/*
* Copyright 2001-2009 Terracotta, Inc.
*
* 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
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
*/
package org.quartz.core;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.concurrent.atomic.AtomicBoolean;
import org.quartz.JobPersistenceException;
import org.quartz.SchedulerException;
import org.quartz.Trigger;
import org.quartz.Trigger.CompletedExecutionInstruction;
import org.quartz.spi.OperableTrigger;
import org.quartz.spi.TriggerFiredBundle;
import org.quartz.spi.TriggerFiredResult;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* <p>
* The thread responsible for performing the work of firing <code>{@link Trigger}</code>
* s that are registered with the <code>{@link QuartzScheduler}</code>.
* </p>
*
* @see QuartzScheduler
* @see org.quartz.Job
* @see Trigger
*
* @author James House
*/
public class QuartzSchedulerThread extends Thread {
/*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* Data members.
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
private QuartzScheduler qs;
private QuartzSchedulerResources qsRsrcs;
private final Object sigLock = new Object();
private boolean signaled;
private long signaledNextFireTime;
private boolean paused;
private AtomicBoolean halted;
private Random random = new Random(System.currentTimeMillis());
// When the scheduler finds there is no current trigger to fire, how long
// it should wait until checking again...
private static long DEFAULT_IDLE_WAIT_TIME = 30L * 1000L;
private long idleWaitTime = DEFAULT_IDLE_WAIT_TIME;
private int idleWaitVariablness = 7 * 1000;
private final Logger log = LoggerFactory.getLogger(getClass());
/*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* Constructors.
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
/**
* <p>
* Construct a new <code>QuartzSchedulerThread</code> for the given
* <code>QuartzScheduler</code> as a non-daemon <code>Thread</code>
* with normal priority.
* </p>
*/
QuartzSchedulerThread(QuartzScheduler qs, QuartzSchedulerResources qsRsrcs) {
this(qs, qsRsrcs, qsRsrcs.getMakeSchedulerThreadDaemon(), Thread.NORM_PRIORITY);
}
/**
* <p>
* Construct a new <code>QuartzSchedulerThread</code> for the given
* <code>QuartzScheduler</code> as a <code>Thread</code> with the given
* attributes.
* </p>
*/
QuartzSchedulerThread(QuartzScheduler qs, QuartzSchedulerResources qsRsrcs, boolean setDaemon, int threadPrio) {
super(qs.getSchedulerThreadGroup(), qsRsrcs.getThreadName());
this.qs = qs;
this.qsRsrcs = qsRsrcs;
this.setDaemon(setDaemon);
if(qsRsrcs.isThreadsInheritInitializersClassLoadContext()) {
log.info("QuartzSchedulerThread Inheriting ContextClassLoader of thread: " + Thread.currentThread().getName());
this.setContextClassLoader(Thread.currentThread().getContextClassLoader());
}
this.setPriority(threadPrio);
// start the underlying thread, but put this object into the 'paused'
// state
// so processing doesn't start yet...
paused = true;
halted = new AtomicBoolean(false);
}
/*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* Interface.
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
void setIdleWaitTime(long waitTime) {
idleWaitTime = waitTime;
idleWaitVariablness = (int) (waitTime * 0.2);
}
private long getRandomizedIdleWaitTime() {
return idleWaitTime - random.nextInt(idleWaitVariablness);
}
/**
* <p>
* Signals the main processing loop to pause at the next possible point.
* </p>
*/
void togglePause(boolean pause) {
synchronized (sigLock) {
paused = pause;
if (paused) {
signalSchedulingChange(0);
} else {
sigLock.notifyAll();
}
}
}
/**
* <p>
* Signals the main processing loop to pause at the next possible point.
* </p>
*/
void halt(boolean wait) {
synchronized (sigLock) {
halted.set(true);
if (paused) {
sigLock.notifyAll();
} else {
signalSchedulingChange(0);
}
}
if (wait) {
boolean interrupted = false;
try {
while (true) {
try {
join();
break;
} catch (InterruptedException _) {
interrupted = true;
}
}
} finally {
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
}
boolean isPaused() {
return paused;
}
/**
* <p>
* Signals the main processing loop that a change in scheduling has been
* made - in order to interrupt any sleeping that may be occuring while
* waiting for the fire time to arrive.
* </p>
*
* @param candidateNewNextFireTime the time (in millis) when the newly scheduled trigger
* will fire. If this method is being called do to some other even (rather
* than scheduling a trigger), the caller should pass zero (0).
