/**
* 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.activemq.apollo.util;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.atomic.AtomicBoolean;
import org.fusesource.hawtdispatch.internal.util.RunnableCountDownLatch;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A helper class for working with services together with a useful base class
* for service implementations.
*
* @version $Revision: 1.1 $
*/
public abstract class ServiceSupport implements Service {
private static final Logger LOG = LoggerFactory.getLogger(ServiceSupport.class);
private AtomicBoolean started = new AtomicBoolean(false);
private AtomicBoolean stopping = new AtomicBoolean(false);
private AtomicBoolean stopped = new AtomicBoolean(false);
private List<ServiceListener>serviceListeners = new CopyOnWriteArrayList<ServiceListener>();
public static void dispose(Service service) {
try {
RunnableCountDownLatch latch = new RunnableCountDownLatch(1);
service.stop(latch);
latch.await();
} catch (Exception e) {
LOG.debug("Could not stop service: " + service + ". Reason: " + e, e);
}
}
public void start() throws Exception {
if (started.compareAndSet(false, true)) {
boolean success = false;
try {
doStart();
success = true;
} finally {
started.set(success);
}
for(ServiceListener l:this.serviceListeners) {
l.started(this);
}
}
}
public void stop() throws Exception {
if (stopped.compareAndSet(false, true)) {
stopping.set(true);
ServiceStopper stopper = new ServiceStopper();
try {
doStop(stopper);
} catch (Exception e) {
stopper.onException(this, e);
}
stopped.set(true);
started.set(false);
stopping.set(false);
for(ServiceListener l:this.serviceListeners) {
l.stopped(this);
}
stopper.throwFirstException();
}
}
/**
* @return true if this service has been started
*/
public boolean isStarted() {
return started.get();
}
/**
* @return true if this service is in the process of closing
*/
public boolean isStopping() {
return stopping.get();
}
/**
* @return true if this service is closed
*/
public boolean isStopped() {
return stopped.get();
}
public void addServiceListener(ServiceListener l) {
this.serviceListeners.add(l);
}
public void removeServiceListener(ServiceListener l) {
this.serviceListeners.remove(l);
}
protected abstract void doStop(ServiceStopper stopper) throws Exception;
protected abstract void doStart() throws Exception;
}