/**
* 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.waveprotocol.box.server.shutdown;
import org.waveprotocol.wave.util.logging.Log;
import java.util.HashSet;
import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;
/**
* Registers and executed by specified priority shutdown tasks.
*
* @author akaplanov@gmail.com (A. Kaplanov)
*/
public class ShutdownManager extends Thread {
interface NamedShutdownable extends Shutdownable {
String getName();
}
private static final Log LOG = Log.get(ShutdownManager.class);
private static ShutdownManager instance;
private final SortedMap<ShutdownPriority, Set<NamedShutdownable>> tasks = new TreeMap<>();
private ShutdownManager() {
super(ShutdownManager.class.getSimpleName());
}
public static synchronized ShutdownManager getInstance() {
if (instance == null) {
instance = new ShutdownManager();
}
return instance;
}
/**
* Requsters shutdown task.
*
* @param shutdownHandler the handler to execute on shutdown.
* @param taskName the name of task.
* @param priority the priority determines shutdown order.
*/
public synchronized void register(final Shutdownable shutdownHandler, final String taskName,
ShutdownPriority priority) {
if (tasks.isEmpty()) {
Runtime.getRuntime().addShutdownHook(this);
}
Set<NamedShutdownable> priorityTasks = tasks.get(priority);
if (priorityTasks == null) {
tasks.put(priority, priorityTasks = new HashSet<>());
}
priorityTasks.add(new NamedShutdownable() {
@Override
public String getName() {
return taskName;
}
@Override
public void shutdown() throws Exception {
shutdownHandler.shutdown();
}
});
}
/**
* Executes on Java shutdown hook.
*/
@Override
public void run() {
LOG.info("Shutdown hook is fired.");
shutdown();
}
private synchronized void shutdown() {
LOG.info("Start of shutdown procedure.");
for (ShutdownPriority priority : tasks.keySet()) {
LOG.info("Shutdown priority class " + priority.name());
for (NamedShutdownable task : tasks.get(priority)) {
LOG.info("Shutdown of " + task.getName() + " ...");
try {
task.shutdown();
} catch (Exception ex) {
LOG.severe("Shutdown of " + task.getName() + " error", ex);
}
}
}
LOG.info("End of shutdown procedure.");
}
}