*/
public void signalSchedulingChange(long candidateNewNextFireTime) {
synchronized(sigLock) {
signaled = true;
signaledNextFireTime = candidateNewNextFireTime;
sigLock.notifyAll();
}
}
public void clearSignaledSchedulingChange() {
synchronized(sigLock) {
signaled = false;
signaledNextFireTime = 0;
}
}
public boolean isScheduleChanged() {
synchronized(sigLock) {
return signaled;
}
}
public long getSignaledNextFireTime() {
synchronized(sigLock) {
return signaledNextFireTime;
}
}
/**
* <p>
* The main processing loop of the <code>QuartzSchedulerThread</code>.
* </p>
*/
@Override
public void run() {
boolean lastAcquireFailed = false;
while (!halted.get()) {
try {
// check if we're supposed to pause...
synchronized (sigLock) {
while (paused && !halted.get()) {
try {
// wait until togglePause(false) is called...
sigLock.wait(1000L);
} catch (InterruptedException ignore) {
}
}
if (halted.get()) {
break;
}
}
int availThreadCount = qsRsrcs.getThreadPool().blockForAvailableThreads();
if(availThreadCount > 0) { // will always be true, due to semantics of blockForAvailableThreads...
List<OperableTrigger> triggers = null;
long now = System.currentTimeMillis();
clearSignaledSchedulingChange();
try {
triggers = qsRsrcs.getJobStore().acquireNextTriggers(
now + idleWaitTime, Math.min(availThreadCount, qsRsrcs.getMaxBatchSize()), qsRsrcs.getBatchTimeWindow());
lastAcquireFailed = false;
if (log.isDebugEnabled())
log.debug("batch acquisition of " + (triggers == null ? 0 : triggers.size()) + " triggers");
} catch (JobPersistenceException jpe) {
if(!lastAcquireFailed) {
qs.notifySchedulerListenersError(
"An error occurred while scanning for the next triggers to fire.",
jpe);
}
lastAcquireFailed = true;
continue;
} catch (RuntimeException e) {
if(!lastAcquireFailed) {
getLog().error("quartzSchedulerThreadLoop: RuntimeException "
+e.getMessage(), e);
}
lastAcquireFailed = true;
continue;
}
if (triggers != null && !triggers.isEmpty()) {
now = System.currentTimeMillis();
long triggerTime = triggers.get(0).getNextFireTime().getTime();
long timeUntilTrigger = triggerTime - now;
while(timeUntilTrigger > 2) {
synchronized (sigLock) {
if (halted.get()) {
break;
}
if (!isCandidateNewTimeEarlierWithinReason(triggerTime, false)) {
try {
// we could have blocked a long while
// on 'synchronize', so we must recompute
now = System.currentTimeMillis();
timeUntilTrigger = triggerTime - now;
if(timeUntilTrigger >= 1)
sigLock.wait(timeUntilTrigger);
} catch (InterruptedException ignore) {
}
}
}
if(releaseIfScheduleChangedSignificantly(triggers, triggerTime)) {
break;
}
now = System.currentTimeMillis();
timeUntilTrigger = triggerTime - now;
}
// this happens if releaseIfScheduleChangedSignificantly decided to release triggers
if(triggers.isEmpty())
continue;
// set triggers to 'executing'
List<TriggerFiredResult> bndles = new ArrayList<TriggerFiredResult>();
boolean goAhead = true;
synchronized(sigLock) {
goAhead = !halted.get();
}
if(goAhead) {
try {
List<TriggerFiredResult> res = qsRsrcs.getJobStore().triggersFired(triggers);
if(res != null)
bndles = res;
} catch (SchedulerException se) {
qs.notifySchedulerListenersError(
"An error occurred while firing triggers '"
+ triggers + "'", se);
//QTZ-179 : a problem occurred interacting with the triggers from the db
//we release them and loop again
for (int i = 0; i < triggers.size(); i++) {
qsRsrcs.getJobStore().releaseAcquiredTrigger(triggers.get(i));
}
continue;
}
}
for (int i = 0; i < bndles.size(); i++) {
TriggerFiredResult result = bndles.get(i);
TriggerFiredBundle bndle = result.getTriggerFiredBundle();
Exception exception = result.getException();
if (exception instanceof RuntimeException) {
getLog().error("RuntimeException while firing trigger " + triggers.get(i), exception);
qsRsrcs.getJobStore().releaseAcquiredTrigger(triggers.get(i));
continue;
}
// it's possible to get 'null' if the triggers was paused,
// blocked, or other similar occurrences that prevent it being
// fired at this time... or if the scheduler was shutdown (halted)
if (bndle == null) {
qsRsrcs.getJobStore().releaseAcquiredTrigger(triggers.get(i));
continue;
}
JobRunShell shell = null;
try {
shell = qsRsrcs.getJobRunShellFactory().createJobRunShell(bndle);
shell.initialize(qs);
} catch (SchedulerException se) {
qsRsrcs.getJobStore().triggeredJobComplete(triggers.get(i), bndle.getJobDetail(), CompletedExecutionInstruction.SET_ALL_JOB_TRIGGERS_ERROR);
continue;
}
if (qsRsrcs.getThreadPool().runInThread(shell) == false) {
// this case should never happen, as it is indicative of the
// scheduler being shutdown or a bug in the thread pool or
// a thread pool being used concurrently - which the docs
// say not to do...
