1 package org.e2etrace.timer;
2
3 /*
4 * Copyright 2006 Gunther Popp
5 *
6 * Licensed under the Apache License, Version 2.0 (the "License");
7 * you may not use this file except in compliance with the License.
8 * You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18
19 /**
20 * Default <code>ITimer</code> implementation.
21 * <p>
22 *
23 * This implementation uses {@link System#currentTimeMillis()} to measure the
24 * duration between the <code>start()</code> and <code>measure()</code>
25 * calls on the timer. The advantage of this approach is that it works with all
26 * JDK releases. The disadvantage is that the accuracy of
27 * <code>currentTimeMillis</code> depends on the underlying operating systems.
28 * On Windows, for example, <code>currentTimeMillis</code> will typically
29 * provide an accuracy of about 10ms, which is too coarse for measuring short
30 * intervals. However, on Linux the accuracy is 1ms, which is exactly what we
31 * want. For details on this issue, please refer to the article "My kingdom for
32 * a good timer!" by Vladimir Roubtsov on JavaWorld (see link below).
33 * <p>
34 *
35 * @author Gunther Popp
36 * @see <a
37 * href="http://www.javaworld.com/javaworld/javaqa/2003-01/01-qa-0110-timing.html">Article
38 * "My kingdom for a good timer!"</a>
39 *
40 */
41 public class DefaultTimer implements ITimer {
42
43 private long duration = -1;
44 private long start = -1;
45
46 /**
47 * Constructor. New instances can only be created by factories
48 * {@link ITimerFactory}
49 */
50 DefaultTimer() {
51
52 }
53
54 /** {@inheritDoc} */
55 public void start() {
56 start = System.currentTimeMillis();
57
58 }
59
60 /** {@inheritDoc} */
61 public long measure() {
62 if (start > 0) {
63 duration = System.currentTimeMillis() - start;
64 }
65
66 return duration;
67
68 }
69
70 }