com.eharmony.aloha

NoEvictionCache

class NoEvictionCache extends AnyRef

A cache that is a hybrid of the Memoizer in Listing 5.19 in Java Concurrency in Practice and https://www.bionicspirit.com/blog/2012/07/02/love-scala.html. Makes sure to put a Promise of the memoized value into the cache only if it's not already there. Then only compute the actual value (in a Future) and complete the Promise with the Future only if the promise was successfully inserted atomically. Otherwise, another promise was snuck in so use the Future associated with that Promise.

val cache = new NoEvictionCache
val slow = () => {Thread.sleep(5000); println("executing slow()"); 1}
val t1 = System.nanoTime                                      // Start the clock
val futures = Seq(                                            // Returns immediately (non-blocking)
      cache("one"){slow()},                                   // Only execute slow() once.
      cache("one"){slow()})
val a = Future.fold(futures)(0)(_+_)                          // Returns immediately (non-blocking)
val t2 = System.nanoTime
println("Runtime for setup: " + (1.0e-9*(t2-t1)).toFloat)     // Prints: "Runtime for setup: 0.001041"
a.onSuccess{ case i =>
  val t3 = System.nanoTime                                    // Determine elapsed time.
  println(i + ", runtime: " + (1.0e-9*(t3-t1)).toFloat)       // Prints: "2, runtime: 5.002082"
}
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Instance Constructors

  1. new NoEvictionCache()(implicit ec: ExecutionContext)

    ec

    an execution context in which to run the futures that are created.

Value Members

  1. final def !=(arg0: AnyRef): Boolean

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  2. final def !=(arg0: Any): Boolean

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  6. def apply[A](key: String)(a: ⇒ A)(implicit arg0: RefInfo[A]): Future[A]

    Cache a value.

    Cache a value.

    A

    type of value to be memoized

    key

    string identifier

    a

    call-by-name value to be cached or retrieved from the cache.

    returns

    a Future containing the result of a

  7. final def asInstanceOf[T0]: T0

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  8. def clone(): AnyRef

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  15. def logging[A](k: (String, String), inserting: Boolean): Unit

    Made protected so that it can be overridden in a test class to test caching.

    Made protected so that it can be overridden in a test class to test caching.

    A

    k
    inserting
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