public static CancellableOperationStarter <V> StartablePut <U, V>(this IQueueSink <U> queue, U valueToPut, V successfulPut)
{
return(delegate(CancellationToken ctoken) {
CancellationTokenSource cts = CancellationTokenSource.CreateLinkedTokenSource(ctoken);
Func <Task <CancellableResult <V> > > taskSource = async delegate {
AcquireWriteResult awr = await queue.AcquireWriteAsync(1, cts.Token);
if (awr is AcquireWriteSucceeded)
{
AcquireWriteSucceeded aws = (AcquireWriteSucceeded)awr;
System.Diagnostics.Debug.Assert(aws.ItemCount == 1);
return new PutCancellableResult <U, V>(queue, valueToPut, successfulPut);
}
else if (awr is AcquireWriteFaulted)
{
AcquireWriteFaulted awf = (AcquireWriteFaulted)awr;
throw awf.Exception;
}
else
{
// ReSharper disable once UnusedVariable
AcquireWriteCancelled awc = (AcquireWriteCancelled)awr;
throw new OperationCanceledException();
}
};
Task <CancellableResult <V> > task;
try {
task = taskSource();
}
catch (OperationCanceledException e) {
#if NET451
var tcs = new TaskCompletionSource <CancellableResult <V> >();
tcs.SetException(e);
tcs.SetCanceled();
task = tcs.Task;
#else
task = Task.FromCanceled <CancellableResult <V> >(e.CancellationToken);
#endif
}
catch (Exception exc) {
#if NET451
var tcs = new TaskCompletionSource <CancellableResult <V> >();
tcs.TrySetException(exc);
task = tcs.Task;
#else
task = Task.FromException <CancellableResult <V> >(exc);
#endif
}
return new CancellableOperation <V>(task, cts);
});
}
public static async Task Enqueue <T>(this IQueueSink <T> queue, T item, CancellationToken ctoken)
{
AcquireWriteResult result = await queue.AcquireWriteAsync(1, ctoken);
result.Visit <DBNull>
(
new Func <AcquireWriteSucceeded, DBNull>
(
succeeded =>
{
System.Diagnostics.Debug.Assert(succeeded.ItemCount == 1);
bool wasCancelled = false;
if (ctoken.IsCancellationRequested)
{
wasCancelled = true;
queue.ReleaseWrite();
}
else
{
queue.ReleaseWrite(item);
}
if (wasCancelled)
{
throw new OperationCanceledException(ctoken);
}
return(DBNull.Value);
}
),
new Func <AcquireWriteCancelled, DBNull>
(
cancelled => { throw new OperationCanceledException(ctoken); }
),
new Func <AcquireWriteFaulted, DBNull>
(
faulted => { throw faulted.Exception; }
)
);
}