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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.handler.timeout;
  
  import io.netty.bootstrap.ServerBootstrap;
  import io.netty.channel.Channel;
  import io.netty.channel.ChannelDuplexHandler;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.ChannelInitializer;
  
  import java.util.concurrent.TimeUnit;
  
  /**
   * Raises a {@link ReadTimeoutException} when no data was read within a certain
   * period of time.
   *
   * <pre>
   * // The connection is closed when there is no inbound traffic
   * // for 30 seconds.
   *
   * public class MyChannelInitializer extends {@link ChannelInitializer}&lt;{@link Channel}&gt; {
   *     public void initChannel({@link Channel} channel) {
   *         channel.pipeline().addLast("readTimeoutHandler", new {@link ReadTimeoutHandler}(30));
   *         channel.pipeline().addLast("myHandler", new MyHandler());
   *     }
   * }
   *
   * // Handler should handle the {@link ReadTimeoutException}.
   * public class MyHandler extends {@link ChannelDuplexHandler} {
   *     {@code @Override}
   *     public void exceptionCaught({@link ChannelHandlerContext} ctx, {@link Throwable} cause)
   *             throws {@link Exception} {
   *         if (cause instanceof {@link ReadTimeoutException}) {
   *             // do something
   *         } else {
   *             super.exceptionCaught(ctx, cause);
   *         }
   *     }
   * }
   *
   * {@link ServerBootstrap} bootstrap = ...;
   * ...
   * bootstrap.childHandler(new MyChannelInitializer());
   * ...
   * </pre>
   * @see WriteTimeoutHandler
   * @see IdleStateHandler
   */
  public class ReadTimeoutHandler extends IdleStateHandler {
      private boolean closed;
  
      /**
       * Creates a new instance.
       *
       * @param timeoutSeconds
       *        read timeout in seconds
       */
      public ReadTimeoutHandler(int timeoutSeconds) {
          this(timeoutSeconds, TimeUnit.SECONDS);
      }
  
      /**
       * Creates a new instance.
       *
       * @param timeout
       *        read timeout
       * @param unit
       *        the {@link TimeUnit} of {@code timeout}
       */
      public ReadTimeoutHandler(long timeout, TimeUnit unit) {
          super(timeout, 0, 0, unit);
      }
  
      @Override
      protected final void channelIdle(ChannelHandlerContext ctx, IdleStateEvent evt) throws Exception {
          assert evt.state() == IdleState.READER_IDLE;
          readTimedOut(ctx);
      }
  
      /**
       * Is called when a read timeout was detected.
       */
      protected void readTimedOut(ChannelHandlerContext ctx) throws Exception {
          if (!closed) {
              ctx.fireExceptionCaught(ReadTimeoutException.INSTANCE);
              ctx.close();
             closed = true;
         }
     }
 }