default TsBlock nextWithTimer() throws Exception {
    OperatorContext context = getOperatorContext();
    long startTime = System.nanoTime();
    TsBlock output = null;
    try {
      output = next();
    } finally {
      context.recordExecutionTime(System.nanoTime() - startTime);
      if (output != null) {
        context.addOutputRows(output.getPositionCount());
      }
      context.recordNextCalled();
    }
    return output;
  }
Returns a future that will be completed when the operator becomes unblocked. If the operator is
not blocked, this method should return {@code NOT_BLOCKED}.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/operator/Operator.java