AsyncManualResetEvent

Overview

This is the async-ready equivalent of ManualResetEvent, similar to Stephen Toub's AsyncManualResetEvent.

Like other "events", an AsyncManualResetEvent is either set or unset at any time. An AsyncManualResetEvent can be changed from unset to set by calling its Set method, and it can be changed from set to unset by calling its Reset method.

When an AsyncManualResetEvent is in the set state, it will satisfy all waiters. Calling Set or Reset when the AsyncManualResetEvent is already in that state is a noop.

The task returned from WaitAsync will enter the Completed state when the AsyncManualResetEvent is in the set state.

API

// An async-compatible manual-reset event.
public sealed class AsyncManualResetEvent
{
  // Creates an async-compatible manual-reset event.
  public AsyncManualResetEvent(); // Defaults to "unset"
  public AsyncManualResetEvent(bool set);

  // Waits for this event to be set.
  public Task WaitAsync();
  public void Wait();
  public void Wait(CancellationToken cancellationToken);

  // Sets the event, atomically completing every task returned by WaitAsync.
  // If the event is already set, this method does nothing.
  public void Set();

  // Resets the event.
  // If the event is already reset, this method does nothing.
  public void Reset();

  // Gets a semi-unique identifier for this asynchronous manual-reset event.
  public int Id { get; }
}

Advanced Usage

AsyncManualResetEvent also supports synchronous waiting with the Wait method.

You can call Wait with an already-cancelled CancellationToken to test whether the AsyncManualResetEvent is in the set state.

Design Notes

WaitAsync does not have explicit CancellationToken support because there are no state changes when a wait is satisfied.

Platform Support

The full API is supported on all platforms.