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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, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  
19  package org.apache.hadoop.metrics2.lib;
20  
21  import java.util.concurrent.ScheduledExecutorService;
22  import java.util.concurrent.ScheduledThreadPoolExecutor;
23  import java.util.concurrent.ThreadFactory;
24  import java.util.concurrent.atomic.AtomicInteger;
25  
26  import org.apache.hadoop.hbase.classification.InterfaceAudience;
27  import org.apache.hadoop.metrics2.MetricsExecutor;
28  
29  /**
30   *  Class to handle the ScheduledExecutorService{@link ScheduledExecutorService} used by
31   *  MetricsRegionAggregateSourceImpl, and
32   *  JmxCacheBuster
33   */
34  @InterfaceAudience.Private
35  public class MetricsExecutorImpl implements MetricsExecutor {
36  
37    @Override
38    public ScheduledExecutorService getExecutor() {
39      return ExecutorSingleton.INSTANCE.scheduler;
40    }
41  
42    @Override
43    public void stop() {
44      if (!getExecutor().isShutdown()) {
45        getExecutor().shutdown();
46      }
47    }
48  
49    private enum ExecutorSingleton {
50      INSTANCE;
51      private final ScheduledExecutorService scheduler = new ScheduledThreadPoolExecutor(1,
52          new ThreadPoolExecutorThreadFactory("HBase-Metrics2-"));
53    }
54  
55    private final static class ThreadPoolExecutorThreadFactory implements ThreadFactory {
56      private final String name;
57      private final AtomicInteger threadNumber = new AtomicInteger(1);
58  
59      private ThreadPoolExecutorThreadFactory(String name) {
60        this.name = name;
61      }
62  
63      @Override
64      public Thread newThread(Runnable runnable) {
65        Thread t = new Thread(runnable, name + threadNumber.getAndIncrement());
66        t.setDaemon(true);
67        return t;
68      }
69    }
70  }