GDTask 1.2.1

GDTask.Nuget

• Ported and Tested in Godot 4.2 with .Net module.
• This is the Nuget Package version based on code from:
  • Atlinx's GDTask addon for Godot
  • Cysharp's UniTask library for Unity

Table of Contents

• Abstract
  • Efficient allocation free async/await integration for Godot
  • GDTask Under the hood
• Installation via Nuget
• Basic API usage
• Task Profiling
• Compare with Standard .Net Task API

Abstract

Clarification: Contents in the abstract section are mostly migrated from the Cysharp's UniTask library for Unity

Efficient allocation free async/await integration for Godot

• Struct-based GDTask<T> and custom AsyncMethodBuilder to achieve zero allocation.
• Provides awaitable functionality for certain Engine event functions.
• Runs completely on Godot PlayerLoop so doesn't use threads.
• Highly compatible behavior with Task/ValueTask/IValueTaskSource.

GDTask Under the hood

• Based on the task-like custom async method builder feature. of C# 7.0, GDTask does not use Threads, SynchronizationContext, or ExecutionContext. Instead, it dispatches the asynchronous tasks onto a standalone singleton node GDTaskPlayerLoopRunner, which results in better performance, and lower allocation.

Installation via Nuget

For .Net CLI

dotnet add package GDTask

For Package Manager Console:

NuGet\Install-Package GDTask

Basic API usage

For more detailed usage, see Unit Tests.

using GodotTasks.Tasks;

// Use GDTaskVoid if this task is only used with ApiUsage().Forget();
public async GDTask ApiUsage()
{
    // Delay the execution after frame(s).
    await GDTask.DelayFrame(100); 
    
    // Delay the execution after delayTimeSpan.
    await GDTask.Delay(TimeSpan.FromSeconds(10), DelayType.Realtime);

    // Delay the execution until the next Process.
    await GDTask.Yield(PlayerLoopTiming.Process);

    // Delay the execution until the next PhysicsProcess.
    await GDTask.WaitForPhysicsProcess();

    // Creates a task that will complete at the next provided PlayerLoopTiming when the supplied predicate evaluates to true
    await GDTask.WaitUntil(() => Time.GetTimeDictFromSystem()["minute"].AsInt32() % 2 == 0);
    
    // Creates a task that will complete at the next provided PlayerLoopTiming when the provided monitorFunction returns a different value.
    await GDTask.WaitUntilValueChanged(Time.Singleton, timeInstance => timeInstance.GetTimeDictFromSystem()["minute"]);
    
    // Creates an awaitable that asynchronously yields to ThreadPool when awaited.
    await GDTask.SwitchToThreadPool();
    
    /* Threaded work */
    
    // Creates an awaitable that asynchronously yields back to the next Process from the main thread when awaited.
    await GDTask.SwitchToMainThread();
    
    /* Main thread work */
    
    await GDTask.NextFrame();

    // Creates a continuation that executes when the target GDTask completes.
    int taskResult = await GDTask.Delay(10).ContinueWith(() => 5);
    
    GDTask<int> task1 = GDTask.Delay(10).ContinueWith(() => 5);
    GDTask<string> task2 = GDTask.Delay(20).ContinueWith(() => "Task Result");
    GDTask<bool> task3 = GDTask.Delay(30).ContinueWith(() => true);

    // Creates a task that will complete when all of the supplied tasks have completed.
    var (task1Result, task2Result, task3Result) = await GDTask.WhenAll(task1, task2, task3);

    try
    {
        // Creates a GDTask that has completed with the specified exception.
        await GDTask.FromException(new ExpectedException());
    }
    catch (ExpectedException) { }
    
    try
    {
        // Creates a GDTask that has completed due to cancellation with the specified cancellation token.
        await GDTask.FromCanceled(CancellationToken.None);
    }
    catch (TaskCanceledException) { }
    
    try
    {
        var source = new CancellationTokenSource();
        source.CancelAfter(100);
        // Creates a task that never completes, with specified CancellationToken.
        await GDTask.Never(source.Token);
    }
    catch (TaskCanceledException) { }
    
    // Queues the specified work to run on the ThreadPool and returns a GDTask handle for that work.
    await GDTask.RunOnThreadPool(
        () => GD.Print(Environment.CurrentManagedThreadId.ToString()),
        configureAwait: true,
        cancellationToken: CancellationToken.None
    );

    // Create a GDTask that wraps around this task.
    await Task.Delay(5).AsGDTask(useCurrentSynchronizationContext: true);

    // Associate a time out to the current GDTask.
    await GDTask.Never(CancellationToken.None).Timeout(TimeSpan.FromMilliseconds(5));

    var node = new Node();
    ((SceneTree)Engine.GetMainLoop()).Root.CallDeferred(Node.MethodName.AddChild, node);
    
    // Creates a task that will complete when the _EnterTree() is called.
    await node.OnEnterTreeAsync();
    
    // Creates a task that will complete when the _Ready() is called.
    await node.OnReadyAsync();
    
    // Gets an instance of IAsyncProcessHandler for making repeatedly calls on OnProcessAsync().
    var processTrigger = node.GetAsyncProcessTrigger();
    
    // Creates a task that will complete when the next _Process(double) is called.
    await processTrigger.OnProcessAsync();
    await processTrigger.OnProcessAsync();
    await processTrigger.OnProcessAsync();
    await processTrigger.OnProcessAsync();
    
    // Gets an instance of IAsyncPhysicsProcessHandler for making repeatedly calls on OnPhysicsProcessAsync().
    var physicsProcessTrigger = node.GetAsyncPhysicsProcessTrigger();
    await physicsProcessTrigger.OnPhysicsProcessAsync();
    await physicsProcessTrigger.OnPhysicsProcessAsync();
    await physicsProcessTrigger.OnPhysicsProcessAsync();
    await physicsProcessTrigger.OnPhysicsProcessAsync();    
    
    node.QueueFree();
    
    // Creates a task that will complete when the Node is receiving NotificationPredelete.
    await node.OnPredeleteAsync();
}

Task Profiling

Clarification: Contents in the task profiling section are mostly migrated from the Cysharp's UniTask library for Unity

When calling TaskTracker.ShowTrackerWindow() in your code base, the GDTask system will create(or reuse) a GDTask Tracker window for inspecting/diagnosing (leaked) GDTasks.

• Do keep in mind this feature is for debugging purposes and it has performance penalties, so stay cautious when calling TaskTracker.ShowTrackerWindow() under the production environment.
• The background status collection system does not start if you have never called TaskTracker.ShowTrackerWindow().
• Closing an active GDTask Tracker window does not stop the background status collection system, remember to toggle off Enable Tracking or set TaskTracker.EnableTracking to false in your code.
• Godot Games embeds sub-windows by default, you can disable the Embed Subwindows option located in ProjectSettings (Advanced Settings enabled)Display/Window/Subwindows/Embed Subwindows for them to become Standalone Windows.
• This window reacts to the window closing command (NotificationWMCloseRequest) correctly so it closes itself when you click the close button, to relaunch this window simply call TaskTracker.ShowTrackerWindow() again.

Compare with Standard .Net Task API

Clarification: Contents in the compare section are mostly migrated from the Cysharp's UniTask library for Unity

Same as the Standard .Net Task APIs, CancellationToken and CancellationTokenSource are widely used by the GDTask APIs as well.<br> Otherwise, the following table shows the GDTask APIs provided that are meant to replace the usage of standard .Net Task APIs.