get method

@override Future<T?> get(String key, { CacheEntryDelegate<T>? delegate, })

Returns the cache value for the specified key.

• key: the key
• delegate: provides the caller a way of changing the CacheEntry before persistence

Implementation

@override
Future<T?> get(String key, {CacheEntryDelegate<T>? delegate}) {
  // Current time
  final now = clock.now();
  // #region Statistics
  Stopwatch? watch;
  Future<CacheEntry?> Function(CacheEntry? entry) posGet1 =
      (CacheEntry? entry) => Future.value(entry);
  Future<T?> Function(T? value) posGet2 = (T? value) => Future.value(value);
  if (statsEnabled) {
    watch = clock.stopwatch()..start();
    posGet1 = (CacheEntry? entry) {
      if (entry == null || entry.isExpired(now)) {
        stats.increaseMisses();
      } else {
        stats.increaseGets();
      }

      return Future.value(entry);
    };
    posGet2 = (T? value) {
      if (watch != null) {
        stats.addGetTime(watch.elapsedMicroseconds);
        watch.stop();
      }

      return Future.value(value);
    };
  }
  // #endregion

  // Gets the entry from the storage
  return _getStorageEntry(key).then(posGet1).then((entry) {
    final expired = entry != null && entry.isExpired(now);
    // Does this entry exists or is expired ?
    if (entry == null || expired) {
      // If expired we need to remove the value from the storage
      final pre = expired
          ? _removeStorageEntry(
              key, CacheEntryExpiredEvent<T>(this, entry.info))
          : Future<void>.value();

      // Invoke the cache loader
      return pre.then((_) => cacheLoader(key)).then((value) {
        // If the value obtained is `null` just return it
        if (value == null) {
          return Future<T?>.value();
        }

        return _newEntry(_entryBuilder(key, value, now, delegate: delegate))
            .then((_) => value);
      }).then(posGet2);
    } else {
      return _getEntryValue(entry, now).then(posGet2);
    }
  });
}