/**
* 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.hadoop.yarn.service;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.yarn.YarnException;
/**
* Composition of services.
*/
public class CompositeService extends AbstractService {
private static final Log LOG = LogFactory.getLog(CompositeService.class);
private List<Service> serviceList = new ArrayList<Service>();
public CompositeService(String name) {
super(name);
}
public Collection<Service> getServices() {
return Collections.unmodifiableList(serviceList);
}
protected synchronized void addService(Service service) {
serviceList.add(service);
}
protected synchronized boolean removeService(Service service) {
return serviceList.remove(service);
}
public synchronized void init(Configuration conf) {
for (Service service : serviceList) {
service.init(conf);
}
super.init(conf);
}
public synchronized void start() {
int i = 0;
try {
for (int n = serviceList.size(); i < n; i++) {
Service service = serviceList.get(i);
service.start();
}
super.start();
} catch (Throwable e) {
LOG.error("Error starting services " + getName(), e);
// Note that the state of the failed service is still INITED and not
// STARTED. Even though the last service is not started completely, still
// call stop() on all services including failed service to make sure cleanup
// happens.
stop(i);
throw new YarnException("Failed to Start " + getName(), e);
}
}
public synchronized void stop() {
if (this.getServiceState() == STATE.STOPPED) {
// The base composite-service is already stopped, don't do anything again.
return;
}
if (serviceList.size() > 0) {
stop(serviceList.size() - 1);
}
super.stop();
}
private synchronized void stop(int numOfServicesStarted) {
// stop in reserve order of start
for (int i = numOfServicesStarted; i >= 0; i--) {
Service service = serviceList.get(i);
try {
service.stop();
} catch (Throwable t) {
LOG.info("Error stopping " + service.getName(), t);
}
}
}
/**
* JVM Shutdown hook for CompositeService which will stop the give
* CompositeService gracefully in case of JVM shutdown.
*/
public static class CompositeServiceShutdownHook extends Thread {
private CompositeService compositeService;
public CompositeServiceShutdownHook(CompositeService compositeService) {
super("CompositeServiceShutdownHook for " + compositeService.getName());
this.compositeService = compositeService;
}
@Override
public void run() {
try {
// Stop the Composite Service
compositeService.stop();
} catch (Throwable t) {
LOG.info("Error stopping " + compositeService.getName(), t);
}
}
}
}