// [1] Use TaskCreationOptions.LongRunning here not because the consituent operations are
// coarse-grained (they aren't and could in fact benefit from parallelization in future iterations),
// but because this hint informs the scheduler not to schedule the task on the local queue
// which - given that this method is called from an HTTP-request-handling thread - would
// schedule it on the same work queue that future HTTP requests would be serviced from.
// Further information here: https://docs.microsoft.com/en-us/dotnet/api/system.threading.tasks.taskscheduler?view=netframework-4.8#long-running-tasks
public object Queue(PipelineBase pipeline,
PipelineRequestTracker?initiator,
bool trackAfterCompletion = false)
{
_pipelinesMutex.WaitOne();
if (_pipelines.ContainsKey(pipeline.Id))
{
return(null);
}
if (pipeline.Status < PipelineBase.PipelineStatus.Pending)
{
return(null);
}
var tracker = new PipelineTracker()
{
Pipeline = pipeline,
Initiator = initiator,
Created = DateTime.UtcNow,
LastAccessed = null,
QueueToken = Guid.NewGuid().ToString(),
OriginalCompletionHandler = pipeline.CompletionHandler,
TrackAfterCompletion = trackAfterCompletion
};
pipeline.CompletionHandler = OnPipelineStateChance;
tracker.Task = Task.Factory.StartNew(pipeline.Execute, TaskCreationOptions.LongRunning /* [1] */);
_pipelines[pipeline.Id] = tracker;
_pipelinesMutex.ReleaseMutex();
return(_pipelines[pipeline.Id].QueueToken);
}
public bool Cancel(Guid pId, object token, PipelineRequestTracker?cancelor)
{
var rv = false;
var realId = ResolveId(pId);
PipelineTracker pipe = null;
_pipelinesMutex.WaitOne();
if (_pipelines.ContainsKey(realId) && (pipe = _pipelines[realId]).QueueToken.Equals(token))
{
if (rv = pipe.Pipeline.Cancel())
{
pipe.Cancelor = cancelor;
}
}
_pipelinesMutex.ReleaseMutex();
return(rv);
}
