    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     */
    017    package 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.java 1162387 2011-08-27 16:05:20Z oheger $
    033     */
    034    public 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        public String toString()
    079        {
    080            return "Lock: " + name + " id = " + instanceId + ": "
    081                    + super.toString();
    082        }
    083    }