Short Polling

[tjx666]

Describe the feature

Why

Nowadays, many ai services are provided by http api, the task normally cost long time, http short polling is a simple way to get the result. For example: https://platform.tripo3d.ai/docs/task#polling

Solution

I previous implement it like following:

import EventEmitter from 'events'

import { omit } from 'lodash-es'
import type { Promisable } from 'type-fest'

interface EventData<D extends Record<string, any> = {}> {
  start: void
  response: D
  error: any
  stop: void
}

type Event = keyof EventData

type Options = RequestInit & {
  interval?: number
  pollingTimeout?: number
}

/**
 * Http Short Polling
 */
export class HttpShortPoll<D> extends EventEmitter {
  url: string
  status: 'init' | 'polling' | 'stopped' = 'init'
  _pollingTimer: NodeJS.Timeout | null = null
  _startTimestamp: number | null = null
  options: Options = {
    interval: 1000,
    // 20 minutes
    pollingTimeout: 1000 * 60 * 20,
  }

  constructor(url: string, options?: Options) {
    super()
    this.url = url
    this.options = { ...this.options, ...options }
  }

  on<E extends Event>(event: E, listener: (data: EventData<D>[E]) => Promisable<void>) {
    return super.on(event, listener)
  }

  emit<E extends Event>(event: E, data?: EventData<D>[E]) {
    return super.emit(event, data)
  }

  start() {
    if (this.status !== 'init') {
      return
    }

    this.status = 'polling'
    this.emit('start')
    this._startTimestamp = Date.now()

    this._pollingTimer = setInterval(async () => {
      if (this.status !== 'polling') {
        return
      }

      if (Date.now() - this._startTimestamp > this.options.pollingTimeout) {
        this.stop()
        return
      }

      try {
        const resp = await fetch(this.url, omit(this.options, ['interval', 'pollingTimeout']))
        const json = await resp.json()
        this.emit('response', json as D)
      } catch (error) {
        console.error(error)
        this.emit('error', error)
        return
      }
    }, this.options.interval)
  }

  stop() {
    this.status = 'stopped'

    if (this._pollingTimer) {
      clearInterval(this._pollingTimer)
      this._pollingTimer = null
    }

    this.emit('stop')
  }
}

// for example
const poll = new HttpShortPoll('https://api.example.com/data', {
  interval: 1000,
  pollingTimeout: 10000,
})
poll.on('start', () => {
  console.log('Polling started')
})
poll.on('response', (data) => {
  console.log('Data received:', data)
})
poll.on('error', (error) => {
  console.error('Error:', error)
})
poll.on('stop', () => {
  console.log('Polling stopped')
})

Additional information

• Would you be willing to help implement this feature?