001/**
002 * Copyright (c) 2011, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package org.openimaj.time;
031
032/**
033 * Timer instances let you track time from start to end of some 
034 * process. The time granularity is in milliseconds.
035 * 
036 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
037 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
038 * 
039 */
040public class Timer {
041        private long start = 0;
042        private long end = 0;
043        
044        /**
045         * Create a timer. The timer will not start unit {@link #start()} is called.
046         */
047        public Timer() {
048        }
049
050        /**
051         * @return instantiate and start a new {@link Timer} instance.
052         */
053        public static Timer timer() {
054                Timer timer = new Timer();
055                
056                timer.start();
057                
058                return timer;
059        }
060
061        /**
062         * Get the duration of the timer in milliseconds. If the timer has
063         * been stopped then this is how long the timer ran for. If the
064         * timer is still running, then this is the time between it starting
065         * and now.
066         * 
067         * @return the duration of the timer in milliseconds
068         */
069        public long duration() {
070                long e = end == 0 ? System.currentTimeMillis() : end;
071                
072                return e - start;
073        }
074
075        /**
076         * Start the timer
077         */
078        public void start() {
079                this.start = System.currentTimeMillis();
080        }
081
082        /**
083         * Stop the timer
084         */
085        public void stop() {
086                this.end = System.currentTimeMillis();
087        }
088}