Memcached Server - Work in progress

This repo contains a Memcached implementation with JavaScript. It listens for new connections on a given TCP port. You can find the part of the protocol implemented here. The full protocol can be found in the references at the end of this document.

Note: This only a little piece of the Memcached protocol.

About

Memcached is an in-memory key-value store for small chunks of arbitrary data (strings, objects) from results of database calls, API calls, or page rendering.

You can find more about Memcached in the references at the end of this document.

Requirements

• Nodejs version >= 12.16.1 LTS

Dependencies

• ms: This package is used for handling with time using friendly time formats.
• dotenv: This package is used to read environment variables.
• Jest: This package is used for unit testing the software.
• uuid: This package is used to generate random and unique strings for the casUnique key.

Installation

In order to start the server you will have to run the following commands in your console:

$ git clone https://github.com/SGarcia710/memcached-nodejs

$ cd memcached-nodejs

$ npm i

Now you will have to create a .env file at the root of the memcached server folder indicating the TCP port.

SERVER_PORT = 9000
SERVER_DOMAIN = localhost

As default, if the server doesn't receive the port through the .env file, it will use 8080.

After everything is seted up, you just have to run npm start at the root of the project and the server is going to listen requests at the given port.

Usage

These are two ways to use the server, throught command line or with the client. Here you will be examples to use both.

Command line

When you have started the server, it will listen any connection through the setted up TCP port. You can use it through the command line using the following command:

$ printf "set myKey 0 300 4 [noreply]\r\ndata\r\n" | nc localhost 8080

Client

There is a simple TCP client to send operations to the server. This is how you can use it:

const TCPClient = require('./utils/client')
const { PORT } = require('./src/assets/config');

const client  =  new  TCPClient(PORT, 'localhost');
client.sendOperation('set key 0 0 4 [noreply]\r\ndata\r\n');
client.sendOperation('add key2 0 0 4\r\ndata\r\n');

It will simply log the server response.

You can check the available commands and usage here.

Tests

Unit tests

The Memcached logical functions and the parser for the client's input have a set of Unit tests made with Jest. In order to run the tests you have to run npm test at the root of the project's folder.

Load tests

TODO

References

• Memcached's official webpage: https://memcached.org/

• JavaScript documentation style guide: https://jsdoc.app/

• JavaScript namin conventions: https://www.robinwieruch.de/javascript-naming-conventions

• LRU Cache: https://github.com/SGarcia710/lru-cache-js

• TCP Server: https://github.com/SGarcia710/tcp-server-nodejs

• The full protocol specification: https://github.com/memcached/memcached/blob/master/doc/protocol.txt

• Jest cheatsheet: https://devhints.io/jest