,msdos5)/boot/grub on this drive. => Grub2 (v1.99) is installed in the MBR of /dev/sdb and looks at sector 1 of the same hard drive for core.img. core.img is at this location and looks for (,msdos5)/boot/grub on this drive. => Windows is installed in the MBR of /dev/sdc. sda1: __________________________________________________________________________ File system: ntfs Boot sector type: Windows Vista/7: NTFS Boot sector info: No errors found in the Boot Parameter Block. Operating System: Boot files: /bootmgr /Boot/BCD sda2: __________________________________________________________________________ File system: ntfs Boot sector type: Windows Vista/7: NTFS Boot sector info: No errors found in the Boot Parameter Block. Operating System: Windows 7 Boot files: /bootmgr /Boot/BCD /Windows/System32/winload.exe sda3: __________________________________________________________________________ File system: Extended Partition Boot sector type: Unknown Boot sector info: sda5: __________________________________________________________________________ File system: ext4 Boot sector type: - Boot sector info: Operating System: Ubuntu 12.04.1 LTS Boot files: /boot/grub/grub.cfg /etc/fstab /boot/grub/core.img sdb1: __________________________________________________________________________ File system: Extended Partition Boot sector type: - Boot sector info: sdb5: __________________________________________________________________________ File system: ext4 Boot sector type: - Boot sector info: Operating System: Boot files: sdb6: __________________________________________________________________________ File system: swap Boot sector type: - Boot sector info: sdb3: __________________________________________________________________________ File system: ntfs Boot sector type: Windows Vista/7: NTFS Boot sector info: According to the info in the boot sector, sdb3 starts at sector 200744960. But according to the info from fdisk, sdb3 starts at sector 2048. According to the info in the boot sector, sdb3 has 823461887 sectors, but according to the info from fdisk, it has 1024204799 sectors. Operating System: Boot files: sdc1: __________________________________________________________________________ File system: ntfs Boot sector type: Windows Vista/7: NTFS Boot sector info: No errors found in the Boot Parameter Block. Operating System: Boot files: ============================ Drive/Partition Info: ============================= Drive: sda _____________________________________________________________________ Disk /dev/sda: 64.0 GB, 64023257088 bytes 255 heads, 63 sectors/track, 7783 cylinders, total 125045424 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes Partition Boot Start Sector End Sector # of Sectors Id System /dev/sda1 2,048 206,847 204,800 7 NTFS / exFAT / HPFS /dev/sda2 208,896 48,957,439 48,748,544 7 NTFS / exFAT / HPFS /dev/sda3 * 48,959,486 124,067,839 75,108,354 5 Extended /dev/sda5 48,959,488 124,067,839 75,108,352 83 Linux Drive: sdb _____________________________________________________________________ Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes Partition Boot Start Sector End Sector # of Sectors Id System /dev/sdb1 1,024,208,894 1,953,523,711 929,314,818 5 Extended /dev/sdb5 1,024,208,896 1,937,897,471 913,688,576 83 Linux /dev/sdb6 1,937,899,520 1,953,523,711 15,624,192 82 Linux swap / Solaris /dev/sdb3 * 2,048 1,024,206,847 1,024,204,800 7 NTFS / exFAT / HPFS Drive: sdc _____________________________________________________________________ Disk /dev/sdc: 320.1 GB, 320072933376 bytes 255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes Partition Boot Start Sector End Sector # of Sectors Id System /dev/sdc1 2,048 625,141,759 625,139,712 7 NTFS / exFAT / HPFS "blkid" output: ________________________________________________________________ Device UUID TYPE LABEL /dev/sda1 A48056DF8056B80E ntfs System Reserved /dev/sda2 A8C6D6A4C6D671D4 ntfs Windows /dev/sda5 fd71c537-3715-44e1-b1fe-07537e22b3dd ext4 /dev/sdb3 6373D03D0A3747A8 ntfs Steam /dev/sdb5 6f5a6eb3-a932-45aa-893e-045b57708270 ext4 /dev/sdb6 469848c8-867a-41b7-b0e1-b813a43c64af swap /dev/sdc1 725D7B961CF34B1B ntfs backup ================================ Mount points: ================================= Device Mount_Point Type Options /dev/sda5 / ext4 (rw,noatime,nodiratime,discard,errors=remount-ro) /dev/sdb5 /home ext4 (rw) =========================== sda5/boot/grub/grub.cfg: =========================== -------------------------------------------------------------------------------- # # DO NOT EDIT THIS FILE # # It is automatically generated by grub-mkconfig using templates # from /etc/grub.d and settings from /etc/default/grub # ### BEGIN /etc/grub.d/00_header ### if [ -s $prefix/grubenv ]; then set have_grubenv=true load_env fi set default="0" if [ "${prev_saved_entry}" ]; then set saved_entry="${prev_saved_entry}" save_env saved_entry set prev_saved_entry= save_env prev_saved_entry set boot_once=true fi function savedefault { if [ -z "${boot_once}" ]; then saved_entry="${chosen}" save_env saved_entry fi } function recordfail { set recordfail=1 if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi } function load_video { insmod vbe insmod vga insmod video_bochs insmod video_cirrus } insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set=root fd71c537-3715-44e1-b1fe-07537e22b3dd if loadfont /usr/share/grub/unicode.pf2 ; then set gfxmode=auto load_video insmod gfxterm insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set=root fd71c537-3715-44e1-b1fe-07537e22b3dd set locale_dir=($root)/boot/grub/locale set lang=en_GB insmod gettext fi terminal_output gfxterm if [ "${recordfail}" = 1 ]; then set timeout=-1 else set timeout=10 fi ### END /etc/grub.d/00_header ### ### BEGIN /etc/grub.d/05_debian_theme ### set menu_color_normal=white/black set menu_color_highlight=black/light-gray if background_color 44,0,30; then clear fi ### END /etc/grub.d/05_debian_theme ### ### BEGIN /etc/grub.d/10_linux ### function gfxmode { set gfxpayload="${1}" if [ "${1}" = "keep" ]; then set vt_handoff=vt.handoff=7 else set vt_handoff= fi } if [ "${recordfail}" != 1 ]; then if [ -e ${prefix}/gfxblacklist.txt ]; then if hwmatch ${prefix}/gfxblacklist.txt 3; then if [ ${match} = 0 ]; then set linux_gfx_mode=keep else set linux_gfx_mode=text fi else set linux_gfx_mode=text fi else set linux_gfx_mode=keep fi else set linux_gfx_mode=text fi export linux_gfx_mode if [ "${linux_gfx_mode}" != "text" ]; then load_video; fi menuentry 'Ubuntu, with Linux 3.2.0-29-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail gfxmode $linux_gfx_mode insmod gzio insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set=root fd71c537-3715-44e1-b1fe-07537e22b3dd linux /boot/vmlinuz-3.2.0-29-generic root=UUID=fd71c537-3715-44e1-b1fe-07537e22b3dd ro quiet splash $vt_handoff initrd /boot/initrd.img-3.2.0-29-generic } menuentry 'Ubuntu, with Linux 3.2.0-29-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod gzio insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set=root fd71c537-3715-44e1-b1fe-07537e22b3dd echo 'Loading Linux 3.2.0-29-generic ...' linux /boot/vmlinuz-3.2.0-29-generic root=UUID=fd71c537-3715-44e1-b1fe-07537e22b3dd ro recovery nomodeset echo 'Loading initial ramdisk ...' initrd /boot/initrd.img-3.2.0-29-generic } ### END /etc/grub.d/10_linux ### ### BEGIN /etc/grub.d/20_linux_xen ### ### END /etc/grub.d/20_linux_xen ### ### BEGIN /etc/grub.d/20_memtest86+ ### menuentry "Memory test (memtest86+)" { insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set=root fd71c537-3715-44e1-b1fe-07537e22b3dd linux16 /boot/memtest86+.bin } menuentry "Memory test (memtest86+, serial console 115200)" { insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set=root fd71c537-3715-44e1-b1fe-07537e22b3dd linux16 /boot/memtest86+.bin console=ttyS0,115200n8 } ### END /etc/grub.d/20_memtest86+ ### ### BEGIN /etc/grub.d/30_os-prober ### menuentry "Windows 7 (loader) (on /dev/sda1)" --class windows --class os { insmod part_msdos insmod ntfs set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root A48056DF8056B80E chainloader +1 } menuentry "Windows 7 (loader) (on /dev/sda2)" --class windows --class os { insmod part_msdos insmod ntfs set root='(hd0,msdos2)' search --no-floppy --fs-uuid --set=root A8C6D6A4C6D671D4 chainloader +1 } ### END /etc/grub.d/30_os-prober ### ### BEGIN /etc/grub.d/40_custom ### # This file provides an easy way to add custom menu entries. Simply type the # menu entries you want to add after this comment. Be careful not to change # the 'exec tail' line above. ### END /etc/grub.d/40_custom ### ### BEGIN /etc/grub.d/41_custom ### if [ -f $prefix/custom.cfg ]; then source $prefix/custom.cfg; fi ### END /etc/grub.d/41_custom ### -------------------------------------------------------------------------------- =============================== sda5/etc/fstab: ================================ -------------------------------------------------------------------------------- # /etc/fstab: static file system information. # # Use 'blkid' to print the universally unique identifier for a # device; this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc nodev,noexec,nosuid 0 0 # / was on /dev/sda5 during installation UUID=fd71c537-3715-44e1-b1fe-07537e22b3dd / ext4 noatime,nodiratime,discard,errors=remount-ro 0 1 # /home was on /dev/sdb5 during installation UUID=6f5a6eb3-a932-45aa-893e-045b57708270 /home ext4 defaults 0 2 # swap was on /dev/sdb6 during installation UUID=469848c8-867a-41b7-b0e1-b813a43c64af none swap sw 0 0 tmpfs /tmp tmpfs defaults,noatime,mode=1777 0 0 -------------------------------------------------------------------------------- =================== sda5: Location of files loaded by Grub: ==================== GiB - GB File Fragment(s) = boot/grub/core.img 1 = boot/grub/grub.cfg 1 = boot/initrd.img-3.2.0-29-generic 2 = boot/vmlinuz-3.2.0-29-generic 1 = initrd.img 2 = vmlinuz 1 ======================== Unknown MBRs/Boot Sectors/etc: ======================== Unknown BootLoader on sda3 00000000 63 6f 70 69 61 20 65 20 63 6f 6c 61 41 63 65 64 |copia e colaAced| 00000010 65 72 20 61 20 74 6f 64 6f 20 6f 20 74 65 78 74 |er a todo o text| 00000020 6f 20 66 61 6c 61 64 6f 20 75 74 69 6c 69 7a 61 |o falado utiliza| 00000030 6e 64 6f 20 61 20 63 6f 6e 76 65 72 73 c3 a3 6f |ndo a convers..o| 00000040 20 64 65 20 74 65 78 74 6f 20 70 61 72 61 20 76 | de texto para v| 00000050 6f 7a 4d 61 6e 69 70 75 6c 61 72 20 61 73 20 64 |ozManipular as d| 00000060 65 66 69 6e 69 c3 a7 c3 b5 65 73 20 71 75 65 20 |efini....es que | 00000070 63 6f 6e 74 72 6f 6c 61 6d 20 6f 20 61 63 65 73 |controlam o aces| 00000080 73 6f 20 64 65 20 57 65 62 73 69 74 65 73 20 61 |so de Websites a| 00000090 20 63 6f 6f 6b 69 65 73 2c 20 4a 61 76 61 53 63 | cookies, JavaSc| 000000a0 72 69 70 74 20 65 20 70 6c 75 67 2d 69 6e 73 4d |ript e plug-insM| 000000b0 61 6e 69 70 75 6c 61 72 20 61 73 20 64 65 66 69 |anipular as defi| 000000c0 6e 69 c3 a7 c3 b5 65 73 20 72 65 6c 61 63 69 6f |ni....es relacio| 000000d0 6e 61 64 61 73 20 63 6f 6d 20 70 72 69 76 61 63 |nadas com privac| 000000e0 69 64 61 64 65 41 63 65 64 65 72 20 61 6f 73 20 |idadeAceder aos | 000000f0 73 65 75 73 20 70 65 72 69 66 c3 a9 72 69 63 6f |seus perif..rico| 00000100 73 20 55 53 42 55 74 69 6c 69 7a 61 72 20 6f 20 |s USBUtilizar o | 00000110 73 65 75 20 6d 69 63 72 6f 66 6f 6e 65 55 74 69 |seu microfoneUti| 00000120 6c 69 7a 61 72 20 61 20 73 75 61 20 63 c3 a2 6d |lizar a sua c..m| 00000130 61 72 61 55 74 69 6c 69 7a 61 72 20 6f 20 73 65 |araUtilizar o se| 00000140 75 20 6d 69 63 72 6f 66 6f 6e 65 20 65 20 61 20 |u microfone e a | 00000150 63 c3 a2 6d 61 72 61 4e c3 a3 6f 20 66 6f 69 20 |c..maraN..o foi | 00000160 70 6f 73 73 c3 ad 76 65 6c 20 65 6e 63 6f 6e 74 |poss..vel encont| 00000170 72 61 72 20 6f 20 63 61 6d 69 6e 68 6f 20 61 62 |rar o caminho ab| 00000180 73 6f 6c 75 74 6f 20 70 61 72 61 20 6f 20 64 69 |soluto para o di| 00000190 72 65 63 74 c3 b3 72 69 6f 20 61 20 65 6d 70 61 |rect..rio a empa| 000001a0 63 6f 74 61 72 2e 4f 20 64 69 72 65 63 74 c3 b3 |cotar.O direct..| 000001b0 72 69 6f 20 64 65 20 65 6e 74 72 61 64 61 00 fe |rio de entrada..| 000001c0 ff ff 83 fe ff ff 02 00 00 00 00 10 7a 04 00 00 |............z...| 000001d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 000001f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 aa |..............U.| 00000200 =============================== StdErr Messages: =============================== xz: (stdin): Compressed data is corrupt xz: (stdin): Compressed data is corrupt awk: cmd. line:36: Math support is not compiled in awk: cmd. line:36: Math support is not compiled in awk: cmd. line:36: Math support is not compiled in awk: cmd. line:36: Math support is not compiled in awk: cmd. line:36: Math support is not compiled in awk: cmd. line:36: Math support is not compiled in Begging / Appreciation ;) If anything else is required to solve my problem, please ask. My only hopes are that I can solve this, and that doing so won't require re-installation of Grub due to how complicated the procedures are, or that I would be needed to reinstall the OS', as I have done so about six times already since friday due to several other issues I've encountered. Thank you, and good day. System Ubuntu 12.04 64-bit / Windows 7 SP1 64-bit 64GB SSD as boot/OS drive, 1TB HDD as /Home Swap and Steam drive.

