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redis-semaphore

2.1.1 • Public • Published

redis-semaphore

NPM version Build status Dependency Status FOSSA Status Coverage Status Maintainability Known Vulnerabilities FOSSA Status

Mutex and Semaphore implementations based on Redis ready for distributed systems

Features

  • Fail-safe (all actions performed by LUA scripts (atomic))

Usage

Installation

npm install --save redis-semaphore ioredis
# or 
yarn add redis-semaphore ioredis

Mutex

See RedisLabs: Locks with timeouts

new Mutex(redisClient, key [, { lockTimeout = 10000, acquireTimeout = 10000, retryInterval = 10, refreshInterval = lockTimeout * 0.8 }])
  • redisClient - required, configured redis client
  • key - required, key for locking resource (final key in redis: mutex:<key>)
  • timeouts optional
    • lockTimeout - ms, time after mutex will be auto released (expired)
    • acquireTimeout - ms, max timeout for .acquire() call
    • retryInterval - ms, time between acquire attempts if resource locked
    • refreshInterval - ms, auto-refresh interval

Example

const Mutex = require('redis-semaphore').Mutex
const Redis = require('ioredis')
 
// TypeScript
// import { Mutex } from 'redis-semaphore'
// import Redis from 'ioredis'
 
const redisClient = new Redis()
 
async function doSomething() {
  const mutex = new Mutex(redisClient, 'lockingResource')
  await mutex.acquire()
  // critical code
  await mutex.release()
}

Semaphore

See RedisLabs: Basic counting sempahore

new Semaphore(redisClient, key, maxCount [, { lockTimeout = 10000, acquireTimeout = 10000, retryInterval = 10, refreshInterval = lockTimeout * 0.8 }])
  • redisClient - required, configured redis client
  • key - required, key for locking resource (final key in redis: semaphore:<key>)
  • maxCount - required, maximum simultaneously resource usage count
  • timeouts optional
    • lockTimeout - ms, time after semaphore will be auto released (expired)
    • acquireTimeout - ms, max timeout for .acquire() call
    • retryInterval - ms, time between acquire attempts if resource locked
    • refreshInterval - ms, auto-refresh interval

Example

const Semaphore = require('redis-semaphore').Semaphore
const Redis = require('ioredis')
 
// TypeScript
// import { Semaphore } from 'redis-semaphore'
// import Redis from 'ioredis'
 
const redisClient = new Redis()
 
async function doSomething() {
  const semaphore = new Semaphore(redisClient, 'lockingResource', 5)
  await semaphore.acquire()
  // maximum 5 simultaneously executions
  await semaphore.release()
}

Fair Semaphore

See RedisLabs: Fair semaphore

new FairSemaphore(redisClient, key, maxCount [, { lockTimeout = 10000, acquireTimeout = 10000, retryInterval = 10, refreshInterval = lockTimeout * 0.8 }])
  • redisClient - required, configured redis client
  • key - required, key for locking resource (final key in redis: semaphore:<key>)
  • maxCount - required, maximum simultaneously resource usage count
  • timeouts optional
    • lockTimeout - ms, time after semaphore will be auto released (expired)
    • acquireTimeout - ms, max timeout for .acquire() call
    • retryInterval - ms, time between acquire attempts if resource locked
    • refreshInterval - ms, auto-refresh interval

Example

const FairSemaphore = require('redis-semaphore').FairSemaphore
const Redis = require('ioredis')
 
// TypeScript
// import { FairSemaphore } from 'redis-semaphore'
// import Redis from 'ioredis'
 
const redisClient = new Redis()
 
async function doSomething() {
  const semaphore = new FairSemaphore(redisClient, 'lockingResource', 5)
  await semaphore.acquire()
  // maximum 5 simultaneously executions
  await semaphore.release()
}

License

MIT

FOSSA Status

Install

npm i redis-semaphore

DownloadsWeekly Downloads

3,161

Version

2.1.1

License

MIT

Unpacked Size

308 kB

Total Files

134

Last publish

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