LRU Cache for fibjs

This module provides an implementation of a Least Recently Used (LRU) cache in JavaScript. The LRU cache is a type of cache in which the least recently used entries are removed when the cache's limit has been reached.

Install

fibjs --install fib-cache

Usage

const { LRU } = require('fib-cache');

const cache = new LRU({ max: 100, ttl: 5000 });

cache.set('key1', 'value1');
console.log(cache.get('key1')); // 'value1'

Class: LRU

The main class exported by this module is LRU. An instance of LRU represents a cache with a specified maximum size and time-to-live (TTL) for its entries.

Constructor

The LRU class is instantiated with an options object. The options object can have the following properties:

max: The maximum number of entries in the cache. If not specified, the cache size is unlimited. ttl: The time-to-live (in milliseconds) for each entry. If not specified, entries do not expire. resolver: A function that will be called to compute the value for a key if it's not in the cache.

Methods

The LRU class provides the following methods:

• clear(): Clears the cache.
• delete(key): Deletes the entry with the specified key from the cache.
• entries(): Returns an array of all entries in the cache.
• evict(): Evicts entries from the cache until it's within its size limit and all remaining entries are within their TTL.
• get(key): Returns the value of the entry with the specified key.
• has(key): Checks if an entry with the specified key exists in the cache.
• keys(): Returns an array of all keys in the cache.
• set(key, value): Sets the value of the entry with the specified key.
• values(): Returns an array of all values in the cache.

Using the Resolver Function in LRU Cache

The resolver function is a powerful feature of the LRU Cache module. It allows you to compute the value for a key if it's not already in the cache. This function is called automatically when you try to get a value for a key that doesn't exist in the cache.

When creating a new instance of the LRU Cache, you can pass a resolver function in the options object:

const lru = new LRU({
    max: 2,
    resolver: (key) => {
        // Compute the value for the key
        return computedValue;
    }
});

The resolver function receives the key as its argument and should return the computed value for that key.