View Javadoc
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.group;
17  
18  import java.net.SocketAddress;
19  import java.util.Set;
20  
21  import org.jboss.netty.bootstrap.ServerBootstrap;
22  import org.jboss.netty.buffer.ChannelBuffer;
23  import org.jboss.netty.buffer.ChannelBuffers;
24  import org.jboss.netty.channel.Channel;
25  import org.jboss.netty.channel.ChannelHandlerContext;
26  import org.jboss.netty.channel.ChannelStateEvent;
27  import org.jboss.netty.channel.ServerChannel;
28  import org.jboss.netty.channel.SimpleChannelUpstreamHandler;
29  import org.jboss.netty.util.CharsetUtil;
30  
31  /**
32   * A thread-safe {@link Set} that contains open {@link Channel}s and provides
33   * various bulk operations on them.  Using {@link ChannelGroup}, you can
34   * categorize {@link Channel}s into a meaningful group (e.g. on a per-service
35   * or per-state basis.)  A closed {@link Channel} is automatically removed from
36   * the collection, so that you don't need to worry about the life cycle of the
37   * added {@link Channel}.  A {@link Channel} can belong to more than one
38   * {@link ChannelGroup}.
39   *
40   * <h3>Broadcast a message to multiple {@link Channel}s</h3>
41   * <p>
42   * If you need to broadcast a message to more than one {@link Channel}, you can
43   * add the {@link Channel}s associated with the recipients and call {@link ChannelGroup#write(Object)}:
44   * <pre>
45   * <strong>{@link ChannelGroup} recipients = new {@link DefaultChannelGroup}();</strong>
46   * recipients.add(channelA);
47   * recipients.add(channelB);
48   * ..
49   * <strong>recipients.write({@link ChannelBuffers}.copiedBuffer(
50   *         "Service will shut down for maintenance in 5 minutes.",
51   *         {@link CharsetUtil}.UTF_8));</strong>
52   * </pre>
53   *
54   * <h3>Simplify shutdown process with {@link ChannelGroup}</h3>
55   * <p>
56   * If both {@link ServerChannel}s and non-{@link ServerChannel}s exist in the
57   * same {@link ChannelGroup}, any requested I/O operations on the group are
58   * performed for the {@link ServerChannel}s first and then for the others.
59   * <p>
60   * This rule is very useful when you shut down a server in one shot:
61   *
62   * <pre>
63   * <strong>{@link ChannelGroup} allChannels = new {@link DefaultChannelGroup}();</strong>
64   *
65   * public static void main(String[] args) throws Exception {
66   *     {@link ServerBootstrap} b = new {@link ServerBootstrap}(..);
67   *     ...
68   *
69   *     // Start the server
70   *     b.getPipeline().addLast("handler", new MyHandler());
71   *     {@link Channel} serverChannel = b.bind(..);
72   *     <strong>allChannels.add(serverChannel);</strong>
73   *
74   *     ... Wait until the shutdown signal reception ...
75   *
76   *     // Close the serverChannel and then all accepted connections.
77   *     <strong>allChannels.close().awaitUninterruptibly();</strong>
78   *     b.releaseExternalResources();
79   * }
80   *
81   * public class MyHandler extends {@link SimpleChannelUpstreamHandler} {
82   *     {@code @Override}
83   *     public void channelOpen({@link ChannelHandlerContext} ctx, {@link ChannelStateEvent} e) {
84   *         // Add all open channels to the global group so that they are
85   *         // closed on shutdown.
86   *         <strong>allChannels.add(e.getChannel());</strong>
87   *     }
88   * }
89   * </pre>
90   * @apiviz.landmark
91   * @apiviz.has org.jboss.netty.channel.group.ChannelGroupFuture oneway - - returns
92   */
93  public interface ChannelGroup extends Set<Channel>, Comparable<ChannelGroup> {
94  
95      /**
96       * Returns the name of this group.  A group name is purely for helping
97       * you to distinguish one group from others.
98       */
99      String getName();
100 
101     /**
102      * Returns the {@link Channel} whose ID matches the specified integer.
103      *
104      * @return the matching {@link Channel} if found. {@code null} otherwise.
105      */
106     Channel find(Integer id);
107 
108     /**
109      * Calls {@link Channel#setInterestOps(int)} for all {@link Channel}s in
110      * this group with the specified {@code interestOps}. Please note that
111      * this operation is asynchronous as {@link Channel#setInterestOps(int)} is.
112      *
113      * @return the {@link ChannelGroupFuture} instance that notifies when
114      *         the operation is done for all channels
115      */
116     ChannelGroupFuture setInterestOps(int interestOps);
117 
118     /**
119      * Calls {@link Channel#setReadable(boolean)} for all {@link Channel}s in
120      * this group with the specified boolean flag. Please note that this
121      * operation is asynchronous as {@link Channel#setReadable(boolean)} is.
122      *
123      * @return the {@link ChannelGroupFuture} instance that notifies when
124      *         the operation is done for all channels
125      */
126     ChannelGroupFuture setReadable(boolean readable);
127 
128     /**
129      * Writes the specified {@code message} to all {@link Channel}s in this
130      * group. If the specified {@code message} is an instance of
131      * {@link ChannelBuffer}, it is automatically
132      * {@linkplain ChannelBuffer#duplicate() duplicated} to avoid a race
133      * condition. Please note that this operation is asynchronous as
134      * {@link Channel#write(Object)} is.
135      *
136      * @return the {@link ChannelGroupFuture} instance that notifies when
137      *         the operation is done for all channels
138      */
139     ChannelGroupFuture write(Object message);
140 
141     /**
142      * Writes the specified {@code message} with the specified
143      * {@code remoteAddress} to all {@link Channel}s in this group.  If the
144      * specified {@code message} is an instance of {@link ChannelBuffer}, it is
145      * automatically {@linkplain ChannelBuffer#duplicate() duplicated} to avoid
146      * a race condition. Please note that this operation is asynchronous as
147      * {@link Channel#write(Object, SocketAddress)} is.
148      *
149      * @return the {@link ChannelGroupFuture} instance that notifies when
150      *         the operation is done for all channels
151      */
152     ChannelGroupFuture write(Object message, SocketAddress remoteAddress);
153 
154     /**
155      * Disconnects all {@link Channel}s in this group from their remote peers.
156      *
157      * @return the {@link ChannelGroupFuture} instance that notifies when
158      *         the operation is done for all channels
159      */
160     ChannelGroupFuture disconnect();
161 
162     /**
163      * Unbinds all {@link Channel}s in this group from their local address.
164      *
165      * @return the {@link ChannelGroupFuture} instance that notifies when
166      *         the operation is done for all channels
167      */
168     ChannelGroupFuture unbind();
169 
170     /**
171      * Closes all {@link Channel}s in this group.  If the {@link Channel} is
172      * connected to a remote peer or bound to a local address, it is
173      * automatically disconnected and unbound.
174      *
175      * @return the {@link ChannelGroupFuture} instance that notifies when
176      *         the operation is done for all channels
177      */
178     ChannelGroupFuture close();
179 }