resync(nowMicros);
    double stableIntervalMicros = SECONDS.toMicros(1L) / permitsPerSecond;
    this.stableIntervalMicros = stableIntervalMicros;
    doSetRate(permitsPerSecond, stableIntervalMicros);
  }

  abstract void doSetRate(double permitsPerSecond, double stableIntervalMicros);

  @Override
  final double doGetRate() {
    return SECONDS.toMicros(1L) / stableIntervalMicros;
  }

  @Override

    long instant = 0L;
    final List<String> events = new ArrayList<>();

    @Override
    public long readMicros() {
      return NANOSECONDS.toMicros(instant);
    }

    void sleepMillis(int millis) {
      sleepMicros("U", MILLISECONDS.toMicros(millis));
    }

    void sleepMicros(String caption, long micros) {
      instant += MICROSECONDS.toNanos(micros);

    long instant = 0L;
    final List<String> events = new ArrayList<>();

    @Override
    public long readMicros() {
      return NANOSECONDS.toMicros(instant);
    }

    void sleepMillis(int millis) {
      sleepMicros("U", MILLISECONDS.toMicros(millis));
    }

    void sleepMicros(String caption, long micros) {
      instant += MICROSECONDS.toNanos(micros);