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  • Script Task/Component and Template Information

    The Script Task and Script component are often used by people developing SSIS packages because they are easy to use and now because SSIS could be perceived to be more developer friendly they are very powerful. That being said we should no be using them everywhere.  There are generally Tasks/Components already provided that will do the job it may be that we have to rethink the way we want to draw our package. I had cause last week to break out the script component in SQL Server 2008 SP1 and found that it was broken.  I don’t know when it broke as I do not use them all that often.  My error was as below.     Something must have overwritten this template information.  I looked in Event Viewer and tried the things it suggested but the templates still did not work.  Here is how I got them eventually to work for me (Your Mileage may vary) Open up a Command Prompt window using an administrator level account and “as an administrator” vsta.exe /hostid SSIS_ScriptTask /setup vsta.exe /hostid SSIS_ScriptComponent /setup   This worked for me.  Hope it helps.

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  • Script Task/Component and Template Information

    The Script Task and Script component are often used by people developing SSIS packages because they are easy to use and now because SSIS could be perceived to be more developer friendly they are very powerful. That being said we should no be using them everywhere.  There are generally Tasks/Components already provided that will do the job it may be that we have to rethink the way we want to draw our package. I had cause last week to break out the script component in SQL Server 2008 SP1 and found that it was broken.  I don’t know when it broke as I do not use them all that often.  My error was as below.     Something must have overwritten this template information.  I looked in Event Viewer and tried the things it suggested but the templates still did not work.  Here is how I got them eventually to work for me (Your Mileage may vary) Open up a Command Prompt window using an administrator level account and “as an administrator” vsta.exe /hostid SSIS_ScriptTask /setup vsta.exe /hostid SSIS_ScriptComponent /setup   This worked for me.  Hope it helps.

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  • "rake db:seed" no method error

    - by louddwarf
    when I try and run the "rake db:seed" command the rails console outputs "NoMethodError: undefined method `db' for #" not quite sure what going on. I'm using netbeans to build my rails project which is using the built-in JRuby 1.2 would that have anything to do with it?

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  • where can I find the rake tasks delivered with rails

    - by ash34
    I am looking for tasks like tmp:clear or db:migrate. Where can I find the code for these tasks. I remember seeing them before but don't recollect where. Also, is there a way I can set some global variables in a .rake file that can be accessed by all tasks in that file without passing them as arguments to each task. thanks, ash

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  • Issues with rake after installing FreeImage on Mac OS X 10.6

    - by Das Ist Nicht
    I am trying to setup my dev environment on my Mac (running Mac OS X 10.6) for my work's rails application. It requires FreeImage and now that I have installed that, I run rake db:migrate and receive the following error: dyld: lazy symbol binding failed: Symbol not found: _FreeImage_SetOutputMessage Referenced from: /Users/username/.ruby_inline/Inline_ImageScience_cdab.bundle Expected in: flat namespace dyld: Symbol not found: _FreeImage_SetOutputMessage Referenced from: /Users/username/.ruby_inline/Inline_ImageScience_cdab.bundle Expected in: flat namespace Trace/BPT trap I have tried searching around for the error but am at a complete loss as to where to go or what to try in order to resolve this issue.

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  • rake does not returning anything

    - by CHID
    Hi, I jus created a rails application. I created a model using ruby script/generate model Article next i edited the my articles.rb file by adding these lines in self.up method def self.up create_table :articles do |t| t.string :title t.text :body t.string :published_at t.timestamps end end Now i ran rake db:migrate . But migrate does not work, it simply does no print anything. Anyone knows where i am going wrong?

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  • Dynamic State Machine in Ruby? Do State Machines Have to be Classes?

