/// <summary>
/// Adds the specified event to the state machine's event queue.
/// </summary>
/// <param name="nsfEvent">The event to queue.</param>
/// <param name="isPriorityEvent">Flag indicating if the event should be queued to the back of the queue (false) or the front of the queue (true).</param>
/// <param name="logEventQueued">Flag indicating if an event queued trace should be added to the trace log.</param>
private void queueEvent(NSFEvent nsfEvent, bool isPriorityEvent, bool logEventQueued)
{
if (!isTopStateMachine())
{
TopStateMachine.queueEvent(nsfEvent, isPriorityEvent, logEventQueued);
return;
}
lock (stateMachineMutex)
{
// Do not allow events to be queued if terminating or terminated,
// except for run to completion event, which may be queued if terminating to allow proper semantics to continue until terminated.
if ((TerminationStatus == NSFEventHandlerTerminationStatus.EventHandlerTerminated) ||
((TerminationStatus == NSFEventHandlerTerminationStatus.EventHandlerTerminating) && (nsfEvent != runToCompletionEvent)))
{
return;
}
// Handle special case of terminate event by setting status and queuing a single terminate event.
// Terminate event must be the last event queued to guarantee safe deletion when it is handled.
if (nsfEvent == terminateEvent)
{
if (TerminationStatus == NSFEventHandlerTerminationStatus.EventHandlerReady)
{
TerminationStatus = NSFEventHandlerTerminationStatus.EventHandlerTerminating;
}
}
// Event limit detection looks for too many events queued for the state machine.
// If more than the specified number of events are queued, the state machine will remove
// its queued events, call the event limit actions, and stop after executing any events queued
// by the limit actions.
if ((EventLimitDetectionEnabled) && (QueuedEvents == EventLimit))
{
EventThread.removeEventsFor(this);
QueuedEvents = 0;
EventLimitActions.execute(new NSFStateMachineContext(this, null, null, null, nsfEvent));
// Stop the state machine so that no more event processing occurs until started again
stopStateMachine();
NSFTraceLog.PrimaryTraceLog.addTrace(NSFTraceTags.ErrorTag, NSFTraceTags.SourceTag, Name, NSFTraceTags.MessageTag, "EventLimit");
return;
}
nsfEvent.Destination = this;
EventThread.queueEvent(nsfEvent, isPriorityEvent, logEventQueued);
++QueuedEvents;
}
}
/// <summary>
/// Handles an event.
/// </summary>
/// <param name="nsfEvent">The event to handle.</param>
/// <returns>Status indicating if the event was handled or not.</returns>
/// <remarks>
/// This method is for use only by the North State Framework's internal logic.
/// It processes the event using UML defined behavior, including run to completion.
/// </remarks>
public NSFEventStatus handleEvent(NSFEvent nsfEvent)
{
lock (stateMachineMutex)
{
--QueuedEvents;
// This should only happen if events are queued without using the queueEvent method
if (QueuedEvents < 0)
{
QueuedEvents = 0;
}
}
// Handle status changing events
if ((nsfEvent == startEvent))
{
RunStatus = NSFEventHandlerRunStatus.EventHandlerStarted;
}
else if (nsfEvent == stopEvent)
{
RunStatus = NSFEventHandlerRunStatus.EventHandlerStopped;
}
else if (nsfEvent == terminateEvent)
{
TerminationStatus = NSFEventHandlerTerminationStatus.EventHandlerTerminated;
EventThread.removeEventHandler(this);
return(NSFEventStatus.NSFEventHandled);
}
else if (nsfEvent == resetEvent)
{
reset();
}
// Don't process events if stopped
if (RunStatus == NSFEventHandlerRunStatus.EventHandlerStopped)
{
return(NSFEventStatus.NSFEventUnhandled);
}
// If not already active, enter state machine at the root
if (!active)
{
enter(new NSFStateMachineContext(this, this, null, null, startEvent), false);
}
// Process the event
NSFEventStatus eventStatus = NSFEventStatus.NSFEventUnhandled;
try
{
eventStatus = processEvent(nsfEvent);
if (eventStatus == NSFEventStatus.NSFEventHandled)
{
runToCompletion();
}
// Consecutive loop detection looks for too many events without the state machine pausing.
// If more than the specified number of transitions occur without a pause, the state machine will remove
// its queued events, call the consecutive loop limit actions, and stop after executing any events queued
// by the actions.
if (ConsecutiveLoopDetectionEnabled)
{
++consecutiveLoopCount;
if (consecutiveLoopCount == ConsecutiveLoopLimit)
{
lock (stateMachineMutex)
{
EventThread.removeEventsFor(this);
QueuedEvents = 0;
}
ConsecutiveLoopLimitActions.execute(new NSFStateMachineContext(this, null, null, null, nsfEvent));
// Stop the state machine so that no more event processing occurs until started again
stopStateMachine();
// Reset consecutive loop count in case state machine is started again
consecutiveLoopCount = 0;
NSFTraceLog.PrimaryTraceLog.addTrace(NSFTraceTags.ErrorTag, NSFTraceTags.SourceTag, Name, NSFTraceTags.MessageTag, "ConsecutiveLoopLimit");
}
else if (QueuedEvents == 0)
{
// If no events are queued for this state machine, then it has paused, indicating it's not in an infinite loop.
consecutiveLoopCount = 0;
}
}
}
catch (Exception exception)
{
handleException(new Exception(nsfEvent.Name + " event handling exception", exception));
}
return(eventStatus);
}