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• error when I use GWT RPC

  - by Sebe

  Hello everyone... I have a problem with Eclipse when I use an RPC.. If I use a single method call it's all in the right direction but if I add a new method to handle the server I get the following error: com.google.gwt.core.client.JavaScriptException: (null): null at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:237) at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:126) at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561) at com.google.gwt.dev.shell.ModuleSpace.invokeNativeBoolean(ModuleSpace.java:184) at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeBoolean(JavaScriptHost.java:35) at com.google.gwt.user.client.rpc.impl.RpcStatsContext.isStatsAvailable(RpcStatsContext.java) at com.google.gwt.user.client.rpc.impl.RequestCallbackAdapter.onResponseReceived(RequestCallbackAdapter.java:221) at com.google.gwt.http.client.Request.fireOnResponseReceived(Request.java:287) at com.google.gwt.http.client.RequestBuilder$1.onReadyStateChange(RequestBuilder.java:395) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103) at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71) at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:157) at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:326) at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:207) at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:126) at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561) at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269) at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91) at com.google.gwt.core.client.impl.Impl.apply(Impl.java) at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:214) at sun.reflect.GeneratedMethodAccessor13.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103) at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71) at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:157) at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:281) at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:531) at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:352) at java.lang.Thread.run(Thread.java:619) Can I have more services in an asynchronous call right? Where am I wrong? This is my implementation MyService: package de.vogella.gwt.helloworld.client; import com.google.gwt.user.client.rpc.RemoteService; public interface MyService extends RemoteService { //chiamo i metodi presenti sul server public void creaXML(String nickname,String pass,String email2,String gio,String mes, String ann); public void setWeb(String userCorrect,String query, String titolo,String snippet,String url); } MyServiceAsync package de.vogella.gwt.helloworld.client; import com.google.gwt.user.client.rpc.AsyncCallback; public interface MyServiceAsync { void creaXML(String nickname,String pass,String email2,String gio,String mes, String ann,AsyncCallback<Void> callback); void setWeb(String userCorrect,String query, String titolo,String snippet,String url, AsyncCallback<Void> callback); } RPCService: package de.vogella.gwt.helloworld.client; import com.google.gwt.core.client.GWT; import com.google.gwt.user.client.rpc.AsyncCallback; import com.google.gwt.user.client.rpc.ServiceDefTarget; import com.google.gwt.user.client.ui.FlexTable; public class RPCService implements MyServiceAsync { MyServiceAsync service = (MyServiceAsync) GWT.create(MyService.class); ServiceDefTarget endpoint = (ServiceDefTarget) service; public RPCService() { endpoint.setServiceEntryPoint(GWT.getModuleBaseURL() + "rpc"); } public void creaXML(String nickname,String pass,String email2,String gio,String mes, String ann,AsyncCallback callback) { service.creaXML(nickname, pass, email2, gio, mes, ann, callback); } public void setWeb(String userCorrect,String query, String titolo,String snippet,String url,AsyncCallback callback) { service.setWeb(userCorrect,query, titolo,snippet,url,callback); } } MyServiceImpl package de.vogella.gwt.helloworld.server; import java.io.*; import org.w3c.dom.*; import org.xml.sax.SAXException; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import javax.xml.transform.*; import javax.xml.transform.dom.DOMSource; import javax.xml.transform.stream.StreamResult; import de.vogella.gwt.helloworld.client.MyService; import com.google.gwt.user.client.ui.FlexTable; import com.google.gwt.user.server.rpc.RemoteServiceServlet; import com.google.gwt.xml.client.Element; import com.google.gwt.xml.client.NodeList; public class MyServiceImpl extends RemoteServiceServlet implements MyService { //metodo che inserisce il nuovo iscritto public void creaXML(String nickname,String pass,String email2,String gio,String mes, String ann){ ....... } public void setWeb(String userCorrect,String query, String titolo,String snippet,String url) { ..... } In the app in client-side I do RPCService rpc2 = New RPCService() rpc2.setWeb(..,...,...,...,callback); and RPCService rpc = New RPCService() rpc.creaXML(..,...,...,...,callback); (in other posizions in the code...) and.. AsyncCallback callback = new AsyncCallback() { public void onFailure(Throwable caught) { Window.alert("Failure!"); } public void onSuccess(Object result) { Window.alert("Successoooooo"); } }; Web.xml: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd"> <web-app> <!-- Servlets --> <!-- Default page to serve --> <welcome-file-list> <welcome-file>De_vogella_gwt_helloworld.html</welcome-file> </welcome-file-list> <servlet> <servlet-name>rPCImpl</servlet-name> <servlet-class>de.vogella.gwt.helloworld.server.MyServiceImpl</servlet-class> </servlet> <servlet-mapping> <servlet-name>rPCImpl</servlet-name> <url-pattern>/de_vogella_gwt_helloworld/rpc</url-pattern> </servlet-mapping> </web-app> Thank you all for your attention Sebe

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• pxe boot fails with message: no DEFAULT or UI configuration directive found

