SchedulerOperationAwaiter
(Infrastructure) Scheduler operation awaiter type used by the code generated for C# await and Visual Basic Await expressions.
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Threading;
namespace System.Reactive.Concurrency
{
[System.Runtime.CompilerServices.NullableContext(1)]
[System.Runtime.CompilerServices.Nullable(0)]
[EditorBrowsable(EditorBrowsableState.Never)]
public sealed class SchedulerOperationAwaiter : INotifyCompletion
{
private readonly Func<Action, IDisposable> _schedule;
private readonly CancellationToken _cancellationToken;
private readonly bool _postBackToOriginalContext;
private readonly CancellationTokenRegistration _ctr;
[System.Runtime.CompilerServices.Nullable(2)]
private volatile Action _continuation;
[System.Runtime.CompilerServices.Nullable(2)]
private volatile IDisposable _work;
public bool IsCompleted => _cancellationToken.IsCancellationRequested;
internal SchedulerOperationAwaiter(Func<Action, IDisposable> schedule, bool postBackToOriginalContext, CancellationToken cancellationToken)
{
_schedule = schedule;
_cancellationToken = cancellationToken;
_postBackToOriginalContext = postBackToOriginalContext;
if (cancellationToken.CanBeCanceled)
_ctr = _cancellationToken.Register(delegate(object this) {
((SchedulerOperationAwaiter)this).Cancel();
}, this);
}
public void GetResult()
{
_cancellationToken.ThrowIfCancellationRequested();
}
public void OnCompleted(Action continuation)
{
if (continuation == null)
throw new ArgumentNullException("continuation");
if (_continuation != null)
throw new InvalidOperationException(Strings_Core.SCHEDULER_OPERATION_ALREADY_AWAITED);
if (_postBackToOriginalContext) {
SynchronizationContext ctx = SynchronizationContext.Current;
if (ctx != null)
continuation = delegate {
ctx.Post(delegate(object a) {
((Action)a)();
}, continuation);
};
}
int ran = 0;
_continuation = delegate {
if (Interlocked.Exchange(ref ran, 1) == 0) {
_ctr.Dispose();
continuation();
}
};
_work = _schedule(_continuation);
}
private void Cancel()
{
_work?.Dispose();
_continuation?.Invoke();
}
}
}