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   /*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project licenses this file to you under the Apache License,
    * version 2.0 (the "License"); you may not use this file except in compliance
    * with the License. You may obtain a copy of the License at:
    *
    *   https://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
   * License for the specific language governing permissions and limitations
   * under the License.
   */
  package io.netty.bootstrap;
  
  import io.netty.channel.Channel;
  import io.netty.channel.ChannelConfig;
  import io.netty.channel.ChannelFuture;
  import io.netty.channel.ChannelFutureListener;
  import io.netty.channel.ChannelHandler;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.ChannelInboundHandlerAdapter;
  import io.netty.channel.ChannelInitializer;
  import io.netty.channel.ChannelOption;
  import io.netty.channel.ChannelPipeline;
  import io.netty.channel.EventLoopGroup;
  import io.netty.channel.ServerChannel;
  import io.netty.util.AttributeKey;
  import io.netty.util.internal.ObjectUtil;
  import io.netty.util.internal.logging.InternalLogger;
  import io.netty.util.internal.logging.InternalLoggerFactory;
  
  import java.util.Collection;
  import java.util.LinkedHashMap;
  import java.util.Map;
  import java.util.Map.Entry;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.TimeUnit;
  
  /**
   * {@link Bootstrap} sub-class which allows easy bootstrap of {@link ServerChannel}
   *
   */
  public class ServerBootstrap extends AbstractBootstrap<ServerBootstrap, ServerChannel> {
  
      private static final InternalLogger logger = InternalLoggerFactory.getInstance(ServerBootstrap.class);
  
      // The order in which child ChannelOptions are applied is important they may depend on each other for validation
      // purposes.
      private final Map<ChannelOption<?>, Object> childOptions = new LinkedHashMap<ChannelOption<?>, Object>();
      private final Map<AttributeKey<?>, Object> childAttrs = new ConcurrentHashMap<AttributeKey<?>, Object>();
      private final ServerBootstrapConfig config = new ServerBootstrapConfig(this);
      private volatile EventLoopGroup childGroup;
      private volatile ChannelHandler childHandler;
  
      public ServerBootstrap() { }
  
      private ServerBootstrap(ServerBootstrap bootstrap) {
          super(bootstrap);
          childGroup = bootstrap.childGroup;
          childHandler = bootstrap.childHandler;
          synchronized (bootstrap.childOptions) {
              childOptions.putAll(bootstrap.childOptions);
          }
          childAttrs.putAll(bootstrap.childAttrs);
      }
  
      /**
       * Specify the {@link EventLoopGroup} which is used for the parent (acceptor) and the child (client).
       */
      @Override
      public ServerBootstrap group(EventLoopGroup group) {
          return group(group, group);
      }
  
      /**
       * Set the {@link EventLoopGroup} for the parent (acceptor) and the child (client). These
       * {@link EventLoopGroup}'s are used to handle all the events and IO for {@link ServerChannel} and
       * {@link Channel}'s.
       */
      public ServerBootstrap group(EventLoopGroup parentGroup, EventLoopGroup childGroup) {
          super.group(parentGroup);
          if (this.childGroup != null) {
              throw new IllegalStateException("childGroup set already");
          }
          this.childGroup = ObjectUtil.checkNotNull(childGroup, "childGroup");
          return this;
      }
  
      /**
       * Allow to specify a {@link ChannelOption} which is used for the {@link Channel} instances once they get created
       * (after the acceptor accepted the {@link Channel}). Use a value of {@code null} to remove a previous set
       * {@link ChannelOption}.
       */
      public <T> ServerBootstrap childOption(ChannelOption<T> childOption, T value) {
          ObjectUtil.checkNotNull(childOption, "childOption");
          synchronized (childOptions) {
             if (value == null) {
                 childOptions.remove(childOption);
             } else {
                 childOptions.put(childOption, value);
             }
         }
         return this;
     }
 
     /**
      * Set the specific {@link AttributeKey} with the given value on every child {@link Channel}. If the value is
      * {@code null} the {@link AttributeKey} is removed
      */
     public <T> ServerBootstrap childAttr(AttributeKey<T> childKey, T value) {
         ObjectUtil.checkNotNull(childKey, "childKey");
         if (value == null) {
             childAttrs.remove(childKey);
         } else {
             childAttrs.put(childKey, value);
         }
         return this;
     }
 
     /**
      * Set the {@link ChannelHandler} which is used to serve the request for the {@link Channel}'s.
      */
     public ServerBootstrap childHandler(ChannelHandler childHandler) {
         this.childHandler = ObjectUtil.checkNotNull(childHandler, "childHandler");
         return this;
     }
 
     @Override
     void init(Channel channel) {
         setChannelOptions(channel, newOptionsArray(), logger);
         setAttributes(channel, newAttributesArray());
 
