StopWatch.java

/*
 * Copyright (c) 2001-2004 Ant-Contrib project.  All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.sf.antcontrib.perf;

/**
 * A stopwatch, useful for 'quick and dirty' performance testing. Typical usage:
 * <pre>
 * StopWatch sw = new StopWatch();  // automatically starts
 * // do something here...
 * sw.stop();
 * System.out.println(sw.toString());   // print the total
 * sw.start();  // restart the stopwatch
 * // do some more things...
 * sw.stop();
 * System.out.println(sw.format(sw.elapsed()); // print the time since the last start
 * System.out.println(sw.toString()); // print the cumulative total
 * </pre>
 * <p>Developed for use with Antelope, migrated to ant-contrib Oct 2003.
 *
 * @author Dale Anson
 * @version   $Revision: 1.4 $
 */
public class StopWatch {

    /** an identifying name for this stopwatch */
    private String name = "";

    /** storage for start time */
    private long startTime = 0;

    /** storage for stop time */
    private long stopTime = 0;

    /** cumulative elapsed time */
    private long totalTime = 0;

    /** is the stopwatch running? */
    private boolean running = false;

    /**
     * Starts the stopwatch.
     */
    public StopWatch() {
        this( "" );
    }

    /**
     * Starts the stopwatch.
     * @param name an identifying name for this StopWatch
     */
    public StopWatch( String name ) {
        this.name = name;
        start();
    }

    /**
     * Starts/restarts the stopwatch. <code>stop</code> must be called prior
     * to restart.
     *
     * @return   the start time, the long returned System.currentTimeMillis().
     */
    public long start() {
        if ( !running )
            startTime = System.currentTimeMillis();
        running = true;
        return startTime;
    }

    /**
     * Stops the stopwatch.
     *
     * @return   the stop time, the long returned System.currentTimeMillis().
     */
    public long stop() {
        stopTime = System.currentTimeMillis();
        if ( running ) {
            totalTime += stopTime - startTime;
        }
        startTime = stopTime;
        running = false;
        return stopTime;
    }

    /**
     * Total cumulative elapsed time.
     *
     * @return   the total time
     */
    public long total() {
	stop();
	long rtn = totalTime;
	totalTime = 0;
        return rtn;
    }

    /**
     * Elapsed time, difference between the last start time and now.
     *
     * @return   the elapsed time
     */
    public long elapsed() {
        return System.currentTimeMillis() - startTime;
    }

    /**
     * @return the name of this StopWatch
     */
    public String getName() {
        return name;
    }

    /**
     * Formats the given time into decimal seconds.    
     * @return the time formatted as mm:ss.ddd
     */
    public String format( long ms ) {
        String total = String.valueOf( ms );
        String frontpad = "000";
        int pad_length = 3 - total.length();
        if ( pad_length >= 0 )
            total = "0." + frontpad.substring( 0, pad_length ) + total;
        else {
            String dec = total.substring( total.length() - 3 );
            total = "";
            int min = 0, sec = 0;
            min = ( int ) ( ms / 60000 );
            sec = min > 0 ? ( int ) ( ( ms - ( min * 60000 ) ) / 1000 ) : ( int ) ( ms / 1000 );
            if ( min > 0 ) {
                total = String.valueOf( min ) + ":" + ( sec < 10 ? "0" : "" ) + String.valueOf( sec ) + "." + dec;
            }
            else {
                total = String.valueOf( sec ) + "." + dec;
            }
        }
        return total + " sec";
    }

    /**
     * Returns the total elapsed time of the stopwatch formatted in decimal seconds.
     * @return [name: mm:ss.ddd]
     */
    public String toString() {
        StringBuffer sb = new StringBuffer();
        sb.append( "[" );
        if ( name != null )
            sb.append( name ).append( ": " );
        sb.append( format( totalTime ) );
        sb.append( "]" );
        return sb.toString();
    }

    public static void main ( String[] args ) {
        StopWatch sw = new StopWatch( "test" );
        
        // test the formatter
        System.out.println( sw.format( 1 ) );
        System.out.println( sw.format( 10 ) );
        System.out.println( sw.format( 100 ) );
        System.out.println( sw.format( 1000 ) );
        System.out.println( sw.format( 100000 ) );
        System.out.println( sw.format( 1000000 ) );
        
        // test the stopwatch
        try {
            System.out.println( "StopWatch: " + sw.getName() );
            Thread.currentThread().sleep( 2000 );
            sw.stop();
            System.out.println( sw.toString() );
            sw.start();
            Thread.currentThread().sleep( 2000 );
            sw.stop();
            System.out.println( "elapsed: " + sw.format( sw.elapsed() ) );
            System.out.println( "total: " + sw.format( sw.total() ) );
        }
        catch ( Exception e ) {
            e.printStackTrace();
        }
    }
}