Stopwatch


1   /*******************************************************************************
2    * Copyright (c) 2000, 2003 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials 
4    * are made available under the terms of the Common Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/cpl-v10.html
7    * 
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  package org.eclipse.ui.internal.misc;
12  
13  import java.util.Map  ;
14  import java.util.HashMap  ;
15  
16  /**
17   * A Stopwatch is used to measure the time elapsed during 
18   * an operation.  To do this create a stopwatch before the
19   * operation is executed and call stop() when the operation 
20   * afterwards.  The elapsed time will be printed.
21   *
22   * A Stopwatch can also be used to measure an interval time.  To
23   * do this create a stopwatch and call printInterval after
24   * every important interval.  The resetInterval method can also
25   * be used to start a new interval.
26   *
27   * A Stopwatch can also be registered for global access.  To 
28   * do this create a stopwatch and call register.  From this point 
29   * on a handle to the stopwatch can be retrieved by calling
30   * Stopwatch.getStopwatch("name").  The stopwatch should be
31   * unregistered when no longer needed.
32   */
33  public class Stopwatch {
34      private long startTime;
35      private long lastTime;
36      private String   name;
37      private static Map   registry;
38  /**
39   * Construct a new Stopwatch and start it.
40   * To reset the watch at a later time just call start() again.
41   */
42  public Stopwatch(String   name) {
43      this.name = name;
44      start();
45  }
46  /**
47   * Get a stopwatch from the registry.
48   */
49  static public Stopwatch getStopwatch(String   name) {
50      if (registry != null)
51          return (Stopwatch)registry.get(name);
52      else
53          return null;
54  }
55  /**
56   * Print the elapsed time since start(), printInterval(), or 
57   * resetInterval() was last called.
58   */
59  public void printInterval(String   hint) {
60      long time = System.currentTimeMillis() - lastTime;
61      System.out.println(name + " '" + hint + "' took " + time + " ms");//$NON-NLS-3$//$NON-NLS-2$//$NON-NLS-1$
62      lastTime = System.currentTimeMillis();
63  }
64  /**
65   * Print the current elapsed time.
66   */
67  public void printTime() {
68      long time = System.currentTimeMillis() - startTime;
69      System.out.print(name + " is now " + time + " ms");//$NON-NLS-2$//$NON-NLS-1$
70  }
71  /**
72   * Add this stopwatch to the registry.
73   */
74  public void register() {
75      if (registry == null)
76          registry = new HashMap  (2);
77      registry.put(name, this);
78  }
79  /**
80   * Reset the interval timer.
81   */
82  public void resetInterval() {
83      lastTime = System.currentTimeMillis();
84  }
85  /**
86   * Start the watch.
87   */
88  public void start() {
89      startTime = lastTime = System.currentTimeMillis();
90      System.out.println(name + " started");//$NON-NLS-1$
91  }
92  /**
93   * Stop the watch and print the elapsed time.
94   */
95  public void stop() {
96      long time = System.currentTimeMillis() - startTime;
97      System.out.println(name + " finished in " + time + " ms");//$NON-NLS-2$//$NON-NLS-1$
98  }
99  /**
100  * Remove this stopwatch from the registry.
101  */
102 public void unregister() {
103     if (registry != null)
104         registry.remove(name);
105 }
106 }
107
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