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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  package org.apache.hadoop.hbase.ipc;
19  
20  import org.apache.hadoop.conf.Configuration;
21  import org.apache.hadoop.hbase.DaemonThreadFactory;
22  
23  import java.io.IOException;
24  import java.util.concurrent.ArrayBlockingQueue;
25  import java.util.concurrent.ThreadPoolExecutor;
26  import java.util.concurrent.TimeUnit;
27  import java.util.concurrent.atomic.AtomicInteger;
28  
29  /**
30   * A very simple {@code }RpcScheduler} that serves incoming requests in order.
31   *
32   * This can be used for HMaster, where no prioritization is needed.
33   */
34  public class FifoRpcScheduler extends RpcScheduler {
35  
36    private final int handlerCount;
37    private final int maxQueueLength;
38    private final AtomicInteger queueSize = new AtomicInteger(0);
39    private ThreadPoolExecutor executor;
40  
41    public FifoRpcScheduler(Configuration conf, int handlerCount) {
42      this.handlerCount = handlerCount;
43      this.maxQueueLength = conf.getInt("hbase.ipc.server.max.callqueue.length",
44          handlerCount * RpcServer.DEFAULT_MAX_CALLQUEUE_LENGTH_PER_HANDLER);
45    }
46  
47    @Override
48    public void init(Context context) {
49      // no-op
50    }
51  
52    @Override
53    public void start() {
54      this.executor = new ThreadPoolExecutor(
55          handlerCount,
56          handlerCount,
57          60,
58          TimeUnit.SECONDS,
59          new ArrayBlockingQueue<Runnable>(maxQueueLength),
60          new DaemonThreadFactory("FifoRpcScheduler.handler"),
61          new ThreadPoolExecutor.CallerRunsPolicy());
62    }
63  
64    @Override
65    public void stop() {
66      this.executor.shutdown();
67    }
68  
69    @Override
70    public boolean dispatch(final CallRunner task) throws IOException, InterruptedException {
71      // Executors provide no offer, so make our own.
72      int queued = queueSize.getAndIncrement();
73      if (maxQueueLength > 0 && queued >= maxQueueLength) {
74        queueSize.decrementAndGet();
75        return false;
76      }
77      executor.submit(new Runnable() {
78        @Override
79        public void run() {
80          task.setStatus(RpcServer.getStatus());
81          task.run();
82          queueSize.decrementAndGet();
83        }
84      });
85      return true;
86    }
87  
88    @Override
89    public int getGeneralQueueLength() {
90      return executor.getQueue().size();
91    }
92  
93    @Override
94    public int getPriorityQueueLength() {
95      return 0;
96    }
97  
98    @Override
99    public int getReplicationQueueLength() {
100     return 0;
101   }
102 
103   @Override
104   public int getActiveRpcHandlerCount() {
105     return executor.getActiveCount();
106   }
107 }