public Task ProduceTasksAsync(int numberOfTasks)
{
ManualResetEvent bufferSpaceAvailableWaitHandle =
new ManualResetEvent(false);
Queue <Type> taskPayloadTypes =
new Queue <Type>(mPayloadTypes);
return(Task.Run(() =>
{
Type currentPayloadType;
IQueuedTaskToken newTaskToken;
QueuedTask newTask;
QueuedTaskResult newLastTaskResult;
EventHandler handleBufferElementRemoved
= (s, e) => bufferSpaceAvailableWaitHandle.Set();
mTaskBuffer.QueuedTaskRetrieved
+= handleBufferElementRemoved;
while (taskPayloadTypes.TryDequeue(out currentPayloadType))
{
for (int i = 0; i < numberOfTasks; i++)
{
newTask = new QueuedTask(Guid.NewGuid())
{
Payload = Activator.CreateInstance(currentPayloadType),
Type = currentPayloadType.FullName
};
newLastTaskResult = new QueuedTaskResult(newTask)
{
Status = QueuedTaskStatus.Unprocessed
};
newTaskToken = new MockQueuedTaskToken(newTask, newLastTaskResult);
mProducedTasks.Add(newTaskToken);
while (!mTaskBuffer.TryAddNewTask(newTaskToken))
{
bufferSpaceAvailableWaitHandle.WaitOne();
bufferSpaceAvailableWaitHandle.Reset();
}
}
}
mTaskBuffer.CompleteAdding();
mTaskBuffer.QueuedTaskRetrieved
-= handleBufferElementRemoved;
}));
}
private async Task PollForQueuedTasksAsync()
{
CancellationToken stopToken = mStopTokenSource
.Token;
//Check cancellation token before starting
// the polling loop
if (stopToken.IsCancellationRequested)
{
return;
}
while (true)
{
try
{
//Check for token cancellation at the beginning of the loop
stopToken.ThrowIfCancellationRequested();
//If the buffer is full, we wait for some space to become available,
// since, even if we can dequeue an task,
// we won't have anywhere to place it yet and we
// may be needlessly helding a lock to that task
if (mTaskBuffer.IsFull)
{
mLogger.Debug("Task buffer is full. Waiting for available space...");
mMetrics.UpdateMetric(AppMetricId.PollerWaitForBufferSpaceCount, m => m.Increment());
await mWaitForClearToAddToBuffer.ToTask();
}
//It may be that the wait handle was signaled
// as part of the Stop operation,
// so we need to check for that as well.
stopToken.ThrowIfCancellationRequested();
//Attempt to dequeue and then check cancellation
IQueuedTaskToken queuedTaskToken = await mTaskQueueConsumer
.DequeueAsync(mRequiredPayloadTypes);
//Before posting the token to the buffer,
// check if cancellation was requested
stopToken.ThrowIfCancellationRequested();
if (queuedTaskToken != null)
{
//If we have found a token, attempt to set it as started
// and only then add it to buffer for processing.
//If not, dispose and discard the token
mLogger.DebugFormat("Task found with id = {0}, type = {1}. Acquiring reservation...",
queuedTaskToken.DequeuedTask.Id,
queuedTaskToken.DequeuedTask.Type);
mMetrics.UpdateMetric(AppMetricId.PollerDequeueCount, m => m.Increment());
mTaskBuffer.TryAddNewTask(queuedTaskToken);
}
else
{
//If there is no task available in the queue, begin waiting for
// a notification of new added tasks
mLogger.Debug("No task dequeued when polled. Waiting for available task...");
mMetrics.UpdateMetric(AppMetricId.PollerWaitForDequeueCount, m => m.Increment());
await mWaitForClearToDequeue.ToTask();
}
//It may be that the wait handle was signaled
// as part of the Stop operation,
// so we need to check for that as well.
stopToken.ThrowIfCancellationRequested();
//Finally, reset all the handles, at the end of the loop
mWaitForClearToAddToBuffer.Reset();
mWaitForClearToDequeue.Reset();
}
catch (OperationCanceledException)
{
mLogger.Debug("Stop requested. Breaking polling loop...");
break;
}
}
mTaskBuffer.CompleteAdding();
}