add break & default logic for NettyDecoder.decode (#2969)

* add break & default logic for NettyDecoder.decode

* fix the bad code smells
Co-authored-by: Ngabry <wu_shao_jie@qq.com>
Co-authored-by: Ngabry.wu <8545796+gabrywu@users.noreply.github.com>
Co-authored-by: Ndailidong <dailidong66@gmail.com>

dolphinscheduler-remote/src/main/java/org/apache/dolphinscheduler/remote/codec/NettyDecoder.java

@@ -24,6 +24,8 @@ import io.netty.handler.codec.ReplayingDecoder;
 import org.apache.dolphinscheduler.remote.command.Command;
 import org.apache.dolphinscheduler.remote.command.CommandHeader;
 import org.apache.dolphinscheduler.remote.command.CommandType;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.util.List;
 
@@ -31,6 +33,7 @@ import java.util.List;
  *  netty decoder
  */
 public class NettyDecoder extends ReplayingDecoder<NettyDecoder.State> {
+    private static final Logger logger = LoggerFactory.getLogger(NettyDecoder.class);
 
     public NettyDecoder(){
         super(State.MAGIC);
@@ -52,15 +55,19 @@ public class NettyDecoder extends ReplayingDecoder<NettyDecoder.State> {
             case MAGIC:
                 checkMagic(in.readByte());
                 checkpoint(State.COMMAND);
+                break;
             case COMMAND:
                 commandHeader.setType(in.readByte());
                 checkpoint(State.OPAQUE);
+                break;
             case OPAQUE:
                 commandHeader.setOpaque(in.readLong());
                 checkpoint(State.BODY_LENGTH);
+                break;
             case BODY_LENGTH:
                 commandHeader.setBodyLength(in.readInt());
                 checkpoint(State.BODY);
+                break;
             case BODY:
                 byte[] body = new byte[commandHeader.getBodyLength()];
                 in.readBytes(body);
@@ -72,6 +79,9 @@ public class NettyDecoder extends ReplayingDecoder<NettyDecoder.State> {
                 out.add(packet);
                 //
                 checkpoint(State.MAGIC);
+                break;
+            default:
+                logger.warn("unknown decoder state {}", state());
         }
     }