public static Task <T> FromException <T>(Exception exception)
{
var source = ValueTaskCompletionSource <T> .Create();
source.TrySetException(exception);
return(source.Task);
}
private void EnsureHasTask()
{
if (!_source.HasTask)
{
_source = ValueTaskCompletionSource <T> .Create();
}
}
public async Task PartiallyCompletedCanceled2WhenAllTest()
{
var taskSources = new ValueTaskCompletionSource <int> [3];
for (var i = 0; i < taskSources.Count(); i++)
{
taskSources[i] = ValueTaskCompletionSource <int> .Create();
}
taskSources[1].SetCanceled();
var task = taskSources.Select(p => p.Task).WhenAll(preserveOrder: true);
Assert.IsFalse(task.IsCompleted);
// Complete the tasks in non-sort order and wait some time in between
taskSources[2].SetResult(2);
await Task.Delay(10);
taskSources[0].SetResult(0);
await Task.Delay(20); // Wait some time to allow the continuations to execute
Assert.IsTrue(task.IsCompleted);
Assert.IsTrue(task.IsCanceled);
await Assert.ThrowsExceptionAsync <TaskCanceledException>(async() =>
{
await task;
});
}
public async Task WhenAllNonGenericTest()
{
var taskSources = new ValueTaskCompletionSource[3];
for (var i = 0; i < taskSources.Count(); i++)
{
taskSources[i] = ValueTaskCompletionSource.Create();
}
var task = taskSources.Select(p => p.Task).WhenAll();
Assert.IsFalse(task.IsCompleted);
// Complete the tasks in non-sort order and wait some time in between
taskSources[1].SetResult();
await Task.Delay(10);
taskSources[2].SetResult();
await Task.Delay(10);
taskSources[0].SetResult();
Assert.IsTrue(task.IsCompletedSuccessfully);
task.GetAwaiter().GetResult();
}
public async Task PartiallyCompletedExceptionNonPreserveOrder2WhenAllTest()
{
var taskSources = new ValueTaskCompletionSource <int> [3];
for (var i = 0; i < taskSources.Count(); i++)
{
taskSources[i] = ValueTaskCompletionSource <int> .Create();
}
taskSources[1].SetException(new CustomException());
var task = taskSources.Select(p => p.Task).WhenAll(preserveOrder: false);
Assert.IsFalse(task.IsCompleted);
// Complete the tasks in non-sort order and wait some time in between
taskSources[2].SetResult(2);
await Task.Delay(10);
taskSources[0].SetResult(0);
Assert.IsTrue(task.IsCompleted);
Assert.IsTrue(task.IsFaulted);
await Assert.ThrowsExceptionAsync <CustomException>(async() =>
{
await task;
});
}
public async Task WhenAllTest()
{
var taskSources = new ValueTaskCompletionSource <int> [3];
for (var i = 0; i < taskSources.Count(); i++)
{
taskSources[i] = ValueTaskCompletionSource <int> .Create();
}
var task = taskSources.Select(p => p.Task).WhenAll(preserveOrder: true);
Assert.IsFalse(task.IsCompleted);
// Complete the tasks in non-sort order and wait some time in between
taskSources[1].SetResult(1);
await Task.Delay(10);
taskSources[2].SetResult(2);
await Task.Delay(10);
taskSources[0].SetResult(0);
await Task.Delay(20); // Wait some time to allow the continuations to execute
Assert.IsTrue(task.IsCompletedSuccessfully);
var result = task.GetAwaiter().GetResult(); // We are allowed only once to get the result.
Assert.IsNotNull(result);
Assert.IsTrue(new[] { 0, 1, 2 }.SequenceEqual(result));
}
public async Task PartiallyCompletedCanceledNonGeneric2WhenAllTest()
{
var taskSources = new ValueTaskCompletionSource[3];
for (var i = 0; i < taskSources.Count(); i++)
{
taskSources[i] = ValueTaskCompletionSource.Create();
}
taskSources[1].SetCanceled();
var task = taskSources.Select(p => p.Task).WhenAll();
Assert.IsFalse(task.IsCompleted);
// Complete the tasks in non-sort order and wait some time in between
taskSources[2].SetResult();
await Task.Delay(10);
taskSources[0].SetResult();
Assert.IsTrue(task.IsCompleted);
Assert.IsTrue(task.IsCanceled);
await Assert.ThrowsExceptionAsync <TaskCanceledException>(async() =>
{
await task;
});
}
public async Task MultipleAsyncIndexOutOfOrder()
{
var FirstSource = ValueTaskCompletionSource.New <int>();
