Function estimateClockResolution

unittests/catch.hpp:10532–10560

    }

    auto estimateClockResolution() -> uint64_t {
        uint64_t sum = 0;
        static const uint64_t iterations = 1000000;

        auto startTime = getCurrentNanosecondsSinceEpoch();

        for( std::size_t i = 0; i < iterations; ++i ) {

            uint64_t ticks;
            uint64_t baseTicks = getCurrentNanosecondsSinceEpoch();
            do {
                ticks = getCurrentNanosecondsSinceEpoch();
            } while( ticks == baseTicks );

            auto delta = ticks - baseTicks;
            sum += delta;

            // If we have been calibrating for over 3 seconds -- the clock
            // is terrible and we should move on.
            // TBD: How to signal that the measured resolution is probably wrong?
            if (ticks > startTime + 3 * nanosecondsInSecond) {
                return sum / i;
            }
        }

        // We're just taking the mean, here. To do better we could take the std. dev and exclude outliers
        // - and potentially do more iterations if there's a high variance.
        return sum/iterations;
    }
    auto getEstimatedClockResolution() -> uint64_t {
        static auto s_resolution = estimateClockResolution();
        return s_resolution;