@rodbe/lru-cache-fs

@rodbe/lru-cache-fs is a TypeScript library that provides a file system-backed Least Recently Used (LRU) cache using the lru-cache package. This library allows you to persist cache data to the file system, automatically managing stale data and ensuring cache state is saved after each operation.

Features

• LRU caching with customizable options.
• Automatic persistence of cache data to the file system.
• Load and dump cache state from/to the file system.
• Provides utility methods to interact with the cache, like clearing the cache, setting items, and removing items.

Installation

npm i @rodbe/lru-cache-fs --save

Usage

This library exntends the lru-cache library, and adds a syncFs property to the cache instance, to enable cache persistence on the FS

Configuration Options

The fsCache accepts all options available in lru-cache along with the following additional parameters:

• cacheName (string): The filename for storing the cached data.

• cachePath (string, optional): The directory path for storing the cache file. Defaults to the user's home directory.

import { homedir } from 'node:os';
import { join } from 'node:path';

import { fsCache } from '@rodbe/lru-cache-fs';

interface MyValue {
  data: string;
}

const myCache = fsCache<string, MyValue>({
  cacheName: 'my-cache-file.json', // or without file extension
  cachePath: join(homedir(), '.my-libray-folder');
  max: 50,
  // how long to live in ms
  ttl: 1000 * 60 * 5,
});

// add value to the cache
myCache.syncFs.setItem('some-key', { someProp: 'some value' });

// retrieve value from the cache
const value = myCache.get('some-key');
console.log(value) // Outputs: { someProp: 'some value' }

// remove key from the cache
myCache.syncFs.removeItem('some-key');

// clear the cache
myCache.syncFs.clear();

Accessing to syncFs methods

Methods	Description	Returns
clear()	Clear the cache entirely, throwing away all values.	void
dump()	Synchronize the memory cache on the file system	void
removeItem(key)	Deletes a key out of the cache.	Returns true if the key was deleted, false otherwise.
setItem(key, value)	Add a value to the cache.	void

Accessing other lru-cache methods

// for example:
myCache.has('key'); // Check if a key is in the cache, returns a boolean.
myCache.dump(); // Return the actual cache in memory, can be passed to LRUCache#load.
// ... and others

Loading Cached Data

When you create a cache instance using fsCache, it will automatically load any cached data from the specified file. If the file doesn't exist or is not in JSON format, the cache will start empty.

Dumping Cache to File

The cache state is automatically saved to the specified file whenever an item is set or removed, or the cache is cleared.

License

MIT License