    - by viatropos
    Question is, are state machines always defined statically (on classes)? Or is there a way for me to have it so each instance of the class with has it's own set of states? I'm checking out Stonepath for implementing a Task Engine. I don't really see the distinction between "states" and "tasks" in there, so I'm thinking I could just map a Task directly to a state. This would allow me to be able to define task-lists (or workflows) dynamically, without having to do things like: aasm_event :evaluate do transitions :to => :in_evaluation, :from => :pending end aasm_event :accept do transitions :to => :accepted, :from => :pending end aasm_event :reject do transitions :to => :rejected, :from => :pending end Instead, a WorkItem (the main workflow/task manager model), would just have many tasks. Then the tasks would work like states, so I could do something like this: aasm_initial_state :initial tasks.each do |task| aasm_state task.name.to_sym end previous_state = nil tasks.each do |tasks| aasm_event task.name.to_sym do transitions :to => "#{task.name}_phase".to_sym, :from => previous_state ? "#{task.name}_phase" : "initial" end previous_state = state end However, I can't do that with the aasm gem because those methods (aasm_state and aasm_event) are class methods, so every instance of the class with that state machine has the same states. I want it so a "WorkItem" or "TaskList" dynmically creates a sequence of states and transitions based on the tasks it has. This would allow me to dynamically define workflows and just have states map to tasks. Are state machines ever used like this?

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  • How can I merge two Linq IEnumerable<T> queries without running them?

    - by makerofthings7
    How do I merge a List<T> of TPL-based tasks for later execution? public async IEnumerable<Task<string>> CreateTasks(){ /* stuff*/ } My assumption is .Concat() but that doesn't seem to work: void MainTestApp() // Full sample available upon request. { List<string> nothingList = new List<string>(); nothingList.Add("whatever"); cts = new CancellationTokenSource(); delayedExecution = from str in nothingList select AccessTheWebAsync("", cts.Token); delayedExecution2 = from str in nothingList select AccessTheWebAsync("1", cts.Token); delayedExecution = delayedExecution.Concat(delayedExecution2); } /// SNIP async Task AccessTheWebAsync(string nothing, CancellationToken ct) { // return a Task } I want to make sure that this won't spawn any task or evaluate anything. In fact, I suppose I'm asking "what logically executes an IQueryable to something that returns data"? Background Since I'm doing recursion and I don't want to execute this until the correct time, what is the correct way to merge the results if called multiple times? If it matters I'm thinking of running this command to launch all the tasks var AllRunningDataTasks = results.ToList(); followed by this code: while (AllRunningDataTasks.Count > 0) { // Identify the first task that completes. Task<TableResult> firstFinishedTask = await Task.WhenAny(AllRunningDataTasks); // ***Remove the selected task from the list so that you don't // process it more than once. AllRunningDataTasks.Remove(firstFinishedTask); // TODO: Await the completed task. var taskOfTableResult = await firstFinishedTask; // Todo: (doen't work) TrustState thisState = (TrustState)firstFinishedTask.AsyncState; // TODO: Update the concurrent dictionary with data // thisState.QueryStartPoint + thisState.ThingToSearchFor Interlocked.Decrement(ref thisState.RunningDirectQueries); Interlocked.Increment(ref thisState.CompletedDirectQueries); if (thisState.RunningDirectQueries == 0) { thisState.TimeCompleted = DateTime.UtcNow; } }

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  • workflow assign task to multiple users

    - by Artru
    I have MOSS. I want to make a page where a user, say administrator, could send some instructions to a server, for example using standard library and make task for a group of users forcing them to read files. After the reading users would press "already read it" and administrator would know who did it/who did not. I created simple workflow in office designer and choose assigne task to Group1, which is in the sharepoint server. After WF run everyone who is in Group1 get message about a task, that's great. However this task is general for group and if we go to the site section "current tasks", we can see it, while I want this task for every person in Group1. Futher question, is it possible to create form where administrator will choose users for this task, 'cause now I munualy set group in WF.

