MaxValueTracker.java

public final class PerfTest {
     private final MaxPerSecondReporter reporter = new MaxPerSecondReporter(max -> {
        System.out.printf("%s %d%n", Instant.now(), max);
    });

    private void onExecutionReport() {
        final long currentNanos = System.nanoTime();
        // calculate end-to-end latency
        final long endToEndLatency = calculateEndToEndLatency();
        reporter.recordSample(currentNanos, endToEndLatency);
    }

    private static final class MaxPerSecondReporter {
        private final LongConsumer maxValueReporter;
        private long lastReportSecond = 0L;
        private long maxValueInThisSecond = 0L;

        MaxPerSecondReporter(final LongConsumer maxValueReporter) {
            this.maxValueReporter = maxValueReporter;
        }

        void recordSample(final long currentNanos, final long endToEndLatency) {
            final long currentSecond = TimeUnit.NANOSECONDS.toSeconds(currentNanos);
            if (lastReportSecond == 0L) {
                lastReportSecond = currentSecond;
            } else if (lastReportSecond != currentSecond) {
                maxValueReporter.accept(maxValueInThisSecond);
                lastReportSecond = currentSecond;
                maxValueInThisSecond = 0L;
            }

            maxValueInThisSecond = Math.max(endToEndLatency, maxValueInThisSecond);
        }
    }
 
}