ValueTaskAwaiter.cs

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using System.Threading;
using System.Threading.Tasks;
using System.Threading.Tasks.Sources;
using Internal.Runtime.CompilerServices;
 
namespace System.Runtime.CompilerServices;
 
public readonly struct ValueTaskAwaiter : ICriticalNotifyCompletion, INotifyCompletion, IStateMachineBoxAwareAwaiter
{
    internal static readonly Action<object> s_invokeActionDelegate = delegate(object state)
    {
        if (!(state is Action action))
        {
            ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.state);
        }
        else
        {
            action();
        }
    };
 
    private readonly ValueTask _value;
 
    public bool IsCompleted
    {
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        get
        {
            return _value.IsCompleted;
        }
    }
 
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    internal ValueTaskAwaiter(in ValueTask value)
    {
        _value = value;
    }
 
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public void GetResult()
    {
        _value.ThrowIfCompletedUnsuccessfully();
    }
 
    public void OnCompleted(Action continuation)
    {
        object obj = _value._obj;
        if (obj is Task task)
        {
            task.GetAwaiter().OnCompleted(continuation);
        }
        else if (obj != null)
        {
            Unsafe.As<IValueTaskSource>(obj).OnCompleted(s_invokeActionDelegate, continuation, _value._token, ValueTaskSourceOnCompletedFlags.UseSchedulingContext | ValueTaskSourceOnCompletedFlags.FlowExecutionContext);
        }
        else
        {
            Task.CompletedTask.GetAwaiter().OnCompleted(continuation);
        }
    }
 
    public void UnsafeOnCompleted(Action continuation)
    {
        object obj = _value._obj;
        if (obj is Task task)
        {
            task.GetAwaiter().UnsafeOnCompleted(continuation);
        }
        else if (obj != null)
        {
            Unsafe.As<IValueTaskSource>(obj).OnCompleted(s_invokeActionDelegate, continuation, _value._token, ValueTaskSourceOnCompletedFlags.UseSchedulingContext);
        }
        else
        {
            Task.CompletedTask.GetAwaiter().UnsafeOnCompleted(continuation);
        }
    }
 
    void IStateMachineBoxAwareAwaiter.AwaitUnsafeOnCompleted(IAsyncStateMachineBox box)
    {
        object obj = _value._obj;
        if (obj is Task task)
        {
            TaskAwaiter.UnsafeOnCompletedInternal(task, box, continueOnCapturedContext: true);
        }
        else if (obj != null)
        {
            Unsafe.As<IValueTaskSource>(obj).OnCompleted(ThreadPool.s_invokeAsyncStateMachineBox, box, _value._token, ValueTaskSourceOnCompletedFlags.UseSchedulingContext);
        }
        else
        {
            TaskAwaiter.UnsafeOnCompletedInternal(Task.CompletedTask, box, continueOnCapturedContext: true);
        }
    }
}
public readonly struct ValueTaskAwaiter<TResult> : ICriticalNotifyCompletion, INotifyCompletion, IStateMachineBoxAwareAwaiter
{
    private readonly ValueTask<TResult> _value;
 
    public bool IsCompleted
    {
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        get
        {
            return _value.IsCompleted;
        }
    }
 
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    internal ValueTaskAwaiter(in ValueTask<TResult> value)
    {
        _value = value;
    }
 
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public TResult GetResult()
    {
        return _value.Result;
    }
 
    public void OnCompleted(Action continuation)
    {
        object obj = _value._obj;
        if (obj is Task<TResult> task)
        {
            task.GetAwaiter().OnCompleted(continuation);
        }
        else if (obj != null)
        {
            Unsafe.As<IValueTaskSource<TResult>>(obj).OnCompleted(ValueTaskAwaiter.s_invokeActionDelegate, continuation, _value._token, ValueTaskSourceOnCompletedFlags.UseSchedulingContext | ValueTaskSourceOnCompletedFlags.FlowExecutionContext);
        }
        else
        {
            Task.CompletedTask.GetAwaiter().OnCompleted(continuation);
        }
    }
 
    public void UnsafeOnCompleted(Action continuation)
    {
        object obj = _value._obj;
        if (obj is Task<TResult> task)
        {
            task.GetAwaiter().UnsafeOnCompleted(continuation);
        }
        else if (obj != null)
        {
            Unsafe.As<IValueTaskSource<TResult>>(obj).OnCompleted(ValueTaskAwaiter.s_invokeActionDelegate, continuation, _value._token, ValueTaskSourceOnCompletedFlags.UseSchedulingContext);
        }
        else
        {
            Task.CompletedTask.GetAwaiter().UnsafeOnCompleted(continuation);
        }
    }
 
    void IStateMachineBoxAwareAwaiter.AwaitUnsafeOnCompleted(IAsyncStateMachineBox box)
    {
        object obj = _value._obj;
        if (obj is Task<TResult> task)
        {
            TaskAwaiter.UnsafeOnCompletedInternal(task, box, continueOnCapturedContext: true);
        }
        else if (obj != null)
        {
            Unsafe.As<IValueTaskSource<TResult>>(obj).OnCompleted(ThreadPool.s_invokeAsyncStateMachineBox, box, _value._token, ValueTaskSourceOnCompletedFlags.UseSchedulingContext);
        }
        else
        {
            TaskAwaiter.UnsafeOnCompletedInternal(Task.CompletedTask, box, continueOnCapturedContext: true);
        }
    }
}