From daad7144ec7c0173439eeadd61590442e40a6051 Mon Sep 17 00:00:00 2001
From: Yorick Peterse <yorickpeterse@gmail.com>
Date: Tue, 3 Apr 2018 15:45:17 +0200
Subject: [PATCH] Support Markdown rendering using multiple projects

This refactors the Markdown pipeline so it supports the rendering of
multiple documents that may belong to different projects. An example of
where this happens is when displaying the event feed of a group. In this
case we retrieve events for all projects in the group. Previously we
would group events per project and render these chunks separately, but
this would result in many SQL queries being executed. By extending the
Markdown pipeline to support this out of the box we can drastically
reduce the number of SQL queries.

To achieve this we introduce a new object to the pipeline:
Banzai::RenderContext. This object simply wraps two other objects: an
optional Project instance, and an optional User instance. On its own
this wouldn't be very helpful, but a RenderContext can also be used to
associate HTML documents with specific Project instances. This work is
done in Banzai::ObjectRenderer and allows us to reuse as many queries
(and results) as possible.
---
 app/controllers/concerns/notes_actions.rb     |  4 +-
 app/controllers/concerns/renders_notes.rb     |  2 +-
 app/controllers/groups_controller.rb          |  4 +-
 app/controllers/projects/notes_controller.rb  |  2 +-
 app/helpers/markup_helper.rb                  |  2 +-
 app/services/events/render_service.rb         | 12 +++---
 app/services/notes/render_service.rb          | 13 +++----
 .../rendering-markdown-multiple-projects.yml  |  5 +++
 lib/banzai/commit_renderer.rb                 |  2 +-
 lib/banzai/filter/issuable_state_filter.rb    |  3 +-
 lib/banzai/filter/redactor_filter.rb          |  6 ++-
 lib/banzai/issuable_extractor.rb              | 14 ++++---
 lib/banzai/object_renderer.rb                 | 32 ++++++++-------
 lib/banzai/redactor.rb                        | 20 +++++-----
 lib/banzai/reference_extractor.rb             |  4 +-
 lib/banzai/reference_parser/base_parser.rb    | 16 ++++++--
 lib/banzai/reference_parser/issue_parser.rb   | 39 ++++++++++++++-----
 lib/banzai/reference_parser/user_parser.rb    |  3 +-
 lib/banzai/render_context.rb                  | 32 +++++++++++++++
 spec/lib/banzai/commit_renderer_spec.rb       |  5 ++-
 spec/lib/banzai/issuable_extractor_spec.rb    |  2 +-
 spec/lib/banzai/object_renderer_spec.rb       |  9 ++++-
 spec/lib/banzai/redactor_spec.rb              |  4 +-
 .../reference_parser/base_parser_spec.rb      | 18 ++++++++-
 .../reference_parser/commit_parser_spec.rb    |  2 +-
 .../commit_range_parser_spec.rb               |  2 +-
 .../external_issue_parser_spec.rb             |  2 +-
 .../reference_parser/issue_parser_spec.rb     |  2 +-
 .../reference_parser/label_parser_spec.rb     |  2 +-
 .../merge_request_parser_spec.rb              |  2 +-
 .../reference_parser/milestone_parser_spec.rb |  2 +-
 .../reference_parser/snippet_parser_spec.rb   |  2 +-
 .../reference_parser/user_parser_spec.rb      |  2 +-
 spec/lib/banzai/render_context_spec.rb        | 37 ++++++++++++++++++
 spec/services/events/render_service_spec.rb   |  6 +--
 spec/services/notes/render_service_spec.rb    | 25 +++++++-----
 spec/support/filter_spec_helper.rb            |  5 +++
 spec/support/reference_parser_helpers.rb      |  8 +++-
 38 files changed, 254 insertions(+), 98 deletions(-)
 create mode 100644 changelogs/unreleased/rendering-markdown-multiple-projects.yml
 create mode 100644 lib/banzai/render_context.rb
 create mode 100644 spec/lib/banzai/render_context_spec.rb

diff --git a/app/controllers/concerns/notes_actions.rb b/app/controllers/concerns/notes_actions.rb
index 839cac3687c..ad4e936a3d4 100644
--- a/app/controllers/concerns/notes_actions.rb
+++ b/app/controllers/concerns/notes_actions.rb
@@ -41,7 +41,7 @@ module NotesActions
     @note = Notes::CreateService.new(note_project, current_user, create_params).execute
 
