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