internal static void WakeUpWaiters(ref AsyncOperation <bool>?listTail, bool result, Exception?error = null)
{
AsyncOperation <bool>?tail = listTail;
if (tail != null)
{
listTail = null;
AsyncOperation <bool> head = tail.Next !;
AsyncOperation <bool> c = head;
do
{
AsyncOperation <bool> next = c.Next !;
c.Next = null;
bool completed = error != null?c.TrySetException(error) : c.TrySetResult(result);
Debug.Assert(completed || c.CancellationToken.CanBeCanceled);
c = next;
}while (c != head);
}
}
public override bool TryComplete(Exception error)
{
AsyncOperation <T> blockedReader = null;
AsyncOperation <bool> waitingReader = null;
bool completeTask = false;
SingleConsumerUnboundedChannel <T> parent = _parent;
lock (parent.SyncObj)
{
// If we're already marked as complete, there's nothing more to do.
if (parent._doneWriting != null)
{
return(false);
}
// Mark as complete for writing.
parent._doneWriting = error ?? ChannelUtilities.s_doneWritingSentinel;
// If we have no more items remaining, then the channel needs to be marked as completed
// and readers need to be informed they'll never get another item. All of that needs
// to happen outside of the lock to avoid invoking continuations under the lock.
if (parent._items.IsEmpty)
{
completeTask = true;
if (parent._blockedReader != null)
{
blockedReader = parent._blockedReader;
parent._blockedReader = null;
}
if (parent._waitingReader != null)
{
waitingReader = parent._waitingReader;
parent._waitingReader = null;
}
}
}
// Complete the channel task if necessary
if (completeTask)
{
ChannelUtilities.Complete(parent._completion, error);
}
Debug.Assert(blockedReader == null || waitingReader == null, "There should only ever be at most one reader.");
// Complete a blocked reader if necessary
if (blockedReader != null)
{
error = ChannelUtilities.CreateInvalidCompletionException(error);
blockedReader.TrySetException(error);
}
// Complete a waiting reader if necessary. (We really shouldn't have both a blockedReader
// and a waitingReader, but it's more expensive to prevent it than to just tolerate it.)
if (waitingReader != null)
{
if (error != null)
{
waitingReader.TrySetException(error);
}
else
{
waitingReader.TrySetResult(item: false);
}
}
// Successfully completed the channel
return(true);
}
