Interval Counter

IntervalCounter is a Counter that also reports the time in seconds since the last update. Useful when you want an alert that fires if a counter stops being incremented — the "Time Since Last Success" pattern applied to event-rate signals rather than a separately-tracked timestamp.

Two time series are published with the same name, distinguished by the statistic tag:

• statistic=count — the underlying counter, reported as a rate-per-second.
• statistic=duration — a gauge of the seconds elapsed since the last increment() call.

Example:

public class Job {

  private final IntervalCounter completions;

  @Inject
  public Job(Registry registry) {
    completions = IntervalCounter.get(registry, registry.createId("job.completions"));
  }

  public void run() {
    doWork();
    completions.increment();
  }
}

Then alert on the duration series rising above a threshold, e.g. statistic,duration,:eq,name,job.completions,:eq,:and,:max,3600,:gt.

Implementation note: IntervalCounter uses Polled Meter with Functions.age under the hood. If you only need the freshness signal (without a separate counter), use a plain polled meter directly — see Age Gauge.