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);
}