     if @note.is_a?(Note)
-      Notes::RenderService.new(current_user).execute([@note], @project)
+      Notes::RenderService.new(current_user).execute([@note])
     end
 
     respond_to do |format|
@@ -56,7 +56,7 @@ module NotesActions
     @note = Notes::UpdateService.new(project, current_user, note_params).execute(note)
 
     if @note.is_a?(Note)
-      Notes::RenderService.new(current_user).execute([@note], @project)
+      Notes::RenderService.new(current_user).execute([@note])
     end
 
     respond_to do |format|
diff --git a/app/controllers/concerns/renders_notes.rb b/app/controllers/concerns/renders_notes.rb
index e7ef297879f..36e3d76ecfe 100644
--- a/app/controllers/concerns/renders_notes.rb
+++ b/app/controllers/concerns/renders_notes.rb
@@ -4,7 +4,7 @@ module RendersNotes
     preload_noteable_for_regular_notes(notes)
     preload_max_access_for_authors(notes, @project)
     preload_first_time_contribution_for_authors(noteable, notes)
-    Notes::RenderService.new(current_user).execute(notes, @project)
+    Notes::RenderService.new(current_user).execute(notes)
 
     notes
   end
diff --git a/app/controllers/groups_controller.rb b/app/controllers/groups_controller.rb
index 283c3e5f1e0..5ac4b8710e2 100644
--- a/app/controllers/groups_controller.rb
+++ b/app/controllers/groups_controller.rb
@@ -173,7 +173,9 @@ class GroupsController < Groups::ApplicationController
       .new(@projects, offset: params[:offset].to_i, filter: event_filter)
       .to_a
 
-    Events::RenderService.new(current_user).execute(@events, atom_request: request.format.atom?)
+    Events::RenderService
+      .new(current_user)
+      .execute(@events, atom_request: request.format.atom?)
   end
 
   def user_actions
diff --git a/app/controllers/projects/notes_controller.rb b/app/controllers/projects/notes_controller.rb
index dd41b9648e8..86c50d88a2a 100644
--- a/app/controllers/projects/notes_controller.rb
+++ b/app/controllers/projects/notes_controller.rb
@@ -68,7 +68,7 @@ class Projects::NotesController < Projects::ApplicationController
   private
 
   def render_json_with_notes_serializer
-    Notes::RenderService.new(current_user).execute([note], project)
+    Notes::RenderService.new(current_user).execute([note])
 
     render json: note_serializer.represent(note)
   end
diff --git a/app/helpers/markup_helper.rb b/app/helpers/markup_helper.rb
index 2fe1927a189..39e7a7fd396 100644
--- a/app/helpers/markup_helper.rb
+++ b/app/helpers/markup_helper.rb
@@ -256,7 +256,7 @@ module MarkupHelper
     return '' unless html.present?
 
     context.merge!(
-      current_user:   (current_user if defined?(current_user)),
+      current_user: (current_user if defined?(current_user)),
 
       # RelativeLinkFilter
       commit:         @commit,
diff --git a/app/services/events/render_service.rb b/app/services/events/render_service.rb
index 0b62d8aedf1..bb72d7685dd 100644
--- a/app/services/events/render_service.rb
+++ b/app/services/events/render_service.rb
@@ -1,15 +1,17 @@
 module Events
   class RenderService < BaseRenderer
     def execute(events, atom_request: false)
-      events.map(&:note).compact.group_by(&:project).each do |project, notes|
-        render_notes(notes, project, atom_request)
-      end
+      notes = events.map(&:note).compact
+
+      render_notes(notes, atom_request)
     end
 
     private
 
-    def render_notes(notes, project, atom_request)
-      Notes::RenderService.new(current_user).execute(notes, project, render_options(atom_request))
+    def render_notes(notes, atom_request)
+      Notes::RenderService
+        .new(current_user)
+        .execute(notes, render_options(atom_request))
     end
 
