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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    *   https://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 io.netty.bootstrap;
17  
18  import io.netty.channel.Channel;
19  import io.netty.channel.ChannelConfig;
20  import io.netty.channel.ChannelFuture;
21  import io.netty.channel.ChannelFutureListener;
22  import io.netty.channel.ChannelHandler;
23  import io.netty.channel.ChannelHandlerContext;
24  import io.netty.channel.ChannelInboundHandlerAdapter;
25  import io.netty.channel.ChannelInitializer;
26  import io.netty.channel.ChannelOption;
27  import io.netty.channel.ChannelPipeline;
28  import io.netty.channel.EventLoopGroup;
29  import io.netty.channel.ServerChannel;
30  import io.netty.util.AttributeKey;
31  import io.netty.util.internal.ObjectUtil;
32  import io.netty.util.internal.logging.InternalLogger;
33  import io.netty.util.internal.logging.InternalLoggerFactory;
34  
35  import java.util.Collection;
36  import java.util.LinkedHashMap;
37  import java.util.Map;
38  import java.util.Map.Entry;
39  import java.util.concurrent.ConcurrentHashMap;
40  import java.util.concurrent.TimeUnit;
41  
42  /**
43   * {@link Bootstrap} sub-class which allows easy bootstrap of {@link ServerChannel}
44   *
45   */
46  public class ServerBootstrap extends AbstractBootstrap<ServerBootstrap, ServerChannel> {
47  
48      private static final InternalLogger logger = InternalLoggerFactory.getInstance(ServerBootstrap.class);
49  
50      // The order in which child ChannelOptions are applied is important they may depend on each other for validation
51      // purposes.
52      private final Map<ChannelOption<?>, Object> childOptions = new LinkedHashMap<ChannelOption<?>, Object>();
53      private final Map<AttributeKey<?>, Object> childAttrs = new ConcurrentHashMap<AttributeKey<?>, Object>();
54      private final ServerBootstrapConfig config = new ServerBootstrapConfig(this);
55      private volatile EventLoopGroup childGroup;
56      private volatile ChannelHandler childHandler;
57  
58      public ServerBootstrap() { }
59  
60      private ServerBootstrap(ServerBootstrap bootstrap) {
61          super(bootstrap);
62          childGroup = bootstrap.childGroup;
63          childHandler = bootstrap.childHandler;
64          synchronized (bootstrap.childOptions) {
65              childOptions.putAll(bootstrap.childOptions);
66          }
67          childAttrs.putAll(bootstrap.childAttrs);
68      }
69  
70      /**
71       * Specify the {@link EventLoopGroup} which is used for the parent (acceptor) and the child (client).
72       */
73      @Override
74      public ServerBootstrap group(EventLoopGroup group) {
75          return group(group, group);
76      }
77  
78      /**
79       * Set the {@link EventLoopGroup} for the parent (acceptor) and the child (client). These
80       * {@link EventLoopGroup}'s are used to handle all the events and IO for {@link ServerChannel} and
81       * {@link Channel}'s.
82       * <p>
83       * <strong>Important:</strong> Usually this is only useful for advanced use-cases and usually
84       * {@link #group(EventLoopGroup)} is the preferred way to configure the group.
85       */
86      public ServerBootstrap group(EventLoopGroup parentGroup, EventLoopGroup childGroup) {
87          super.group(parentGroup);
88          if (this.childGroup != null) {
89              throw new IllegalStateException("childGroup set already");
90          }
91          this.childGroup = ObjectUtil.checkNotNull(childGroup, "childGroup");
92          return this;
93      }
94  
95      /**
96       * Allow to specify a {@link ChannelOption} which is used for the {@link Channel} instances once they get created
97       * (after the acceptor accepted the {@link Channel}). Use a value of {@code null} to remove a previous set
98       * {@link ChannelOption}.
99       */
100     public <T> ServerBootstrap childOption(ChannelOption<T> childOption, T value) {
101         ObjectUtil.checkNotNull(childOption, "childOption");
102         synchronized (childOptions) {
103             if (value == null) {
104                 childOptions.remove(childOption);
105             } else {
106                 childOptions.put(childOption, value);
107             }
108         }
109         return this;
110     }
111 
112     /**
113      * Set the specific {@link AttributeKey} with the given value on every child {@link Channel}. If the value is
114      * {@code null} the {@link AttributeKey} is removed
115      */
116     public <T> ServerBootstrap childAttr(AttributeKey<T> childKey, T value) {
117         ObjectUtil.checkNotNull(childKey, "childKey");
118         if (value == null) {
119             childAttrs.remove(childKey);
120         } else {
121             childAttrs.put(childKey, value);
122         }
123         return this;
124     }
125 
126     /**
127      * Set the {@link ChannelHandler} which is used to serve the request for the {@link Channel}'s.