         ChannelPipeline p = channel.pipeline();
 
         final EventLoopGroup currentChildGroup = childGroup;
         final ChannelHandler currentChildHandler = childHandler;
         final Entry<ChannelOption<?>, Object>[] currentChildOptions = newOptionsArray(childOptions);
         final Entry<AttributeKey<?>, Object>[] currentChildAttrs = newAttributesArray(childAttrs);
         final Collection<ChannelInitializerExtension> extensions = getInitializerExtensions();
 
         p.addLast(new ChannelInitializer<Channel>() {
             @Override
             public void initChannel(final Channel ch) {
                 final ChannelPipeline pipeline = ch.pipeline();
                 ChannelHandler handler = config.handler();
                 if (handler != null) {
                     pipeline.addLast(handler);
                 }
 
                 ch.eventLoop().execute(new Runnable() {
                     @Override
                     public void run() {
                         pipeline.addLast(new ServerBootstrapAcceptor(
                                 ch, currentChildGroup, currentChildHandler, currentChildOptions, currentChildAttrs,
                                 extensions));
                     }
                 });
             }
         });
         if (!extensions.isEmpty() && channel instanceof ServerChannel) {
             ServerChannel serverChannel = (ServerChannel) channel;
             for (ChannelInitializerExtension extension : extensions) {
                 try {
                     extension.postInitializeServerListenerChannel(serverChannel);
                 } catch (Exception e) {
                     logger.warn("Exception thrown from postInitializeServerListenerChannel", e);
                 }
             }
         }
     }
 
     @Override
     public ServerBootstrap validate() {
         super.validate();
         if (childHandler == null) {
             throw new IllegalStateException("childHandler not set");
         }
         if (childGroup == null) {
             logger.warn("childGroup is not set. Using parentGroup instead.");
             childGroup = config.group();
         }
         return this;
     }
 
     private static class ServerBootstrapAcceptor extends ChannelInboundHandlerAdapter {
 
         private final EventLoopGroup childGroup;
         private final ChannelHandler childHandler;
         private final Entry<ChannelOption<?>, Object>[] childOptions;
         private final Entry<AttributeKey<?>, Object>[] childAttrs;
         private final Runnable enableAutoReadTask;
         private final Collection<ChannelInitializerExtension> extensions;
 
         ServerBootstrapAcceptor(
                 final Channel channel, EventLoopGroup childGroup, ChannelHandler childHandler,
                 Entry<ChannelOption<?>, Object>[] childOptions, Entry<AttributeKey<?>, Object>[] childAttrs,
                 Collection<ChannelInitializerExtension> extensions) {
             this.childGroup = childGroup;
             this.childHandler = childHandler;
             this.childOptions = childOptions;
             this.childAttrs = childAttrs;
             this.extensions = extensions;
 
             // Task which is scheduled to re-enable auto-read.
             // It's important to create this Runnable before we try to submit it as otherwise the URLClassLoader may
             // not be able to load the class because of the file limit it already reached.
             //
             // See https://github.com/netty/netty/issues/1328
             enableAutoReadTask = new Runnable() {
                 @Override
                 public void run() {
                     channel.config().setAutoRead(true);
                 }
             };
         }
 
         @Override
         @SuppressWarnings("unchecked")
         public void channelRead(ChannelHandlerContext ctx, Object msg) {
             final Channel child = (Channel) msg;
 
             child.pipeline().addLast(childHandler);
 
             setChannelOptions(child, childOptions, logger);
             setAttributes(child, childAttrs);
 
             if (!extensions.isEmpty()) {
                 for (ChannelInitializerExtension extension : extensions) {
                     try {
                         extension.postInitializeServerChildChannel(child);
                     } catch (Exception e) {
                         logger.warn("Exception thrown from postInitializeServerChildChannel", e);
                     }
                 }
             }
 
             try {
                 childGroup.register(child).addListener(new ChannelFutureListener() {
                     @Override
                     public void operationComplete(ChannelFuture future) throws Exception {
                         if (!future.isSuccess()) {
                             forceClose(child, future.cause());
                         }
                     }
                 });
             } catch (Throwable t) {
                 forceClose(child, t);
             }
         }
 
         private static void forceClose(Channel child, Throwable t) {
             child.unsafe().closeForcibly();
             logger.warn("Failed to register an accepted channel: {}", child, t);
         }
 
         @Override
         public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
             final ChannelConfig config = ctx.channel().config();
             if (config.isAutoRead()) {
                 // stop accept new connections for 1 second to allow the channel to recover
                 // See https://github.com/netty/netty/issues/1328
                 config.setAutoRead(false);
                 ctx.channel().eventLoop().schedule(enableAutoReadTask, 1, TimeUnit.SECONDS);
             }
             // still let the exceptionCaught event flow through the pipeline to give the user
             // a chance to do something with it
             ctx.fireExceptionCaught(cause);
         }
     }
 
     @Override
     @SuppressWarnings("CloneDoesntCallSuperClone")
     public ServerBootstrap clone() {
         return new ServerBootstrap(this);
     }
 
     /**
      * Return the configured {@link EventLoopGroup} which will be used for the child channels or {@code null}
      * if non is configured yet.
      *
      * @deprecated Use {@link #config()} instead.
      */
     @Deprecated
     public EventLoopGroup childGroup() {
         return childGroup;
     }
 
     final ChannelHandler childHandler() {
         return childHandler;
     }
 
     final Map<ChannelOption<?>, Object> childOptions() {
         synchronized (childOptions) {
             return copiedMap(childOptions);
         }
     }
 
     final Map<AttributeKey<?>, Object> childAttrs() {
         return copiedMap(childAttrs);
     }
 
     @Override
     public final ServerBootstrapConfig config() {
         return config;
     }
 }