generational-cache

Generational Arena based cache impls. in 100% safe, [no_std] compatible Rust.

Usage

generational-cache is a library crate. You may include it in your Cargo.toml as follows:

[dependencies]
generational-cache = "0.2.2"

Refer to latest git API Documentation or Crate Documentation for more details.

Examples

1. LRU Cache (generational_cache::cache::LRUCache)

   A generational arena based LRU cache implementation.

   #[no_std]
   
   use generational_cache::prelude::*;
   
   const CAPACITY: usize = 3;
   
   // users can choose between different map and vector implementations
   let mut cache = LRUCache::<_, i32, u64, AllocBTreeMap<_, _>>::with_backing_vector(Array::<_, CAPACITY>::new());
   
   cache.insert(-1, 1).unwrap();
   cache.insert(-2, 2).unwrap();
   cache.insert(-3, 3).unwrap();
   
   assert_eq!(cache.least_recent().unwrap(), (&-1, &1));
   assert_eq!(cache.most_recent().unwrap(), (&-3, &3));
   
   assert_eq!(cache.insert(-4, 4).unwrap(), Eviction::Block { key: -1, value: 1});
   
   assert_eq!(cache.least_recent().unwrap(), (&-2, &2));
   assert_eq!(cache.most_recent().unwrap(), (&-4, &4));
   
   assert_eq!(cache.insert(-2, 42).unwrap(), Eviction::Value(2));
   
   assert_eq!(cache.least_recent().unwrap(), (&-3, &3));
   assert_eq!(cache.most_recent().unwrap(), (&-2, &42));
   
   assert_eq!(cache.remove(&-42).unwrap(), Lookup::Miss);
   assert_eq!(cache.query(&-42).unwrap(), Lookup::Miss);
   
   assert_eq!(cache.query(&-3).unwrap(), Lookup::Hit(&3));
   
   assert_eq!(cache.least_recent().unwrap(), (&-4, &4));
   assert_eq!(cache.most_recent().unwrap(), (&-3, &3));
   
   assert_eq!(cache.remove(&-2).unwrap(), Lookup::Hit(42));
   
   assert_eq!(cache.query(&-2).unwrap(), Lookup::Miss);
   
   // zero capacity LRUCache is unusable
   let mut cache = LRUCache::<_, i32, u64, AllocBTreeMap<_, _>>::with_backing_vector(Array::<_, 0_usize>::new());
   
   match cache.insert(0, 0) {
       Err(LRUCacheError::ListUnderflow) => {}
       _ => unreachable!("Wrong error on list underflow."),
   };

(… we plan on adding more cache implementations in the future).

License

This repository is licensed under the MIT License. See License for more details.