v0.16.0

🪟 W-TinyLFU (Windowed Tiny LFU) Policy!

Version 0.16.0 introduces the W-TinyLFU eviction policy, a state-of-the-art cache replacement algorithm that delivers excellent hit rates:

Key Features:

• 🪟 W-TinyLFU Policy - Two-segment architecture (window + protected) for optimal caching

  • Window segment (FIFO) captures recent items
  • Protected segment (LFU) keeps frequently accessed items
  • Configurable window_ratio for workload tuning

• 🎯 Superior Hit Rates - 5-15% better than traditional LRU on mixed workloads

• 🛡️ Cache Pollution Protection - Prevents one-hit wonders from evicting valuable data

• ⚙️ Configurable - Tune window_ratio to emphasize recency vs frequency

Basic Example:

use cachelito::cache;

// Basic W-TinyLFU cache
#[cache(limit = 1000, policy = "w_tinylfu")]
fn fetch_user_data(user_id: u64) -> UserData {
    database.fetch_user(user_id)
}

// Custom window ratio for recency emphasis
#[cache(
    limit = 1000,
    policy = "w_tinylfu",
    window_ratio = 0.3  // 30% window, 70% protected
)]
fn fetch_trending_content(id: u64) -> Content {
    api_client.fetch(id)
}

How It Works:

W-TinyLFU splits the cache into two segments:

1. Window (20% by default): Recent items using FIFO
2. Protected (80%): Frequently accessed items using LFU

This dual-segment approach provides excellent performance across various workload patterns.

Configuration Options:

• window_ratio (0.01-0.99, default: 0.20) - Balance between recency and frequency
  • Smaller (0.1-0.15): More emphasis on frequency (stable workloads)
  • Larger (0.3-0.4): More emphasis on recency (changing workloads)

Current Status (v0.16.0):

This is the initial, fully functional implementation of W-TinyLFU. Future versions will add:

• Count-Min Sketch admission policy
• Automatic periodic decay
• Segment-specific metrics

Examples:

• examples/w_tinylfu.rs - Complete demonstration with multiple scenarios
• tests/w_tinylfu_policy_tests.rs - Test suite

What's Changed

• Add W-TinyLFU (Windowed TinyLFU) policy support by @josepdcs in #37

Full Changelog: 0.15.0...0.16.0