getLog().error("ThreadPool.runInThread() return false!");
qsRsrcs.getJobStore().triggeredJobComplete(triggers.get(i), bndle.getJobDetail(), CompletedExecutionInstruction.SET_ALL_JOB_TRIGGERS_ERROR);
}
}
continue; // while (!halted)
}
} else { // if(availThreadCount > 0)
// should never happen, if threadPool.blockForAvailableThreads() follows contract
continue; // while (!halted)
}
long now = System.currentTimeMillis();
long waitTime = now + getRandomizedIdleWaitTime();
long timeUntilContinue = waitTime - now;
synchronized(sigLock) {
try {
if(!halted.get()) {
// QTZ-336 A job might have been completed in the mean time and we might have
// missed the scheduled changed signal by not waiting for the notify() yet
// Check that before waiting for too long in case this very job needs to be
// scheduled very soon
if (!isScheduleChanged()) {
sigLock.wait(timeUntilContinue);
}
}
} catch (InterruptedException ignore) {
}
}
} catch(RuntimeException re) {
getLog().error("Runtime error occurred in main trigger firing loop.", re);
}
} // while (!halted)
// drop references to scheduler stuff to aid garbage collection...
qs = null;
qsRsrcs = null;
}
private boolean releaseIfScheduleChangedSignificantly(
List<OperableTrigger> triggers, long triggerTime) {
if (isCandidateNewTimeEarlierWithinReason(triggerTime, true)) {
// above call does a clearSignaledSchedulingChange()
for (OperableTrigger trigger : triggers) {
qsRsrcs.getJobStore().releaseAcquiredTrigger(trigger);
}
triggers.clear();
return true;
}
return false;
}
private boolean isCandidateNewTimeEarlierWithinReason(long oldTime, boolean clearSignal) {
// So here's the deal: We know due to being signaled that 'the schedule'
// has changed. We may know (if getSignaledNextFireTime() != 0) the
// new earliest fire time. We may not (in which case we will assume
// that the new time is earlier than the trigger we have acquired).
// In either case, we only want to abandon our acquired trigger and
// go looking for a new one if "it's worth it". It's only worth it if
// the time cost incurred to abandon the trigger and acquire a new one
// is less than the time until the currently acquired trigger will fire,
// otherwise we're just "thrashing" the job store (e.g. database).
//
// So the question becomes when is it "worth it"? This will depend on
// the job store implementation (and of course the particular database
// or whatever behind it). Ideally we would depend on the job store
// implementation to tell us the amount of time in which it "thinks"
// it can abandon the acquired trigger and acquire a new one. However
// we have no current facility for having it tell us that, so we make
// a somewhat educated but arbitrary guess ;-).
synchronized(sigLock) {
if (!isScheduleChanged())
return false;
boolean earlier = false;
if(getSignaledNextFireTime() == 0)
earlier = true;
else if(getSignaledNextFireTime() < oldTime )
earlier = true;
if(earlier) {
// so the new time is considered earlier, but is it enough earlier?
long diff = oldTime - System.currentTimeMillis();
if(diff < (qsRsrcs.getJobStore().supportsPersistence() ? 70L : 7L))
earlier = false;
}
if(clearSignal) {
clearSignaledSchedulingChange();
}
return earlier;
}
}
public Logger getLog() {
return log;
}
} // end of QuartzSchedulerThread