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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.Executors;
22  import java.util.concurrent.ThreadFactory;
23  import java.util.concurrent.atomic.AtomicInteger;
24  
25  /**
26   * A factory to create worker threads with a given name prefix.
27   */
28  public final class WorkerThreadFactory implements ThreadFactory {
29  
30      private final ThreadFactory factory;
31  
32      private final String namePrefix;
33  
34      private final AtomicInteger threadIndex;
35  
36      private static final AtomicInteger POOL_INDEX = new AtomicInteger();
37  
38      /**
39       * Creates a new thread factory whose threads will have names using the specified prefix.
40       *
41       * @param namePrefix The prefix for the thread names, may be {@code null} or empty to derive the prefix from the
42       *            caller's simple class name.
43       */
44      public WorkerThreadFactory(String namePrefix) {
45          this.factory = Executors.defaultThreadFactory();
46          this.namePrefix =
47                  ((namePrefix != null && namePrefix.length() > 0) ? namePrefix : getCallerSimpleClassName() + '-')
48                          + POOL_INDEX.getAndIncrement()
49                          + '-';
50          threadIndex = new AtomicInteger();
51      }
52  
53      private static String getCallerSimpleClassName() {
54          StackTraceElement[] stack = new Exception().getStackTrace();
55          if (stack == null || stack.length <= 2) {
56              return "Worker-";
57          }
58          String name = stack[2].getClassName();
59          name = name.substring(name.lastIndexOf('.') + 1);
60          return name;
61      }
62  
63      public Thread newThread(Runnable r) {
64          Thread thread = factory.newThread(r);
65          thread.setName(namePrefix + threadIndex.getAndIncrement());
66          thread.setDaemon(true);
67          return thread;
68      }
69  }