public T load()

in sdk1/src/main/java/com/amazonaws/services/dynamodbv2/datamodeling/internal/TTLCache.java [98:129]

• 21 lines of code
• 5 McCabe index (conditional complexity)

  public T load(final String key, Function<String, T> f) {
    final LockedState<T> ls = cache.get(key);

    if (ls == null) {
      // The entry doesn't exist yet, so load a new one.
      return loadNewEntryIfAbsent(key, f);
    } else if (clock.timestampNano() - ls.getState().lastUpdatedNano
        > ttlInNanos + TTL_GRACE_IN_NANO) {
      // The data has expired past the grace period.
      // Evict the old entry and load a new entry.
      cache.remove(key);
      return loadNewEntryIfAbsent(key, f);
    } else if (clock.timestampNano() - ls.getState().lastUpdatedNano <= ttlInNanos) {
      // The data hasn't expired. Return as-is from the cache.
      return ls.getState().data;
    } else if (!ls.tryLock()) {
      // We are in the TTL grace period. If we couldn't grab the lock, then some other
      // thread is currently loading the new value. Because we are in the grace period,
      // use the cached data instead of waiting for the lock.
      return ls.getState().data;
    }

    // We are in the grace period and have acquired a lock.
    // Update the cache with the value determined by the loading function.
    try {
      T loadedData = f.apply(key);
      ls.update(loadedData, clock.timestampNano());
      return ls.getState().data;
    } finally {
      ls.unlock();
    }
  }