chore: add heartbeat

packages/extension/src/background.ts

@@ -5,7 +5,7 @@
 
 /* global chrome */
 
 import '@polkadot/extension-inject/crossenv';
 
 import type { RequestSignatures, TransportRequestMessage } from '@polkadot/extension-base/background/types';
 
@@ -15,6 +15,7 @@
 import { keyring } from '@polkadot/ui-keyring';
 import { assert } from '@polkadot/util';
 import { cryptoWaitReady } from '@polkadot/util-crypto';
+import { runHeartbeat, startHeartbeat } from './heartbeat';
 
 // setup the notification (same a FF default background, white text)
 withErrorLog(() => chrome.action.setBadgeBackgroundColor({ color: '#d90000' }));
@@ -77,6 +78,27 @@
   getActiveTabs();
 });
 
+// add heartbeat using alarms to prevent the service worker from being killed as
+// much as possible.
+chrome.alarms.onAlarm.addListener(async () => {
+  await runHeartbeat()
+});
+
+chrome.runtime.onInstalled.addListener(({ reason }) => {
+  if (
+    reason !== chrome.runtime.OnInstalledReason.INSTALL &&
+    reason !== chrome.runtime.OnInstalledReason.UPDATE
+  ) {
+    return;
+  }
+
+  chrome.alarms.create('heartbeat', {
+    periodInMinutes: 0.5
+  });
+});
+
+startHeartbeat();
+
 // initial setup
 cryptoWaitReady()
   .then((): void => {

packages/extension/src/heartbeat.ts

@@ -0,0 +1,39 @@
+// Copyright 2019-2024 @polkadot/extension authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+/**
+ * Heartbeat functions as described by google.
+ *
+ * @see https://developer.chrome.com/docs/extensions/develop/migrate/to-service-workers#keep_a_service_worker_alive_continuously
+ */
+
+let heartbeatInterval: string | number | NodeJS.Timeout | undefined;
+
+export async function runHeartbeat () {
+  await chrome.storage.local.set({ 'last-heartbeat': new Date().getTime() });
+}
+
+/**
+ * Starts the heartbeat interval which keeps the service worker alive. Call
+ * this sparingly when you are doing work which requires persistence, and call
+ * stopHeartbeat once that work is complete.
+ */
+export async function startHeartbeat () {
+  // Run the heartbeat once at service worker startup.
+  runHeartbeat().then(() => {
+    // Then again every 20 seconds.
+    heartbeatInterval = setInterval(runHeartbeat, 20 * 1000);
+  });
+}
+
+export async function stopHeartbeat () {
+  clearInterval(heartbeatInterval);
+}
+
+/**
+ * Returns the last heartbeat stored in extension storage, or undefined if
+ * the heartbeat has never run before.
+ */
+export async function getLastHeartbeat () {
+  return (await chrome.storage.local.get('last-heartbeat'))['last-heartbeat'];
+}