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.

This is a updated and maintained fork of hclarke/cachemap.

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

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

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

• 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 enable the dashmap feature, which uses dashmap internally and allows:
  • getting Arc<V> pointers, in case values need to outlive the map, and
  • adding Arc<V> directly, allowing unsized values, and re-using Arc<V>s from elsewhere.
• Clients can optionally enable the abi_stable feature which will derive abi_stable::StableAbi on the type.

• There is no cache invalidation: the only way to remove things from a CacheMap is to drop it.