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.api.util.internal;
20
21 import java.util.concurrent.atomic.AtomicInteger;
22
23 /**
24 * Concurrency utilities.
25 *
26 * @author <a href="mailto:tibordigana@apache.org">Tibor Digana (tibor17)</a>
27 * @since 2.19
28 */
29 public final class ConcurrencyUtils {
30 private ConcurrencyUtils() {
31 throw new IllegalStateException("not instantiable constructor");
32 }
33
34 /**
35 * Decreases {@code counter} to zero, or does not change the counter if negative.
36 * This method pretends been atomic. Only one thread can succeed setting the counter to zero.
37 *
38 * @param runner run if this Thread has concurrently decremented the counter down to zero
39 * @param counter atomic counter
40 */
41 @SuppressWarnings("checkstyle:emptyforiteratorpad")
42 public static void runIfZeroCountDown(Runnable runner, AtomicInteger counter) {
43 for (; ; ) {
44 int c = counter.get();
45 if (c > 0) {
46 int newCounter = c - 1;
47 if (counter.compareAndSet(c, newCounter)) {
48 boolean isZero = newCounter == 0;
49 if (isZero) {
50 runner.run();
51 }
52 break;
53 }
54 } else {
55 break;
56 }
57 }
58 }
59 }