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  • Sysprep and Capture task sequence failing using MDT 2010

    - by Nic Young
    I have created a Windows Deployment Services server in Windows 2008 R2. When I originally set it up I was able to successfully use MDT 2010 to create my boot images as well as creating task sequences that would sysprep and capture, and deploy my custom .wim files. Everything was working perfectly. About a month later I boot up my Windows 7 x86 image and run Windows updates to keep my image up to date. I then go and run my sysprep and capture task sequence and I get the following errors: I searched online for the cause of this error message and it just seems to be a generic permission denied type of error message. I then decided to completely rebuild my VM image from scratch and try again. I am still getting the same error messages as before. The following is what I have tried troubleshooting this issue: Troubleshooting: I have ensured that that UAC and the firewall is turned completely off when trying to capture the image. I have tried recreating the task sequence and making sure that the deployment share is updated. I have ensured that the local Administrator account is enabled and has the same password as specified in the task sequence. I have tried joining the computer to the domain and running the task sequence and I get a different error: I have attempted to run the script from the command prompt with "Run as Administrator" and I still receive the same errors above. For testing purposes I have ensured that Everyone has read/write access to my deployment share. I have spent days on trying to resolve this to no avail. Any ideas? EDIT: Below is the log info from C:\Windows\Deploymentlogs\BDD.log as requested. <![LOG[LTI Windows PE applied successfully]LOG]!><time="11:48:34.000+000" date="07-25-2012" component="LTIApply" context="" type="1" thread="" file="LTIApply"> <![LOG[LTIApply processing completed successfully.]LOG]!><time="11:48:34.000+000" date="07-25-2012" component="LTIApply" context="" type="1" thread="" file="LTIApply"> <![LOG[Microsoft Deployment Toolkit version: 6.0.2223.0]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="ZTIDrivers" context="" type="1" thread="" file="ZTIDrivers"> <![LOG[The task sequencer log is located at C:\Users\nicy\AppData\Local\Temp\SMSTSLog\SMSTS.LOG. For task sequence failures, please consult this log.]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="ZTIDrivers" context="" type="1" thread="" file="ZTIDrivers"> <![LOG[Processing drivers for an X86 operating system.]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="ZTIDrivers" context="" type="1" thread="" file="ZTIDrivers"> <![LOG[TargetOS is the current SystemDrive]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="ZTIDrivers" context="" type="1" thread="" file="ZTIDrivers"> <![LOG[Property DriverCleanup is now = DONE]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="ZTIDrivers" context="" type="1" thread="" file="ZTIDrivers"> <![LOG[Compare Image processor Type with Original [X86] = [X86].]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="ZTIDrivers" context="" type="1" thread="" file="ZTIDrivers"> <![LOG[Prepare machine for Sysprep.]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="ZTIDrivers" context="" type="1" thread="" file="ZTIDrivers"> <![LOG[No driver actions can be taken for OS Images installed from *.wim files.]