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 }