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 */
026public final class StopWatch {
027
028    private long start;
029
030    /**
031     * Starts the stop watch
032     */
033    public StopWatch() {
034        this.start = System.currentTimeMillis();
035    }
036
037    /**
038     * Starts the stop watch from the given timestamp
039     */
040    public StopWatch(Date startTimestamp) {
041        start = startTimestamp.getTime();
042    }
043
044    /**
045     * Creates the stop watch
046     *
047     * @param start whether it should start immediately
048     */
049    public StopWatch(boolean start) {
050        if (start) {
051            this.start = System.currentTimeMillis();
052        }
053    }
054
055    /**
056     * Starts or restarts the stop watch
057     */
058    public void restart() {
059        start = System.currentTimeMillis();
060    }
061
062    /**
063     * Returns the time taken in millis.
064     *
065     * @return time in millis, or <tt>0</tt> if not started yet.
066     */
067    public long taken() {
068        if (start > 0) {
069            return System.currentTimeMillis() - start;
070        } else {
071            return 0;
072        }
073    }
074
075}