GULRU

A simple Least Recently Used (LRU) cache wrapper for functions (both sync and async). Caches results of expensive function calls and evicts the least recently used items when the cache is full.

Features

• 🔄 Supports both synchronous and asynchronous functions
• 🗑️ Automatic eviction when cache exceeds maxSize
• ⚡ Huge performance boost for recursive or expensive computations
• 🪶 Lightweight, no dependencies except object-hash

Installation

npm install gulru

Usage

1. Sync Function

const { LRU } = require("gulru")

// Naive Fibonacci with memoization via LRU
const fib = LRU(function f(n) {
  if (n <= 1) return n
  return f(n - 1) + f(n - 2)
}, 1000)

console.log(fib(40)) // 102334155 (fast!)

2. Async Function

const { asyncLRU } = require("gulru")

// Example: fetch user data with caching
const fetchUser = asyncLRU(async (id) => {
  console.log("Fetching user from DB:", id)
  // Simulate db call
  return { id, name: "User " + id }
}, 100)

;(async () => {
  console.log(await fetchUser(1)) // Actually calls function
  console.log(await fetchUser(1)) // Instant from cache
})()

Benchmark

We tested with Fibonacci(40):

Normal Fib: ~800 ms
LRU Fib: ~2 ms
Iterative Fib: ~0.05 ms

✅ Results all match: 102334155 ⚡ LRU version is ~300x faster than naive recursion.

When to Use

• Recursive algorithms (Fibonacci, dynamic programming problems)
• Expensive computations with repeated inputs
• API/database calls you want to cache safely

License

MIT