#sync #data-structure #cache #hash-map


A concurrent insert-only hashmap for caching values

1 unstable release

0.1.0 Apr 14, 2021

#4 in #hash-map

MIT license

104 lines


CacheMap is a data structure for concurrently caching values.

the cache function will look up a value in the map, or generate and store a new one using the provided function


use cachemap::CacheMap;
let m = CacheMap::new();

let fst = m.cache("key", || 5u32).as_ref();
let snd = m.cache("key", || 7u32).as_ref();

assert_eq!(*fst, *snd);
assert_eq!(*fst, 5u32);

Features 🌞

  • can cache values concurrently (using &CacheMap<K,V> rather than &mut CacheMap<K,V>)
  • returned references use the map's lifetime, so clients can avoid smart pointers
  • clients can optionally get Arc<V> pointers, in case values need to outlive the map
  • values can be addes as Arc<V>, allowing unsized values, and re-using Arc<V>s from elsewhere

MisFeatures 💧

A cache with a bad policy is another name for a memory leak

this map provides only one way to remove things from the cache: drop the entire map.