anchor.diff:    var _data = _Data();
   
     final _firstScanCompleter = Completer();
  -  Timer? _pollingTimer;
  +  Completer? _ongoingRecentScan;
  +  Timer? _recentScanTimer;
     Timer? _reloadTimer;
   
     NameTracker(this._db);
  
positive.code: final _logger = Logger('pub.name_tracker');
  
  /// The interval to update recent package name list.
  const _pollingInterval = Duration(minutes: 15);
  
  /// The interval to reload the full package name list from scratch.
  const _reloadInterval = Duration(days: 1);
  
negative.code:   }
  
    Future<void> _scanRecentPackages() async {
      if (_ongoingRecentScan != null) {
        await _ongoingRecentScan!.future;
        return;
      }
      _ongoingRecentScan ??= Completer();
      final start = clock.now().toUtc();
      final ts = _data._lastStartedTs.subtract(const Duration(hours: 1));
      _logger.info('Scanning recent packages starting from "$ts"...');
      try {
        final query = _db!.query<Package>()
          ..order('-lastVersionPublished')
          ..filter('lastVersionPublished >', ts);
        await for (final p in query.run()) {
          _data.add(TrackedPackage.fromPackage(p));
        }
  
        final moderatedPkgQuery = _db!.query<ModeratedPackage>()
          ..order('moderated')
          ..filter('moderated >', ts);
  
        await for (final p in moderatedPkgQuery.run()) {
          _data.addModeratedName(p.name!);
        }
  
        _data._lastStartedTs = start;
        _logger
            .info('Recent packages scanned in ${clock.now().difference(start)}.');
      } finally {
        final c = _ongoingRecentScan;
        if (c != null && !c.isCompleted) {
          _ongoingRecentScan = null;
          c.complete();
        }
      }
    }
  
    /// Updates this [NameTracker] by polling the Datastore periodically.
    Future<void> startTracking() async {
      await reloadFromDatastore().timeout(_reloadTimeout);
      _recentScanTimer ??= Timer.periodic(_recentScanInterval, (_) async {
        try {
          await _scanRecentPackages();
        } catch (e, st) {
          _logger.warning(
              'Failed to update name tracker with recent packages.', e, st);
        }
      });
      _reloadTimer ??= Timer.periodic(_reloadInterval, (_) async {
  