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1   /**
2    * Copyright 2010 The Apache Software Foundation
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *     http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing, software
15   * distributed under the License is distributed on an "AS IS" BASIS,
16   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17   * See the License for the specific language governing permissions and
18   * limitations under the License.
19   */
20  package org.apache.hadoop.hbase.master;
21  
22  import java.lang.Thread.UncaughtExceptionHandler;
23  import java.util.concurrent.Executors;
24  
25  import org.apache.hadoop.hbase.Server;
26  
27  import com.google.common.util.concurrent.ThreadFactoryBuilder;
28  
29  /**
30   * Base class used bulk assigning and unassigning regions.
31   * Encapsulates a fixed size thread pool of executors to run assignment/unassignment.
32   * Implement {@link #populatePool(java.util.concurrent.ExecutorService)} and
33   * {@link #waitUntilDone(long)}.  The default implementation of
34   * the {@link #getUncaughtExceptionHandler()} is to abort the hosting
35   * Server.
36   */
37  public abstract class BulkAssigner {
38    final Server server;
39  
40    /**
41     * @param server An instance of Server
42     */
43    public BulkAssigner(final Server server) {
44      this.server = server;
45    }
46  
47    /**
48     * @return What to use for a thread prefix when executor runs.
49     */
50    protected String getThreadNamePrefix() {
51      return this.server.getServerName() + "-" + this.getClass().getName(); 
52    }
53  
54    protected UncaughtExceptionHandler getUncaughtExceptionHandler() {
55      return new UncaughtExceptionHandler() {
56        @Override
57        public void uncaughtException(Thread t, Throwable e) {
58          // Abort if exception of any kind.
59          server.abort("Uncaught exception in " + t.getName(), e);
60        }
61      };
62    }
63  
64    protected int getThreadCount() {
65      return this.server.getConfiguration().
66        getInt("hbase.bulk.assignment.threadpool.size", 20);
67    }
68  
69    protected long getTimeoutOnRIT() {
70      return this.server.getConfiguration().
71        getLong("hbase.bulk.assignment.waiton.empty.rit", 5 * 60 * 1000);
72    }
73  
74    protected abstract void populatePool(final java.util.concurrent.ExecutorService pool);
75  
76    public boolean bulkAssign() throws InterruptedException {
77      return bulkAssign(true);
78    }
79  
80    /**
81     * Run the bulk assign.
82     * @param sync Whether to assign synchronously.
83     * @throws InterruptedException
84     * @return True if done.
85     */
86    public boolean bulkAssign(boolean sync) throws InterruptedException {
87      boolean result = false;
88      ThreadFactoryBuilder builder = new ThreadFactoryBuilder();
89      builder.setDaemon(true);
90      builder.setNameFormat(getThreadNamePrefix() + "-%1$d");
91      builder.setUncaughtExceptionHandler(getUncaughtExceptionHandler());
92      int threadCount = getThreadCount();
93      java.util.concurrent.ExecutorService pool =
94        Executors.newFixedThreadPool(threadCount, builder.build());
95      try {
96        populatePool(pool);
97        // How long to wait on empty regions-in-transition.  If we timeout, the
98        // RIT monitor should do fixup.
99        if (sync) result = waitUntilDone(getTimeoutOnRIT());
100     } finally {
101       // We're done with the pool.  It'll exit when its done all in queue.
102       pool.shutdown();
103     }
104     return result;
105   }
106 
107   /**
108    * Wait until bulk assign is done.
109    * @param timeout How long to wait.
110    * @throws InterruptedException
111    * @return True if the condition we were waiting on happened.
112    */
113   protected abstract boolean waitUntilDone(final long timeout)
114   throws InterruptedException;
115 }