polling using redux-saga

index.ts

import { delay } from 'redux-saga';
import { put, take, race, call, cancel, takeEvery } from 'redux-saga/effects';
import { Upload, addJob, removeJob } from '../actions/job';

function* upload(action: Upload) {
  try {
    const { file, jobId: id } = action.payload;

    yield put(addJob({ id }));

    // polling
    while (true) {
      const { end } = yield race({
        poll: call(poll, file),
        end: take('POLL_END')
      });

      if (end) {
        yield put(removeJob({ id }));
        yield cancel();
      }
    }
  } catch (e) {
    yield put({ type: 'ERROR' });
  }
}

function* poll(file: File) {
  while (true) {
    try {
      const { status } = yield fetchFoo(file);

      if (status === 'ok') yield put({ type: 'POLL_END' });
      yield call(delay, 5000);
    } catch (e) {
      yield put({ type: 'POLL_ERROR' });
    }
  }
}

export function* uploadingProcess() {
  yield takeEvery('UPLOAD', upload); // don't use takeLatest for parallel processing
}

export function* rootSaga() {
  yield all([fork(uploadingProcess)]);
}