content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF 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
   *
   *    http://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 org.apache.spark.network.protocol;
  
  import java.util.List;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.channel.ChannelHandler;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.handler.codec.MessageToMessageDecoder;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Decoder used by the client side to encode server-to-client responses.
   * This encoder is stateless so it is safe to be shared by multiple threads.
   */
  @ChannelHandler.Sharable
  public final class MessageDecoder extends MessageToMessageDecoder<ByteBuf> {
  
    private static final Logger logger = LoggerFactory.getLogger(MessageDecoder.class);
  
    @Override
    public void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) {
      Message.Type msgType = Message.Type.decode(in);
      Message decoded = decode(msgType, in);
      assert decoded.type() == msgType;
      logger.trace("Received message {}: {}", msgType, decoded);
      out.add(decoded);
    }
  
    private Message decode(Message.Type msgType, ByteBuf in) {
      switch (msgType) {
        case ChunkFetchRequest:
          return ChunkFetchRequest.decode(in);
  
        case ChunkFetchSuccess:
          return ChunkFetchSuccess.decode(in);
  
        case ChunkFetchFailure:
          return ChunkFetchFailure.decode(in);
  
        case RpcRequest:
          return RpcRequest.decode(in);
  
        case RpcResponse:
          return RpcResponse.decode(in);
  
        case RpcFailure:
          return RpcFailure.decode(in);
  
        case OneWayMessage:
          return OneWayMessage.decode(in);
  
        case StreamRequest:
          return StreamRequest.decode(in);
  
        case StreamResponse:
          return StreamResponse.decode(in);
  
        case StreamFailure:
          return StreamFailure.decode(in);
  
        default:
          throw new IllegalArgumentException("Unexpected message type: " + msgType);
      }
    }
  }
  