[Blocking Task Queue] #nodejs

blocking-task-queue.js

const EventEmitter = require('events')

class TaskQueue extends EventEmitter {
  constructor(size) {
    super()
    this.size = size
    this.jobs = new Set()
  }

  async push(task) {
    while (this.jobs.size >= this.size) {
      await new Promise(resolve => this.once('pop', resolve))
    }
    const id = Symbol()
    this.jobs.add(id)
    task().finally(() => {
      this.jobs.delete(id)
      this.emit('pop')
    })
  }
}