Does not refresh project statistics on read-only instance

ProjectStatistics#refresh! may be run on a Geo secondary

app/models/project_statistics.rb

@@ -37,6 +37,8 @@ class ProjectStatistics < ApplicationRecord
   end
 
   def refresh!(only: [])
+    return if Gitlab::Database.read_only?
+
     COLUMNS_TO_REFRESH.each do |column, generator|
       if only.empty? || only.include?(column)
         public_send("update_#{column}") # rubocop:disable GitlabSecurity/PublicSend

spec/models/project_statistics_spec.rb

@@ -201,6 +201,23 @@ RSpec.describe ProjectStatistics do
         statistics.refresh!(only: [:commit_count])
       end
     end
+
+    context 'when the database is read-only' do
+      it 'does nothing' do
+        allow(Gitlab::Database).to receive(:read_only?) { true }
+
+        expect(statistics).not_to receive(:update_commit_count)
+        expect(statistics).not_to receive(:update_repository_size)
+        expect(statistics).not_to receive(:update_wiki_size)
+        expect(statistics).not_to receive(:update_lfs_objects_size)
+        expect(statistics).not_to receive(:update_snippets_size)
+        expect(statistics).not_to receive(:save!)
+        expect(Namespaces::ScheduleAggregationWorker)
+          .not_to receive(:perform_async)
+
+        statistics.refresh!
+      end
+    end
   end
 
   describe '#update_commit_count' do