1 package org.apache.maven.surefire.junitcore.pc;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import java.util.concurrent.Semaphore;
23
24 /**
25 * @author Tibor Digana (tibor17)
26 * @since 2.16
27 *
28 * @see Balancer
29 */
30 final class ThreadResourcesBalancer implements Balancer
31 {
32 private final Semaphore balancer;
33 private final int numPermits;
34
35 /**
36 * <tt>fair</tt> set to false.
37 *
38 * @param numPermits number of permits to acquire when maintaining concurrency on tests.
39 * Must be >0 and < {@link Integer#MAX_VALUE}.
40 *
41 * @see #ThreadResourcesBalancer(int, boolean)
42 */
43 ThreadResourcesBalancer( int numPermits )
44 {
45 this( numPermits, false );
46 }
47
48 /**
49 * @param numPermits number of permits to acquire when maintaining concurrency on tests.
50 * Must be >0 and < {@link Integer#MAX_VALUE}.
51 * @param fair <tt>true</tt> guarantees the waiting schedulers to wake up in order they acquired a permit
52 */
53 ThreadResourcesBalancer( int numPermits, boolean fair )
54 {
55 balancer = new Semaphore( numPermits, fair );
56 this.numPermits = numPermits;
57 }
58
59 /**
60 * Acquires a permit from this balancer, blocking until one is available.
61 *
62 * @return <code>true</code> if current thread is <em>NOT</em> interrupted
63 * while waiting for a permit.
64 */
65 public boolean acquirePermit()
66 {
67 try
68 {
69 balancer.acquire();
70 return true;
71 }
72 catch ( InterruptedException e )
73 {
74 return false;
75 }
76 }
77
78 /**
79 * Releases a permit, returning it to the balancer.
80 */
81 public void releasePermit()
82 {
83 balancer.release();
84 }
85
86 public void releaseAllPermits()
87 {
88 balancer.release( numPermits );
89 }
90 }