public void open() {
      if (!isOpen) {
        isOpen = true;
        this.timerContext = timer.time();
        CodahaleMetrics.this.incrementCounter(MetricsConstant.ACTIVE_CALLS + name);
      } else {
        LOGGER.warn("Scope named " + name + " is not closed, cannot be opened.");
      }
    }
Opens scope, and makes note of the time started, increments run counter
standalone-metastore/metastore-common/src/main/java/org/apache/hadoop/hive/common/metrics/metrics2/CodahaleMetrics.java