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1   /*
2    * Copyright 2009 Red Hat, Inc.
3    *
4    * Red Hat licenses this file to you under the Apache License, version 2.0
5    * (the "License"); you may not use this file except in compliance with the
6    * License.  You may obtain a copy of the License at:
7    *
8    *    http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package org.jboss.netty.channel.socket.nio;
17  
18  import java.nio.channels.Selector;
19  import java.util.concurrent.Executor;
20  import java.util.concurrent.Executors;
21  import java.util.concurrent.RejectedExecutionException;
22  
23  import org.jboss.netty.channel.Channel;
24  import org.jboss.netty.channel.ChannelPipeline;
25  import org.jboss.netty.channel.ChannelSink;
26  import org.jboss.netty.channel.group.ChannelGroup;
27  import org.jboss.netty.channel.socket.ServerSocketChannel;
28  import org.jboss.netty.channel.socket.ServerSocketChannelFactory;
29  import org.jboss.netty.util.internal.ExecutorUtil;
30  
31  /**
32   * A {@link ServerSocketChannelFactory} which creates a server-side NIO-based
33   * {@link ServerSocketChannel}.  It utilizes the non-blocking I/O mode which
34   * was introduced with NIO to serve many number of concurrent connections
35   * efficiently.
36   *
37   * <h3>How threads work</h3>
38   * <p>
39   * There are two types of threads in a {@link NioServerSocketChannelFactory};
40   * one is boss thread and the other is worker thread.
41   *
42   * <h4>Boss threads</h4>
43   * <p>
44   * Each bound {@link ServerSocketChannel} has its own boss thread.
45   * For example, if you opened two server ports such as 80 and 443, you will
46   * have two boss threads.  A boss thread accepts incoming connections until
47   * the port is unbound.  Once a connection is accepted successfully, the boss
48   * thread passes the accepted {@link Channel} to one of the worker
49   * threads that the {@link NioServerSocketChannelFactory} manages.
50   *
51   * <h4>Worker threads</h4>
52   * <p>
53   * One {@link NioServerSocketChannelFactory} can have one or more worker
54   * threads.  A worker thread performs non-blocking read and write for one or
55   * more {@link Channel}s in a non-blocking mode.
56   *
57   * <h3>Life cycle of threads and graceful shutdown</h3>
58   * <p>
59   * All threads are acquired from the {@link Executor}s which were specified
60   * when a {@link NioServerSocketChannelFactory} was created.  Boss threads are
61   * acquired from the {@code bossExecutor}, and worker threads are acquired from
62   * the {@code workerExecutor}.  Therefore, you should make sure the specified
63   * {@link Executor}s are able to lend the sufficient number of threads.
64   * It is the best bet to specify {@linkplain Executors#newCachedThreadPool() a cached thread pool}.
65   * <p>
66   * Both boss and worker threads are acquired lazily, and then released when
67   * there's nothing left to process.  All the related resources such as
68   * {@link Selector} are also released when the boss and worker threads are
69   * released.  Therefore, to shut down a service gracefully, you should do the
70   * following:
71   *
72   * <ol>
73   * <li>unbind all channels created by the factory,
74   * <li>close all child channels accepted by the unbound channels, and
75   *     (these two steps so far is usually done using {@link ChannelGroup#close()})</li>
76   * <li>call {@link #releaseExternalResources()}.</li>
77   * </ol>
78   *
79   * Please make sure not to shut down the executor until all channels are
80   * closed.  Otherwise, you will end up with a {@link RejectedExecutionException}
81   * and the related resources might not be released properly.
82   *
83   * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
84   * @author <a href="http://gleamynode.net/">Trustin Lee</a>
85   *
86   * @version $Rev: 2200 $, $Date: 2010-02-23 14:42:39 +0900 (Tue, 23 Feb 2010) $
87   *
88   * @apiviz.landmark
89   */
90  public class NioServerSocketChannelFactory implements ServerSocketChannelFactory {
91  
92      final Executor bossExecutor;
93      private final Executor workerExecutor;
94      private final ChannelSink sink;
95  
96      /**
97       * Creates a new instance.  Calling this constructor is same with calling
98       * {@link #NioServerSocketChannelFactory(Executor, Executor, int)} with 2 *
99       * the number of available processors in the machine.  The number of
100      * available processors is obtained by {@link Runtime#availableProcessors()}.
101      *
102      * @param bossExecutor
103      *        the {@link Executor} which will execute the boss threads
104      * @param workerExecutor
105      *        the {@link Executor} which will execute the I/O worker threads
106      */
107     public NioServerSocketChannelFactory(
108             Executor bossExecutor, Executor workerExecutor) {
109         this(bossExecutor, workerExecutor, SelectorUtil.DEFAULT_IO_THREADS);
110     }
111 
112     /**
113      * Creates a new instance.
114      *
115      * @param bossExecutor
116      *        the {@link Executor} which will execute the boss threads
117      * @param workerExecutor
118      *        the {@link Executor} which will execute the I/O worker threads
119      * @param workerCount
120      *        the maximum number of I/O worker threads
121      */
122     public NioServerSocketChannelFactory(
123             Executor bossExecutor, Executor workerExecutor,
124             int workerCount) {
125         if (bossExecutor == null) {
126             throw new NullPointerException("bossExecutor");
127         }
128         if (workerExecutor == null) {
129             throw new NullPointerException("workerExecutor");
130         }
131         if (workerCount <= 0) {
132             throw new IllegalArgumentException(
133                     "workerCount (" + workerCount + ") " +
134                     "must be a positive integer.");
135         }
136         this.bossExecutor = bossExecutor;
137         this.workerExecutor = workerExecutor;
138         sink = new NioServerSocketPipelineSink(workerExecutor, workerCount);
139     }
140 
141     public ServerSocketChannel newChannel(ChannelPipeline pipeline) {
142         return new NioServerSocketChannel(this, pipeline, sink);
143     }
144 
145     public void releaseExternalResources() {
146         ExecutorUtil.terminate(bossExecutor, workerExecutor);
147     }
148 }