  - by spockaroo

  I am trying to pxe-boot a machine (client), and in the process I am trying to setup a tftp server that this machine can boot off. On the server, which runs Ubuntu 10.10, I have setup dhcp, dns, nfs, and tftp-hpa servers. All the servers/deamons start fine. I tested the tftp server by using a tftp client and downloading a file that the server directory hosts. My /etc/xinet.d/tftp looks like this service tftp { disable = no socket_type = dgram wait = yes user = nobody server = /usr/sbin/in.tftpd server_args = -v -s /var/lib/tftpboot only_from = 10.1.0.0/24 interface = 10.1.0.1 } My /etc/default/tftpd-hpa looks like this RUN_DAEMON="yes" OPTIONS="-l -s /var/lib/tftpboot" TFTP_USERNAME="tftp" TFTP_DIRECTORY="/var/lib/tftpboot" TFTP_ADDRESS="0.0.0.0:69" TFTP_OPTIONS="--secure" My /var/lib/tftpboot/ directory looks like this initrd.img-2.6.35-25-generic-pae vmlinuz-2.6.35-25-generic-pae pxelinux.0 pxelinux.cfg -- default I did sudo chmod 644 /var/lib/tftpboot/pxelinux.cfg/default chmod 755 /var/lib/tftpboot/initrd.img-2.6.35-25-generic-pae chmod 755 /var/lib/tftpboot/vmlinuz-2.6.35-25-generic-pae /var/lib/tftpboot/pxelinux.cfg has the following contents SERIAL 0 19200 0 LABEL linux KERNEL vmlinuz-2.6.35-25-generic-pae APPEND root=/dev/nfs initrd=initrd.img-2.6.35-25-generic-pae nfsroot=10.1.0.1:/nfsroot ip=dhcp console=ttyS0,19200n8 rw I copied /var/lib/tftpboot/pxelinux.0 from /usr/lib/syslinux/ after installing the package syslinux-common. Also just for completeness, /etc/dhcp3/dhcpd.conf the following lines (relevant to this interface) subnet 10.1.0.0 netmask 255.255.255.0 { range 10.1.0.100 10.1.0.240; option routers 10.1.0.1; option broadcast-address 10.1.0.255; option domain-name-servers 10.1.0.1; filename "pxelinux.0"; } When I boot the client machine, and watch the output over the serial port, I notice that the client requests an ip address from the server and gets it. Then I see TFTP being displayed - indicating that it is trying to connect to the TFTP server. This succeeds, and I see TFTP.|, which return immediately displaying the following message PXELINUX 4.01 debian-20100714 Copyright (C) 1994-2010 H. Peter Anvin et al No DEFAULT or UI configuration directive found! boot: /var/log/syslog shows Feb 20 15:24:05 ch in.tftpd[2821]: tftp: client does not accept options What option is it talking about in the syslog? I assume it is referring to OPTIONS or TFTP_OPTIONS, but what am I doing wrong?

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• publishing asp.net website give "Object reference not set to an instance of an object." error

  - by Johan

  Good day I am using VS 2008 I am getting fed up with this error. I have search all over the web and tried every possible suggestion to this error I could find. 1. delete app_code, build, add files back, publish. (did not work) 2. delete temporary asp.net files (did not work) in the end I even tried the command line and get the following stacktrace. error ASPRUNTIME: Object reference not set to an instance of an object. [NullReferenceException]: Object reference not set to an instance of an object. at System.Web.Compilation.BuildManager.CopyPrecompiledFile(VirtualFile vfile, String destPhysicalPath) at System.Web.Compilation.BuildManager.CopyStaticFilesRecursive(VirtualDirect ory sourceVdir, String destPhysicalDir, Boolean topLevel) at System.Web.Compilation.BuildManager.CopyStaticFilesRecursive(VirtualDirect ory sourceVdir, String destPhysicalDir, Boolean topLevel) at System.Web.Compilation.BuildManager.CopyStaticFilesRecursive(VirtualDirect ory sourceVdir, String destPhysicalDir, Boolean topLevel) at System.Web.Compilation.BuildManager.PrecompileAppInternal(VirtualPath star tingVirtualDir) at System.Web.Compilation.BuildManager.PrecompileApp(VirtualPath startingVirt ualDir) at System.Web.Compilation.BuildManager.PrecompileApp(ClientBuildManagerCallba ck callback) at System.Web.Compilation.BuildManagerHost.PrecompileApp(ClientBuildManagerCa llback callback) at System.Web.Compilation.BuildManagerHost.PrecompileApp(ClientBuildManagerCa llback callback) at System.Web.Compilation.ClientBuildManager.PrecompileApplication(ClientBuil dManagerCallback callback, Boolean forceCleanBuild) at System.Web.Compilation.ClientBuildManager.PrecompileApplication(ClientBuil dManagerCallback callback) at System.Web.Compilation.Precompiler.Main(String[] args) I used the following command line: aspnet_compiler.exe -p d:\code\websites\brokerweb -v / d:\code\websites\published -f -c -errorstack -u Please help as I cannot publish this site at all at present and it worked fine for quite a long time now before this stupid error. Regards Johan

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• HttpRequest.BeginWebRequest not executing asynchronously