var SecondSource = ValueTaskCompletionSource.New <int>();
await using var Enumerator = new[] { FirstSource.Task, SecondSource.Task }.InterleaveIndex().GetAsyncEnumerator();
var Waiter = Enumerator.MoveNextAsync();
Assert.IsFalse(Waiter.IsCompleted);
SecondSource.TrySetResult(108);
Assert.IsTrue(await Waiter);
Assert.IsTrue(Enumerator.Current.result.IsCompleted);
Assert.AreEqual(SecondSource.Task.Result, Enumerator.Current.result.Result);
Assert.AreEqual(1, Enumerator.Current.index);
Waiter = Enumerator.MoveNextAsync();
Assert.IsFalse(Waiter.IsCompleted);
FirstSource.TrySetResult(42);
Assert.IsTrue(await Waiter);
Assert.IsTrue(Enumerator.Current.result.IsCompleted);
Assert.AreEqual(FirstSource.Task.Result, Enumerator.Current.result.Result);
Assert.AreEqual(0, Enumerator.Current.index);
Assert.IsFalse(await Enumerator.MoveNextAsync());
}
public async Task ExceptionAsync()
{
var FirstSource = ValueTaskCompletionSource.New <int>();
await using var Enumerator = new[] { FirstSource.Task }.Interleave().GetAsyncEnumerator();
var Waiter = Enumerator.MoveNextAsync();
Assert.IsFalse(Waiter.IsCompleted);
FirstSource.TrySetException(new ApplicationException("Test"));
Assert.IsTrue(await Waiter);
try
{
await Enumerator.Current;
Assert.Fail("Did not throw");
}
catch (ApplicationException)
{
}
Assert.IsFalse(await Enumerator.MoveNextAsync());
}
static async Task ValueTaskCompletionSourceExampleAsync()
{
var vtcs = new ValueTaskCompletionSource <int>(false);
var are = new AutoResetEvent(false);
var t1 = Task.Run(() =>
{
int v = 0;
while (true)
{
Thread.Sleep(1_000); // attempts to execute await t before set result
vtcs.SetResult(v++);
are.WaitOne();
}
});
var t2 = Task.Run(async() =>
{
while (true)
{
ValueTask <int> t = vtcs.Task;
var result = await t.ConfigureAwait(false);
Console.WriteLine($"{result}");
are.Set();
}
});
await Task.WhenAll(t1, t2).ConfigureAwait(false);
}
public Task GetTask(short token)
{
lock (this)
{
CheckTokenInsideLock(token);
if (_task != null)
{
}
else if (_exception is OperationCanceledException)
{
_task = TaskUtils.TaskFactory <T> .Canceled;
}
else if (_exception != null)
{
_task = TaskUtils.FromException <T>(_exception);
}
else if (_isComplete)
{
_task = typeof(T) == typeof(Nothing) ? TaskUtils.CompletedTask : TaskUtils.TaskFactory <T> .FromResult(_result);
}
else
{
_source = ValueTaskCompletionSource <T> .Create();
_task = _source.Task;
}
return(_task);
}
}
public void DefaultInstanceBehavior()
{
ValueTaskCompletionSource <int> source = default;
Assert.True(source.IsNull);
Assert.False(source.IsOptimized);
Assert.False(source.TrySetResult(42));
}
public void FallbackTask(bool shouldFault)
{
Counters.Reset();
var source = ValueTaskCompletionSource <int> .CreateFallback();
Assert.Equal(1, Counters.TaskAllocated.Value);
Assert.False(source.IsOptimized);
Verify(source, shouldFault);
}
/// <summary>
/// Transitions the underlying <see cref="ValueTask{TResult}"/> object
/// into the <see cref="TaskStatus.Faulted"/> or <see cref="TaskStatus.Canceled"/> state,
/// depending on the type of exception.
/// </summary>
/// <typeparam name="TResult">
/// The type of the result value associated with the <see cref="ValueTaskCompletionSource{TResult}"/>.
/// </typeparam>
/// <param name="taskCompletionSource">The task completion source.</param>
/// <param name="exception">The exception to bind to the <see cref="ValueTask{TResult}"/>.</param>
/// <exception cref="ArgumentNullException">
/// Thrown if any of <paramref name="taskCompletionSource"/> or <paramref name="exception"/> is <c>null</c>.
/// </exception>
/// <exception cref="InvalidOperationException">
/// The <see cref="ValueTask{TResult}"/> is already in one of the three final states:
/// <see cref="TaskStatus.RanToCompletion"/>, <see cref="TaskStatus.Faulted"/>,
/// or <see cref="TaskStatus.Canceled"/>.
