Nougat Predominant Middleware

    ricordo

    0.2.3 • Public • Published

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    RICORDO

    Micro caching / memo library with ttl support.

    When you need some caching, and setting up Redis is too much. Ricordo is a 700 bytes library that fully supports Node.js and the browser. With time-to-live support and full control on the number of cached keys.

    Table of Contents

    Installation

    If using npm:

    npm install ricordo

    If not:

    <script src="https://unpkg.com/ricordo/dist/ricordo.umd.js"></script>

    Usage

    Ricordo usage is pretty straightforward:

    1. Create a new Ricordo instance passing a function to cache and some optional arguments.
    2. Use the function.

    Caching a function

    const Ricordo = require('ricordo'); // Node.js
    
    const demoFunc = a => `hello ${a}`;
    
    // Cache function
    const cached = new Ricordo(demoFunc);
    
    // Use function
    cached('world'); // No cache hit.
    cached('world'); // cache hit.

    Expesive functions

    const Ricordo = require('ricordo'); // Node.js
    
    const fibonacci = n => (n < 2) ? n : fibonacci(n - 1) + fibonacci(n - 2);
    
    // Cache function
    const cached = new Ricordo(fibonacci);
    
    // First execution
    cached(40); // 1200ms
    
    // Cached execution
    cached(40); // 0ms
    cached(40); // 0ms
    cached(40); // 0ms

    Using TTL (time-to-live)

    Ricordo supports a time-to-live prop on a newly created instance. ttl define (in ms) the lifespan of the cached key. The key will be removed from cache after ttl if there are no hits to that key.

    NOTE: ttl must be above 1000ms.

    const Ricordo = require('ricordo'); // Node.js
    
    // Cache function
    const cached = new Ricordo(a => `hello ${a}`, {
      ttl: 5000 * 1000, // lifespan of key.
    });
    
    // ####### 1 #######
    // First execution
    cached('world'); // no cache hit => insertion.
    
    // Executing function after ttl
    setTimeout(() => cached('world'), 5000 * 1001); // No cache hit => New insertion
    
    // ####### 2 #######
    // First execution
    cached('world'); // no cache hit => insertion.
    cached('world'); // cache hit => ttl will be renewed.
    
    // Executing function after ttl
    setTimeout(() => cached('world'), 5000 * 1001); // cache hit!!! 🎉

    Setting limits on number of cached keys

    You can set a limit on the number of keys that can be cached. When limit n of inserted keys is hit, the cache will return to ideal n of items. The keys that are kept when limit is hit are the ideal n of items most accessed in the ttl iterval.

    NOTE: A range is used so the operations of sorting and deleting the useless keys will be less frequent.

    const Ricordo = require('ricordo'); // Node.js
    
    // Cache function
    const cached = new Ricordo(a => `hello ${a}`, {
      ttl: 5000 * 1000, // lifespan of key.
      ideal: 2, // Ideal number of cached keys
      limit: 4, // Max number of cached keys
    });
    
    cached('A'); // No cache
    cached('B'); // No cache
    cached('C'); // No cache
    
    // Accessing keys A, B for 5 times.
    [1, 2, 3, 4, 5].forEach(e => {
      cached('A'); // From cache
      cached('B'); // From cache
    });
    
    // Accessing C key for 2 times.
    [1, 2].forEach(e => {
      cached('C'); // From cache
    });
    
    // On the next insertion the `limit` (4) is hit
    // => Only the `ideal` (2) items that are most accessed will be kept. => (A, B)
    cached('D') // New insertion
    
    // Then...
    cached('A') // From cache
    cached('B') // From cache
    cached('C') // No cache

    Destroy cache

    Every ricordo instance has a destroy method. This method will clear every cached key.

    const Ricordo = require('ricordo'); // Node.js
    
    // Cache function
    const cached = new Ricordo(a => `hello ${a}`);
    
    cached('A'); // No cache
    cached('B'); // No cache
    
    cached('A'); // From cache
    cached('B'); // From cache
    
    // Destroy every cached key.
    cache.destroy();
    
    cached('A'); // No cache
    cached('B'); // No cache

    Force deletion

    If force flag is enabled, cached keys will be deleted after ttl. Also if there are multiple hits to that key.

    const Ricordo = require('ricordo'); // Node.js
    
    // Specifying force flag.
    const cached = new Ricordo(a => `hello ${a}`, { ttl: 1000, force: true });
    
    cached('A'); // No cache
    cached('A'); // From cache
    cached('A'); // From cache
    
    setTimeout(() => cached('A'), 1001) // No cache => lifespan not renewed.

    Caching React component

    import React, { Component } from 'react';
    import Ricordo from 'ricordo';
    
    const C = a => <h1>hello {a}</h1>;
    
    const cached = new Ricordo(C);
    
    class App extends Component {
    
      // Invoking cached function => now 'world' is a registered key
      // The next time that the function will be computed with 'world' as argument,
      // the previously created component will be returned.
      render = () => <div>{cached('world')}</div>;
    }

    API

    Ricordo

    param type required default spec
    func function yes Function to cache.
    config object no undefined Defines cache behavior.

    Config

    param type required default spec
    ttl number [> 1000] no undefined Lifespan of cached key
    ideal number no [yes, if limit is specified] undefined Ideal number of cached keys
    limit number no [yes, if ideal is specified] undefined Max number of cached keys
    force boolean no false If set to true, cache will not be renewed after ttl

    Destroy

    param type required default spec
    key any no undefined key to delete from cache. If no key is specified, every key will be deleted.

    License

    MIT.

    Keywords

    none

    Install

    npm i ricordo

    DownloadsWeekly Downloads

    1

    Version

    0.2.3

    License

    MIT

    Unpacked Size

    36.3 kB

    Total Files

    12

    Last publish

    Collaborators

    • lucagez