View Javadoc

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   */
20  package org.apache.mina.service.executor;
21  
22  import java.util.concurrent.BlockingQueue;
23  import java.util.concurrent.LinkedBlockingQueue;
24  
25  import org.apache.mina.api.IoHandler;
26  import org.slf4j.Logger;
27  import org.slf4j.LoggerFactory;
28  
29  /**
30   * Use this executor if you want the {@link IoHandler} events of a session to be executed in order and on the same
31   * thread. In your {@link IoHandler} code you don't need to care about session level concurrency.
32   * 
33   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
34   */
35  public final class OrderedHandlerExecutor implements IoHandlerExecutor {
36  
37      private static final Logger LOG = LoggerFactory.getLogger(OrderedHandlerExecutor.class);
38  
39      private Worker[] workers;
40  
41      /**
42       * Create an {@link OrderedHandlerExecutor} with a given number of thread and a given queue size.
43       * 
44       * @param workerThreadCount the worker thread count
45       * @param queueSize the size of the queue for each worker thread
46       */
47      public OrderedHandlerExecutor(int workerThreadCount, int queueSize) {
48          LOG.debug("creating OrderedHandlerExecutor workerThreadCount = {} queueSize = {}", workerThreadCount, queueSize);
49          workers = new Worker[workerThreadCount];
50  
51          for (int i = 0; i < workerThreadCount; i++) {
52              workers[i] = new Worker(i, queueSize);
53          }
54          for (int i = 0; i < workerThreadCount; i++) {
55              workers[i].start();
56          }
57          LOG.debug("workers started");
58      }
59  
60      /**
61       * {@inheritDoc}
62       */
63      @Override
64      public void execute(Event event) {
65          try {
66              int workerIndex = (int) (event.getSession().getId() % workers.length);
67              LOG.debug("executing event {} in worker {}", event, workerIndex);
68              workers[workerIndex].enqueue(event);
69          } catch (InterruptedException e) {
70              // interrupt the world
71              return;
72          }
73      }
74  
75      /** thread in charge of gathering events from a queue and running them */
76      private static class Worker extends Thread {
77  
78          private static HandlerCaller caller = new HandlerCaller();
79  
80          private final BlockingQueue<Event> queue;
81  
82          public Worker(int index, int queueSize) {
83              super("IoHandlerWorker " + index);
84              queue = new LinkedBlockingQueue<Event>(queueSize);
85          }
86  
87          public void enqueue(Event event) throws InterruptedException {
88              LOG.debug("enqueing event : {}", event);
89              queue.put(event);
90          }
91  
92          /**
93           * {@inheritDoc}
94           */
95          @Override
96          public void run() {
97              for (;;) {
98                  try {
99  
100                     Event e = queue.take();
101                     LOG.debug("dequeing event {}", e);
102                     e.visit(caller);
103 
104                 } catch (InterruptedException e) {
105                     // end this thread
106                     return;
107                 }
108             }
109         }
110     }
111 }