internal ValueTask <FlushResult> FlushAsync(CancellationToken cancellationToken)
{
CompletionData completionData;
CancellationTokenRegistration cancellationTokenRegistration;
ValueTask <FlushResult> result;
lock (_sync)
{
var wasEmpty = CommitUnsynchronized();
// AttachToken before completing reader awaiter in case cancellationToken is already completed
cancellationTokenRegistration = _writerAwaitable.BeginOperation(cancellationToken, s_signalWriterAwaitable, this);
// If the writer is completed (which it will be most of the time) then return a completed ValueTask
if (_writerAwaitable.IsCompleted)
{
var flushResult = new FlushResult();
GetFlushResult(ref flushResult);
result = new ValueTask <FlushResult>(flushResult);
}
else
{
// Otherwise it's async
result = new ValueTask <FlushResult>(_writer, token: 0);
}
// Complete reader only if new data was pushed into the pipe
// Avoid throwing in between completing the reader and scheduling the callback
// if the intent is to allow pipe to continue reading the data
if (!wasEmpty)
{
_readerAwaitable.Complete(out completionData);
}
else
{
completionData = default;
}
// I couldn't find a way for flush to induce backpressure deadlock
// if it always adds new data to pipe and wakes up the reader but assert anyway
Debug.Assert(_writerAwaitable.IsCompleted || _readerAwaitable.IsCompleted);
}
cancellationTokenRegistration.Dispose();
TrySchedule(_readerScheduler, completionData);
return(result);
}
private void PrepareFlushUnsynchronized(out CompletionData completionData, out ValueTask <FlushResult> result, CancellationToken cancellationToken)
{
var completeReader = CommitUnsynchronized();
// AttachToken before completing reader awaiter in case cancellationToken is already completed
_writerAwaitable.BeginOperation(cancellationToken, s_signalWriterAwaitable, this);
// If the writer is completed (which it will be most of the time) then return a completed ValueTask
if (_writerAwaitable.IsCompleted)
{
FlushResult flushResult = default;
GetFlushResult(ref flushResult);
result = new ValueTask <FlushResult>(flushResult);
}
else
{
// Otherwise it's async
result = new ValueTask <FlushResult>(_writer, token: 0);
}
// Complete reader only if new data was pushed into the pipe
// Avoid throwing in between completing the reader and scheduling the callback
// if the intent is to allow pipe to continue reading the data
if (completeReader)
{
_readerAwaitable.Complete(out completionData);
}
else
{
completionData = default;
}
// I couldn't find a way for flush to induce backpressure deadlock
// if it always adds new data to pipe and wakes up the reader but assert anyway
Debug.Assert(_writerAwaitable.IsCompleted || _readerAwaitable.IsCompleted);
}
