Enable label reference caching

to reduce SQL queries

Changelog: performance

ee/spec/lib/banzai/filter/references/epic_reference_filter_spec.rb

@@ -278,13 +278,15 @@ RSpec.describe Banzai::Filter::References::EpicReferenceFilter do
         reference_filter(markdown, context)
       end.count
 
+      expect(control_count).to eq 1
+
       markdown = "#{epic.to_reference} #{epic.group.full_path}&9999991 #{epic.group.full_path}&9999992 &9999993 #{epic2.to_reference(group)} #{epic2.group.full_path}&9999991 something/cool&12"
 
       # Since we're not batching queries across groups,
       # we have to account for that.
       # 1 for both groups, 1 for epics in each group == 3
       # TODO: https://gitlab.com/gitlab-org/gitlab/-/issues/330359
-      max_count = control_count + 1
+      max_count = control_count + 2
 
       expect do
         reference_filter(markdown, context)

lib/banzai/filter/references/label_reference_filter.rb

@@ -8,21 +8,57 @@ module Banzai
         self.reference_type = :label
         self.object_class   = Label
 
+        def parent_records(parent, ids)
+          return Label.none unless parent.is_a?(Project) || parent.is_a?(Group)
+
+          labels         = find_labels(parent)
+          label_ids      = ids.map {|y| y[:label_id]}.compact
+          label_names    = ids.map {|y| y[:label_name]}.compact
+          id_relation    = labels.where(id: label_ids)
+          label_relation = labels.where(title: label_names)
+
+          Label.from_union([id_relation, label_relation])
+        end
+
         def find_object(parent_object, id)
-          find_labels(parent_object).find(id)
+          key = reference_cache.records_per_parent[parent_object].keys.find do |k|
+            k[:label_id] == id[:label_id] || k[:label_name] == id[:label_name]
+          end
+
+          reference_cache.records_per_parent[parent_object][key] if key
+        end
+
+        # Transform a symbol extracted from the text to a meaningful value
+        #
+        # This method has the contract that if a string `ref` refers to a
+        # record `record`, then `parse_symbol(ref) == record_identifier(record)`.
+        #
+        # This contract is slightly broken here, as we only have either the label_id
+        # or the label_name, but not both.  But below, we have both pieces of information.
+        # But it's accounted for in `find_object`
+        def parse_symbol(symbol, match_data)
+          { label_id: match_data[:label_id]&.to_i, label_name: match_data[:label_name]&.tr('"', '') }
+        end
+
+        # We assume that most classes are identifying records by ID.
+        #
+        # This method has the contract that if a string `ref` refers to a
+        # record `record`, then `class.parse_symbol(ref) == record_identifier(record)`.
+        # See note in `parse_symbol` above
+        def record_identifier(record)
+          { label_id: record.id, label_name: record.title }
         end
 
         def references_in(text, pattern = Label.reference_pattern)
           labels = {}
-          unescaped_html = unescape_html_entities(text).gsub(pattern) do |match|
-            namespace = $~[:namespace]
-            project = $~[:project]
-            project_path = reference_cache.full_project_path(namespace, project)
-            label = find_label_cached(project_path, $~[:label_id], $~[:label_name])
-
-            if label
-              labels[label.id] = yield match, label.id, project, namespace, $~
-              "#{REFERENCE_PLACEHOLDER}#{label.id}"
+
+          unescaped_html = unescape_html_entities(text).gsub(pattern).with_index do |match, index|
+            ident = identifier($~)
+            label = yield match, ident, $~[:project], $~[:namespace], $~
+
+            if label != match
+              labels[index] = label
+              "#{REFERENCE_PLACEHOLDER}#{index}"
             else
               match
             end
@@ -33,20 +69,6 @@ module Banzai
           escape_with_placeholders(unescaped_html, labels)
         end
 
-        def find_label_cached(parent_ref, label_id, label_name)
-          cached_call(:banzai_find_label_cached, label_name&.tr('"', '') || label_id, path: [object_class, parent_ref]) do
-            find_label(parent_ref, label_id, label_name)
-          end
-        end
-
-        def find_label(parent_ref, label_id, label_name)
-          parent = parent_from_ref(parent_ref)
-          return unless parent
-
-          label_params = label_params(label_id, label_name)
-          find_labels(parent).find_by(label_params)
-        end
-
         def find_labels(parent)
           params = if parent.is_a?(Group)
                      { group_id: parent.id,
@@ -60,21 +82,6 @@ module Banzai
           LabelsFinder.new(nil, params).execute(skip_authorization: true)
         end
 
