fix(background/Heartbeat): use alarm instead of storage.set (#495)

Co-authored-by: Radu-Cristian Popa <[email protected]>

src/background/services/heartbeat.ts

@@ -1,19 +1,43 @@
-import type { StorageService } from '.'
+import type { Browser } from 'webextension-polyfill'
 
 export class Heartbeat {
-  private interval: ReturnType<typeof setInterval>
-
-  constructor(private storage: StorageService) {}
+  constructor(private browser: Browser) {}
 
   start() {
-    this.interval = setInterval(this.run.bind(this), 20 * 1000)
-  }
+    const alarms = this.browser.alarms
+    // The minimum supported cross-browser period is 1 minute. So, we create 4
+    // alarms at a 0,15,30,45 seconds delay. So, we'll get an alarm every 15s -
+    // and that'll help us keep the background script alive.
+
+    // Note that the first alarm will trigger after a minute, but this maybe
+    // fine for our use case, as we may have enough events between start and
+    // first minute that our extension stays alive.
+    setTimeout(
+      () => alarms.create('keep-alive-alarm-0', { periodInMinutes: 1 }),
+      0
+    )
+    setTimeout(
+      () => alarms.create('keep-alive-alarm-1', { periodInMinutes: 1 }),
+      15 * 1000
+    )
+    setTimeout(
+      () => alarms.create('keep-alive-alarm-2', { periodInMinutes: 1 }),
+      30 * 1000
+    )
+    setTimeout(
+      () => alarms.create('keep-alive-alarm-3', { periodInMinutes: 1 }),
+      45 * 1000
+    )
 
-  run() {
-    void this.storage.get(['version'])
+    alarms.onAlarm.addListener(() => {
+      // doing nothing is enough to keep it alive
+    })
   }
 
   stop() {
-    clearInterval(this.interval)
+    this.browser.alarms.clear('keep-alive-alarm-0')
+    this.browser.alarms.clear('keep-alive-alarm-1')
+    this.browser.alarms.clear('keep-alive-alarm-2')
+    this.browser.alarms.clear('keep-alive-alarm-3')
   }
 }