001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.configuration;
018
019/**
020 * <p>
021 * A simple class acting as lock.
022 * </p>
023 * <p>
024 * Instances of this class are used by some configuration classes to synchronize
025 * themselves.
026 * </p>
027 *
028 * @author <a
029 *         href="http://commons.apache.org/configuration/team-list.html">Commons
030 *         Configuration team</a>
031 * @since 1.7
032 * @version $Id: Lock.html 901729 2014-03-15 20:24:09Z oheger $
033 */
034public class Lock
035{
036    /** A string used internally to synchronize counter updates. */
037    private static String counterLock = "Lock";
038
039    /** A counter for generating unique instance IDs. */
040    private static int counter;
041
042    /** The name of this lock. */
043    private final String name;
044
045    /** The unique ID of this lock instance. */
046    private final int instanceId;
047
048    /**
049     * Creates a new instance of {@code Lock} with the specified name.
050     *
051     * @param name the name of this lock
052     */
053    public Lock(String name)
054    {
055        this.name = name;
056        synchronized (counterLock)
057        {
058            instanceId = ++counter;
059        }
060    }
061
062    /**
063     * Returns the name of this lock.
064     *
065     * @return the name of this lock
066     */
067    public String getName()
068    {
069        return name;
070    }
071
072    /**
073     * Returns a string representation of this object. This implementation
074     * returns a string which contains the lock name and the instance ID.
075     *
076     * @return a string for this object
077     */
078    @Override
079    public String toString()
080    {
081        return "Lock: " + name + " id = " + instanceId + ": "
082                + super.toString();
083    }
084}