     def render_options(atom_request)
diff --git a/app/services/notes/render_service.rb b/app/services/notes/render_service.rb
index a77e98c2b07..efc9d6da2aa 100644
--- a/app/services/notes/render_service.rb
+++ b/app/services/notes/render_service.rb
@@ -3,19 +3,18 @@ module Notes
     # Renders a collection of Note instances.
     #
     # notes - The notes to render.
-    # project - The project to use for redacting.
-    # user - The user viewing the notes.
-
+    #
     # Possible options:
+    #
     # requested_path - The request path.
     # project_wiki - The project's wiki.
     # ref - The current Git reference.
     # only_path - flag to turn relative paths into absolute ones.
     # xhtml - flag to save the html in XHTML
-    def execute(notes, project, **opts)
-      renderer = Banzai::ObjectRenderer.new(project, current_user, **opts)
-
-      renderer.render(notes, :note)
+    def execute(notes, options = {})
+      Banzai::ObjectRenderer
+        .new(user: current_user, redaction_context: options)
+        .render(notes, :note)
     end
   end
 end
diff --git a/changelogs/unreleased/rendering-markdown-multiple-projects.yml b/changelogs/unreleased/rendering-markdown-multiple-projects.yml
new file mode 100644
index 00000000000..8685772c089
--- /dev/null
+++ b/changelogs/unreleased/rendering-markdown-multiple-projects.yml
@@ -0,0 +1,5 @@
+---
+title: Support Markdown rendering using multiple projects
+merge_request:
+author:
+type: performance
diff --git a/lib/banzai/commit_renderer.rb b/lib/banzai/commit_renderer.rb
index f5ff95e3eb3..c351a155ae5 100644
--- a/lib/banzai/commit_renderer.rb
+++ b/lib/banzai/commit_renderer.rb
@@ -3,7 +3,7 @@ module Banzai
     ATTRIBUTES = [:description, :title].freeze
 
     def self.render(commits, project, user = nil)
-      obj_renderer = ObjectRenderer.new(project, user)
+      obj_renderer = ObjectRenderer.new(user: user, default_project: project)
 
       ATTRIBUTES.each { |attr| obj_renderer.render(commits, attr) }
     end
diff --git a/lib/banzai/filter/issuable_state_filter.rb b/lib/banzai/filter/issuable_state_filter.rb
index 8f541dcfdb2..1a415232545 100644
--- a/lib/banzai/filter/issuable_state_filter.rb
+++ b/lib/banzai/filter/issuable_state_filter.rb
@@ -11,7 +11,8 @@ module Banzai
       def call
         return doc unless context[:issuable_state_filter_enabled]
 
-        extractor = Banzai::IssuableExtractor.new(project, current_user)
+        context = RenderContext.new(project, current_user)
+        extractor = Banzai::IssuableExtractor.new(context)
         issuables = extractor.extract([doc])
 
         issuables.each do |node, issuable|
diff --git a/lib/banzai/filter/redactor_filter.rb b/lib/banzai/filter/redactor_filter.rb
index 9f9882b3b40..caf11fe94c4 100644
--- a/lib/banzai/filter/redactor_filter.rb
+++ b/lib/banzai/filter/redactor_filter.rb
@@ -7,7 +7,11 @@ module Banzai
     #
     class RedactorFilter < HTML::Pipeline::Filter
       def call
-        Redactor.new(project, current_user).redact([doc]) unless context[:skip_redaction]
+        unless context[:skip_redaction]
+          context = RenderContext.new(project, current_user)
+
+          Redactor.new(context).redact([doc])
+        end
 
         doc
       end
diff --git a/lib/banzai/issuable_extractor.rb b/lib/banzai/issuable_extractor.rb
index 49603d0b363..ae7dc71e7eb 100644
--- a/lib/banzai/issuable_extractor.rb
+++ b/lib/banzai/issuable_extractor.rb
@@ -12,11 +12,11 @@ module Banzai
       [@data-reference-type="issue" or @data-reference-type="merge_request"]
     ).freeze
 
-    attr_reader :project, :user
+    attr_reader :context
 
-    def initialize(project, user)
-      @project = project
-      @user = user
+    # context - An instance of Banzai::RenderContext.
+    def initialize(context)
+      @context = context
     end
 
     # Returns Hash in the form { node => issuable_instance }
@@ -25,8 +25,10 @@ module Banzai
         document.xpath(QUERY)
       end
 
-      issue_parser = Banzai::ReferenceParser::IssueParser.new(project, user)
-      merge_request_parser = Banzai::ReferenceParser::MergeRequestParser.new(project, user)
+      issue_parser = Banzai::ReferenceParser::IssueParser.new(context)
+
+      merge_request_parser =
+        Banzai::ReferenceParser::MergeRequestParser.new(context)
 
       issuables_for_nodes = issue_parser.records_for_nodes(nodes).merge(
         merge_request_parser.records_for_nodes(nodes)
diff --git a/lib/banzai/object_renderer.rb b/lib/banzai/object_renderer.rb
index 2691be81623..a176f1e261b 100644
--- a/lib/banzai/object_renderer.rb
+++ b/lib/banzai/object_renderer.rb
@@ -13,14 +13,13 @@ module Banzai
   # As an example, rendering the attribute `note` would place the unredacted
   # HTML into `note_html` and the redacted HTML into `redacted_note_html`.
   class ObjectRenderer
-    attr_reader :project, :user
+    attr_reader :context
 