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="ZTIDrivers" context="" type="1" thread="" file="ZTIDrivers"> <![LOG[ZTIDrivers processing completed successfully.]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="ZTIDrivers" context="" type="1" thread="" file="ZTIDrivers"> <![LOG[Command completed, return code = -2147467259]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="LiteTouch" context="" type="1" thread="" file="LiteTouch"> <![LOG[Litetouch deployment failed, Return Code = -2147467259 0x80004005]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="LiteTouch" context="" type="3" thread="" file="LiteTouch"> <![LOG[For more information, consult the task sequencer log ...\SMSTS.LOG.]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="LiteTouch" context="" type="1" thread="" file="LiteTouch"> <![LOG[Property RetVal is now = -2147467259]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="LiteTouch" context="" type="1" thread="" file="LiteTouch"> <![LOG[Unable to copy log to the network as no SLShare value was specified.]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="LiteTouch" context="" type="1" thread="" file="LiteTouch"> <![LOG[CleanStartItems Complete]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="LiteTouch" context="" type="1" thread="" file="LiteTouch"> <![LOG[Unregistering TSCore.dll.]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="LiteTouch" context="" type="1" thread="" file="LiteTouch"> <![LOG[About to run command: wscript.exe "\\server\deploymentshare$\Scripts\LTICleanup.wsf"]LOG]!><time="11:48:35.000+000" date="07-25-2012" component="LiteTouch" context="" type="1" thread="" file="LiteTouch"> <![LOG[Microsoft Deployment Toolkit version: 6.0.2223.0]LOG]!><time="11:48:36.000+000" date="07-25-2012" component="LTICleanup" context="" type="1" thread="" file="LTICleanup"> <![LOG[Removing AutoAdminLogon registry entries]LOG]!><time="11:48:36.000+000" date="07-25-2012" component="LTICleanup" context="" type="1" thread="" file="LTICleanup"> <![LOG[VSSMaxSize not specified using 5% of volume.]LOG]!><time="11:48:36.000+000" date="07-25-2012" component="LTICleanup" context="" type="1" thread="" file="LTICleanup"> <![LOG[Logs contained 7 errors and 0 warnings.]LOG]!><time="11:48:36.000+000" date="07-25-2012" component="LTICleanup" context="" type="1" thread="" file="LTICleanup"> <![LOG[Stripping BDD commands from unattend.xml template.]LOG]!><time="11:48:36.000+000" date="07-25-2012" component="LTICleanup" context="" type="1" thread="" file="LTICleanup"> <![LOG[Modified unattend.xml saved to C:\windows\panther\unattend.xml]LOG]!><time="11:48:36.000+000" date="07-25-2012" component="LTICleanup" context="" type="1" thread="" file="LTICleanup"> <![LOG[Checking mapped network drive.]LOG]!><time="11:48:36.000+000" date="07-25-2012" component="LTICleanup" context="" type="1" thread="" file="LTICleanup"> <![LOG[testing drive Z: mapped to \\server\deploymentshare$]LOG]!><time="11:48:36.000+000" date="07-25-2012" component="LTICleanup" context="" type="1" thread="" file="LTICleanup"> <![LOG[Disconnecting drive Z: mapped to \\server\deploymentshare$]LOG]!><time="11:48:36.000+000" date="07-25-2012" component="LTICleanup" context="" type="1" thread="" file="LTICleanup"> <![LOG[Cleaning up C:\MININT directory.]LOG]!><time="11:48:36.000+000" date="07-25-2012" component="LTICleanup" context="" type="1" thread="" file="LTICleanup"> <![LOG[Cleaning up TOOLS, SCRIPTS, and PACKAGES directories.]LOG]!><time="11:48:36.000+000" date="07-25-2012" component="LTICleanup" context="" type="1" thread="" file="LTICleanup">

