Short Polling

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?

The issue provides a proposed TypeScript HttpShortPoll implementation but names no repository files or tests. Start by reading ofetch’s public API and test layout, then determine where polling belongs and verify interval, timeout, response, error, and stop behavior.