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.eclipse.aether.util.concurrency;
20
21 import java.util.concurrent.Executor;
22 import java.util.concurrent.ExecutorService;
23 import java.util.concurrent.LinkedBlockingQueue;
24 import java.util.concurrent.ThreadPoolExecutor;
25 import java.util.concurrent.TimeUnit;
26
27 import org.eclipse.aether.RepositorySystemSession;
28 import org.eclipse.aether.util.ConfigUtils;
29
30 /**
31 * Utilities for executors and sizing them.
32 *
33 * @since 1.9.5
34 */
35 public final class ExecutorUtils {
36 /**
37 * Shared instance of "direct executor".
38 */
39 public static final Executor DIRECT_EXECUTOR = Runnable::run;
40
41 /**
42 * Creates new thread pool {@link ExecutorService}. The {@code poolSize} parameter but be greater than 1.
43 */
44 public static ExecutorService threadPool(int poolSize, String namePrefix) {
45 if (poolSize < 2) {
46 throw new IllegalArgumentException("Invalid poolSize: " + poolSize + ". Must be greater than 1.");
47 }
48 return new ThreadPoolExecutor(
49 poolSize,
50 poolSize,
51 3L,
52 TimeUnit.SECONDS,
53 new LinkedBlockingQueue<>(),
54 new WorkerThreadFactory(namePrefix));
55 }
56
57 /**
58 * Returns {@link #DIRECT_EXECUTOR} or result of {@link #threadPool(int, String)} depending on value of
59 * {@code size} parameter.
60 */
61 public static Executor executor(int size, String namePrefix) {
62 if (size <= 1) {
63 return DIRECT_EXECUTOR;
64 } else {
65 return threadPool(size, namePrefix);
66 }
67 }
68
69 /**
70 * To be used with result of {@link #executor(int, String)} method, shuts down instance if it is
71 * {@link ExecutorService}.
72 */
73 public static void shutdown(Executor executor) {
74 if (executor instanceof ExecutorService) {
75 ((ExecutorService) executor).shutdown();
76 }
77 }
78
79 /**
80 * Retrieves and validates requested thread count based on session and specified keys, or if none provided, the
81 * provided default value. This method validates result on top of what {@link ConfigUtils} does.
82 *
83 * @throws IllegalArgumentException if default value is less than 1.
84 * @see ConfigUtils#getInteger(RepositorySystemSession, int, String...)
85 */
86 public static int threadCount(RepositorySystemSession session, int defaultValue, String... keys) {
87 if (defaultValue < 1) {
88 throw new IllegalArgumentException("Invalid defaultValue: " + defaultValue + ". Must be greater than 0.");
89 }
90 int threadCount = ConfigUtils.getInteger(session, defaultValue, keys);
91 if (threadCount < 1) {
92 throw new IllegalArgumentException("Invalid value: " + threadCount + ". Must be greater than 0.");
93 }
94 return threadCount;
95 }
96 }