ordo

Ordo - Redis distributed lock system

Ordo - is a latin word Queue, that's what this library looks like. Concurrent access!

Installation

Use npm to install:

npm install --save ordo

Usage

For basic example try to look at /examples directory.

Defaults

• TTL - 10 seconds
• Timeout - 10 seconds
• Delay - 25 Ms

Basic

const Ordo = require('ordo');
 
const lock = new Ordo();
 
lock
.lock('user')
.then(() => {
    console.log('Obtained lock #1');
 
    setTimeout(() => {
        lock
        .release('user')
        .then(() => {
            console.log('Released lock #1');
        });
    }, 1000);
});
 
lock
.lock('user')
.then(() => {
    console.log('Obtained lock #2');
 
    return lock.release('user');
})
.then(() => {
    console.log('Released lock #2');
});

Callback/Promise style

const Ordo = require('ordo');
const lock = new Ordo();
 
// You can use this library in Promise-way
lock.lock('user#1').then(info => {
    console.log(info);
});
 
// You can use library in callback-way style
lock.lock('user#1', (err, info) => {
    console.log(info);
});

Options

You also can use options to have some client customizations:

• port - Redis port (Default: 6379)
• host - Redis host (Default: localhost)
• client - Custom Redis client (You should use redis package for it)
• password - Auth password
• database - Redis database
• prefix - Custom prefix (Default: ordo:lock:)

Also you can use redis-uri to connect in e.g.:

const Ordo = require('ordo');
 
const lock = new Ordo('redis://locahost:6379');

TTL/Timeout

TTL - Time lock will live in Redis
Timeout - When trying to set lock library reach this timeout Exception will be thrown Delay - Default delay between lock attempts

You can customize lock acquire with ttl, timeout and delay options:

const Ordo = require('Ordo');
 
const lock = new Ordo();
// This lock will have TTL 1 second and will try to be acquired in 1.5 second
// with a 500 ms delay between attempts .
lock.lock('user#1', {ttl: 1, timeout: 1.5, delay: 500}).then(info => {
    console.log(info.attempts); // Attempts to acquire lock
    console.log(info.elapsed); // Elapsed time in MS to acquire lock
});

Errors/Exceptions

There is three type of errors can be thrown by this library:

• RedisError - this error thrown on every redis error.
• AcquireError - this error thrown when we failed to acquire lock in requested timeout
• ReleaseError - this error thrown when we try to release unknown/expired lock

Debugging

For debugging reasons Ordo uses debug library. To enable debugging just use DEBUG env variable with value: ordo, in e.g.:

DEBUG=ordo node index.js

License

MIT License

Copyright (c) 2016 Pavel Makarenko

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.