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  • ParallelWork: Feature rich multithreaded fluent task execution library for WPF

    - by oazabir
    ParallelWork is an open source free helper class that lets you run multiple work in parallel threads, get success, failure and progress update on the WPF UI thread, wait for work to complete, abort all work (in case of shutdown), queue work to run after certain time, chain parallel work one after another. It’s more convenient than using .NET’s BackgroundWorker because you don’t have to declare one component per work, nor do you need to declare event handlers to receive notification and carry additional data through private variables. You can safely pass objects produced from different thread to the success callback. Moreover, you can wait for work to complete before you do certain operation and you can abort all parallel work while they are in-flight. If you are building highly responsive WPF UI where you have to carry out multiple job in parallel yet want full control over those parallel jobs completion and cancellation, then the ParallelWork library is the right solution for you. I am using the ParallelWork library in my PlantUmlEditor project, which is a free open source UML editor built on WPF. You can see some realistic use of the ParallelWork library there. Moreover, the test project comes with 400 lines of Behavior Driven Development flavored tests, that confirms it really does what it says it does. The source code of the library is part of the “Utilities” project in PlantUmlEditor source code hosted at Google Code. The library comes in two flavors, one is the ParallelWork static class, which has a collection of static methods that you can call. Another is the Start class, which is a fluent wrapper over the ParallelWork class to make it more readable and aesthetically pleasing code. ParallelWork allows you to start work immediately on separate thread or you can queue a work to start after some duration. You can start an immediate work in a new thread using the following methods: void StartNow(Action doWork, Action onComplete) void StartNow(Action doWork, Action onComplete, Action<Exception> failed) For example, ParallelWork.StartNow(() => { workStartedAt = DateTime.Now; Thread.Sleep(howLongWorkTakes); }, () => { workEndedAt = DateTime.Now; }); Or you can use the fluent way Start.Work: Start.Work(() => { workStartedAt = DateTime.Now; Thread.Sleep(howLongWorkTakes); }) .OnComplete(() => { workCompletedAt = DateTime.Now; }) .Run(); Besides simple execution of work on a parallel thread, you can have the parallel thread produce some object and then pass it to the success callback by using these overloads: void StartNow<T>(Func<T> doWork, Action<T> onComplete) void StartNow<T>(Func<T> doWork, Action<T> onComplete, Action<Exception> fail) For example, ParallelWork.StartNow<Dictionary<string, string>>( () => { test = new Dictionary<string,string>(); test.Add("test", "test"); return test; }, (result) => { Assert.True(result.ContainsKey("test")); }); Or, the fluent way: Start<Dictionary<string, string>>.Work(() => { test = new Dictionary<string, string>(); test.Add("test", "test"); return test; }) .OnComplete((result) => { Assert.True(result.ContainsKey("test")); }) .Run(); You can also start a work to happen after some time using these methods: DispatcherTimer StartAfter(Action onComplete, TimeSpan duration) DispatcherTimer StartAfter(Action doWork,Action onComplete,TimeSpan duration) You can use this to perform some timed operation on the UI thread, as well as perform some operation in separate thread after some time. ParallelWork.StartAfter( () => { workStartedAt = DateTime.Now; Thread.Sleep(howLongWorkTakes); }, () => { workCompletedAt = DateTime.Now; }, waitDuration); Or, the fluent way: Start.Work(() => { workStartedAt = DateTime.Now; Thread.Sleep(howLongWorkTakes); }) .OnComplete(() => { workCompletedAt = DateTime.Now; }) .RunAfter(waitDuration);   There are several overloads of these functions to have a exception callback for handling exceptions or get progress update from background thread while work is in progress. For example, I use it in my PlantUmlEditor to perform background update of the application. // Check if there's a newer version of the app Start<bool>.Work(() => { return UpdateChecker.HasUpdate(Settings.Default.DownloadUrl); }) .OnComplete((hasUpdate) => { if (hasUpdate) { if (MessageBox.Show(Window.GetWindow(me), "There's a newer version available. Do you want to download and install?", "New version available", MessageBoxButton.YesNo, MessageBoxImage.Information) == MessageBoxResult.Yes) { ParallelWork.StartNow(() => { var tempPath = System.IO.Path.Combine( Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), Settings.Default.SetupExeName); UpdateChecker.DownloadLatestUpdate(Settings.Default.DownloadUrl, tempPath); }, () => { }, (x) => { MessageBox.Show(Window.GetWindow(me), "Download failed. When you run next time, it will try downloading again.", "Download failed", MessageBoxButton.OK, MessageBoxImage.Warning); }); } } }) .OnException((x) => { MessageBox.Show(Window.GetWindow(me), x.Message, "Download failed", MessageBoxButton.OK, MessageBoxImage.Exclamation); }); The above code shows you how to get exception callbacks on the UI thread so that you can take necessary actions on the UI. Moreover, it shows how you can chain two parallel works to happen one after another. Sometimes you want to do some parallel work when user does some activity on the UI. For example, you might want to save file in an editor while user is typing every 10 second. In such case, you need to make sure you don’t start another parallel work every 10 seconds while a work is already queued. You need to make sure you start a new work only when there’s no other background work going on. Here’s how you can do it: private void ContentEditor_TextChanged(object sender, EventArgs e) { if (!ParallelWork.IsAnyWorkRunning()) { ParallelWork.StartAfter(SaveAndRefreshDiagram, TimeSpan.FromSeconds(10)); } } If you want to shutdown your application and want to make sure no parallel work is going on, then you can call the StopAll() method. ParallelWork.StopAll(); If you want to wait for parallel works to complete without a timeout, then you can call the WaitForAllWork(TimeSpan timeout). It will block the current thread until the all parallel work completes or the timeout period elapses. result = ParallelWork.WaitForAllWork(TimeSpan.FromSeconds(1)); The result is true, if all parallel work completed. If it’s false, then the timeout period elapsed and all parallel work did not complete. For details how this library is built and how it works, please read the following codeproject article: ParallelWork: Feature rich multithreaded fluent task execution library for WPF http://www.codeproject.com/KB/WPF/parallelwork.aspx If you like the article, please vote for me.

