1 /***
2 * Copyright 2003-2010 Terracotta, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package net.sf.ehcache.constructs.nonstop.util;
18
19 import java.util.concurrent.ThreadFactory;
20 import java.util.concurrent.atomic.AtomicInteger;
21
22 /***
23 * A custom {@link ThreadFactory} that maintains a count of how many threads this factory has created
24 *
25 * @author Abhishek Sanoujam
26 *
27 */
28 public class CountingThreadFactory implements ThreadFactory {
29
30 private final AtomicInteger count = new AtomicInteger();
31 private final ThreadFactory actualFactory;
32
33 /***
34 * Constructor accepting the actual thread factory that will create the threads
35 *
36 * @param actualFactory
37 * the actual factory
38 */
39 public CountingThreadFactory(ThreadFactory actualFactory) {
40 this.actualFactory = actualFactory;
41 }
42
43 /***
44 * {@inheritDoc}
45 */
46 public Thread newThread(Runnable r) {
47 Thread newThread = actualFactory.newThread(new RunnableWithLifeCycle(this, r));
48 if (newThread != null) {
49 count.incrementAndGet();
50 }
51 return newThread;
52 }
53
54 /***
55 * Returns the number of threads this factory has created and currently alive
56 *
57 * @return Returns the number of threads this factory has created and currently alive
58 */
59 public int getNumberOfThreads() {
60 return count.get();
61 }
62
63 private void threadExecutionComplete() {
64 count.decrementAndGet();
65 }
66
67 /***
68 * Runnable which also fires lifecycle events
69 *
70 * @author Abhishek Sanoujam
71 *
72 */
73 private static class RunnableWithLifeCycle implements Runnable {
74
75 private final Runnable actualRunnable;
76 private final CountingThreadFactory countingThreadFactory;
77
78 /***
79 * Constructor accepting a {@link CountingThreadFactory} and the actual runnable
80 *
81 * @param countingThreadFactory
82 * @param actualRunnable
83 */
84 public RunnableWithLifeCycle(CountingThreadFactory countingThreadFactory, Runnable actualRunnable) {
85 super();
86 this.countingThreadFactory = countingThreadFactory;
87 this.actualRunnable = actualRunnable;
88 }
89
90 /***
91 * {@inheritDoc}
92 */
93 public void run() {
94 try {
95 if (actualRunnable != null) {
96 actualRunnable.run();
97 }
98 } finally {
99 countingThreadFactory.threadExecutionComplete();
100 }
101 }
102
103 }
104
105 }