Module cache 

modo::cache

In-memory LRU cache.

This module is always available; no feature flag is required.

Provides

• LruCache — fixed-capacity least-recently-used cache backed by a HashMap for O(1) key-value lookup and a VecDeque for recency tracking.

Performance

The overall complexity of get and put is O(n) because updating the recency order requires a linear scan of the deque. For small caches (up to a few thousand entries) this is negligible in practice.

Thread safety

LruCache is not Sync. Wrap it in std::sync::RwLock (or std::sync::Mutex) when sharing across threads; because get requires &mut self, even read-only lookups need an exclusive lock.

Quick start

use std::num::NonZeroUsize;
use modo::cache::LruCache;

let mut cache: LruCache<&str, u32> = LruCache::new(NonZeroUsize::new(2).unwrap());
cache.put("a", 1);
cache.put("b", 2);
assert_eq!(cache.get(&"a"), Some(&1));

// Inserting a third entry evicts "b" (least recently used).
cache.put("c", 3);
assert!(cache.get(&"b").is_none());

Structs

LruCache

A fixed-capacity, in-memory least-recently-used (LRU) cache.