Semaphore

A very simple Semaphore, with an easy to use API and excellent TypeScript typings.

Installation

npm install --save ts-semaphore

Usage

const Semaphore = require('ts-semaphore')

const limit = new Semaphore(2)

// Only two requests will be sent at a time

limit.use(async () => {
  console.log((await fetch('https://google.com/')).code)
})

limit.use(async () => {
  console.log((await fetch('https://twitter.com/')).code)
})

limit.use(async () => {
  console.log((await fetch('https://facebook.com/')).code)
})

API

new Semaphore(limit: number)

Creates a new Semaphore instance.

Semaphore#aquire(): Promise<void>

Aquire a lock from the semaphore, returns a Promise that resolves when the caller holds a lock.

Semaphore#release(): void

Release a lock back to the semaphore.

Semaphore#use<T>(fn: () => T | PromiseLike<T>): Promise<T>

Aquire a lock from the semaphore, then run fn. If fn returns a Promise, wait for that promise to settle, then release the lock back to the semaphore.

Returns a Promise that will settle with the return value of fn.