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.celeborn.common.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);
  
    public static final MessageDecoder INSTANCE = new MessageDecoder();
  
    private MessageDecoder() {}
  
    @Override
    public void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) {
      Message.Type msgType = Message.Type.decode(in);
      Message decoded = Message.decode(msgType, in);
      assert decoded.type() == msgType;
      logger.trace("Received message {}: {}", msgType, decoded);
      out.add(decoded);
    }
  }
  