PERF: limit unread count to 99 in blue circle

This revises: e605542c4e

Previous commit was faulty

app/models/user.rb

@@ -439,26 +439,36 @@ class User < ActiveRecord::Base
   # expensive queries
   MAX_UNREAD_NOTIFICATIONS = 99
 
+  def self.max_unread_notifications
+    @max_unread_notifications ||= MAX_UNREAD_NOTIFICATIONS
+  end
+
+  def self.max_unread_notifications=(val)
+    @max_unread_notifications = val
+  end
+
   def unread_notifications
     @unread_notifications ||= begin
       # perf critical, much more efficient than AR
       sql = <<~SQL
-        SELECT COUNT(*) FROM notifications n
-        LEFT JOIN topics t ON t.id = n.topic_id
-         WHERE t.deleted_at IS NULL AND
-          n.notification_type <> :pm AND
-          n.user_id = :user_id AND
-          n.id > :seen_notification_id AND
-          NOT read
-        LIMIT :limit
-
+        SELECT COUNT(*) FROM (
+          SELECT 1 FROM
+          notifications n
+          LEFT JOIN topics t ON t.id = n.topic_id
+           WHERE t.deleted_at IS NULL AND
+            n.notification_type <> :pm AND
+            n.user_id = :user_id AND
+            n.id > :seen_notification_id AND
+            NOT read
+          LIMIT :limit
+        ) AS X
       SQL
 
       DB.query_single(sql,
         user_id: id,
         seen_notification_id: seen_notification_id,
         pm:  Notification.types[:private_message],
-        limit: MAX_UNREAD_NOTIFICATIONS
+        limit: User.max_unread_notifications
     )[0].to_i
     end
   end

spec/models/user_spec.rb

@@ -1668,6 +1668,26 @@ describe User do
     end
   end
 
+  describe "#unread_notifications" do
+    before do
+      User.max_unread_notifications = 3
+    end
+
+    after do
+      User.max_unread_notifications = nil
+    end
+
+    it "limits to MAX_UNREAD_NOTIFICATIONS" do
+      user = Fabricate(:user)
+
+      4.times do
+        Notification.create!(user_id: user.id, notification_type: 1, read: false, data: '{}')
+      end
+
+      expect(user.unread_notifications).to eq(3)
+    end
+  end
+
   describe "#unstage" do
     let!(:staged_user) { Fabricate(:staged, email: 'staged@account.com', active: true, username: 'staged1', name: 'Stage Name') }
     let(:params) { { email: 'staged@account.com', active: true, username: 'unstaged1', name: 'Foo Bar' } }