slf4j-ext/src/main/java/org/slf4j/profiler/StopWatch.java

/**
 * Copyright (c) 2004-2011 QOS.ch
 * All rights reserved.
 *
 * Permission is hereby granted, free  of charge, to any person obtaining
 * a  copy  of this  software  and  associated  documentation files  (the
 * "Software"), to  deal in  the Software without  restriction, including
 * without limitation  the rights to  use, copy, modify,  merge, publish,
 * distribute,  sublicense, and/or sell  copies of  the Software,  and to
 * permit persons to whom the Software  is furnished to do so, subject to
 * the following conditions:
 *
 * The  above  copyright  notice  and  this permission  notice  shall  be
 * included in all copies or substantial portions of the Software.
 *
 * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
 * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
 * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */
package org.slf4j.profiler;

/**
 * A very basic @{link TimeInstrument} which can be started and stopped 
 * once and only once.
 * 
 * @author Ceki Gülcü
 *
 */
public class StopWatch implements TimeInstrument {

  private String name;
  private long startTime;
  private long stopTime;
  TimeInstrumentStatus status;

  public StopWatch(String name) {
    start(name);
  }

  StopWatch(StopWatch original) {
    this.name = original.name;
    this.startTime = original.startTime;
    this.stopTime = original.stopTime;
    this.status = original.status;
  }

  
  public void start(String name) {
    this.name = name;
    startTime = System.nanoTime();
    status = TimeInstrumentStatus.STARTED;
  }
  
  public String getName() {
    return name;
  }

  public TimeInstrument stop() {
    if(status == TimeInstrumentStatus.STOPPED) {
      return this;
    } 
    return stop(System.nanoTime());
  }

  public StopWatch stop(long stopTime) {
    this.status = TimeInstrumentStatus.STOPPED;
    this.stopTime = stopTime;
    return this;
  }
  
  @Override
  public String toString() {
    StringBuilder buf = new StringBuilder();
    buf.append("StopWatch [");
    buf.append(name);
    buf.append("] ");

    switch (status) {
    case STARTED:
      buf.append("STARTED");
      break;
    case STOPPED:
      buf.append("elapsed time: ");
      buf.append(Util.durationInDurationUnitsAsStr(elapsedTime(), DurationUnit.MICROSECOND));
      break;
    default:
      throw new IllegalStateException("Status " + status + " is not expected");
    }
    return buf.toString();
  }

  public final long elapsedTime() {
    if (status == TimeInstrumentStatus.STARTED) {
      return 0;
    } else {
      return stopTime - startTime;
    }
  }

  public TimeInstrumentStatus getStatus() {
    return status;
  }

  public void print() {
   System.out.println(toString());
  }
  
  public void log() {
    throw new UnsupportedOperationException("A stopwatch instance does not know how to log");
  }
  
}