override def multiGet[K1 <: K]()

in storehaus-core/src/main/scala/com/twitter/storehaus/ReadThroughStore.scala [52:79]

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

  override def multiGet[K1 <: K](ks: Set[K1]): Map[K1, Future[Option[V]]] = {
    // attempt to read from cache first
    val cacheResults : Map[K1, Future[Either[Option[V], Exception]]] =
      cache.multiGet(ks).map { case (k, fut) =>
        (k, fut.map { optv => Left(optv) } rescue { case x: Exception => Future.value(Right(x)) })
      }

    // attempt to read all failed keys and cache misses from backing store
    val f: Future[Map[K1, Option[V]]] =
      FutureOps.mapCollect(cacheResults).flatMap { cacheResult =>
        val failedKeys = cacheResult.filter { _._2.isRight }.keySet
        val responses = cacheResult.filter { _._2.isLeft }.map { case (k, r) => (k, r.left.get) }
        val hits = responses.filter(_._2.isDefined)
        val missedKeys = responses.filter { _._2.isEmpty }.keySet

        val remaining = missedKeys ++ failedKeys
        if (remaining.isEmpty) {
          Future.value(hits) // no cache misses
        } else {
          FutureOps.mapCollect(backingStore.multiGet(remaining)).flatMap { storeResult =>
            // write fetched keys to cache, best effort
            FutureOps.mapCollect(cache.multiPut(storeResult))(FutureCollector.bestEffort)
              .map { u => hits ++ storeResult }
          }
        }
      }
    FutureOps.liftValues(ks, f, { (k: K1) => Future.None })
  }