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  • SSW Scrum Rule: Do you know to use clear task descriptions?

    - by Martin Hinshelwood
    When you create tasks in Scrum you are doing this within a time box and you tend to add only the information you need to remember what the task is. And the entire Team was at the meeting and were involved in the discussions around the task, so why do you need more? Once you have accepted a task you should then add as much information as possible so that anyone can pick up that task; what if your numbers come up? Will you be into work the next day? Figure: What if your numbers come up in the lottery? What if the Team runs a syndicate and all your numbers come up? The point is that anything can happen and you need to protect the integrity of the project, the company and the Customer. Add as much information to the task as you think is necessary for anyone to work on the task. If you need to add rich text and images you can do this by attaching an email to the task.   Figure: Bad example, there is not enough information for a non team member to complete this task Figure: Julie provided a lot more information and another team should be able to pick this up. This has been published as Do you know to ensure that relevant emails are attached to tasks in our Rules to Better Scrum using TFS.   Technorati Tags: Scrum,SSW Rules,TFS 2010

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  • Error happening when running "rake db:create RAILS_ENV='development' "

    - by Dean
    Hi, I am getting this error in my terminal when i execute the command above, Deans-MacBook:depot dean$ rake db:create RAILS_ENV='development' (in /Users/dean/src/RailsBook/depot) Couldn't create database for {"username"=>"root", "adapter"=>"mysql", "database"=>"depot_development", "host"=>"localhost", "password"=>nil}, charset: utf8, collation: utf8_unicode_ci (if you set the charset manually, make sure you have a matching collation) In database config file i have the following: development: adapter: mysql database: depot_development username: root password: host: localhost I have the mysql gem installed and now i am unsure on what to do next. I am running snow leopard on a Macbook. Does anyone know why this error is happening? Thanks in Advance Dean

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  • Database not completely updated in rails migration

    - by Aatish Sai
    I am new to Ruby on Rails. I have a migration called create user class CreateUsers < ActiveRecord::Migration def change create_table :users do |t| t.column :username, :string, :limit => 25, :default => "", :null => false t.column :hashed_password, :string, :limit => 40, :default => "", :null => false t.column :first_name, :string, :limit => 25, :default => "", :null => false t.column :last_name, :string, :limit => 40, :default => "", :null => false t.column :email, :string, :limit => 50, :default => "", :null => false t.column :display_name, :string, :limit => 25, :default => "", :null => false t.column :user_level, :integer, :limit => 3, :default => 0, :null => false end User.create(:username=>'test',:hashed_password=>'test',:first_name=>'test',:last_name=>'test',:email=>'[email protected]',:display_name=> 'test',:user_level=>9) end end When I run rake db:migrate the table is created with the columns as mentioned above but the test data are not there mysql>select * from users; Empty set (0.00 sec) EDIT I just dropped the whole database and restarted the migration and now it is showing the following error. rake aborted! An error has occurred, all later migrations canceled: Can't mass-assign protected attributes: username, hashed_password, first_name, last_name, email, display_name, user_level What am I doing wrong please help? Thank you.

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  • Why does running rake gems:unpack result in a Gem::FilePermissionError

    - by Globalkeith
    I'm attempting to upgrade the friendly_id gem in a rails project. I have removed the old gem from the vendor directory, installed the new gem from rubygems.org. When I type: rake gems:unpack I get the following response: ERROR: While executing gem ... (Gem::FilePermissionError) You don't have write permissions into the /usr/lib/ruby/gems/1.8 directory. Sure, I realise I can sudo it, but what I don't understand is if I would like to unpack the gem into my project vender directory, why does it need access to /usr/lib/ruby/gems....

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  • "rake test" doesn't load fixtures?

