observe method

DVSchemaFinding? observe(DVBackfillLoad load, DateTime now)

Adjusts the rate for load; returns DV-SCHEMA-003 once, when the rate has stayed below the floor for longer than the patience.

Implementation

DVSchemaFinding? observe(DVBackfillLoad load, DateTime now) {
  final Duration? lag = load.replicaLag;
  final double? latency = load.writeLatencyIncrease;
  final bool over =
      (lag != null && lag > settings.targetReplicaLag) ||
      (latency != null && latency > settings.maxWriteLatencyIncrease);
  _rate = over
      ? math.max(1, _rate / 2)
      : _rate + settings.tier.startingRate / 10;

  if (_rate >= settings.floor) {
    _belowFloorSince = null;
    _reported = false;
    return null;
  }
  final DateTime since = _belowFloorSince ??= now;
  if (_reported || now.difference(since) < settings.patience) return null;
  _reported = true;
  return DVSchemaFinding(
    'DV-SCHEMA-003',
    'The backfill has run below its floor of ${settings.floor} rows/s '
        'since ${since.toIso8601String()}, longer than its patience of '
        '${settings.patience}. The database cannot take it at this load.',
  );
}