@Override
    public void channelRead(ChannelHandlerContext ctx, Object message)
        throws Exception {
      FullHttpRequest request = (FullHttpRequest) message;
      handleRequest(ctx, request);
      request.release();
    }
Unregister a specific dag

This method and registerDag must be synchronized externally to prevent races in shuffle token registration/unregistration

@param dir
@param applicationIdString
@param dagIdentifier
llap-server/src/java/org/apache/hadoop/hive/llap/shufflehandler/ShuffleHandler.java