    - by Pavel K.
    when i run rake test --trace here's what happens ** Invoke test (first_time) ** Execute test ** Invoke test:units (first_time) ** Invoke db:test:prepare (first_time) ** Invoke db:abort_if_pending_migrations (first_time) ** Invoke environment (first_time) ** Execute environment ** Execute db:abort_if_pending_migrations ** Execute db:test:prepare ** Invoke db:test:load (first_time) ** Invoke db:test:purge (first_time) ** Invoke environment ** Execute db:test:purge ** Execute db:test:load ** Invoke db:schema:load (first_time) ** Invoke environment ** Execute db:schema:load ** Execute test:units /usr/bin/ruby1.8 -I"lib:test".... (and after that fails because there's no fixtures loaded) why doesn't it load fixtures (i thought that would be default behaviour) and how do i make it load fixtures before executing tests??? p.s. my test/test_helper.rb content is: ENV["RAILS_ENV"] = "test" require File.expand_path(File.dirname(__FILE__) + "/../config/environment") require 'test_help' class ActiveSupport::TestCase self.use_transactional_fixtures = true self.use_instantiated_fixtures = false fixtures :all end (rails 2.3.4)

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  • Rails 3 MySQL 2 reports an error in what looks to be valid SQL syntax

    - by John Judd
    I am trying to use the following bit of code to help in seeding my database. I need to add data continually over development and do not want to have to completely reseed data every time I add something new to the seeds.rb file. So I added the following function to insert the data if it doesn't already exist. def AddSetting(group, name, value, desc) Admin::Setting.create({group: group, name: name, value: value, description: desc}) unless Admin::Setting.find_by_sql("SELECT * FROM admin_settings WHERE group = '#{group}' AND name = '#{name}';").exists? end AddSetting('google', 'analytics_id', '', 'The ID of your Google Analytics account.') AddSetting('general', 'page_title', '', '') AddSetting('general', 'tag_line', '', '') This function is included in the db/seeds.rb file. Is this the right way to do this? However I am getting the following error when I try to run it through rake. rake aborted! Mysql2::Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'group = 'google' AND name = 'analytics_id'' at line 1: SELECT * FROM admin_settings WHERE group = 'google' AND name = 'analytics_id'; Tasks: TOP => db:seed (See full trace by running task with --trace) Process finished with exit code 1 What is confusing me is that I am generating correct SQL as far as I can tell. In fact my code generates the SQL and I pass that to the find_by_sql function for the model, Rails itself can't be changing the SQL, or is it? SELECT * FROM admin_settings WHERE group = 'google' AND name = 'analytics_id'; I've written a lot of SQL over the years and I've looked through similar questions here. Maybe I've missed something, but I cannot see it.

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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 called 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 cleaned up 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# level syntax sugar. There is no difference to await a async method or a normal method. A method returning Task will be 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); } } The above code is already cleaned up, but there are still a lot of things. More clean up can be done, and the state machine can be 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> void IAsyncStateMachine.MoveNext() { try { switch (this.State) { // Orginal code is splitted by "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; IAsyncStateMachine this1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this1.MoveNext()); // Callback 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; IAsyncStateMachine this2 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this2.MoveNext()); // Callback 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] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { // 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 as IAsyncStateMachine).MoveNext(); // Original code are in this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clear - 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 Since it is about callback, the simplification  can go even further – the entire state machine can be completely purged. 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 literally pretending to wait. In a await expression, a Task object will be return immediately so that caller 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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  • 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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  • Sorting tasks to assign

    - by Diego
    I've got a problem that I don't know where to start. I'd realy appreciate some help. The problem: I have several T task that must be done in D days by just 1 employee (let's forget using several resources right now). Each task can be done in some times (not all tasks can be done all time). e.g.: If my employee starts working at 8 o'clock and one task is "call a client". Maybe the client office opens at 9 o'clock. Also each task has a duration (really estimated). It is supposed that the D days are enough to do all task. I've to sort the tasks to the employee. e.g.: at monday 8:00 do task 7, then at 9:30 starts with task 2. In the example task 7 duration would be 1 and a half hour. Thanks for the help! Diego PD: If someone has a way to make this and it is not an algorithm never minds, please answer and I'll manage to think the algorithm. I just don't know how to face the problem. Edit Would Project be usefull? Edit 2 Tasks / Jobs dependency is NOT required

