def select[K, V]()

in storehaus-core/src/main/scala/com/twitter/storehaus/ReadableStore.scala [49:92]

• 18 lines of code
• 3 McCabe index (conditional complexity)

  def select[K, V](
      stores: Seq[ReadableStore[K, V]])(pred: Option[V] => Boolean): ReadableStore[K, V] =
    new ReplicatedReadableStore(stores)(pred)

  /**
   * Returns a ReadableStore[K, V] that attempts reads out of the
   * supplied Seq[ReadableStore[K, V]] in order and returns the first
   * successful value that passes the supplied predicate.
   */
  def find[K, V](
      stores: Seq[ReadableStore[K, V]])(pred: Option[V] => Boolean): ReadableStore[K, V] =
    new SearchingReadableStore(stores)(pred)

  /**
   * Returns a new ReadableStore[K, V] that queries all of the stores
   * and returns the first values that are not exceptions.
   */
  def first[K, V](stores: Seq[ReadableStore[K, V]]): ReadableStore[K, V] =
    select(stores)(_ => true)

  /**
   * Returns a new ReadableStore[K, V] that queries all of the stores
   * and returns the first values that are not exceptions and that are
   * present (ie, not equivalent to Future.None).
   */
  def firstPresent[K, V](stores: Seq[ReadableStore[K, V]]): ReadableStore[K, V] =
    select(stores)(_.isDefined)

  /** Factory method to create a ReadableStore from a Map. */
  def fromMap[K, V](m: Map[K, V]): ReadableStore[K, V] = new MapStore(m)

  /** Factory method to create a ReadableStore from an IndexedSeq. */
  def fromIndexedSeq[T](iseq: IndexedSeq[T]): ReadableStore[Int, T] =
    new IndexedSeqReadableStore(iseq)

  /**
   * Treat a Function1 like a ReadableStore
   */
  def fromFn[K, V](getfn: (K) => Option[V]): ReadableStore[K, V] = new AbstractReadableStore[K, V] {
    // I know Future(getfn(k)) looks similar, we've seen some high costs with that
    override def get(k: K) =
      try { Future.value(getfn(k)) }
      catch { case e: Throwable => Future.exception(e) }
  }