org.apache.slider.server.services.utility.EndOfServiceWaiter.java Source code

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Here is the source code for org.apache.slider.server.services.utility.EndOfServiceWaiter.java

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/*
 * 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.slider.server.services.utility;

import org.apache.hadoop.service.Service;
import org.apache.hadoop.service.ServiceStateChangeListener;

import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicBoolean;

/**
 * Wait for a service to stop.
 * 
 * WARNING: the notification may come in as soon as the service enters
 * the stopped state: it may take some time for the actual stop operation
 * to complete.
 */
public class EndOfServiceWaiter implements ServiceStateChangeListener {

    private final AtomicBoolean finished = new AtomicBoolean(false);
    private final String name;
    private Service service;

    /**
     * Wait for a service; use the service name as this instance's name
     * @param service service
     */
    public EndOfServiceWaiter(Service service) {
        this(service.getName(), service);
    }

    /**
     * Wait for a service
     * @param name name for messages
     * @param service service
     */
    public EndOfServiceWaiter(String name, Service service) {
        this.name = name;
        this.service = service;
        service.registerServiceListener(this);
    }

    public synchronized void waitForServiceToStop(long timeout) throws InterruptedException, TimeoutException {
        service.waitForServiceToStop(timeout);
        if (!finished.get()) {
            wait(timeout);
            if (!finished.get()) {
                throw new TimeoutException(name + " did not finish after " + timeout + " milliseconds");
            }
        }
    }

    /**
     * Wait for service state change callbacks; notify self if the service has
     * now stopped
     * @param service service
     */
    @Override
    public synchronized void stateChanged(Service service) {
        if (service.isInState(Service.STATE.STOPPED)) {
            finished.set(true);
            notify();
        }
    }

}