/*
* JBoss, Home of Professional Open Source
* Copyright 2005, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jbpm.jobexecutor;
import java.util.Collection;
import java.util.Date;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.jbpm.client.Command;
import org.jbpm.client.CommandService;
/** this thread is responsible for acquiring jobs in the job that need to be
* executed and then let the JobExecutor dispatch the acquired ids to one of the
* JobExecutorThreads in the pool. There is only one dispatcher thread per
* JobExecutor.
*
* @author Tom Baeyens, Guillaume Porcher
*/
public class DispatcherThread extends Thread {
private static final Logger log = Logger.getLogger(DispatcherThread.class.getName());
JobExecutor jobExecutor;
boolean isActive;
boolean checkForNewJobs;
int currentIdleInterval;
Object semaphore = new Object();
DispatcherThread(JobExecutor jobExecutor) {
this(jobExecutor, "DispatcherThread");
}
DispatcherThread(JobExecutor jobExecutor, String name) {
super(name);
this.jobExecutor = jobExecutor;
}
public void run() {
log.info("starting...");
isActive = true;
currentIdleInterval = jobExecutor.getIdleMillis();
try {
while (isActive) {
try {
// checkForNewJobs is set to true in jobWasAdded() below
checkForNewJobs = false;
// try to acquire jobs
Collection<Long> acquiredJobDbids = acquireJobs();
// no exception so resetting the currentIdleInterval
currentIdleInterval = jobExecutor.getIdleMillis();
if ((acquiredJobDbids != null) && (!acquiredJobDbids.isEmpty())) {
putAcquiredJobDbidsOnQueue(acquiredJobDbids);
log.info("added jobs "+acquiredJobDbids+" to the queue");
} else if (isActive) {
long waitPeriod = getWaitPeriod();
if (waitPeriod > 0) {
synchronized (semaphore) {
if (!checkForNewJobs) {
log.fine(getName()+" will wait for max "+waitPeriod+"ms on "+jobExecutor);
semaphore.wait(waitPeriod);
log.fine(getName()+" woke up");
} else {
log.fine("skipped wait because new message arrived");
}
}
}
}
} catch (InterruptedException e) {
log.info((isActive ? "active" : "inactivated") + " job dispatcher thread '" + getName() + "' got interrupted");
} catch (Exception e) {
log.log(Level.SEVERE, "exception in job executor thread. waiting " + currentIdleInterval + " milliseconds", e);
try {
synchronized (semaphore) {
semaphore.wait(currentIdleInterval);
}
} catch (InterruptedException e2) {
log.log(Level.FINEST, "delay after exception got interrupted", e2);
}
// after an exception, the current idle interval is doubled to prevent
// continuous exception generation when e.g. the db is unreachable
currentIdleInterval = currentIdleInterval * 2;
}
}
} catch (Throwable t) {
t.printStackTrace();
} finally {
log.info(getName() + " leaves cyberspace");
}
}
protected void putAcquiredJobDbidsOnQueue(Collection<Long> acquiredJobDbids) {
log.fine("pushing jobs on the queue "+acquiredJobDbids);
while (acquiredJobDbids!=null) {
try {
jobExecutor.getJobDbidsQueue().put(acquiredJobDbids);
log.finest("jobs "+acquiredJobDbids+" were put on the queue");
acquiredJobDbids = null;
} catch (InterruptedException e) {
log.finest("putting acquired job dbids got interrupted. retrying...");
}
}
}
protected Collection<Long> acquireJobs() {
CommandService commandService = jobExecutor.getCommandExecutor();
Command acquireJobsCommand = jobExecutor.getAcquireJobsCommand();
return (Collection<Long>) commandService.execute(acquireJobsCommand);
}
protected Date getNextDueDate() {
CommandService commandService = jobExecutor.getCommandExecutor();
Command getNextDueDate = jobExecutor.getNextDueDateCommand();
return (Date) commandService.execute(getNextDueDate);
}
protected long getWaitPeriod() {
long interval = jobExecutor.getIdleMillis();
Date nextDueDate = getNextDueDate();
if (nextDueDate != null) {
long currentTimeMillis = System.currentTimeMillis();
long nextDueDateTime = nextDueDate.getTime();
if (nextDueDateTime < currentTimeMillis + currentIdleInterval) {
interval = nextDueDateTime - currentTimeMillis;
}
}
if (interval < 0) {
interval = 0;
}
return interval;
}
public void deactivate() {
deactivate(false);
}
public void deactivate(boolean join) {
if (isActive) {
log.fine("deactivating "+getName());
isActive = false;
interrupt();
if (join) {
while (isAlive()) {
try {
log.fine("joining "+getName());
join();
} catch (InterruptedException e) {
log.finest("joining "+getName()+" got interrupted");
}
}
}
} else {
log.finest("ignoring deactivate: "+getName()+" is not active");
}
}
public void jobWasAdded() {
log.finest("notifying job executor dispatcher thread of new job");
synchronized (semaphore) {
checkForNewJobs = true;
semaphore.notify();
}
}
public boolean isActive() {
return isActive;
}
}