search_engine_cache

A high-performance collection of cache implementations in Rust, featuring LRU, LFU, and Landlord eviction policies.

Cache Types

LRU Cache (Least Recently Used)

Evicts the least recently accessed items first. Perfect for general-purpose caching where recent access patterns predict future access.

Use when:

• You want simple, predictable behavior
• Recent items are likely to be accessed again
• Access recency matters more than frequency

LFU Cache (Least Frequently Used)

Evicts items based on access frequency, with optional weighted support for priority-based eviction.

Use when:

• Popular items should stay cached longer
• Access frequency is a better predictor than recency
• Items have different importance levels (weighted mode)

Landlord Cache

A weight-based cache with dynamic priority updates. Priority increases on access and items are evicted based on lowest priority.

Use when:

• Items have different costs or sizes
• You need fine-grained control over eviction priorities
• Cache efficiency optimization is critical

Installation

Add this to your Cargo.toml:

[dependencies]
search_engine_cache = "0.1.0"

Quick Start

LRU Cache

use search_engine_cache::lru::LRUCache;

fn main() {
    let mut cache = LRUCache::new(3);
    
    cache.put(1, "apple");
    cache.put(2, "banana");
    cache.put(3, "cherry");
    
    // Access an item (makes it "recently used")
    cache.get(&1);
    
    // Adding a 4th item evicts the least recently used (key 2)
    cache.put(4, "date");
    
    assert_eq!(cache.get(&2), None);  // Evicted
    assert_eq!(cache.get(&1), Some(&"apple"));  // Still present
}

LFU Cache (Unweighted)

use search_engine_cache::lfu_w::LFUCache;

fn main() {
    let mut cache = LFUCache::new(3, false);
    
    cache.put(1, "apple", None);
    cache.put(2, "banana", None);
    cache.put(3, "cherry", None);
    
    // Access item 1 multiple times (increases frequency)
    cache.get(&1);
    cache.get(&1);
    cache.get(&1);
    
    // Access item 2 once
    cache.get(&2);
    
    // Adding a 4th item evicts the least frequent (key 3)
    cache.put(4, "date", None);
    
    assert_eq!(cache.get(&3), None);  // Evicted (freq=1)
    assert_eq!(cache.get(&1), Some(&"apple"));  // Safe (freq=4)
}