  - by Shawn Simon

  I have the following code: Private Function CreateRequest() As HttpWebRequest Dim request As HttpWebRequest = HttpWebRequest.Create(_url) request.Method = "POST" request.ContentType = "application/x-www-form-urlencoded" Dim postData As String = String.Join("&", GetPostData().Select(Function(s) String.Format("{0}={1}", s.Key, HttpUtility.UrlEncode(s.Value))).ToArray) Dim data As Byte() = (New ASCIIEncoding).GetBytes(postData) request.Timeout = _maxTimeoutSeconds * 1000 Dim stream = request.GetRequestStream stream.Write(data, 0, data.Length) stream.Close() Return request End Function Public Sub SendAsync(ByVal callback As Action(Of ResponseBase)) Dim request = CreateRequest() _attemptCount += 1 Dim reqID As Integer If _loggingContext IsNot Nothing Then Try reqID = Log.NotesRequest(_url.ToString, GetPostData, _loggingContext) Catch ex As Exception ErrorTracker.LogError(ex) End Try End If Dim responseState As New ResponseState responseState.LoggedNotesRequestID = reqID responseState.Request = request responseState.Callback = callback Dim response = request.BeginGetResponse(New AsyncCallback(AddressOf RespCallback), responseState) End Sub Private Sub RespCallback(ByVal ar As IAsyncResult) Dim responseState As ResponseState = CType(ar.AsyncState, ResponseState) ' Process response... I set up the request to go to a mock server which sleeps for 30 seconds. When I call BeginGetResponse, the application just waits at that line of code for the response. I want it to carry on with the app, and then just run the callback whenever it finishes. This code is run from a web page, and my callback just logs the response and sends an email. I don't want to use to have to wait for the response.

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• JQuery how to resubmit form after ajax call success

  - by Steven Rosato

  I am using JQuery to perform form submission through an ajax request. I use form.submit(function() { if( success ) { return true; } validate(); //proceeds to an ajax call return false; } On request success I want to either proceed with form submission or user callback. Therefore, if the user callback is undefined, I will submit the form on form validation success (from my validate function). config = { successCallback: function() { success = true; form.submit(); //does not work } }; validate = function() { $.ajax( ... success: function(data) { //code logic config.successCallback(); } ); }; The ajax success callback will call config.successCallback() and if it was never overridden by the user, it would proceed to normal form submission. I tried using an instance variable (success) to make sure 'return true' would proceed to default form submission. Unfortunately this is not working. It seems that the 'return false' statement that prevents default form submission will neglect any further submit calls even if an instance variable was set. It only works after clicking the submit button another time (that makes it twice for it to work). Is there any workaround for this. I want to both use a user callback when provided but proceed with default form submission when not, and since I am using an ajax function to validate the form, the ajax success callback is complicating things.

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• Why must we "change temporary credentials for token credentials" in OAuth?

  - by PK

  Can't the server just "upgrade" the temporary credentials to token credentials and retain the same key and secret? The client can then start doing authenticated calls right away after the recieving the callback from the server stating that the temporary credentials has been "upgraded". Of cause if the temporary credentials have not be upgrade (i.e. client doesn't wait for callback) the authenticated call fails. So the question is why make an extra call to the server after the callback to "exchange" temporary credentials for token credentials?

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• Jquery Cycle Plugin Question - turning off relative links to photos so it goes to a URL

  - by alpdog14

  I am using Jquery Cycle Plugin and it has a side panel that highlights as the photos change and currently when I click on the text the associated photo pulls up then I have to click on the photo to go to the URL but I would like the text itself to link to the URL. I have looked at the fn.cycle.defaults but not sure what to change and I tried a few things but nothing works. If anyone can help me figure this out it would be most helpful. Here are the fn.cycle.defaults: fx: 'fade', // one of: fade, shuffle, zoom, scrollLeft, etc timeout: 4000, // milliseconds between slide transitions (0 to disable auto advance) continuous: 0, // true to start next transition immediately after current one completes speed: 1000, // speed of the transition (any valid fx speed value) speedIn: null, // speed of the 'in' transition speedOut: null, // speed of the 'out' transition next: null, // id of element to use as click trigger for next slide prev: null, // id of element to use as click trigger for previous slide prevNextClick: null, // callback fn for prev/next clicks: function(isNext, zeroBasedSlideIndex, slideElement) pager: null, // id of element to use as pager container pagerClick: null, // callback fn for pager clicks: function(zeroBasedSlideIndex, slideElement) pagerEvent: null, // event which drives the pager navigation pagerAnchorBuilder: null, // callback fn for building anchor links before: null, // transition callback (scope set to element to be shown) after: null, // transition callback (scope set to element that was shown) end: null, // callback invoked when the slideshow terminates (use with autostop or nowrap options) easing: null, // easing method for both in and out transitions easeIn: null, // easing for "in" transition easeOut: null, // easing for "out" transition shuffle: null, // coords for shuffle animation, ex: { top:15, left: 200 } animIn: null, // properties that define how the slide animates in animOut: null, // properties that define how the slide animates out cssBefore: null, // properties that define the initial state of the slide before transitioning in cssAfter: null, // properties that defined the state of the slide after transitioning out fxFn: null, // function used to control the transition height: 'auto', // container height startingSlide: 0, // zero-based index of the first slide to be displayed sync: 1, // true if in/out transitions should occur simultaneously random: 0, // true for random, false for sequence (not applicable to shuffle fx) fit: 0, // force slides to fit container pause: true, // true to enable "pause on hover" autostop: 0, // true to end slideshow after X transitions (where X == slide count) autostopCount: 0, // number of transitions (optionally used with autostop to define X) delay: 0, // additional delay (in ms) for first transition (hint: can be negative) slideExpr: null, // expression for selecting slides (if something other than all children is required) cleartype: 0, // true if clearType corrections should be applied (for IE) nowrap: 0 // true to prevent slideshow from wrapping }; I have tried changing the pageClick and pagerEvent but nothing seems to be working. Please help!!!

