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* Licensed under the Apache License, Version 2.0 (the "License"); you *
* may not use this file except in compliance with the License. You *
* may obtain a copy of the License at: *
* *
* http://www.apache.org/licenses/LICENSE-2.0 *
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* distributed under the License is distributed on an "AS IS" BASIS, *
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package org.apache.james.util.watchdog;
import org.apache.avalon.cornerstone.services.scheduler.PeriodicTimeTrigger;
import org.apache.avalon.cornerstone.services.scheduler.Target;
import org.apache.avalon.cornerstone.services.scheduler.TimeScheduler;
/**
* This class is a factory to produce Watchdogs, each of which is associated
* with a single TimeScheduler Target and a TimeScheduler object.
*
* This could be used in James by adding a server configuration
* parameter:
*
* schedulerWatchdogs = conf.getChild("useSchedulerWatchdogs").getValueAsBoolean(false);
*
* getting the TimeScheduler component:
*
* scheduler = (TimeScheduler) compMgr.lookup(TimeScheduler.ROLE);
*
* and changing AbstractJamesService.getWatchdogFactory to look
* something like:
*
* protected WatchdogFactory getWatchdogFactory() {
* WatchdogFactory theWatchdogFactory = null;
* if (schedulerWatchdogs) {
* theWatchdogFactory = new SchedulerWatchdogFactory(scheduler, timeout);
* } else {
* theWatchdogFactory = new ThreadPerWatchdogFactory(threadPool, timeout);
* }
* if (theWatchdogFactory instanceof LogEnabled) {
* ((LogEnabled)theWatchdogFactory).enableLogging(getLogger());
* }
* return theWatchdogFactory;
* }
*
*/
public class SchedulerWatchdogFactory implements WatchdogFactory {
/**
* The thread pool used to generate InaccurateTimeoutWatchdogs
*/
private TimeScheduler myTimeScheduler;
private long timeout = -1;
/**
* Creates the factory and sets the TimeScheduler used to implement
* the watchdogs.
*
* @param theTimeScheduler the scheduler that manages Watchdog triggering
* for Watchdogs produced by this factory
* @param timeout the timeout for Watchdogs produced by this factory
*/
public SchedulerWatchdogFactory(TimeScheduler theTimeScheduler, long timeout) {
this.timeout = timeout;
myTimeScheduler = theTimeScheduler;
}
/**
* @see org.apache.james.util.watchdog.WatchdogFactory#getWatchdog(WatchdogTarget)
*/
public Watchdog getWatchdog(WatchdogTarget theTarget) {
return new SchedulerWatchdog(theTarget);
}
/**
* An inner class that acts as an adaptor between the Watchdog
* interface and the TimeScheduler interface.
*/
private class SchedulerWatchdog implements Watchdog {
/**
* The in-scheduler identifier for this trigger.
*/
private String triggerID = null;
/**
* The WatchdogTarget that is passed in when this
* SchedulerWatchdog is initialized
*/
private WatchdogTarget theWatchdogTarget;
/**
* Constructor for the SchedulerWatchdog
*
* @param theTarget the target triggered by this Watchdog
*/
SchedulerWatchdog(WatchdogTarget theTarget) {
// TODO: This should be made more robust then just
// using toString()
triggerID = this.toString();
theWatchdogTarget = theTarget;
}
/**
* Start this Watchdog, causing it to begin monitoring. The Watchdog can
* be stopped and restarted.
*/
public void start() {
PeriodicTimeTrigger theTrigger = new PeriodicTimeTrigger((int)SchedulerWatchdogFactory.this.timeout, -1);
Target theTarget = new Target() {
public void targetTriggered(String targetID) {
theWatchdogTarget.execute();
}
};
SchedulerWatchdogFactory.this.myTimeScheduler.addTrigger(triggerID, theTrigger, theTarget);
}
/**
* Reset this Watchdog. Resets any conditions in the implementations
* (time to expiration, etc.) to their original values
*/
public void reset() {
SchedulerWatchdogFactory.this.myTimeScheduler.resetTrigger(triggerID);
}
/**
* Stop this Watchdog, terminating the monitoring condition. The monitor
* can be restarted with a call to startWatchdog.
*/
public void stop() {
SchedulerWatchdogFactory.this.myTimeScheduler.removeTrigger(triggerID);
}
}
}