com.connecterra.util.event
Class AbstractEventProcessor

java.lang.Object
  com.connecterra.util.event.AbstractEventProcessor

All Implemented Interfaces:

EventProcessor

Direct Known Subclasses:

AbstractPhysicalDevice, AbstractWorkflowModulePlugin

public class AbstractEventProcessor
extends Object
implements EventProcessor

This class encapsulates a common pattern of use of EventReceiver and EventProcessor. This class optionally creates and then holds an EventReceiver instance, and implements the EventProcessor interface. It provides a set of protected methods for queueing Event instances on the receiver which are then handled, either one at a time and in order, or scheduled for the future, on threads in the Scheduler.

Nested Class Summary

protected static class

AbstractEventProcessor.PeriodicEventHandle This class contains the state for a periodic event.

Method Summary

protected void	doASAP(Event task) Queues an Event immediately.
protected void	doASAPOrBlock(Event task) Queues an Event immediately.
protected void	doASAPOrDrop(Event task) Queues an Event immediately.
protected void	doASAPOrThrow(Event task) Queues an Event immediately.
protected void	doLater(long delay, Event task) Queues an event to be handled after delay milliseconds.
protected void	doPeriodic(AbstractEventProcessor.PeriodicEventHandle handle, long interval, PeriodicEvent task) Queues an event whose handler will be invoked every interval milliseconds until cancelled, by calling the PeriodicEvent.stop() method on the event or by calling doPeriodic again with the same handle.
protected EventReceiver	getEventReceiver()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.connecterra.util.event.EventProcessor

handleEvent

Method Detail

getEventReceiver

protected EventReceiver getEventReceiver()

Returns:

the EventReceiver which handles queued events.

doASAP

protected void doASAP(Event task)

Queues an Event immediately. Because this method queues the event event if the queue is over the high water mark, it should be avoided except when necessary. Instead, AbstractEventProcessor.doASAPOrBlock(com.connecterra.util.event.Event), AbstractEventProcessor.doASAPOrThrow(com.connecterra.util.event.Event), or AbstractEventProcessor.doASAPOrDrop(com.connecterra.util.event.Event) should be used, depending on the appropriate behavior for that event.

Parameters:

task - the Event to be queued

doASAPOrBlock

protected void doASAPOrBlock(Event task)
                      throws InterruptedException

Queues an Event immediately. If the queue is at or above the high water mark, then the method blocks until the queue shrinks below the high water mark.

Parameters:

task - the Event to be queued

Throws:

InterruptedException - if the thread is interrupted while the call is blocked waiting for the queue to shrink below the high water mark.

doASAPOrDrop

protected void doASAPOrDrop(Event task)

Queues an Event immediately. If the queue is at or above the high water mark, then the event is silently dropped.

Parameters:

task - the Event to be queued

doASAPOrThrow

protected void doASAPOrThrow(Event task)
                      throws QueueFullException

Queues an Event immediately. If the queue is at or above the high water mark, then QueueFullException is thrown.

Parameters:

task - the Event to be queued

Throws:

QueueFullException - if the queue is at or above the high water mark

doLater

protected void doLater(long delay,
                       Event task)

Queues an event to be handled after delay milliseconds. The AlarmClock instance passed to the constructor or AbstractEventProcessor.initialize(com.connecterra.util.event.EventReceiver, com.connecterra.util.event.AlarmClock) method is used to perform the delay.

Parameters:

delay - the number of milliseconds in the future after which the event will be queued.

task - the Event to be handled later

Throws:

IllegalStateException - if the AbstractEventProcessor was created with no AlarmClock.

doPeriodic

protected void doPeriodic(AbstractEventProcessor.PeriodicEventHandle handle,
                          long interval,
                          PeriodicEvent task)

Queues an event whose handler will be invoked every interval milliseconds until cancelled, by calling the PeriodicEvent.stop() method on the event or by calling doPeriodic again with the same handle.

The interval specifies the time between the start of each successive invocation. For example, if the interval is 100 ms and the handler takes 12 ms to run, then the next invocation will occur 88 ms after the previous one finishes. If an invocation takes longer than the interval, then the next invocation is queued immediately.

Parameters:

handle - a PeriodicEventHandle instance

interval - the time in milliseconds between invocations of the event handler.

task - a PeriodicEvent value