public static async Task <Option <T> > Dequeue <T>(this IQueueSource <T> queue, CancellationToken ctoken) { AcquireReadResult result = await queue.AcquireReadAsync(1, ctoken); return(result.Visit <Option <T> > ( new Func <AcquireReadSucceeded, Option <T> > ( succeeded => { if (succeeded.ItemCount == 0) { return new None <T>(); } else { System.Diagnostics.Debug.Assert(succeeded.ItemCount == 1); bool wasCancelled = false; if (ctoken.IsCancellationRequested) { wasCancelled = true; queue.ReleaseRead(0); } else { queue.ReleaseRead(1); } if (wasCancelled) { throw new OperationCanceledException(ctoken); } return new Some <T>(((AcquireReadSucceeded <T>)succeeded).Items[0]); } } ), new Func <AcquireReadCancelled, Option <T> > ( cancelled => { throw new OperationCanceledException(ctoken); } ), new Func <AcquireReadFaulted, Option <T> > ( faulted => { throw faulted.Exception; } ) )); }
private async Task SimpleQueueTestAsync() { AsyncQueue <int> queue = new AsyncQueue <int>(11); Func <Task> producer = async delegate() { #region for (int i = 0; i < 20; ++i) { System.Diagnostics.Debug.WriteLine("Acquiring write..."); AcquireWriteResult result = await queue.AcquireWriteAsync(1, CancellationToken.None); result.Visit <DBNull> ( new Func <AcquireWriteSucceeded, DBNull> ( succeeded => { System.Diagnostics.Debug.WriteLine("Write-acquire succeeded, offset " + succeeded.Offset + ", acquired " + succeeded.ItemCount + " spaces"); Assert.AreEqual(1, succeeded.ItemCount); if (succeeded.ItemCount >= 1) { System.Diagnostics.Debug.WriteLine("Releasing write (1)..."); queue.ReleaseWrite(i); } else { System.Diagnostics.Debug.WriteLine("Releasing write (0)..."); queue.ReleaseWrite(); } return(DBNull.Value); } ), new Func <AcquireWriteCancelled, DBNull> ( cancelled => { throw new OperationCanceledException(); } ), new Func <AcquireWriteFaulted, DBNull> ( faulted => { throw faulted.Exception; } ) ); } System.Diagnostics.Debug.WriteLine("Writing EOF..."); queue.WriteEof(); #endregion }; Func <Task> consumer = async delegate() { #region bool more = true; while (more) { System.Diagnostics.Debug.WriteLine("Acquiring read..."); const int ACQUIRE_COUNT = 3; AcquireReadResult result = await queue.AcquireReadAsync(ACQUIRE_COUNT, CancellationToken.None); result.Visit <DBNull> ( new Func <AcquireReadSucceeded, DBNull> ( succeeded => { System.Diagnostics.Debug.WriteLine("Read-acquire succeeded, offset " + succeeded.Offset + ", acquired " + succeeded.ItemCount + " items"); Assert.IsInstanceOfType(succeeded, typeof(AcquireReadSucceeded <int>)); if (succeeded is AcquireReadSucceeded <int> ) { AcquireReadSucceeded <int> succeeded2 = (AcquireReadSucceeded <int>)succeeded; System.Diagnostics.Debug.WriteLine("{ " + string.Join(", ", succeeded2.Items) + " }"); } if (succeeded.ItemCount < ACQUIRE_COUNT) { System.Diagnostics.Debug.WriteLine("Setting \"more\" flag to false..."); more = false; } System.Diagnostics.Debug.WriteLine("Releasing read (" + succeeded.ItemCount + ")..."); queue.ReleaseRead(succeeded.ItemCount); return(DBNull.Value); } ), new Func <AcquireReadCancelled, DBNull> ( cancelled => { throw new OperationCanceledException(); } ), new Func <AcquireReadFaulted, DBNull> ( faulted => { throw faulted.Exception; } ) ); } #endregion }; Task tProducer = Task.Run(producer); Task tConsumer = Task.Run(consumer); await Task.WhenAll(tProducer, tConsumer); }