locky

locky

Fast resource locking system based on redis.

Install

npm install locky

Usage

import redis from "redis";
import { createClient } from "locky";

// Create a new locky client.
const locky = createClient({ redis: () => redis.createClient() });

// Lock the resource 'article:12' with the locker 20.
await locky.lock("article:12", 20);

// Refresh the lock TTL of the resource 'article:12'.
await locky.refresh("article:12");

// Unlock the resource 'article:12.
await locky.unlock("article:12");

// Get the locker of the resource 'article:12'.
await locky.getLocker("article:12");

createClient(options)

Create a new locky client with some options.

redis

Type: import('redis').ClientOpts | (() => import('redis').RedisClient)

If you specify an object, the properties will be used to call redis.createClient method.

createClient({
  redis: {
    port: 6379,
    host: "127.0.0.1",
    connect_timeout: 200,
  },
});

If you specify a function, it will be called to create redis clients.

import redis from "redis";

createClient({
  redis: () => redis.createClient(),
});

ttl

Type: number

Define the expiration time of the lock in ms. Defaults to null (no expiration).

const locky = createClient({ ttl: 2000 });

prefix

Type: string, default: "locky:"

Define the prefix of every keys used by locky.

const locky = createClient({ prefix: "something:" });

locky.startExpirateWorker()

Start an expiration worker, it means locky will emit "expire" events.

locky.lock(options, [callback])

Lock a resource for a locker.

If the resource was already locked, you can't lock it but by passing force: true.

const locked = await locky.lock({
  resource: "article:23",
  locker: 20,
  force: false,
});
// `locked` is `true` if lock has been taken, `false` if not

resource

Type: string | number

Which resource would you like to lock.

locker

Type: string | number

Which locker should lock the resource, can by any string.

force

Type: boolean

Should we take a lock if it's already locked?

locky.refresh(resource, [callback])

Refresh the lock ttl of a resource, if the resource is not locked, do nothing.

// Refresh the resource "article:23".
locky.refresh('article:23').then(...);

locky.unlock(resource, [callback])

Unlock a resource, if the resource is not locked, do nothing.

// Unlock the resource "article:23".
locky.unlock('article:23').then(...);

locky.getLocker(resource, [callback])

Return the locker of a resource, if the resource is not locked, return null.

// Return the locker of the resource "article:23".
locky.getLocker('article:23').then(...);

Events

"lock"

Emitted when a resource is locked.

locky.on("lock", (resource, locker) => {
  /* ... */
});

"unlock"

Emitted when a resource is unlocked.

locky.on("unlock", (resource) => {
  /* ... */
});

"expire"

Emitted when the lock on a resource has expired.

locky.on("expire", (resource) => {
  /* ... */
});

License

MIT

Changelog

4.0.1 (2022-07-26)

Bug Fixes

• worker: fix worker lock algorithm (ccf24ef)