-        # Parameters to pass to `Label.find_by` based on the given arguments
-        #
-        # id   - Integer ID to pass. If present, returns {id: id}
-        # name - String name to pass. If `id` is absent, finds by name without
-        #        surrounding quotes.
-        #
-        # Returns a Hash.
-        def label_params(id, name)
-          if name
-            { name: name.tr('"', '') }
-          else
-            { id: id.to_i }
-          end
-        end
-
         def url_for_object(label, parent)
           label_url_method =
             if context[:label_url_method]
@@ -121,6 +128,14 @@ module Banzai
           presenter = object.present(issuable_subject: project || group)
           LabelsHelper.label_tooltip_title(presenter)
         end
+
+        def parent
+          project || group
+        end
+
+        def requires_unescaping?
+          true
+        end
       end
     end
   end

lib/banzai/filter/references/reference_cache.rb

@@ -29,15 +29,15 @@ module Banzai
             refs = Hash.new { |hash, key| hash[key] = Set.new }
 
             nodes.each do |node|
-              node.to_html.scan(regex) do
-                path = if parent_type == :project
+              prepare_node_for_scan(node).scan(regex) do
+                parent_path = if parent_type == :project
                                 full_project_path($~[:namespace], $~[:project])
                               else
                                 full_group_path($~[:group])
                               end
 
                 ident = filter.identifier($~)
-                refs[path] << ident if ident
+                refs[parent_path] << ident if ident
               end
             end
 
@@ -55,9 +55,23 @@ module Banzai
           @per_reference ||= {}
 
           @per_reference[parent_type] ||= begin
-            refs = references_per_parent.keys.to_set
+            refs = references_per_parent.keys
+            parent_ref = {}
 
-            find_for_paths(refs.to_a).index_by(&:full_path)
+            # if we already have a parent, no need to query it again
+            refs.each do |ref|
+              next unless ref
+
+              if context[:project]&.full_path == ref
+                parent_ref[ref] = context[:project]
+              elsif context[:group]&.full_path == ref
+                parent_ref[ref] = context[:group]
+              end
+
+              refs -= [ref] if parent_ref[ref]
+            end
+
+            find_for_paths(refs).index_by(&:full_path).merge(parent_ref)
           end
         end
 
@@ -87,7 +101,7 @@ module Banzai
           @_records_per_project[filter.object_class.to_s.underscore]
         end
 
-        def relation_for_paths(paths)
+        def objects_for_paths(paths)
           klass = parent_type.to_s.camelize.constantize
           result = klass.where_full_path_in(paths)
           return result if parent_type == :group
@@ -102,7 +116,7 @@ module Banzai
             to_query = paths - cache.keys
 
             unless to_query.empty?
-              records = relation_for_paths(to_query)
+              records = objects_for_paths(to_query)
 
               found = []
               records.each do |record|
@@ -119,7 +133,7 @@ module Banzai
 
             cache.slice(*paths).values.compact
           else
-            relation_for_paths(paths)
+            objects_for_paths(paths)
           end
         end
 
@@ -170,6 +184,16 @@ module Banzai
         def refs_cache
           Gitlab::SafeRequestStore["banzai_#{parent_type}_refs".to_sym] ||= {}
         end
+
+        def prepare_node_for_scan(node)
+          html = node.to_html
+
+          filter.requires_unescaping? ? unescape_html_entities(html) : html
+        end
+
+        def unescape_html_entities(text)
+          CGI.unescapeHTML(text.to_s)
+        end
       end
     end
   end

lib/banzai/filter/references/reference_filter.rb

@@ -109,6 +109,10 @@ module Banzai
           context[:group]
         end
 
+        def requires_unescaping?
+          false
+        end
+
         private
 
