/// <summary>
/// Function adds to the list of TaskRequests a TaskProxy will
/// wait on.
/// </summary>
/// <param name="req">The TaskRequest to wait on</param>
/// <returns>The Guid (TaskID) associated with the request.
/// This TaskID is used to query for results once the
/// TaskProxy signals the client that all task requests have
/// been serviced.</returns>
/// <remarks>Note: The TaskRequest queued may or may not have set
/// a notification callback, if one has been set the TaskProxy will
/// REPLACE it with its own notification callback.</remarks>
/// <exception cref="ArgumentNullException">Thrown if a null
/// TaskRequest is added</exception>
public Guid AddTaskRequest(TaskRequest req)
{
if (req == null)
{
throw new ArgumentNullException("TaskRequest is null");
}
// Assign taskID if we have to
if (req.TaskID == Guid.Empty)
{
req.TaskID = Guid.NewGuid();
}
Guid taskID = req.TaskID;
// Enqueue task
lock (m_requestQ.SyncRoot)
{
if (m_status != enuTaskProxyStatus.AcceptingRequests)
{
throw new InvalidOperationException("Proxy is no longer accepting requests - Check TaskProxy status");
}
// Link notify callback to TaskProxy
// note use of = instead of +=
// single TaskProxy is sole subscriber
// to this request being serviced
req.NotifyCb = new TaskRequest.NotificationCallback(this.OnTPTaskComplete);
m_requestQ.Enqueue(req);
m_nTasksPending++;
}
return(taskID);
}
public static void QueueTaskRequest(TaskRequest req)
{
lock (TPTask.requestQ.SyncRoot)
{
// Add request item to TPTask requestQ
TPTask.requestQ.Enqueue(req);
}
}
/// <summary>
/// Procedure enforces the leader-followers behavior of TPTask threads
/// </summary>
/// <remarks></remarks>
public void Service()
{
// Every thread that comes thru here ups the thread count
Interlocked.Increment(ref nNumTasks);
while (true)
{
// Begin critical section
lock (this)
{
Console.WriteLine("Checking for leader");
// While a leader has been selected...wait around
while (bLeaderAvailable)
{
Console.WriteLine("Waiting to be leader");
m_leaderSignal.WaitOnSignal();
Console.WriteLine("Received leader signal");
}
// Assert self as leader before leaving critical section
bLeaderAvailable = true;
// Leave critical section
Console.WriteLine("Leaving as leader");
}
// Only one thread active at this point
Console.WriteLine("Waiting on work");
// waiting on work
m_workSignal.WaitOnSignal();
Console.WriteLine("Got work");
bool bExitLoop = false;
// Nothing else to do so this thread can exit or be recycled
if (requestQ.Count == 0)
{
// No work to do so let other threads (next leader) wait on work
m_workSignal.Reset();
bExitLoop = true;
}
// Begin critical section
lock (this)
{
// Signal self is no longer the leader
bLeaderAvailable = false;
// Signal a follower to become the new leader
m_leaderSignal.Signal();
// Leave critical section
}
if (bExitLoop)
{
// If this task is not marked as recyclable
// then it must exit if no requests are
// pending
if (!m_bRecycleTask)
{
// Thread on its way out so decrease thread count
Interlocked.Decrement(ref nNumTasks);
break;
}
}
else
{
try
{
// Dequeue Service request
TaskRequest req = (TaskRequest)requestQ.Dequeue();
// Set taskID
this.TaskID = req.TaskID;
// Execute Callback
object objRes = req.TaskCb(req.Context);
// If any one subscribed, then fire LFTaskDone event
if (TPTaskComplete != null)
{
TPTaskCompleteEventArgs tceArg = new TPTaskCompleteEventArgs();
tceArg.TaskID = req.TaskID;
tceArg.Result = objRes;
TPTaskComplete(tceArg);
}
}
catch (Exception e) // Catch any exceptions thrown
{
// If any one subscribed, then fire LFTaskFailed event
if (TPTaskComplete != null)
{
TPTaskCompleteEventArgs tceArg = new TPTaskCompleteEventArgs();
tceArg.TaskID = this.TaskID;
// Signal that we had errors so that
// clients can check the
// ExceptionMessage property
tceArg.HasErrors = true;
tceArg.Result = e.Message;
TPTaskComplete(tceArg);
}
}
finally
{
// Reset task ID
this.TaskID = Guid.Empty;
}
}
} // End-while(true)
} // End-Method Service()
/// <summary>
/// Function queues a TaskRequest to the TaskPool
/// </summary>
/// <param name="req">The TaskRequest to queue</param>
/// <returns>A Guid used as a TaskID - if the TaskPool is in the process of
/// Shutting down then Guid.Empty is returned</returns>
/// <exception cref="ArgumentNullException">Thrown if TaskRequest
/// is null or not valid</exception>
public static Guid QueueTask(TaskRequest req)
{
if (req == null || !req.IsValid)
{
throw new ArgumentNullException("TaskRequest is null or contains null valued callbacks");
}
// If taskpool is shutting down then return Guid.Empty
if (bShuttingDown)
{
return(Guid.Empty);
}
if (!bInitialized)
{
Initialize();
}
Guid taskID = Guid.Empty;
try
{
/*lock( TPTask.requestQ.SyncRoot )
* {
* // Generate Guid - task id if none exists
* if( req.TaskID == Guid.Empty )
* req.TaskID = Guid.NewGuid();
*
* taskID = req.TaskID;
*
* // Add request item to TPTask requestQ
* TPTask.requestQ.Enqueue( req );
* }// End-lock on TPTask.requestQ
*/
// Generate Guid - task id if none exists
if (req.TaskID == Guid.Empty)
{
req.TaskID = Guid.NewGuid();
}
taskID = req.TaskID;
TPTask.QueueTaskRequest(req);
TaskPool.workSignal.Signal();
// Tag taskID to notification callback
lock (ClientNotification.SyncRoot)
{
if (taskID != Guid.Empty && req.NotifyCb != null)
{
ClientNotification.Add(taskID, req.NotifyCb);
}
} // End-lock on ClientNotification
}
catch (Exception /*e*/)
{}
// Return taskID to client
return(taskID);
}
