/* 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.activiti.engine.impl.jobexecutor;
import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;
import org.activiti.engine.ActivitiOptimisticLockingException;
import org.activiti.engine.impl.interceptor.CommandExecutor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
*
* @author Daniel Meyer
*/
public class AcquireJobsRunnableImpl implements AcquireJobsRunnable {
private static Logger log = LoggerFactory.getLogger(AcquireJobsRunnableImpl.class);
protected final JobExecutor jobExecutor;
protected volatile boolean isInterrupted = false;
protected volatile boolean isJobAdded = false;
protected final Object MONITOR = new Object();
protected final AtomicBoolean isWaiting = new AtomicBoolean(false);
protected long millisToWait = 0;
public AcquireJobsRunnableImpl(JobExecutor jobExecutor) {
this.jobExecutor = jobExecutor;
}
public synchronized void run() {
log.info("{} starting to acquire jobs", jobExecutor.getName());
final CommandExecutor commandExecutor = jobExecutor.getCommandExecutor();
while (!isInterrupted) {
isJobAdded = false;
int maxJobsPerAcquisition = jobExecutor.getMaxJobsPerAcquisition();
try {
AcquiredJobs acquiredJobs = commandExecutor.execute(jobExecutor.getAcquireJobsCmd());
for (List<String> jobIds : acquiredJobs.getJobIdBatches()) {
jobExecutor.executeJobs(jobIds);
}
// if all jobs were executed
millisToWait = jobExecutor.getWaitTimeInMillis();
int jobsAcquired = acquiredJobs.getJobIdBatches().size();
if (jobsAcquired >= maxJobsPerAcquisition) {
millisToWait = 0;
}
} catch (ActivitiOptimisticLockingException optimisticLockingException) {
// See http://jira.codehaus.org/browse/ACT-1390
if (log.isDebugEnabled()) {
log.debug("Optimistic locking exception during job acquisition. If you have multiple job executors running against the same database, " +
"this exception means that this thread tried to acquire a job, which already was acquired by another job executor acquisition thread." +
"This is expected behavior in a clustered environment. " +
"You can ignore this message if you indeed have multiple job executor acquisition threads running against the same database. " +
"Exception message: {}", optimisticLockingException.getMessage());
}
} catch (Throwable e) {
log.error("exception during job acquisition: {}", e.getMessage(), e);
millisToWait = jobExecutor.getWaitTimeInMillis();
}
if ((millisToWait > 0) && (!isJobAdded)) {
try {
if (log.isDebugEnabled()) {
log.debug("job acquisition thread sleeping for {} millis", millisToWait);
}
synchronized (MONITOR) {
if(!isInterrupted) {
isWaiting.set(true);
MONITOR.wait(millisToWait);
}
}
if (log.isDebugEnabled()) {
log.debug("job acquisition thread woke up");
}
} catch (InterruptedException e) {
if (log.isDebugEnabled()) {
log.debug("job acquisition wait interrupted");
}
} finally {
isWaiting.set(false);
}
}
}
log.info("{} stopped job acquisition", jobExecutor.getName());
}
public void stop() {
synchronized (MONITOR) {
isInterrupted = true;
if(isWaiting.compareAndSet(true, false)) {
MONITOR.notifyAll();
}
}
}
public void jobWasAdded() {
isJobAdded = true;
if(isWaiting.compareAndSet(true, false)) {
// ensures we only notify once
// I am OK with the race condition
synchronized (MONITOR) {
MONITOR.notifyAll();
}
}
}
public long getMillisToWait() {
return millisToWait;
}
public void setMillisToWait(long millisToWait) {
this.millisToWait = millisToWait;
}
}