Merge branch 'fix/remove-extra-notifications-fetch' into 'develop'

Fix: notifications fetcher double fetching on every tick

See merge request pleroma/pleroma-fe!1164

src/services/backend_interactor_service/backend_interactor_service.js

@@ -12,10 +12,6 @@ const backendInteractorService = credentials => ({
     return notificationsFetcher.startFetching({ store, credentials })
   },
 
-  fetchAndUpdateNotifications ({ store }) {
-    return notificationsFetcher.fetchAndUpdate({ store, credentials })
-  },
-
   startFetchingFollowRequests ({ store }) {
     return followRequestFetcher.startFetching({ store, credentials })
   },

src/services/notifications_fetcher/notifications_fetcher.service.js

@@ -27,14 +27,18 @@ const fetchAndUpdate = ({ store, credentials, older = false }) => {
     }
     const result = fetchNotifications({ store, args, older })
 
-    // load unread notifications repeatedly to provide consistency between browser tabs
+    // If there's any unread notifications, try fetch notifications since
+    // the newest read notification to check if any of the unread notifs
+    // have changed their 'seen' state (marked as read in another session), so
+    // we can update the state in this session to mark them as read as well.
+    // The normal maxId-check does not tell if older notifications have changed
     const notifications = timelineData.data
     const readNotifsIds = notifications.filter(n => n.seen).map(n => n.id)
-    if (readNotifsIds.length) {
+    const numUnseenNotifs = notifications.length - readNotifsIds.length
+    if (numUnseenNotifs > 0) {
       args['since'] = Math.max(...readNotifsIds)
       fetchNotifications({ store, args, older })
     }
-
     return result
   }
 }