/**
* 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
* <p/>
* http://www.apache.org/licenses/LICENSE-2.0
* <p/>
* 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.model.util.Preconditions;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
* Life cycle control.
*
* @author akaplanov@gmail.com (A. Kaplanov)
*/
public class LifeCycle {
private static int SHUTDOWN_TIMEOUT_SEC = 2;
private final String name;
private final ShutdownPriority shutdownPriority;
private final Shutdownable shutdownHandler;
private final Semaphore semaphore = new Semaphore(Integer.MAX_VALUE);
private final ShutdownManager shutdownManager;
private boolean started;
/**
* Creates lifecycle.
*
* @param name the name of task.
* @param shutdownPriority determines shutdown order.
* @param shutdownHandler the handler executed on shutdown.
*/
public LifeCycle(String name, ShutdownPriority shutdownPriority, Shutdownable shutdownHandler) {
this(name, shutdownPriority, shutdownHandler, ShutdownManager.getInstance());
}
/**
* Creates lifecycle.
*
* @param name the name of task.
* @param shutdownPriority determines shutdown order.
* @param shutdownHandler the handler executed on shutdown.
* @param shutdownManager the shutdown manager.
*/
public LifeCycle(String name, ShutdownPriority shutdownPriority, Shutdownable shutdownHandler,
ShutdownManager shutdownManager) {
this.name = name;
this.shutdownPriority = shutdownPriority;
this.shutdownHandler = shutdownHandler;
this.shutdownManager = shutdownManager;
}
/**
* Starts lifecycle.
*/
public synchronized void start() {
Preconditions.checkArgument(!started, name + " is already started.");
started = true;
shutdownManager.register(new Shutdownable() {
@Override
public void shutdown() throws Exception {
synchronized (LifeCycle.this) {
if (shutdownHandler != null) {
shutdownHandler.shutdown();
}
if (!semaphore.tryAcquire(Integer.MAX_VALUE, SHUTDOWN_TIMEOUT_SEC, TimeUnit.SECONDS)) {
throw new TimeoutException();
}
started = false;
}
}
}, name, shutdownPriority);
}
/**
* Enters to execution block of task.
*/
public synchronized void enter() {
checkIsStarted();
try {
semaphore.acquire();
} catch (InterruptedException ex) {
throw new RuntimeException(ex);
}
}
/**
* Leaves execution block of task.
*/
public synchronized void leave() {
semaphore.release();
}
private void checkIsStarted() {
if (!started) {
throw new IllegalStateException(name + " is not started");
}
}
}