arbor-lru-cache

A thread-safe LRU cache library.

Example

To use the cache:

main :: IO main = do -- Provide a configuration that includes how many simultaneous in -- flight requests are allowed and now many entries the cache can store let config = A.CacheConfig { A.maxRequestsInFlight = 1 , A.maxOccupancy = 1 } -- Create a cache providing the config and functions that handle retrieval -- and eviction. cache <- A.makeCache config retrieve evict -- Perform your lookups _ <- A.lookup 1 cache _ <- A.lookup 2 cache _ <- A.lookup 3 cache return () -- Implement value retrieval function. If the same key is looked up multiple -- times, the cache guarantees that the retrieve function is called only once -- for that key up until it is evicted. retrieve :: Int -> IO String retrieve mk = ... -- Perform any cleanup that should occur when an entry is evicted -- Please be aware that if your code is concurrent, the eviction function may -- be called whilst the you code is concurrently using a value it has looked up. -- Your code is wholly responsible for ensuring this case still works. evict :: Int -> String -> IO () evict mk mv = ...