Cache-manager-fs-hash NPM

Node Cache Manager store for Filesystem

Package to cache key-value pairs in JSON files.

Installation

npm install cache-manager-fs-hash

Features

Saves anything that is JSON.stringify-able to disk
Buffers are saved as well (if they reach a certain size they will be stored to separate files)
Works well with the cluster module

Usage example

Here is an example that demonstrates how to implement the Filesystem cache store.

const {DiskStore} = require('cache-manager-fs-hash');

const diskStore = new DiskStore({
    path: 'diskcache', // path for cached files (default: cache)
    ttl: 60 * 60 * 1000, // time to life in milliseconds 
                         // (default: never expires)
    zip: true, // zip files to save disk space (default: false)
});

(async () => {
    await diskStore.set('key', 'value');
    console.log(await diskStore.get('key')); // "value"

    await diskStore.del('key');
    console.log(await diskStore.get('key')); // undefined

    await diskStore.set('key', 'value', 1000); // with custom TTL
    console.log(await diskStore.ttl('key')); // 999 milliseconds

    // delete stored files
    await diskStore.reset();
})();

Here is an example that demonstrates how to use the store with the node-cache-manager module.

const cacheManager = require('cache-manager');
const {DiskStore} = require('cache-manager-fs-hash');

const diskCache = cacheManager.createCache(new DiskStore({
    path: 'diskcache', // path for cached files
    // ... other options
}));


(async () => {

    await diskCache.set('key', 'value');
    console.log(await diskCache.get('key')); // "value"

    console.log(await getUserCached(5)); // {id: 5, name: '...'}
    console.log(await getUserCached(5)); // {id: 5, name: '...'}

    function getUserCached(userId) {
        return diskCache.wrap(userId, function () {
            return getUser(userId);
        });
    }

    async function getUser(userId) {
        await new Promise(r => setTimeout(r, 100)); // sleep 0.1 seconds
        return {id: userId, name: '...' + Math.random()};
    }

})();

How it works

The filename is determined by the md5 hash of the key. (The key is also saved in the file to detect hash collisions. In this case it will just return a cache miss). Writing is performed with .lock files so that multiple instances of the library (e.g. using the cluster module) do not interfere with one another.