/// </exception>
public static void SetExceptionOrCanceled <TResult>(
this ValueTaskCompletionSource <TResult> taskCompletionSource,
Exception exception)
{
if (!TrySetExceptionOrCanceled(taskCompletionSource, exception))
{
throw new InvalidOperationException(
"The underlying Task<TResult> is already in one of the three final states:" +
" RanToCompletion, Faulted, or Canceled.");
}
}
public void OptimizedTask(bool shouldFault)
{
Counters.Reset();
var source = ValueTaskCompletionSource <int> .CreateOptimized();
#if DEBUG
Assert.Equal(1, Counters.TaskAllocated.Value);
#endif
Assert.True(source.IsOptimized);
Verify(source, shouldFault);
}
public async Task Complete()
{
using var TaskSource = ValueTaskCompletionSource.New();
var Task = TaskSource.Task;
Assert.IsFalse(Task.IsCompleted);
Assert.IsTrue(TaskSource.TrySetResult());
await Task;
}
public async Task CompleteResult()
{
using var TaskSource = ValueTaskCompletionSource.New <int>();
var Task = TaskSource.Task;
Assert.IsFalse(Task.IsCompleted);
Assert.IsTrue(TaskSource.TrySetResult(123));
var Result = await Task;
Assert.AreEqual(123, Result);
}
public async Task SingleAsync()
{
var FirstSource = ValueTaskCompletionSource.New <int>();
await using var Enumerator = new[] { FirstSource.Task }.Interleave().GetAsyncEnumerator();
var Waiter = Enumerator.MoveNextAsync();
Assert.IsFalse(Waiter.IsCompleted);
FirstSource.TrySetResult(42);
Assert.IsTrue(await Waiter);
Assert.IsTrue(Enumerator.Current.IsCompleted);
Assert.AreEqual(FirstSource.Task.Result, Enumerator.Current.Result);
Assert.IsFalse(await Enumerator.MoveNextAsync());
}
public async Task ExceptionResult()
{
using var TaskSource = ValueTaskCompletionSource.New <int>();
var Task = TaskSource.Task;
Assert.IsFalse(Task.IsCompleted);
Assert.IsTrue(TaskSource.TrySetException(new ApplicationException()));
try
{
var Result = await Task;
Assert.Fail("Should not reach here");
}
catch (ApplicationException)
{
}
}
public async Task CancelEnumerableWith()
{
var FirstSource = ValueTaskCompletionSource.New <int>();
var CancelSource = new CancellationTokenSource();
await using var Enumerator = new[] { FirstSource.Task }.Interleave().WithCancellation(CancelSource.Token).GetAsyncEnumerator();
var Waiter = Enumerator.MoveNextAsync();
CancelSource.Cancel();
try
{
await Waiter;
Assert.Fail("Did not cancel");
}
catch (OperationCanceledException)
{
}
}
private void Verify(ValueTaskCompletionSource <int> source, bool shouldFault)
{
var task = source.Task;
Assert.False(task.IsCompleted);
Assert.False(task.Status == TaskStatus.RanToCompletion);
if (shouldFault)
{
Assert.True(source.TrySetException(new FormatException()));
Assert.False(source.TrySetResult(42));
Assert.False(source.TrySetException(new FormatException()));
for (int i = 0; i < 2; i++) // can check multiple times
{
Assert.True(task.IsFaulted);
Assert.True(task.IsCompleted);
Assert.False(task.Status == TaskStatus.RanToCompletion);
var ex = Assert.Throws <AggregateException>(() => task.Result);
Assert.IsType <FormatException>(ex.InnerException);
}
}
else
{
Assert.True(source.TrySetResult(42));
Assert.False(source.TrySetResult(42));
Assert.False(source.TrySetException(new FormatException()));
for (int i = 0; i < 2; i++) // can check multiple times
{
Assert.False(task.IsFaulted);
Assert.True(task.IsCompleted);
Assert.True(task.Status == TaskStatus.RanToCompletion);
Assert.Equal(42, task.Result);
}
}
Assert.False(source.IsNull); // still good
}
public static ValueTask WaitForExitAsync(this Process process, CancellationToken cancellation = default)
{
var tcs = ValueTaskCompletionSource.Create();
#pragma warning disable CA1062
process.EnableRaisingEvents = true;
#pragma warning restore CA1062
process.Exited += (s, o) => tcs.TrySetResult();
// This is needed in order to prevent a race condition when the process exits before we can setup our event handler.
process.Refresh();
if (process.HasExited)
{
tcs.TrySetResult();
}
if (cancellation.CanBeCanceled)
{
cancellation.Register(() => tcs.TrySetCanceled());
}
return(tcs.Task);
}
/// <summary>
/// Attempts to transition the underlying <see cref="ValueTask{TResult}"/> object
/// into the <see cref="TaskStatus.Faulted"/> or <see cref="TaskStatus.Canceled"/> state,
/// depending on the type of exception.
/// </summary>
/// <typeparam name="TResult">
/// The type of the result value associated with the <see cref="ValueTaskCompletionSource{TResult}"/>.
/// </typeparam>
/// <param name="taskCompletionSource">The task completion source.</param>
/// <param name="exception">The exception to bind to the <see cref="ValueTask{TResult}"/>.</param>
/// <returns>True if the operation was succesful, false otherwise.</returns>
/// <exception cref="ArgumentNullException">
/// Thrown if any of <paramref name="taskCompletionSource"/> or <paramref name="exception"/> is <c>null</c>.
/// </exception>
public static bool TrySetExceptionOrCanceled <TResult>(
this ValueTaskCompletionSource <TResult> taskCompletionSource,
Exception exception)
{
if (exception == null)
{
throw new ArgumentNullException(nameof(exception));
}
if (exception is OperationCanceledException operationCanceledException)
{
var cancellationToken = operationCanceledException.CancellationToken;
if (cancellationToken != default)
{
return(taskCompletionSource.TrySetCanceled(cancellationToken));
}
return(taskCompletionSource.TrySetCanceled());
}
return(taskCompletionSource.TrySetException(exception));
}
