tiny-lru

What is tiny-lru?

The tiny-lru npm package is a lightweight, in-memory Least Recently Used (LRU) cache. It is designed to be simple and efficient, making it suitable for use in environments where memory usage and performance are critical.

What are tiny-lru's main functionalities?

Creating an LRU Cache

This feature allows you to create an LRU cache with a specified maximum size. The cache will automatically evict the least recently used items when the size limit is reached.

const LRU = require('tiny-lru');
const cache = LRU(100); // Create a cache with a max size of 100 items

Setting and Getting Cache Items

You can store items in the cache using the `set` method and retrieve them using the `get` method. If the item is not found, `get` will return `undefined`.

cache.set('key', 'value');
const value = cache.get('key'); // 'value'

Deleting Cache Items

This feature allows you to delete specific items from the cache using the `delete` method.

cache.set('key', 'value');
cache.delete('key');
const value = cache.get('key'); // undefined

Clearing the Cache

You can clear all items from the cache using the `clear` method, which removes all entries.

cache.set('key1', 'value1');
cache.set('key2', 'value2');
cache.clear();
const value1 = cache.get('key1'); // undefined
const value2 = cache.get('key2'); // undefined

Cache Size and Item Count

This feature allows you to check the current number of items in the cache using the `size` property.

cache.set('key1', 'value1');
cache.set('key2', 'value2');
const size = cache.size; // 2

Other packages similar to tiny-lru

lru-cache

The lru-cache package is another popular LRU cache implementation for Node.js. It offers more features and configuration options compared to tiny-lru, such as time-to-live (TTL) settings for cache entries and more detailed cache statistics.

quick-lru

The quick-lru package is a minimalist LRU cache implementation that focuses on performance and simplicity. It is similar to tiny-lru in terms of its lightweight nature but offers a slightly different API.

node-cache

The node-cache package provides a simple and efficient in-memory caching solution with support for TTL and other advanced features. It is more feature-rich compared to tiny-lru, making it suitable for more complex caching needs.

README

Tiny LRU

Least Recently Used cache for Client or Server.

Using the factory

import {lru} from "tiny-lru";
const cache = lru(max, ttl = 0, resetTtl = false);

Using the Class

import {LRU} from "tiny-lru";
const cache = new LRU(max, ttl = 0, resetTtl = false);

import {LRU} from "tiny-lru";
class MyCache extends LRU {}

Interoperability

Lodash provides a memoize function with a cache that can be swapped out as long as it implements the right interface. See the lodash docs for more on memoize.

Example

_.memoize.Cache = lru().constructor;
const memoized = _.memoize(myFunc);
memoized.cache.max = 10;

Testing

Tiny-LRU has 100% code coverage with its tests.

--------------|---------|----------|---------|---------|-------------------
File          | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
--------------|---------|----------|---------|---------|-------------------
All files     |     100 |    89.85 |     100 |     100 |                  
 tiny-lru.cjs |     100 |    89.85 |     100 |     100 | 11-31,130-138,172
--------------|---------|----------|---------|---------|-------------------

API

Properties

first

Item in "first" or "bottom" position; default is null

Example

const cache = lru();

cache.first; // null - it's a new cache!

last

Item in "last" or "top" position; default is null

Example

const cache = lru();

cache.last; // null - it's a new cache!

max

Max items to hold in cache; default is 1000

Example

const cache = lru(500);

cache.max; // 500

resetTtl

Resets item.expiry with each set() if true; default is false

Example

const cache = lru(500, 5*6e4, true);

cache.resetTtl; // true

size

Number of items in cache

Example

const cache = lru();

cache.size; // 0 - it's a new cache!

ttl

Milliseconds an item will remain in cache; lazy expiration upon next get() of an item

Example

const cache = lru(100, 3e4);

cache.ttl; // 30000;

Methods

clear

Clears the contents of the cache

return {Object} LRU instance

Example

cache.clear();

delete

Removes item from cache

param  {String} key Item key
return {Object}     LRU instance

Example

cache.delete("myKey");

entries(["key1", "key2"])

Returns an Array cache items

param  {Array} keys (Optional) Cache item keys to get
return {Object} LRU instance

Example

cache.entries(['myKey1', 'myKey2']);

evict

Evicts the least recently used item from cache

return {Object} LRU instance

Example

cache.evict();

expiresAt

Gets expiration time for cached item

param  {String} key Item key
return {Mixed}      Undefined or number (epoch time)

Example

const item = cache.expiresAt("myKey");

get

Gets cached item and moves it to the front

param  {String} key Item key
return {Mixed}      Undefined or Item value

Example

const item = cache.get("myKey");

has

Returns a Boolean indicating if key is in cache

return {Object} LRU instance

Example

cache.has('myKey');

keys

Returns an Array of cache item keys.

return {Array} Array of keys

Example

console.log(cache.keys());

set

Sets item in cache as first

param  {String} key   Item key
param  {Mixed}  value Item value
return {Object}       LRU instance

Example

cache.set("myKey", {prop: true});

values(["key1", "key2"])

Returns an Array cache items

param  {Array} keys (Optional) Cache item keys to get
return {Array} Cache items

Example

cache.values(['abc', 'def']);

License

Copyright (c) 2023 Jason Mulligan Licensed under the BSD-3 license.