/// <summary>Dequeues an item, and then fixes up our state around writers and completion.</summary> /// <returns>The dequeued item.</returns> private T DequeueItemAndPostProcess() { BoundedChannel <T> parent = _parent; Debug.Assert(Monitor.IsEntered(parent.SyncObj)); // Dequeue an item. T item = parent._items.DequeueHead(); if (parent._doneWriting != null) { // We're done writing, so if we're now empty, complete the channel. if (parent._items.IsEmpty) { ChannelUtilities.Complete(parent._completion, parent._doneWriting); } } else { // If there are any writers blocked, there's now room for at least one // to be promoted to have its item moved into the items queue. We need // to loop while trying to complete the writer in order to find one that // hasn't yet been canceled (canceled writers transition to canceled but // remain in the physical queue). // // (It's possible for _doneWriting to be non-null due to Complete // having been called but for there to still be blocked/waiting writers. // This is a temporary condition, after which Complete has set _doneWriting // and then exited the lock; at that point it'll proceed to clean this up, // so we just ignore them.) while (!parent._blockedWriters.IsEmpty) { WriterInteractor <T> w = parent._blockedWriters.DequeueHead(); if (w.Success(default))
private void CompleteIfDone(UnboundedChannel <T> parent) { if (parent._doneWriting != null && parent._items.IsEmpty) { // If we've now emptied the items queue and we're not getting any more, complete. ChannelUtilities.Complete(parent._completion, parent._doneWriting); } }
public override bool TryRead(out T item) { SingleConsumerUnboundedChannel<T> parent = _parent; if (parent._items.TryDequeue(out item)) { if (parent._doneWriting != null && parent._items.IsEmpty) { ChannelUtilities.Complete(parent._completion, parent._doneWriting); } return true; } return false; }
private ValueTask <T> ReadAsyncCore(CancellationToken cancellationToken) { if (cancellationToken.IsCancellationRequested) { return(new ValueTask <T>(Task.FromCanceled <T>(cancellationToken))); } UnboundedChannel <T> parent = _parent; lock (parent.SyncObj) { parent.AssertInvariants(); // If there are any items, return one. if (parent._items.TryDequeue(out T item)) { // Dequeue an item if (parent._doneWriting != null && parent._items.IsEmpty) { // If we've now emptied the items queue and we're not getting any more, complete. ChannelUtilities.Complete(parent._completion, parent._doneWriting); } return(new ValueTask <T>(item)); } // There are no items, so if we're done writing, fail. if (parent._doneWriting != null) { return(ChannelUtilities.GetInvalidCompletionValueTask <T>(parent._doneWriting)); } // If we're able to use the singleton reader, do so. if (!cancellationToken.CanBeCanceled) { AsyncOperation <T> singleton = _readerSingleton; if (singleton.TryOwnAndReset()) { parent._blockedReaders.EnqueueTail(singleton); return(singleton.ValueTaskOfT); } } // Otherwise, create and queue a reader. var reader = new AsyncOperation <T>(parent._runContinuationsAsynchronously, cancellationToken); parent._blockedReaders.EnqueueTail(reader); return(reader.ValueTaskOfT); } }
public override bool TryRead(out T item) { UnboundedChannel <T> parent = _parent; // Dequeue an item if we can if (parent._items.TryDequeue(out item)) { if (parent._doneWriting != null && parent._items.IsEmpty) { // If we've now emptied the items queue and we're not getting any more, complete. ChannelUtilities.Complete(parent._completion, parent._doneWriting); } return(true); } item = default; return(false); }
private ValueTask <T> ReadAsyncCore(CancellationToken cancellationToken) { if (cancellationToken.IsCancellationRequested) { return(new ValueTask <T>(Task.FromCanceled <T>(cancellationToken))); } UnboundedChannel <T> parent = _parent; lock (parent.SyncObj) { parent.AssertInvariants(); // If there are any items, return one. if (parent._items.TryDequeue(out T item)) { // Dequeue an item if (parent._doneWriting != null && parent._items.IsEmpty) { // If we've now emptied the items queue and we're not getting any more, complete. ChannelUtilities.Complete(parent._completion, parent._doneWriting); } return(new ValueTask <T>(item)); } // There are no items, so if we're done writing, fail. if (parent._doneWriting != null) { return(ChannelUtilities.GetInvalidCompletionValueTask <T>(parent._doneWriting)); } // Otherwise, queue the reader. var reader = ReaderInteractor <T> .Create(parent._runContinuationsAsynchronously, cancellationToken); parent._blockedReaders.EnqueueTail(reader); return(new ValueTask <T>(reader.Task)); } }
public override bool TryComplete(Exception error) { UnboundedChannel <T> parent = _parent; bool completeTask; lock (parent.SyncObj) { parent.AssertInvariants(); // If we've already marked the channel as completed, bail. if (parent._doneWriting != null) { return(false); } // Mark that we're done writing. parent._doneWriting = error ?? ChannelUtilities.s_doneWritingSentinel; completeTask = parent._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(parent._completion, error); } // At this point, _blockedReaders and _waitingReaders will not be mutated: // they're only mutated by readers while holding the lock, and only if _doneWriting is null. // freely manipulate _blockedReaders and _waitingReaders without any concurrency concerns. ChannelUtilities.FailOperations <AsyncOperation <T>, T>(parent._blockedReaders, ChannelUtilities.CreateInvalidCompletionException(error)); ChannelUtilities.WakeUpWaiters(ref parent._waitingReadersTail, result: false, error: error); // Successfully transitioned to completed. return(true); }
/// <summary>Dequeues an item, and then fixes up our state around writers and completion.</summary> /// <returns>The dequeued item.</returns> private T DequeueItemAndPostProcess() { BoundedChannel <T> parent = _parent; Debug.Assert(Monitor.IsEntered(parent.SyncObj)); // Dequeue an item. T item = parent._items.DequeueHead(); // If we're now empty and we're done writing, complete the channel. if (parent._doneWriting != null && parent._items.IsEmpty) { ChannelUtilities.Complete(parent._completion, parent._doneWriting); } // If there are any writers blocked, there's now room for at least one // to be promoted to have its item moved into the items queue. We need // to loop while trying to complete the writer in order to find one that // hasn't yet been canceled (canceled writers transition to canceled but // remain in the physical queue). while (!parent._blockedWriters.IsEmpty) { WriterInteractor <T> w = parent._blockedWriters.DequeueHead(); if (w.Success(default(VoidResult))) { parent._items.EnqueueTail(w.Item); return(item); } } // There was no blocked writer, so see if there's a WaitToWriteAsync // we should wake up. ChannelUtilities.WakeUpWaiters(ref parent._waitingWriters, result: true); // Return the item return(item); }
/// <summary>Dequeues an item, and then fixes up our state around writers and completion.</summary> /// <returns>The dequeued item.</returns> private T DequeueItemAndPostProcess() { BoundedChannel <T> parent = _parent; Debug.Assert(Monitor.IsEntered(parent.SyncObj)); // Dequeue an item. T item = parent._items.DequeueHead(); // If we're now empty and we're done writing, complete the channel. if (parent._doneWriting != null && parent._items.IsEmpty) { ChannelUtilities.Complete(parent._completion, parent._doneWriting); } // If there are any writers blocked, there's now room for at least one // to be promoted to have its item moved into the items queue. We need // to loop while trying to complete the writer in order to find one that // hasn't yet been canceled (canceled writers transition to canceled but // remain in the physical queue). while (!parent._blockedWriters.IsEmpty) { WriterInteractor <T> w = parent._blockedWriters.DequeueHead(); if (w.Success(default))
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); }