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   /*
    * Copyright 2013 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.codec.memcache.binary;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.CombinedChannelDuplexHandler;
  import io.netty.handler.codec.PrematureChannelClosureException;
  import io.netty.handler.codec.memcache.LastMemcacheContent;
  import io.netty.util.internal.UnstableApi;
  
  import java.util.List;
  import java.util.concurrent.atomic.AtomicLong;
  
  /**
   * The client codec that combines the proper encoder and decoder.
   * <p/>
   * Use this codec if you want to implement a memcache client that speaks the binary protocol. It
   * combines both the {@link BinaryMemcacheResponseDecoder} and the {@link BinaryMemcacheRequestEncoder}.
   * <p/>
   * Optionally, it counts the number of outstanding responses and raises an exception if - on connection
   * close - the list is not 0 (this is turned off by default). You can also define a chunk size for the
   * content, which defaults to 8192. This chunk size is the maximum, so if smaller chunks arrive they
   * will be passed up the pipeline and not queued up to the chunk size.
   */
  @UnstableApi
  public final class BinaryMemcacheClientCodec extends
          CombinedChannelDuplexHandler<BinaryMemcacheResponseDecoder, BinaryMemcacheRequestEncoder> {
  
      private final boolean failOnMissingResponse;
      private final AtomicLong requestResponseCounter = new AtomicLong();
  
      /**
       * Create a new {@link BinaryMemcacheClientCodec} with the default settings applied.
       */
      public BinaryMemcacheClientCodec() {
          this(AbstractBinaryMemcacheDecoder.DEFAULT_MAX_CHUNK_SIZE);
      }
  
      /**
       * Create a new {@link BinaryMemcacheClientCodec} and set a custom chunk size.
       *
       * @param decodeChunkSize the maximum chunk size.
       */
      public BinaryMemcacheClientCodec(int decodeChunkSize) {
          this(decodeChunkSize, false);
      }
  
      /**
       * Create a new {@link BinaryMemcacheClientCodec} with custom settings.
       *
       * @param decodeChunkSize       the maximum chunk size.
       * @param failOnMissingResponse report if after close there are outstanding requests.
       */
      public BinaryMemcacheClientCodec(int decodeChunkSize, boolean failOnMissingResponse) {
          this.failOnMissingResponse = failOnMissingResponse;
          init(new Decoder(decodeChunkSize), new Encoder());
      }
  
      private final class Encoder extends BinaryMemcacheRequestEncoder {
  
          @Override
          protected void encode(ChannelHandlerContext ctx, Object msg, List<Object> out) throws Exception {
              super.encode(ctx, msg, out);
  
              if (failOnMissingResponse && msg instanceof LastMemcacheContent) {
                  requestResponseCounter.incrementAndGet();
              }
          }
      }
  
      private final class Decoder extends BinaryMemcacheResponseDecoder {
  
          Decoder(int chunkSize) {
              super(chunkSize);
          }
  
          @Override
          protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
              int oldSize = out.size();
              super.decode(ctx, in, out);
  
              if (failOnMissingResponse) {
                  final int size = out.size();
                  for (int i = oldSize; i < size; i ++) {
                      Object msg = out.get(i);
                     if (msg instanceof LastMemcacheContent) {
                         requestResponseCounter.decrementAndGet();
                     }
                 }
             }
         }
 
         @Override
         public void channelInactive(ChannelHandlerContext ctx) throws Exception {
             super.channelInactive(ctx);
 
             if (failOnMissingResponse) {
                 long missingResponses = requestResponseCounter.get();
                 if (missingResponses > 0) {
                     ctx.fireExceptionCaught(new PrematureChannelClosureException(
                         "channel gone inactive with " + missingResponses +
                             " missing response(s)"));
                 }
             }
         }
     }
 }