Crate generational_cache

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 = "0.2.0"

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

Examples

#1: 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.

Modules

• arena
  Module providing abstractions for a generational arena implemenation.
• cache
  Module providing abstractions to represent caches.
• collections
  Module providing generic collections used by this crate.
• map
  Module providing abstractions to implement maps.
• prelude
• vector
  Module providing abstractions for reperesenting vectors.