1 /*
2 * Copyright 2012 The Netty Project
3 *
4 * The Netty Project licenses this file to you under the Apache License,
5 * version 2.0 (the "License"); you may not use this file except in compliance
6 * with the 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.ExternalResourceReleasable;
30 import org.jboss.netty.util.internal.ExecutorUtil;
31
32 /**
33 * A {@link ServerSocketChannelFactory} which creates a server-side NIO-based
34 * {@link ServerSocketChannel}. It utilizes the non-blocking I/O mode which
35 * was introduced with NIO to serve many number of concurrent connections
36 * efficiently.
37 *
38 * <h3>How threads work</h3>
39 * <p>
40 * There are two types of threads in a {@link NioServerSocketChannelFactory};
41 * one is boss thread and the other is worker thread.
42 *
43 * <h4>Boss threads</h4>
44 * <p>
45 * Each bound {@link ServerSocketChannel} has its own boss thread.
46 * For example, if you opened two server ports such as 80 and 443, you will
47 * have two boss threads. A boss thread accepts incoming connections until
48 * the port is unbound. Once a connection is accepted successfully, the boss
49 * thread passes the accepted {@link Channel} to one of the worker
50 * threads that the {@link NioServerSocketChannelFactory} manages.
51 *
52 * <h4>Worker threads</h4>
53 * <p>
54 * One {@link NioServerSocketChannelFactory} can have one or more worker
55 * threads. A worker thread performs non-blocking read and write for one or
56 * more {@link Channel}s in a non-blocking mode.
57 *
58 * <h3>Life cycle of threads and graceful shutdown</h3>
59 * <p>
60 * All threads are acquired from the {@link Executor}s which were specified
61 * when a {@link NioServerSocketChannelFactory} was created. Boss threads are
62 * acquired from the {@code bossExecutor}, and worker threads are acquired from
63 * the {@code workerExecutor}. Therefore, you should make sure the specified
64 * {@link Executor}s are able to lend the sufficient number of threads.
65 * It is the best bet to specify {@linkplain Executors#newCachedThreadPool() a cached thread pool}.
66 * <p>
67 * Both boss and worker threads are acquired lazily, and then released when
68 * there's nothing left to process. All the related resources such as
69 * {@link Selector} are also released when the boss and worker threads are
70 * released. Therefore, to shut down a service gracefully, you should do the
71 * following:
72 *
73 * <ol>
74 * <li>unbind all channels created by the factory,
75 * <li>close all child channels accepted by the unbound channels, and
76 * (these two steps so far is usually done using {@link ChannelGroup#close()})</li>
77 * <li>call {@link #releaseExternalResources()}.</li>
78 * </ol>
79 *
80 * Please make sure not to shut down the executor until all channels are
81 * closed. Otherwise, you will end up with a {@link RejectedExecutionException}
82 * and the related resources might not be released properly.
83 *
84 * @apiviz.landmark
85 */
86 public class NioServerSocketChannelFactory implements ServerSocketChannelFactory {
87
88 final Executor bossExecutor;
89 private final WorkerPool<NioWorker> workerPool;
90 private final ChannelSink sink;
91
92 /**
93 * Create a new {@link NioServerSocketChannelFactory} using {@link Executors#newCachedThreadPool()}
94 * for the boss and worker.
95 *
96 * See {@link #NioServerSocketChannelFactory(Executor, Executor)}
97 */
98 public NioServerSocketChannelFactory() {
99 this(Executors.newCachedThreadPool(), Executors.newCachedThreadPool());
100 }
101
102 /**
103 * Creates a new instance. Calling this constructor is same with calling
104 * {@link #NioServerSocketChannelFactory(Executor, Executor, int)} with 2 *
105 * the number of available processors in the machine. The number of
106 * available processors is obtained by {@link Runtime#availableProcessors()}.
107 *
108 * @param bossExecutor
109 * the {@link Executor} which will execute the boss threads
110 * @param workerExecutor
111 * the {@link Executor} which will execute the I/O worker threads
112 */
113 public NioServerSocketChannelFactory(
114 Executor bossExecutor, Executor workerExecutor) {
115 this(bossExecutor, workerExecutor, SelectorUtil.DEFAULT_IO_THREADS);
116 }
117
118 /**
119 * Creates a new instance.
120 *
121 * @param bossExecutor
122 * the {@link Executor} which will execute the boss threads
123 * @param workerExecutor
124 * the {@link Executor} which will execute the I/O worker threads
125 * @param workerCount
126 * the maximum number of I/O worker threads
127 */
128 public NioServerSocketChannelFactory(
129 Executor bossExecutor, Executor workerExecutor,
130 int workerCount) {
131 this(bossExecutor, new NioWorkerPool(workerExecutor, workerCount));
132 }
133
134 /**
135 * Creates a new instance.
136 *
137 * @param bossExecutor
138 * the {@link Executor} which will execute the boss threads
139 * @param workerPool
140 * the {@link WorkerPool} which will be used to obtain the {@link NioWorker} that execute
141 * the I/O worker threads
142 */
143 public NioServerSocketChannelFactory(
144 Executor bossExecutor, WorkerPool<NioWorker> workerPool) {
145 if (bossExecutor == null) {
146 throw new NullPointerException("bossExecutor");
147 }
148 if (workerPool == null) {
149 throw new NullPointerException("workerPool");
150 }
151
152 this.bossExecutor = bossExecutor;
153 this.workerPool = workerPool;
154 sink = new NioServerSocketPipelineSink(workerPool);
155 }
156
157 public ServerSocketChannel newChannel(ChannelPipeline pipeline) {
158 return new NioServerSocketChannel(this, pipeline, sink);
159 }
160
161 public void releaseExternalResources() {
162 ExecutorUtil.terminate(bossExecutor);
163 if (workerPool instanceof ExternalResourceReleasable) {
164 ((ExternalResourceReleasable) workerPool).releaseExternalResources();
165 }
166 }
167 }