Function monitorHandler

service/src/modifyHandler.ts:58–83

(
  opts: MonitorOptions,
  handler: (req: TRequest) => ObservableInput<TNext>
)

 * Useful for getting progress events from effects that don't notify of progress intrinsically.
 */
export function monitorHandler<TRequest, TNext>(
  opts: MonitorOptions,
  handler: (req: TRequest) => ObservableInput<TNext>
): (req: TRequest) => Observable<TNext> {
  const { interval, progressCallback } = opts;
  return (req: TRequest) => {
    const monitorElapsed = rxjsInterval(interval).pipe(
      map((i) => (i + 1) * interval),
      startWith(0)
    );

    let monitorSub = new Subscription();
    const handlingResult = from(handler(req)).pipe(
      tap({
        subscribe() {
          monitorSub = monitorElapsed.subscribe({ next: progressCallback });
        },
        finalize() {
          monitorSub.unsubscribe();
        },
      })
    );

    return handlingResult;
  };
}