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.camel.util;
018
019import java.util.Date;
020
021/**
022 * A very simple stop watch.
023 * <p/>
024 * This implementation is not thread safe and can only time one task at any given time.
025 *
026 * @version 
027 */
028public final class StopWatch {
029
030    private long start;
031    private long stop;
032
033    /**
034     * Starts the stop watch
035     */
036    public StopWatch() {
037        this(true);
038    }
039
040    /**
041     * Starts the stop watch from the given timestamp
042     */
043    public StopWatch(Date startTimestamp) {
044        start = startTimestamp.getTime();
045    }
046
047    /**
048     * Creates the stop watch
049     *
050     * @param started whether it should start immediately
051     */
052    public StopWatch(boolean started) {
053        if (started) {
054            restart();
055        }
056    }
057
058    /**
059     * Starts or restarts the stop watch
060     */
061    public void restart() {
062        start = System.currentTimeMillis();
063        stop = 0;
064    }
065
066    /**
067     * Stops the stop watch
068     *
069     * @return the time taken in millis.
070     */
071    public long stop() {
072        stop = System.currentTimeMillis();
073        return taken();
074    }
075
076    /**
077     * Returns the time taken in millis.
078     *
079     * @return time in millis
080     */
081    public long taken() {
082        if (start > 0 && stop > 0) {
083            return stop - start;
084        } else if (start > 0) {
085            return System.currentTimeMillis() - start;
086        } else {
087            return 0;
088        }
089    }
090
091}