private bool TryComplete(Exception error = null)
{
bool completeTask;
lock (SyncObj)
{
AssertInvariants();
// If we've already marked the channel as completed, bail.
if (_doneWriting != null)
{
return(false);
}
// Mark that we're done writing.
_doneWriting = error ?? ChannelUtilities.DoneWritingSentinel;
completeTask = _items.IsEmpty;
}
// If there are no items in the queue, complete the channel's task,
// as no more data can possibly arrive at this point. We do this outside
// of the lock in case we'll be running synchronous completions, and we
// do it before completing blocked/waiting readers, so that when they
// wake up they'll see the task as being completed.
if (completeTask)
{
ChannelUtilities.Complete(_completion, error);
}
// At this point, _blockedReaders/Writers and _waitingReaders/Writers will not be mutated:
// they're only mutated by readers/writers while holding the lock, and only if _doneWriting is null.
// We also know that only one thread (this one) will ever get here, as only that thread
// will be the one to transition from _doneWriting false to true. As such, we can
// freely manipulate _blockedReaders and _waitingReaders without any concurrency concerns.
ChannelUtilities.FailInteractors <ReaderInteractor <T>, T>(_blockedReaders, error);
ChannelUtilities.FailInteractors <WriterInteractor <T>, VoidResult>(_blockedWriters, error);
ChannelUtilities.WakeUpWaiters(ref _waitingReaders, result: false);
ChannelUtilities.WakeUpWaiters(ref _waitingWriters, result: false);
// Successfully transitioned to completed.
return(true);
}
private bool TryComplete(Exception error = null)
{
lock (SyncObj)
{
AssertInvariants();
// Mark the channel as being done. Since there's no buffered data, we can complete immediately.
if (_completion.Task.IsCompleted)
{
return(false);
}
ChannelUtilities.Complete(_completion, error);
// Fail any blocked readers/writers, as there will be no writers/readers to pair them with.
ChannelUtilities.FailInteractors <ReaderInteractor <T>, T>(_blockedReaders, ChannelUtilities.CreateInvalidCompletionException(error));
ChannelUtilities.FailInteractors <WriterInteractor <T>, VoidResult>(_blockedWriters, ChannelUtilities.CreateInvalidCompletionException(error));
// Let any waiting readers and writers know there won't be any more data
ChannelUtilities.WakeUpWaiters(ref _waitingReaders, result: false, error: error);
ChannelUtilities.WakeUpWaiters(ref _waitingWriters, result: false, error: error);
}
return(true);
}
