Return true if this metric will actively record metrics, and false otherwise. If the returned value is false, the manipulator operations will have no effect. A metric will be inactive if either (1) it was not initialized with a valid metric identifier or (2) the associated metric category has been disabled (see the MetricsManager method setCategoryEnabled). Note that invoking this method is logically equivalent to the expression 0 != collector() && metricId().category()‐>enabled().