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  • How do I create a scheduled task, via command line, which includes advanced options

    - by David
    I'm trying to create a scheduled task (in WinXP) which runs every 10 minutes, starting at 16:00:00 to 06:00:00, daily, from the command line. Currently, I can create a scheduled task which runs every 10 minutes, starting at 16:00:00, daily, by using the following command: SCHTASKS.EXE /CREATE /SC MINUTE /MO 10 /TN "Scheduled task name" /ST 16:00:00 /SD 01/01/2000 /TR task.bat /RU SYSTEM The question is, how do I modify the previous command so that it stops running at 06:00:00?

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  • Can we use the task list from "another" web site of same site collection as task list for Sharepoint

    - by Khurram Aziz
    Can I specify/use an existing task list from "another" website but from same site collection to be used in my Sequential Sharepoint Workflow? I am using Visual Studio to code the workflow, and it will be deployed in /subsite, the root site already has a task list to which everyone has connected to Outlook etc...Instead of creating a new task list in /subsite and asking concerned to subscribe to this new task list...I want to use the existing one..

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  • can't backup to a NAS drive as offline schedule task

    - by imageng
    I have seen this problem issue discussed in several forums including this one, but could not find a solution. On MS server 2003 I configured a Backup task, the target backup is on a NAS disc (Seagate BlackArmor NAS 110). The backup task is working well as a scheduled task or by a direct command, when I am logged on. It is not working when the user is offline (in this case - Administrator). I already tried the following actions: 1) addressing to the target as network drive (Y:location..), 2)Using UNC instead, 3) making the drive a domain member (the NAS admin S/W allows to define itself as a domain member) The result log message for 1 and 2 is: "The operation was not performed because the specified media cannot be found." The result log message for 3 is empty file. The schedule task "RUN" command is: C:\WINDOWS\system32\ntbackup.exe backup "@C:\Documents and Settings\Administrator\Local Settings\Application Data\Microsoft\Windows NT\NTBackup\data\de-board.bks" /a /d "Set created 2/14/2010 at 5:10 PM" /v:yes /r:no /rs:no /hc:off /m incremental /j "de-board" /l:s /f "\10.0.0.8\public\Backups\IBMServer\de-board.bkf" 10.0.0.8 is the static IP of the NAS. "Run only if logged on" is NOT marked. Password of the administrator user is set. It is obvious that there is no access to the NAS when the user is logged-out. Do you have any idea how can I solve it? Thanks

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  • Windows 7 scheduled task returns 0x2

    - by demmith
    I have identical scheduled tasks running in Windows XP Pro and Windows 7. The XP Pro one runs fine, the Windows 7 one always returns 0x2 (which means, "The system cannot find the file specified"; however, executing from the command line is no problem) in the Last Run Result column of the Task Scheduler UI. The scheduled task executes a .bat file daily. The .bat file contains a call to execute a Perl script. As I stated in the previous paragraph, it executes under XP without any trouble but under Windows 7, no dice. The task under Windows 7 is set to "run whether the user is logged on or not." In this case it is me, I am the only user of the system. It is also set to "Run with highest privileges." And it is not hidden. The .bat file executes perfectly well from the command line - it calls the Perl script as expected and the Perl script does its thing. I have searched far and wide looking for an appropriate answer to this issue. So far I have found nothing. What the devil is going on with this Win7 scheduled task? I am ready to pull my hair out.

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  • Task queue java api

    - by user268515
    Hi i'm working in task queue concept.... First i struggled to program using task queue and i asked many doubts in stack overflow and Google app engine java. After a search i got a sample program for task queue. http://gaejexperiments.wordpress.com/2009/11/24/episode-10-using-the-task-queue-service/ It will very useful for beginners Like me. Regards, Sharun.

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