ActiveInterval acquireInvoked(boolean reentry) {
        if (reentry) {
            reentryCount.incrementAndGet();
            cumulativeReentryCount.incrementAndGet();
            return () -> { };
        }

        acquireCount.incrementAndGet();
        cumulativeAcquireCount.incrementAndGet();
        return acquireStats.startNewInterval();
    }
Returns a Runnable that must be invoked when the acquire() finishes.
zkfacade/src/main/java/com/yahoo/vespa/curator/stats/LockMetrics.java