public override Task <bool> WaitToReadAsync(CancellationToken cancellationToken)
{
if (cancellationToken.IsCancellationRequested)
{
return(Task.FromCanceled <bool>(cancellationToken));
}
BoundedChannel <T> parent = _parent;
lock (parent.SyncObj)
{
parent.AssertInvariants();
// If there are any items available, a read is possible.
if (!parent._items.IsEmpty)
{
return(ChannelUtilities.s_trueTask);
}
// There were no items available, so if we're done writing, a read will never be possible.
if (parent._doneWriting != null)
{
return(parent._doneWriting != ChannelUtilities.s_doneWritingSentinel ?
Task.FromException <bool>(parent._doneWriting) :
ChannelUtilities.s_falseTask);
}
// There were no items available, but there could be in the future, so ensure
// there's a blocked reader task and return it.
return(ChannelUtilities.GetOrCreateWaiter(ref parent._waitingReaders, parent._runContinuationsAsynchronously, cancellationToken));
}
}
public override bool TryRead(out T item)
{
BoundedChannel <T> parent = _parent;
lock (parent.SyncObj)
{
parent.AssertInvariants();
// Get an item if there is one.
if (!parent._items.IsEmpty)
{
item = DequeueItemAndPostProcess();
return(true);
}
}
item = default(T);
return(false);
}
