1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. 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,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.maven.surefire.junitcore.pc;
20
21 /**
22 * The Balancer controls the maximum of concurrent threads in the current Scheduler(s) and prevents
23 * from own thread resources exhaustion if other group of schedulers share the same pool of threads.
24 * <br>
25 * If a permit is available, {@link #acquirePermit()} simply returns and a new test is scheduled
26 * by {@link Scheduler#schedule(Runnable)} in the current runner. Otherwise waiting for a release.
27 * One permit is released as soon as the child thread has finished.
28 *
29 * @author Tibor Digana (tibor17)
30 * @since 2.16
31 */
32 public interface Balancer {
33
34 /**
35 * Acquires a permit from this balancer, blocking until one is available.
36 *
37 * @return {@code true} if current thread is <b>NOT</b> interrupted
38 * while waiting for a permit.
39 */
40 boolean acquirePermit();
41
42 /**
43 * Releases a permit, returning it to the balancer.
44 */
45 void releasePermit();
46
47 void releaseAllPermits();
48 }