128      */
129     public ServerBootstrap childHandler(ChannelHandler childHandler) {
130         this.childHandler = ObjectUtil.checkNotNull(childHandler, "childHandler");
131         return this;
132     }
133 
134     @Override
135     void init(Channel channel) throws Throwable {
136         setChannelOptions(channel, newOptionsArray(), logger);
137         setAttributes(channel, newAttributesArray());
138 
139         ChannelPipeline p = channel.pipeline();
140 
141         final EventLoopGroup currentChildGroup = childGroup;
142         final ChannelHandler currentChildHandler = childHandler;
143         final Entry<ChannelOption<?>, Object>[] currentChildOptions = newOptionsArray(childOptions);
144         final Entry<AttributeKey<?>, Object>[] currentChildAttrs = newAttributesArray(childAttrs);
145         final Collection<ChannelInitializerExtension> extensions = getInitializerExtensions();
146 
147         p.addLast(new ChannelInitializer<Channel>() {
148             @Override
149             public void initChannel(final Channel ch) {
150                 final ChannelPipeline pipeline = ch.pipeline();
151                 ChannelHandler handler = config.handler();
152                 if (handler != null) {
153                     pipeline.addLast(handler);
154                 }
155 
156                 ch.eventLoop().execute(new Runnable() {
157                     @Override
158                     public void run() {
159                         pipeline.addLast(new ServerBootstrapAcceptor(
160                                 ch, currentChildGroup, currentChildHandler, currentChildOptions, currentChildAttrs,
161                                 extensions));
162                     }
163                 });
164             }
165         });
166         if (!extensions.isEmpty() && channel instanceof ServerChannel) {
167             ServerChannel serverChannel = (ServerChannel) channel;
168             for (ChannelInitializerExtension extension : extensions) {
169                 try {
170                     extension.postInitializeServerListenerChannel(serverChannel);
171                 } catch (Exception e) {
172                     logger.warn("Exception thrown from postInitializeServerListenerChannel", e);
173                 }
174             }
175         }
176     }
177 
178     @Override
179     public ServerBootstrap validate() {
180         super.validate();
181         if (childHandler == null) {
182             throw new IllegalStateException("childHandler not set");
183         }
184         if (childGroup == null) {
185             logger.warn("childGroup is not set. Using parentGroup instead.");
186             childGroup = config.group();
187         }
188         return this;
189     }
190 
191     private static class ServerBootstrapAcceptor extends ChannelInboundHandlerAdapter {
192 
193         private final EventLoopGroup childGroup;
194         private final ChannelHandler childHandler;
195         private final Entry<ChannelOption<?>, Object>[] childOptions;
196         private final Entry<AttributeKey<?>, Object>[] childAttrs;
197         private final Runnable enableAutoReadTask;
198         private final Collection<ChannelInitializerExtension> extensions;
199 
200         ServerBootstrapAcceptor(
201                 final Channel channel, EventLoopGroup childGroup, ChannelHandler childHandler,
202                 Entry<ChannelOption<?>, Object>[] childOptions, Entry<AttributeKey<?>, Object>[] childAttrs,
203                 Collection<ChannelInitializerExtension> extensions) {
204             this.childGroup = childGroup;
205             this.childHandler = childHandler;
206             this.childOptions = childOptions;
207             this.childAttrs = childAttrs;
208             this.extensions = extensions;
209 
210             // Task which is scheduled to re-enable auto-read.
211             // It's important to create this Runnable before we try to submit it as otherwise the URLClassLoader may
212             // not be able to load the class because of the file limit it already reached.
213             //
214             // See https://github.com/netty/netty/issues/1328
215             enableAutoReadTask = new Runnable() {
216                 @Override
217                 public void run() {
218                     channel.config().setAutoRead(true);
219                 }
220             };
221         }
222 
223         @Override
224         @SuppressWarnings("unchecked")
225         public void channelRead(ChannelHandlerContext ctx, Object msg) {
226             final Channel child = (Channel) msg;
227 
228             child.pipeline().addLast(childHandler);
229 
230             try {
231                 setChannelOptions(child, childOptions, logger);
232             } catch (Throwable cause) {
233                 forceClose(child, cause);
234                 return;
235             }
236             setAttributes(child, childAttrs);
237 
238             if (!extensions.isEmpty()) {
239                 for (ChannelInitializerExtension extension : extensions) {
240                     try {
241                         extension.postInitializeServerChildChannel(child);
242                     } catch (Exception e) {
243                         logger.warn("Exception thrown from postInitializeServerChildChannel", e);
244                     }
245                 }
246             }
247 
248             try {
249                 childGroup.register(child).addListener(new ChannelFutureListener() {
250                     @Override
251                     public void operationComplete(ChannelFuture future) throws Exception {
252                         if (!future.isSuccess()) {
253                             forceClose(child, future.cause());
254                         }
255                     }
256                 });
257             } catch (Throwable t) {
258                 forceClose(child, t);
259             }
260         }
261 
262         private static void forceClose(Channel child, Throwable t) {
263             child.unsafe().closeForcibly();
264             logger.warn("Failed to register an accepted channel: {}", child, t);
265         }
266 
267         @Override
268         public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
269             final ChannelConfig config = ctx.channel().config();
270             if (config.isAutoRead()) {
271                 // stop accept new connections for 1 second to allow the channel to recover
272                 // See https://github.com/netty/netty/issues/1328
273                 config.setAutoRead(false);
274                 ctx.channel().eventLoop().schedule(enableAutoReadTask, 1, TimeUnit.SECONDS);
275             }
276             // still let the exceptionCaught event flow through the pipeline to give the user
277             // a chance to do something with it
278             ctx.fireExceptionCaught(cause);
279         }
280     }
281 
282     @Override
283     @SuppressWarnings("CloneDoesntCallSuperClone")
284     public ServerBootstrap clone() {
285         return new ServerBootstrap(this);
286     }
287 
288     /**
289      * Return the configured {@link EventLoopGroup} which will be used for the child channels or {@code null}
290      * if non is configured yet.
291      *
292      * @deprecated Use {@link #config()} instead.
293      */
294     @Deprecated
295     public EventLoopGroup childGroup() {
296         return childGroup;
297     }
298 
299     final ChannelHandler childHandler() {
300         return childHandler;
301     }
302 
303     final Map<ChannelOption<?>, Object> childOptions() {
304         synchronized (childOptions) {
305             return copiedMap(childOptions);
306         }
307     }
308 
309     final Map<AttributeKey<?>, Object> childAttrs() {
310         return copiedMap(childAttrs);
311     }
312 
313     @Override
314     public final ServerBootstrapConfig config() {
315         return config;
316     }
317 }