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• JSONP request using jquery $.getJSON not working on well formed JSON.

  - by Antti

  I'm not sure is it possible now from the url I am trying. Please see this url: http://www.heiaheia.com/voimakaksikko/stats.json It always serves the same padding function "voimakaksikkoStats". It is well formed JSON, but I have not been able to load it from remote server. Does it need some work from the server side or can it be loaded with javascript? I think the problems gotta to have something to with that callback function... JQuery is not requirement, but it would be nice. This (callback=voimakaksikkoStats) returns nothing (firebug - net - response), and alert doesn't fire: $.getJSON("http://www.heiaheia.com/voimakaksikko/stats.json?callback=voimakaksikkoStats", function(data){ alert(data); }) but this (callback=?): $.getJSON("http://www.heiaheia.com/voimakaksikko/stats.json?callback=?", function(data){ alert(data); }) returns: voimakaksikkoStats({"Top5Sports":[],"Top5Tests":{"8":"No-exercise ennuste","1":"Painoindeksi","2":"Vy\u00f6t\u00e4r\u00f6n ymp\u00e4rys","10":"Cooperin testi","4":"Etunojapunnerrus"},"Top5CitiesByTests":[],"Top5CitiesByExercises":[],"ExercisesLogged":0,"Top5CitiesByUsers":[""],"TestsTaken":22,"RegisteredUsers":1}); But I cannot access it... In both examples the alert never fires. Can someone help?

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• compiling openss7

  - by deddihp

  hello, i got an error while compiling openss7. Do you know what happen ? Thanks.... gcc -DHAVE_CONFIG_H -I. -I. -I. -DLFS=1 -imacros ./config.h -imacros ./include/sys/config.h -I. -I./include -I./include -nostdinc -iwithprefix include -DLINUX -D__KERNEL__ -I/usr/src/linux-headers-lbm-2.6.28-11-generic -I/lib/modules/2.6.28-11-generic/build/include -Iinclude2 -I/lib/modules/2.6.28-11-generic/build/include -I/lib/modules/2.6.28-11-generic/build/arch/x86/include -include /lib/modules/2.6.28-11-generic/build/include/linux/autoconf.h -Iubuntu/include -I/lib/modules/2.6.28-11-generic/build/ubuntu/include -I/lib/modules/2.6.28-11-generic/build/arch/x86/include/asm/mach-default '-DKBUILD_STR(s)=#s' '-DKBUILD_BASENAME=KBUILD_STR('`echo libLfS_specfs_a-specfs.o | sed -e 's,lib.*_a-,,;s,\.o,,;s,-,_,g'`')' -DMODULE -D__NO_VERSION__ -DEXPORT_SYMTAB -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -Werror-implicit-function-declaration -O2 -m32 -msoft-float -mregparm=3 -freg-struct-return -mpreferred-stack-boundary=2 -march=i586 -mtune=generic -Wa,-mtune=generic32 -pipe -Wno-sign-compare -fno-asynchronous-unwind-tables -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -fno-stack-protector -fno-omit-frame-pointer -fno-optimize-sibling-calls -Wdeclaration-after-statement -Wno-pointer-sign -fwrapv -ffreestanding -c -o libLfS_specfs_a-specfs.o `test -f 'src/kernel/specfs.c' || echo './'`src/kernel/specfs.c In file included from src/kernel/specfs.c:123: src/kernel/strspecfs.c: In function ‘specfs_init_cache’: src/kernel/strspecfs.c:1406: warning: passing argument 5 of ‘kmem_cache_create’ from incompatible pointer type src/kernel/strspecfs.c:1406: error: too many arguments to function ‘kmem_cache_create’ In file included from src/kernel/specfs.c:126: src/kernel/strlookup.c: In function ‘cdev_lookup’: src/kernel/strlookup.c:508: warning: format not a string literal and no format arguments src/kernel/strlookup.c:514: warning: format not a string literal and no format arguments src/kernel/strlookup.c:521: warning: format not a string literal and no format arguments src/kernel/strlookup.c: In function ‘cdrv_lookup’: src/kernel/strlookup.c:562: warning: format not a string literal and no format arguments src/kernel/strlookup.c: In function ‘fmod_lookup’: src/kernel/strlookup.c:604: warning: format not a string literal and no format arguments src/kernel/strlookup.c: In function ‘cdev_search’: src/kernel/strlookup.c:709: warning: format not a string literal and no format arguments src/kernel/strlookup.c:716: warning: format not a string literal and no format arguments src/kernel/strlookup.c: In function ‘fmod_search’: src/kernel/strlookup.c:768: warning: format not a string literal and no format arguments src/kernel/strlookup.c: In function ‘cmin_search’: src/kernel/strlookup.c:823: warning: format not a string literal and no format arguments src/kernel/strlookup.c:830: warning: format not a string literal and no format arguments src/kernel/strlookup.c:840: warning: format not a string literal and no format arguments src/kernel/strlookup.c:848: warning: format not a string literal and no format arguments In file included from src/kernel/specfs.c:129: src/kernel/strattach.c: In function ‘check_mnt’: src/kernel/strattach.c:131: error: ‘struct vfsmount’ has no member named ‘mnt_namespace’ src/kernel/strattach.c:131: error: ‘struct task_struct’ has no member named ‘namespace’ src/kernel/strattach.c: In function ‘do_fattach’: src/kernel/strattach.c:200: error: ‘struct nameidata’ has no member named ‘dentry’ src/kernel/strattach.c:200: error: ‘struct nameidata’ has no member named ‘mnt’ src/kernel/strattach.c:200: error: ‘struct nameidata’ has no member named ‘dentry’ src/kernel/strattach.c:203: error: ‘struct nameidata’ has no member named ‘mnt’ src/kernel/strattach.c:208: error: ‘struct nameidata’ has no member named ‘mnt’ src/kernel/strattach.c:208: error: ‘struct nameidata’ has no member named ‘mnt’ src/kernel/strattach.c:208: error: ‘struct nameidata’ has no member named ‘dentry’ src/kernel/strattach.c:226: error: implicit declaration of function ‘path_release’ src/kernel/strattach.c: In function ‘do_fdetach’: src/kernel/strattach.c:253: error: ‘struct nameidata’ has no member named ‘dentry’ src/kernel/strattach.c:253: error: ‘struct nameidata’ has no member named ‘mnt’ src/kernel/strattach.c:255: error: ‘struct nameidata’ has no member named ‘mnt’ src/kernel/strattach.c:257: error: ‘struct nameidata’ has no member named ‘dentry’ src/kernel/strattach.c:262: error: ‘struct nameidata’ has no member named ‘mnt’ src/kernel/strattach.c:265: error: ‘struct nameidata’ has no member named ‘mnt’ In file included from src/kernel/specfs.c:132: src/kernel/strpipe.c: In function ‘do_spipe’: src/kernel/strpipe.c:372: warning: assignment discards qualifiers from pointer target type make[4]: *** [libLfS_specfs_a-specfs.o] Error 1 make[4]: Leaving directory `/home/deddihp/dev/source/openss7-0.9.2.G/streams-0.9.2.4' make[3]: *** [all-recursive] Error 1 make[3]: Leaving directory `/home/deddihp/dev/source/openss7-0.9.2.G/streams-0.9.2.4' make[2]: *** [all] Error 2 make[2]: Leaving directory `/home/deddihp/dev/source/openss7-0.9.2.G/streams-0.9.2.4' make[1]: *** [all-recursive] Error 1 make[1]: Leaving directory `/home/deddihp/dev/source/openss7-0.9.2.G' make: *** [all] Error 2

