FIFO memoization

A First-In-First-Out memoization cache is one that uses queuing logic for its backing store, expunging the elements at the front of the queue when a predetermined threshold is exceeded.

In simple terms, the FIFO memoization cache will remove the element that has been in the cache the longest.

General use

To create a core.memoize FIFO-backed memoized function use the clojure.core.memoize/fifo function with an optional seed map or a :fifo/threshold parameter:

(memo/fifo function <seed> <:fifo/threshold number>)

Example code is as follows:

(ns your.lib
  (:require [clojure.core.memoize :as memo]))

(def memoized-fun
  (memo/fifo identity {} :fifo/threshold 3))

The default :fifo/threshold value is 32 and refers to the number of elements in the cache required before the FIFO logic is applied.

Please read the clojure.core.cache information regarding FIFO caches for more detailed information, use cases and usage patterns.

As always, you should measure your system's characteristics to determine the best eviction strategy for your purposes.