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fast-ttl-cache

An in-memory cache implemented in Node.js, featuring configurable ttl and a maximum size. It uses a doubly linked list data structure and lazy deletion for expired data, all without relying on any JavaScript timer methods.

Installation

npm install fast-ttl-cache --save

Usage

import FastTTLCache from 'fast-ttl-cache';

const cache = new FastTTLCache({
  ttl: 5 * 1000, // ttl in millseconds, get an outdated data will return null and delete it
  capacity: 1000, // max capacity, When the capacity is exceeded, the least recently updated data will be removed.
  cloneLevel: 0, // 0 (no clone), 1 (shallow clone), 2 (deep clone), defaults to 0
});

cache.put('key1', 'value1');
cache.put('key2', 'value2');
cache.put('key3', 'value3');
console.log(cache.get('key2')); // return value2

// wait for 5 seconds
await new Promise(resolve => setTimeout(resolve, 5000));

cache.get('key1'); // return null and key1 will be removed
cache.size; // return 2, key2 & key3 are outdated but are not been removed yet

cache.get('key3'); // return null and key2 & key3 will be removed
cache.size; // return 0

API

FastTTLCache(options) consturctor

• options.ttl: number of millseconds, defaults to Infinity
• options.capacity: number of max capacity, defaults to Infinity
• options.cloneLevel: number of clone level, defaults to 0 (no clone), 1 (shallow clone), 2 (deep clone)

FastTTLCache.prototype.put(key, value)

• Add or update the value into cache with key and timestamp.

FastTTLCache.prototype.get(key)

• Get the value of the key from cache, return null if the key is not exists or has been expired.
• if cloneLevel is 0, return the original data
• if cloneLevel is 1, return the shallow cloned data
• if cloneLevel is 2, return the deep cloned data

FastTTLCache.prototype.size

• return the current size of cache, note because of the lazy deletion mechanism, it's not the exact number of cache items that are valid.

License

MIT