@Override
        public String toString() {
            final String elapsedString = ModelStringUtil.formatDurationString(elapsed / NANOS_IN_ONE_MILLI);
            final String deltaElapsedString = ModelStringUtil.formatDurationString(
                    deltaElapsed / NANOS_IN_ONE_MILLI);
            final String deltaCallsPerSecondStr = ModelStringUtil.formatCsv(deltaCallsPerSecond);
            final String callsPerSecondStr = ModelStringUtil.formatCsv(callsPerSecond);
            return name +
                   ": " +
                   "Delta " + deltaCalls + " in " + deltaElapsedString + " " + deltaCallsPerSecondStr + " calls/sec " +
                   "Total " + calls + " in " + elapsedString + " " + callsPerSecondStr + " calls/sec";
        }
Creates a non-static {@link LocalMetrics} for transient use in a class/method.

@param isEnabled If false returns an instance that does nothing apart from call
                 the passed runnables/suppliers.
stroom-util/src/main/java/stroom/util/logging/SimpleMetrics.java