         # Returns a data attribute String to attach to a reference link

spec/lib/banzai/filter/references/label_reference_filter_spec.rb

@@ -702,4 +702,72 @@ RSpec.describe Banzai::Filter::References::LabelReferenceFilter do
       expect(result.css('a').first.text).to eq "#{label.name} in #{project.full_name}"
     end
   end
+
+  context 'checking N+1' do
+    let_it_be(:group)              { create(:group) }
+    let_it_be(:group2)             { create(:group) }
+    let_it_be(:project)            { create(:project, :public, namespace: group) }
+    let_it_be(:project2)           { create(:project, :public, namespace: group2) }
+    let_it_be(:project3)           { create(:project, :public) }
+    let_it_be(:project_label)      { create(:label, project: project) }
+    let_it_be(:project_label2)     { create(:label, project: project) }
+    let_it_be(:project2_label)     { create(:label, project: project2) }
+    let_it_be(:group2_label)       { create(:group_label, group: group2, color: '#00ff00') }
+    let_it_be(:project_reference)  { "#{project_label.to_reference}" }
+    let_it_be(:project_reference2) { "#{project_label2.to_reference}" }
+    let_it_be(:project2_reference) { "#{project2_label.to_reference}" }
+    let_it_be(:group2_reference)   { "#{project2.full_path}~#{group2_label.name}" }
+
+    it 'does not have N+1 per multiple references per project', :use_sql_query_cache do
+      markdown = "#{project_reference}"
+      control_count = 1
+
+      expect do
+        reference_filter(markdown)
+      end.not_to exceed_all_query_limit(control_count)
+
+      markdown = "#{project_reference} ~qwert ~werty ~ertyu ~rtyui #{project_reference2}"
+
+      expect do
+        reference_filter(markdown)
+      end.not_to exceed_all_query_limit(control_count)
+    end
+
+    it 'has N+1 for multiple unique project/group references', :use_sql_query_cache do
+      # reference to already loaded project, only one query
+      markdown = "#{project_reference}"
+      control_count = 1
+
+      expect do
+        reference_filter(markdown, project: project)
+      end.not_to exceed_all_query_limit(control_count)
+
+      # Since we're not batching label queries across projects/groups,
+      # queries increase when a new project/group is added.
+      # TODO: https://gitlab.com/gitlab-org/gitlab/-/issues/330359
+      # first reference to already loaded project (1),
+      # second reference requires project and namespace (2), and label (1)
+      markdown = "#{project_reference} #{group2_reference}"
+      max_count = control_count + 3
+
+      expect do
+        reference_filter(markdown)
+      end.not_to exceed_all_query_limit(max_count)
+
+      # third reference to already queried project/namespace, nothing extra (no N+1 here)
+      markdown = "#{project_reference} #{group2_reference} #{project2_reference}"
+
+      expect do
+        reference_filter(markdown)
+      end.not_to exceed_all_query_limit(max_count)
+
+      # last reference needs another namespace and label query (2)
+      markdown = "#{project_reference} #{group2_reference} #{project2_reference} #{project3.full_path}~test_label"
+      max_count += 2
+
+      expect do
+        reference_filter(markdown)
+      end.not_to exceed_all_query_limit(max_count)
+    end
+  end
 end

spec/lib/banzai/filter/references/reference_cache_spec.rb

@@ -55,11 +55,12 @@ RSpec.describe Banzai::Filter::References::ReferenceCache do
         cache_single.load_records_per_parent
       end.count
 
+      expect(control_count).to eq 1
+
       # Since this is an issue filter that is not batching issue queries
       # across projects, we have to account for that.
-      # 1 for both projects, 1 for issues in each project == 3
-      # TODO: https://gitlab.com/gitlab-org/gitlab/-/issues/330359
-      max_count = control_count + 1
+      # 1 for original issue, 2 for second route/project, 1 for other issue
+      max_count = control_count + 3
 
       expect do
         cache.load_references_per_parent(filter.nodes)

spec/lib/banzai/filter/references/snippet_reference_filter_spec.rb

@@ -233,13 +233,15 @@ RSpec.describe Banzai::Filter::References::SnippetReferenceFilter do
         reference_filter(markdown)
       end.count
 
+      expect(control_count).to eq 1
+
       markdown = "#{reference} $9999990 $9999991 $9999992 $9999993 #{reference2} something/cool$12"
 
       # Since we're not batching snippet queries across projects,
       # we have to account for that.
       # 1 for both projects, 1 for snippets in each project == 3
       # TODO: https://gitlab.com/gitlab-org/gitlab/-/issues/330359
-      max_count = control_count + 1
+      max_count = control_count + 2
 
       expect do
         reference_filter(markdown)

spec/lib/gitlab/import_export/project/tree_restorer_spec.rb

@@ -600,9 +600,8 @@ RSpec.describe Gitlab::ImportExport::Project::TreeRestorer do
           setup_import_export_config('light')
           setup_reader(reader)
 
-          expect(project)
-            .to receive(:merge_requests)
-            .and_raise(exception)
+          expect(project).to receive(:merge_requests).and_call_original
+          expect(project).to receive(:merge_requests).and_raise(exception)
         end
 
         it 'report post import error' do
@@ -618,12 +617,9 @@ RSpec.describe Gitlab::ImportExport::Project::TreeRestorer do
           setup_import_export_config('light')
           setup_reader(reader)
 
-          expect(project)
-            .to receive(:merge_requests)
-            .and_raise(exception)
-          expect(project)
-            .to receive(:merge_requests)
-            .and_call_original
+          expect(project).to receive(:merge_requests).and_call_original
+          expect(project).to receive(:merge_requests).and_raise(exception)
+          expect(project).to receive(:merge_requests).and_call_original
           expect(restored_project_json).to eq(true)
         end