public static CancellableOperationStarter <V> StartableGet <U, V>(this IQueueSource <U> queue, Func <U, V> convertResult, V eofResult)
{
return(delegate(CancellationToken ctoken)
{
CancellationTokenSource cts = CancellationTokenSource.CreateLinkedTokenSource(ctoken);
Func <Task <CancellableResult <V> > > taskSource = async delegate()
{
AcquireReadResult arr = await queue.AcquireReadAsync(1, cts.Token);
if (arr is AcquireReadSucceeded <U> )
{
AcquireReadSucceeded <U> succeededResult = (AcquireReadSucceeded <U>)arr;
if (succeededResult.ItemCount == 1)
{
return new GetCancellableResult <U, V>(queue, succeededResult.Items[0], convertResult);
}
else
{
System.Diagnostics.Debug.Assert(succeededResult.ItemCount == 0);
return new GetEofCancellableResult <U, V>(queue, eofResult);
}
}
else if (arr is AcquireReadFaulted)
{
AcquireReadFaulted faultedResult = (AcquireReadFaulted)arr;
throw faultedResult.Exception;
}
else
{
AcquireReadCancelled cancelledResult = (AcquireReadCancelled)arr;
throw new OperationCanceledException();
}
};
Task <CancellableResult <V> > task = null;
try
{
task = Task.Run(taskSource);
}
catch (OperationCanceledException e)
{
task = Task.FromCanceled <CancellableResult <V> >(e.CancellationToken);
}
catch (Exception exc)
{
task = Task.FromException <CancellableResult <V> >(exc);
}
return new CancellableOperation <V>(task, cts);
});
}
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; }
)
));
}
public async Task <AcquireReadResult> AcquireReadAsync(int desiredItems, CancellationToken ctoken)
{
AcquireReadResult parentResult = await parent.AcquireReadAsync(desiredItems, ctoken);
if (parentResult is AcquireReadSucceeded <T> )
{
AcquireReadSucceeded <T> parentSuccess = (AcquireReadSucceeded <T>)parentResult;
ImmutableList <U> sequence = ImmutableList <U> .Empty.AddRange(parentSuccess.Items.Select(func));
return(new AcquireReadSucceeded <U>(parentSuccess.Offset, sequence));
}
else
{
return(parentResult);
}
}
public async Task <AcquireReadResult> AcquireReadAsync(int desiredItems, CancellationToken ctoken)
{
AcquireReadResult parentResult = await parent.AcquireReadAsync(desiredItems, ctoken);
if (parentResult is AcquireReadSucceeded <T> )
{
AcquireReadSucceeded <T> parentSuccess = (AcquireReadSucceeded <T>)parentResult;
ImmutableList <Tuple <int, T> > sequence = ImmutableList <Tuple <int, T> > .Empty;
foreach (var x in Enumerable.Range(0, parentSuccess.ItemCount))
{
sequence = sequence.Add(new Tuple <int, T>(index + x, parentSuccess.Items[x]));
}
return(new AcquireReadSucceeded <Tuple <int, T> >(parentSuccess.Offset, sequence));
}
else
{
return(parentResult);
}
}