ntfy/web/src/app/Poller.js

import api from "./Api";
import subscriptionManager from "./SubscriptionManager";

const delayMillis = 2000; // 2 seconds
const intervalMillis = 300000; // 5 minutes

class Poller {
  constructor() {
    this.timer = null;
  }

  startWorker() {
    if (this.timer !== null) {
      return;
    }
    console.log(`[Poller] Starting worker`);
    this.timer = setInterval(() => this.pollAll(), intervalMillis);
    setTimeout(() => this.pollAll(), delayMillis);
  }

  async pollAll() {
    console.log(`[Poller] Polling all subscriptions`);
    const subscriptions = await subscriptionManager.all();
    for (const s of subscriptions) {
      try {
        // TODO(eslint): Switch to Promise.all
        // eslint-disable-next-line no-await-in-loop
        await this.poll(s);
      } catch (e) {
        console.log(`[Poller] Error polling ${s.id}`, e);
      }
    }
  }

  async poll(subscription) {
    console.log(`[Poller] Polling ${subscription.id}`);

    const since = subscription.last;
    const notifications = await api.poll(subscription.baseUrl, subscription.topic, since);
    if (!notifications || notifications.length === 0) {
      console.log(`[Poller] No new notifications found for ${subscription.id}`);
      return;
    }
    console.log(`[Poller] Adding ${notifications.length} notification(s) for ${subscription.id}`);
    await subscriptionManager.addNotifications(subscription.id, notifications);
  }

  pollInBackground(subscription) {
    const fn = async () => {
      try {
        await this.poll(subscription);
      } catch (e) {
        console.error(`[App] Error polling subscription ${subscription.id}`, e);
      }
    };
    setTimeout(() => fn(), 0);
  }
}

const poller = new Poller();
export default poller;