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.group.ChannelGroup;
26 import org.jboss.netty.channel.socket.ClientSocketChannelFactory;
27 import org.jboss.netty.channel.socket.SocketChannel;
28 import org.jboss.netty.util.internal.ExecutorUtil;
29
30 /**
31 * A {@link ClientSocketChannelFactory} which creates a client-side NIO-based
32 * {@link SocketChannel}. It utilizes the non-blocking I/O mode which was
33 * introduced with NIO to serve many number of concurrent connections
34 * efficiently.
35 *
36 * <h3>How threads work</h3>
37 * <p>
38 * There are two types of threads in a {@link NioClientSocketChannelFactory};
39 * one is boss thread and the other is worker thread.
40 *
41 * <h4>Boss thread</h4>
42 * <p>
43 * One {@link NioClientSocketChannelFactory} has one boss thread. It makes
44 * a connection attempt on request. Once a connection attempt succeeds,
45 * the boss thread passes the connected {@link Channel} to one of the worker
46 * threads that the {@link NioClientSocketChannelFactory} manages.
47 *
48 * <h4>Worker threads</h4>
49 * <p>
50 * One {@link NioClientSocketChannelFactory} can have one or more worker
51 * threads. A worker thread performs non-blocking read and write for one or
52 * more {@link Channel}s in a non-blocking mode.
53 *
54 * <h3>Life cycle of threads and graceful shutdown</h3>
55 * <p>
56 * All threads are acquired from the {@link Executor}s which were specified
57 * when a {@link NioClientSocketChannelFactory} was created. A boss thread is
58 * acquired from the {@code bossExecutor}, and worker threads are acquired from
59 * the {@code workerExecutor}. Therefore, you should make sure the specified
60 * {@link Executor}s are able to lend the sufficient number of threads.
61 * It is the best bet to specify {@linkplain Executors#newCachedThreadPool() a cached thread pool}.
62 * <p>
63 * Both boss and worker threads are acquired lazily, and then released when
64 * there's nothing left to process. All the related resources such as
65 * {@link Selector} are also released when the boss and worker threads are
66 * released. Therefore, to shut down a service gracefully, you should do the
67 * following:
68 *
69 * <ol>
70 * <li>close all channels created by the factory usually using
71 * {@link ChannelGroup#close()}, and</li>
72 * <li>call {@link #releaseExternalResources()}.</li>
73 * </ol>
74 *
75 * Please make sure not to shut down the executor until all channels are
76 * closed. Otherwise, you will end up with a {@link RejectedExecutionException}
77 * and the related resources might not be released properly.
78 *
79 * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
80 * @author <a href="http://gleamynode.net/">Trustin Lee</a>
81 *
82 * @version $Rev: 2200 $, $Date: 2010-02-23 14:42:39 +0900 (Tue, 23 Feb 2010) $
83 *
84 * @apiviz.landmark
85 */
86 public class NioClientSocketChannelFactory implements ClientSocketChannelFactory {
87
88 private final Executor bossExecutor;
89 private final Executor workerExecutor;
90 private final NioClientSocketPipelineSink sink;
91
92 /**
93 * Creates a new instance. Calling this constructor is same with calling
94 * {@link #NioClientSocketChannelFactory(Executor, Executor, int)} with 2 *
95 * the number of available processors in the machine. The number of
96 * available processors is obtained by {@link Runtime#availableProcessors()}.
97 *
98 * @param bossExecutor
99 * the {@link Executor} which will execute the boss thread
100 * @param workerExecutor
101 * the {@link Executor} which will execute the I/O worker threads
102 */
103 public NioClientSocketChannelFactory(
104 Executor bossExecutor, Executor workerExecutor) {
105 this(bossExecutor, workerExecutor, SelectorUtil.DEFAULT_IO_THREADS);
106 }
107
108 /**
109 * Creates a new instance.
110 *
111 * @param bossExecutor
112 * the {@link Executor} which will execute the boss thread
113 * @param workerExecutor
114 * the {@link Executor} which will execute the I/O worker threads
115 * @param workerCount
116 * the maximum number of I/O worker threads
117 */
118 public NioClientSocketChannelFactory(
119 Executor bossExecutor, Executor workerExecutor,
120 int workerCount) {
121 if (bossExecutor == null) {
122 throw new NullPointerException("bossExecutor");
123 }
124 if (workerExecutor == null) {
125 throw new NullPointerException("workerExecutor");
126 }
127 if (workerCount <= 0) {
128 throw new IllegalArgumentException(
129 "workerCount (" + workerCount + ") " +
130 "must be a positive integer.");
131 }
132
133 this.bossExecutor = bossExecutor;
134 this.workerExecutor = workerExecutor;
135 sink = new NioClientSocketPipelineSink(bossExecutor, workerExecutor, workerCount);
136 }
137
138 public SocketChannel newChannel(ChannelPipeline pipeline) {
139 return new NioClientSocketChannel(this, pipeline, sink, sink.nextWorker());
140 }
141
142 public void releaseExternalResources() {
143 ExecutorUtil.terminate(bossExecutor, workerExecutor);
144 }
145 }