LRU Memorise Fn

A simple memorise function that uses a fast LRU cache under the hood.

Basic features

• Works in Node and the browser
• Memorises both sync and async functions.
• Automatic cache key generation from function arguments
• Cache TTL / value expiry
• Fully typed: memorised functions inherit their source function types.
• Bring your own cache or cache-keygen function, or we create one for you.
• Cache is exposed for the memorised function, if you want to access it and modify or manually clear.

Usage

import memorise from "lru-memorise";

const answerMyToughQuestion = (question: string) => {
  // ... heavy compute
  return response;
};

const memorisedFn = memorise(answerMyToughQuestion);

memorisedFn(`What's the meaning of life?`); // Calls source fn, response cached #1.
memorisedFn(`Are you an AI?`); // Calls source fn, response cached #2.

memorisedFn(`What's the meaning of life?`); // Returns cached value #1
memorisedFn(`Are you an AI?`); // Returns cached value #2

Options

Note, all options are optional

| Option | Default | Description | | ---------------- | --------------- | --------------------------------------------------------------------------------------------------------- | | cache | undefined | Bring your own LRU cache, as long as it supports standard set and get operations | | cacheKeyResolver | defaultFn | Function used to generate unique cache key from arguments. Takes array of arguments, and return a string. | | lruOptions | { max: 1000 } | Default options for tiny-lru. The two options are max and ttl. |

Bring your own cache

Under the hood we use tiny-lru, but you can bring your own, or create your cache outside and use it.

If you don't provide one, we create a cache for you. This cache is exposed through the _cache function, if you want to have access to it.

Bring your own cache key resolver

We have a simple function to generate a cache key from function arguments, using JSON.stringify. You can of course pass your own custom one if you have a more complex situation, or want to cache to behave differently. It should return a string.

type Resolver = (...args: any[]) => string;

Tiny-LRU Options

By default, we limit the max cache size to 1000 keys, and we don't set a TTL on the key values.

Type LRUOPtions = {
  max: number // Max number of keys in Cache
  ttl: number // Expiry of items in cache
}