content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * Licensed 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 com.alibaba.csp.sentinel.cluster.server.codec;
  
  import com.alibaba.csp.sentinel.cluster.codec.EntityDecoder;
  import com.alibaba.csp.sentinel.cluster.codec.request.RequestEntityDecoder;
  import com.alibaba.csp.sentinel.cluster.request.ClusterRequest;
  import com.alibaba.csp.sentinel.cluster.server.codec.registry.RequestDataDecodeRegistry;
  import com.alibaba.csp.sentinel.log.RecordLog;
  
  import io.netty.buffer.ByteBuf;
  
  /**
   * <p>Default entity decoder for any {@link ClusterRequest} entity.</p>
   *
   * <p>Decode format:</p>
   * <pre>
   * +--------+---------+---------+
   * | xid(4) | type(1) | data... |
   * +--------+---------+---------+
   * </pre>
   *
   * @author Eric Zhao
   * @since 1.4.0
   */
  public class DefaultRequestEntityDecoder implements RequestEntityDecoder<ByteBuf, ClusterRequest> {
  
      @Override
      public ClusterRequest decode(ByteBuf source) {
          if (source.readableBytes() >= 5) {
              int xid = source.readInt();
              int type = source.readByte();
  
              EntityDecoder<ByteBuf, ?> dataDecoder = RequestDataDecodeRegistry.getDecoder(type);
              if (dataDecoder == null) {
                  RecordLog.warn("Unknown type of request data decoder: {}", type);
                  return null;
              }
  
              Object data;
              if (source.readableBytes() == 0) {
                  data = null;
              } else {
                  data = dataDecoder.decode(source);
              }
  
              return new ClusterRequest<>(xid, type, data);
          }
          return null;
      }
  }
  