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• TemplateField button causing GridView Invalid Postback

  - by Carter

  Ok, so I've got a template field in a gridview that contains just a simple button... <asp:GridView ID="KeywordsGridView" AllowPaging="false" AutoGenerateColumns="false" BackColor="white" GridLines="None" HeaderStyle-CssClass="Table_Header" RowStyle-CssClass="Table_Style" runat="server"> <Columns> <asp:TemplateField> <ItemTemplate> <asp:Button runat="server" /> </ItemTemplate> </asp:TemplateField> <asp:BoundField DataField="References" SortExpression="References" HeaderText="Total References" /> <asp:BoundField DataField="Keyword" SortExpression="Keyword" HeaderText="Keyword" /> </Columns> </asp:GridView> Whenever I click the button I get the error... Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation. I've found a decent amount of articles referencing this issue, including a couple on SO, for example... http://stackoverflow.com/questions/228969/asp-net-invalid-postback-or-callback-argument-event-validation-is-enabled-usi and... http://stackoverflow.com/questions/103560/invalid-postback-or-callback-argument I might just be misunderstanding, but as far as I can tell they don't really help me. How do I get this to go away without setting enableEventValidation="false"?

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• how to know which response data is associated with its requested url (using RollingCurl.php) ?

  - by Ken

  I am writing a web application that grabs the http response headers from multiple sites (with RollingCurl.php) then stores it in an array and at the end outputs it in json format. Since some sites do redirects to new locations, $info (array) in “request_callback” function always has an url ($info[‘url’]) where the requested url was redirect.to, and it’s quite expected. But how to put a requested url in $info ($info[‘requested_url’]) and to know which $info (response data) is associated with its requested url? $urls = array( ‘http://google.com’, ‘http://microsoft.com’ // more urls here ); $json = array(); if ( $urls ) { $rc = new RollingCurl("request_callback"); $rc->window_size = 20; foreach ($urls as $url) { $request = new Request($url); $rc->add($request); } $rc->execute(); echo json_encode($json); } function request_callback($response, $info) { global $json; $json['status'][] = $info; } from RollingCurl.php: // send the return values to the callback function. $callback = $this->callback; if (is_callable($callback)){ $info[‘requested_url’] = ??? // How to put requested url here??? call_user_func($callback, $output, $info); }

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