/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.servicemix.components.util;
import java.util.Date;
import javax.jbi.JBIException;
import javax.resource.spi.work.Work;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.servicemix.components.varscheduler.ScheduleIterator;
import org.apache.servicemix.components.varscheduler.Scheduler;
import org.apache.servicemix.components.varscheduler.SchedulerTask;
import org.apache.servicemix.executors.Executor;
import org.apache.servicemix.executors.ExecutorFactory;
import org.apache.servicemix.jbi.framework.ComponentContextImpl;
/**
* An implementation inheritence class for a component which polls some resource
* at periodic intervals to decide if there is an event to process.
*
* @version $Revision: 564374 $
*/
public abstract class PollingComponentSupport extends ComponentSupport implements Work {
private static final Log LOG = LogFactory.getLog(PollingComponentSupport.class);
private Executor executor;
private Scheduler scheduler;
private Date firstTime;
private long period = 5000;
private long delay;
private SchedulerTask schedulerTask;
private ScheduleIterator scheduleIterator;
private boolean started;
private boolean scheduleExecutedFlag;
/**
* Polls the underlying resource to see if some event is required
*
* @throws JBIException
*/
public abstract void poll() throws Exception;
public void release() {
}
public void run() {
try {
poll();
} catch (Exception e) {
LOG.error("Caught exception while polling: " + e, e);
}
}
// Properties
// -------------------------------------------------------------------------
public Executor getExecutor() {
return executor;
}
public long getDelay() {
return delay;
}
public void setDelay(long delay) {
this.delay = delay;
}
public Date getFirstTime() {
return firstTime;
}
public void setFirstTime(Date firstTime) {
this.firstTime = firstTime;
}
public long getPeriod() {
return period;
}
public void setPeriod(long period) {
this.period = period;
}
public Scheduler getScheduler() {
return scheduler;
}
public void setScheduler(Scheduler scheduler) {
this.scheduler = scheduler;
}
public synchronized void start() throws JBIException {
if (!started) {
started = true;
if (schedulerTask != null) {
schedulerTask.cancel();
}
schedulerTask = new PollSchedulerTask();
this.scheduler.schedule(schedulerTask, scheduleIterator);
}
super.start();
}
public synchronized void stop() throws JBIException {
if (schedulerTask != null) {
schedulerTask.cancel();
schedulerTask = null;
}
scheduleExecutedFlag = false;
started = false;
super.stop();
}
public synchronized void shutDown() throws JBIException {
stop();
scheduler.cancel();
executor.shutdown();
scheduler = null;
scheduleIterator = null;
executor = null;
super.shutDown();
}
// Implementation methods
// -------------------------------------------------------------------------
protected void init() throws JBIException {
if (scheduler == null) {
scheduler = new Scheduler(true);
}
if (scheduleIterator == null) {
scheduleIterator = new PollScheduleIterator();
}
if (executor == null) {
ComponentContextImpl context = (ComponentContextImpl) getContext();
ExecutorFactory factory = context.getContainer()
.getExecutorFactory();
executor = factory.createExecutor("component."
+ context.getComponentName());
}
super.init();
}
private class PollSchedulerTask extends SchedulerTask {
public void run() {
try {
// lets run the work inside the JCA worker pools to ensure
// the threads are setup correctly when we actually do stuff
getExecutor().execute(PollingComponentSupport.this);
} catch (Throwable e) {
LOG.error("Failed to schedule work: " + e, e);
}
}
}
private class PollScheduleIterator implements ScheduleIterator {
public Date nextExecution() {
long nextTime = System.currentTimeMillis();
if (scheduleExecutedFlag) {
nextTime += period;
} else {
if (firstTime != null) {
nextTime = firstTime.getTime();
}
nextTime += delay;
scheduleExecutedFlag = true;
}
return started ? new Date(nextTime) : null;
}
}
}