2017/06/13 [Medium] redux-saga factories and decorators

04_network_down.js

export function* checkConnection () {
  let interval = 1

  // eslint-disable-next-line no-constant-condition
  while (true) {
    // race == wait for effect which comes first
    const { timeout, up } = yield race({
      // ping triggered manually
      // e.g: 'reconnect now' button
      ping: take(action.networkPing),

      // sth recovered network
      up: take(action.networkUp),

      // wait before next ping
      timeout: call(delay, interval * 1000)
    })

    // nothing happened, trigger ping and wait for next
    if (timeout) {
      yield put(action.networkPing())
      interval = Math.min(60, interval * 2)
    } else if (up) {
      break
    }
  }
}

export function* ping () {
  const pingTimeout = 5000
  const { ping } = yield race({
    ping: call(pingRequest),
    timeout: call(delay, pingTimeout)
  })

  if (ping) {
    yield put(action.networkUp())
  }
}

export default function* () {
  yield takeLatest(action.networkPing, ping)
  yield takeLatest(action.networkDown, checkConnection)
}