1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
|
/*
* Derby - Class org.apache.derbyTesting.functionTests.util.Barrier
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.derbyTesting.functionTests.util;
import junit.framework.Assert;
/**
* In the absence of java.util.concurrent.CyclicBarrier on some of the
* platforms we test, create our own barrier class. This class allows
* threads to wait for one another on specific locations, so that they
* know they're all in the expected state.
*/
public class Barrier {
/** Number of threads to wait for at the barrier. */
private int numThreads;
/** Create a barrier for the specified number of threads. */
public Barrier(int numThreads) {
this.numThreads = numThreads;
}
/**
* Wait until {@code numThreads} have called {@code await()} on this
* barrier, then proceed.
*
* @throws InterruptedException if the thread is interrupted while
* waiting for the other threads to reach the barrier.
*/
public synchronized void await() throws InterruptedException {
Assert.assertTrue(
"Too many threads reached the barrier", numThreads > 0);
if (--numThreads <= 0) {
// All threads have reached the barrier. Go ahead!
notifyAll();
}
// Some threads haven't reached the barrier yet. Let's wait.
while (numThreads > 0) {
wait();
}
}
}
|
