Add notification grouping for follow notifications (#32085)

app/javascript/mastodon/actions/notification_groups.ts

@@ -68,10 +68,15 @@ function dispatchAssociatedRecords(
     dispatch(importFetchedStatuses(fetchedStatuses));
 }
 
+const supportedGroupedNotificationTypes = ['favourite', 'reblog'];
+
 export const fetchNotifications = createDataLoadingThunk(
   'notificationGroups/fetch',
   async (_params, { getState }) =>
-    apiFetchNotificationGroups({ exclude_types: getExcludedTypes(getState()) }),
+    apiFetchNotificationGroups({
+      grouped_types: supportedGroupedNotificationTypes,
+      exclude_types: getExcludedTypes(getState()),
+    }),
   ({ notifications, accounts, statuses }, { dispatch }) => {
     dispatch(importFetchedAccounts(accounts));
     dispatch(importFetchedStatuses(statuses));
@@ -93,6 +98,7 @@ export const fetchNotificationsGap = createDataLoadingThunk(
   'notificationGroups/fetchGap',
   async (params: { gap: NotificationGap }, { getState }) =>
     apiFetchNotificationGroups({
+      grouped_types: supportedGroupedNotificationTypes,
       max_id: params.gap.maxId,
       exclude_types: getExcludedTypes(getState()),
     }),
@@ -109,6 +115,7 @@ export const pollRecentNotifications = createDataLoadingThunk(
   'notificationGroups/pollRecentNotifications',
   async (_params, { getState }) => {
     return apiFetchNotificationGroups({
+      grouped_types: supportedGroupedNotificationTypes,
       max_id: undefined,
       exclude_types: getExcludedTypes(getState()),
       // In slow mode, we don't want to include notifications that duplicate the already-displayed ones

app/javascript/mastodon/api/notifications.ts

@@ -31,6 +31,7 @@ export const apiFetchNotifications = async (
 
 export const apiFetchNotificationGroups = async (params?: {
   url?: string;
+  grouped_types?: string[];
   exclude_types?: string[];
   max_id?: string;
   since_id?: string;

app/models/notification.rb

@@ -20,6 +20,7 @@ class Notification < ApplicationRecord
   self.inheritance_column = nil
 
   include Paginable
+  include Redisable
 
   LEGACY_TYPE_CLASS_MAP = {
     'Mention' => :mention,
@@ -30,7 +31,9 @@ class Notification < ApplicationRecord
     'Poll' => :poll,
   }.freeze
 
-  GROUPABLE_NOTIFICATION_TYPES = %i(favourite reblog).freeze
+  # `set_group_key!` needs to be updated if this list changes
+  GROUPABLE_NOTIFICATION_TYPES = %i(favourite reblog follow).freeze
+  MAXIMUM_GROUP_SPAN_HOURS = 12
 
   # Please update app/javascript/api_types/notification.ts if you change this
   PROPERTIES = {
@@ -123,6 +126,30 @@ class Notification < ApplicationRecord
     end
   end
 
+  def set_group_key!
+    return if filtered? || Notification::GROUPABLE_NOTIFICATION_TYPES.exclude?(type)
+
+    type_prefix = case type
+                  when :favourite, :reblog
+                    [type, target_status&.id].join('-')
+                  when :follow
+                    type
+                  else
+                    raise NotImplementedError
+                  end
+    redis_key   = "notif-group/#{account.id}/#{type_prefix}"
+    hour_bucket = activity.created_at.utc.to_i / 1.hour.to_i
+
+    # Reuse previous group if it does not span too large an amount of time
+    previous_bucket = redis.get(redis_key).to_i
+    hour_bucket = previous_bucket if hour_bucket < previous_bucket + MAXIMUM_GROUP_SPAN_HOURS
+
+    # We do not concern ourselves with race conditions since we use hour buckets
+    redis.set(redis_key, hour_bucket, ex: MAXIMUM_GROUP_SPAN_HOURS.hours.to_i)
+
+    self.group_key = "#{type_prefix}-#{hour_bucket}"
+  end
+
   class << self
     def browserable(types: [], exclude_types: [], from_account_id: nil, include_filtered: false)
       requested_types = if types.empty?

app/services/notify_service.rb

@@ -3,8 +3,6 @@
 class NotifyService < BaseService
   include Redisable
 
-  MAXIMUM_GROUP_SPAN_HOURS = 12
-
   # TODO: the severed_relationships type probably warrants email notifications
   NON_EMAIL_TYPES = %i(
     admin.report
@@ -216,7 +214,7 @@ class NotifyService < BaseService
     return if drop?
 
     @notification.filtered = filter?
-    @notification.group_key = notification_group_key
+    @notification.set_group_key!
     @notification.save!
 
     # It's possible the underlying activity has been deleted
@@ -236,23 +234,6 @@ class NotifyService < BaseService
 
   private
 
-  def notification_group_key
-    return nil if @notification.filtered || Notification::GROUPABLE_NOTIFICATION_TYPES.exclude?(@notification.type)
-
-    type_prefix = "#{@notification.type}-#{@notification.target_status.id}"
-    redis_key   = "notif-group/#{@recipient.id}/#{type_prefix}"
-    hour_bucket = @notification.activity.created_at.utc.to_i / 1.hour.to_i
-
-    # Reuse previous group if it does not span too large an amount of time
-    previous_bucket = redis.get(redis_key).to_i
-    hour_bucket = previous_bucket if hour_bucket < previous_bucket + MAXIMUM_GROUP_SPAN_HOURS
-
-    # We do not concern ourselves with race conditions since we use hour buckets
-    redis.set(redis_key, hour_bucket, ex: MAXIMUM_GROUP_SPAN_HOURS.hours.to_i)
-
-    "#{type_prefix}-#{hour_bucket}"
-  end
-
   def drop?
     DropCondition.new(@notification).drop?
   end