public async Task WaitAsync(CancellationToken cancellationToken = default(CancellationToken))
{
var spinner = new SpinWait();
while (true)
{
var capturedCounter = Interlocked.CompareExchange(ref counter, 0, 0);
var nextCounter = capturedCounter - 1;
if (Interlocked.CompareExchange(ref counter, nextCounter, capturedCounter) == capturedCounter)
{
if (capturedCounter > 0)
{
return;
}
else
{
var latch = new AsyncLatch();
var waitContext = new WaitContext {
Latch = latch
};
try {
waitContexts.Enqueue(waitContext);
await latch.WaitAsync(cancellationToken).ConfigureAwait(false);
return;
} catch (OperationCanceledException e) {
if (ResolveWaitContextUndoAsync(waitContext))
{
throw;
}
else
{
await waitContext.Latch.WaitAsync(CancellationToken.None).ConfigureAwait(false);
return;
}
// return ResolveWaitContextUndoAsync(waitContext, e);
}
}
}
spinner.SpinOnce();
}
}
public Task WaitAsync(CancellationToken token = default(CancellationToken))
{
var spinner = new SpinWait();
while (!token.IsCancellationRequested)
{
var previousValue = Interlocked.CompareExchange(ref state, kStateNeutral, kStateSet);
if (previousValue == kStateSet)
{
return(Task.FromResult(false));
}
var nextValue = previousValue + 1;
if (Interlocked.CompareExchange(ref state, nextValue, previousValue) == previousValue)
{
var latch = new AsyncLatch();
latches.Enqueue(latch);
return(latch.WaitAsync(token));
}
spinner.SpinOnce();
}
token.ThrowIfCancellationRequested();
// impossible code
throw new InvalidStateException();
}
