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