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.oio;
17
18 import java.util.concurrent.Executor;
19 import java.util.concurrent.Executors;
20 import java.util.concurrent.RejectedExecutionException;
21
22 import org.jboss.netty.channel.Channel;
23 import org.jboss.netty.channel.ChannelPipeline;
24 import org.jboss.netty.channel.group.ChannelGroup;
25 import org.jboss.netty.channel.socket.ClientSocketChannelFactory;
26 import org.jboss.netty.channel.socket.SocketChannel;
27 import org.jboss.netty.util.ThreadNameDeterminer;
28 import org.jboss.netty.util.internal.ExecutorUtil;
29
30 /**
31 * A {@link ClientSocketChannelFactory} which creates a client-side blocking
32 * I/O based {@link SocketChannel}. It utilizes the good old blocking I/O API
33 * which is known to yield better throughput and latency when there are
34 * relatively small number of connections to serve.
35 *
36 * <h3>How threads work</h3>
37 * <p>
38 * There is only one type of threads in {@link OioClientSocketChannelFactory};
39 * worker threads.
40 *
41 * <h4>Worker threads</h4>
42 * <p>
43 * Each connected {@link Channel} has a dedicated worker thread, just like a
44 * traditional blocking I/O thread model.
45 *
46 * <h3>Life cycle of threads and graceful shutdown</h3>
47 * <p>
48 * Worker threads are acquired from the {@link Executor} which was specified
49 * when a {@link OioClientSocketChannelFactory} was created (i.e. {@code workerExecutor}.)
50 * Therefore, you should make sure the specified {@link Executor} is able to
51 * lend the sufficient number of threads.
52 * <p>
53 * Worker threads are acquired lazily, and then released when there's nothing
54 * left to process. All the related resources are also released when the
55 * worker threads are released. Therefore, to shut down a service gracefully,
56 * you should do the following:
57 *
58 * <ol>
59 * <li>close all channels created by the factory usually using
60 * {@link ChannelGroup#close()}, and</li>
61 * <li>call {@link #releaseExternalResources()}.</li>
62 * </ol>
63 *
64 * Please make sure not to shut down the executor until all channels are
65 * closed. Otherwise, you will end up with a {@link RejectedExecutionException}
66 * and the related resources might not be released properly.
67 *
68 * <h3>Limitation</h3>
69 * <p>
70 * A {@link SocketChannel} created by this factory does not support asynchronous
71 * operations. Any I/O requests such as {@code "connect"} and {@code "write"}
72 * will be performed in a blocking manner.
73 *
74 * @apiviz.landmark
75 */
76 public class OioClientSocketChannelFactory implements ClientSocketChannelFactory {
77
78 private final Executor workerExecutor;
79 final OioClientSocketPipelineSink sink;
80 private boolean shutdownExecutor;
81
82 /**
83 * Creates a new instance with a {@link Executors#newCachedThreadPool()} as worker executor.
84 *
85 * See {@link #OioClientSocketChannelFactory(Executor)}
86 */
87 public OioClientSocketChannelFactory() {
88 this(Executors.newCachedThreadPool());
89 shutdownExecutor = true;
90 }
91
92 /**
93 * Creates a new instance.
94 *
95 * @param workerExecutor
96 * the {@link Executor} which will execute the I/O worker threads
97 */
98 public OioClientSocketChannelFactory(Executor workerExecutor) {
99 this(workerExecutor, null);
100 }
101
102 /**
103 * Creates a new instance.
104 *
105 * @param workerExecutor
106 * the {@link Executor} which will execute the I/O worker threads
107 * @param determiner
108 * the {@link ThreadNameDeterminer} to set the thread names.
109 */
110 public OioClientSocketChannelFactory(Executor workerExecutor,
111 ThreadNameDeterminer determiner) {
112 if (workerExecutor == null) {
113 throw new NullPointerException("workerExecutor");
114 }
115 this.workerExecutor = workerExecutor;
116 sink = new OioClientSocketPipelineSink(workerExecutor, determiner);
117 }
118
119 public SocketChannel newChannel(ChannelPipeline pipeline) {
120 return new OioClientSocketChannel(this, pipeline, sink);
121 }
122
123 public void shutdown() {
124 if (shutdownExecutor) {
125 ExecutorUtil.shutdownNow(workerExecutor);
126 }
127 }
128
129 public void releaseExternalResources() {
130 ExecutorUtil.shutdownNow(workerExecutor);
131 }
132 }