-    # project - A Project to use for redacting Markdown.
+    # default_project - A default Project to use for redacting Markdown.
     # user - The user viewing the Markdown/HTML documents, if any.
     # redaction_context - A Hash containing extra attributes to use during redaction
-    def initialize(project, user = nil, redaction_context = {})
-      @project = project
-      @user = user
+    def initialize(default_project: nil, user: nil, redaction_context: {})
+      @context = RenderContext.new(default_project, user)
       @redaction_context = base_context.merge(redaction_context)
     end
 
@@ -48,17 +47,21 @@ module Banzai
       pipeline = HTML::Pipeline.new([])
 
       objects.map do |object|
-        pipeline.to_document(Banzai.render_field(object, attribute))
+        document = pipeline.to_document(Banzai.render_field(object, attribute))
+
+        context.associate_document(document, object)
+
+        document
       end
     end
 
     def post_process_documents(documents, objects, attribute)
       # Called here to populate cache, refer to IssuableExtractor docs
-      IssuableExtractor.new(project, user).extract(documents)
+      IssuableExtractor.new(context).extract(documents)
 
       documents.zip(objects).map do |document, object|
-        context = context_for(object, attribute)
-        Banzai::Pipeline[:post_process].to_document(document, context)
+        pipeline_context = context_for(document, object, attribute)
+        Banzai::Pipeline[:post_process].to_document(document, pipeline_context)
       end
     end
 
@@ -66,20 +69,21 @@ module Banzai
     #
     # Returns an Array containing the redacted documents.
     def redact_documents(documents)
-      redactor = Redactor.new(project, user)
+      redactor = Redactor.new(context)
 
       redactor.redact(documents)
     end
 
     # Returns a Banzai context for the given object and attribute.
-    def context_for(object, attribute)
-      @redaction_context.merge(object.banzai_render_context(attribute))
+    def context_for(document, object, attribute)
+      @redaction_context.merge(object.banzai_render_context(attribute)).merge(
+        project: context.project_for_node(document)
+      )
     end
 
     def base_context
       {
-        current_user: user,
-        project: project,
+        current_user: context.current_user,
         skip_redaction: true
       }
     end
diff --git a/lib/banzai/redactor.rb b/lib/banzai/redactor.rb
index fd457bebf03..28928d6f376 100644
--- a/lib/banzai/redactor.rb
+++ b/lib/banzai/redactor.rb
@@ -2,13 +2,15 @@ module Banzai
   # Class for removing Markdown references a certain user is not allowed to
   # view.
   class Redactor
-    attr_reader :user, :project
+    attr_reader :context
 
-    # project - A Project to use for redacting links.
-    # user - The currently logged in user (if any).
-    def initialize(project, user = nil)
-      @project = project
-      @user = user
+    # context - An instance of `Banzai::RenderContext`.
+    def initialize(context)
+      @context = context
+    end
+
+    def user
+      context.current_user
     end
 
     # Redacts the references in the given Array of documents.
@@ -70,11 +72,11 @@ module Banzai
     end
 
     def redact_cross_project_references(documents)
-      extractor = Banzai::IssuableExtractor.new(project, user)
+      extractor = Banzai::IssuableExtractor.new(context)
       issuables = extractor.extract(documents)
 
       issuables.each do |node, issuable|
-        next if issuable.project == project
+        next if issuable.project == context.project_for_node(node)
 
         node['class'] = node['class'].gsub('has-tooltip', '')
         node['title'] = nil
@@ -95,7 +97,7 @@ module Banzai
       end
 
       per_type.each do |type, nodes|
-        parser = Banzai::ReferenceParser[type].new(project, user)
+        parser = Banzai::ReferenceParser[type].new(context)
 
         visible.merge(parser.nodes_visible_to_user(user, nodes))
       end
diff --git a/lib/banzai/reference_extractor.rb b/lib/banzai/reference_extractor.rb
index 7e6357f8a00..78588299c18 100644
--- a/lib/banzai/reference_extractor.rb
+++ b/lib/banzai/reference_extractor.rb
@@ -10,8 +10,8 @@ module Banzai
     end
 
     def references(type, project, current_user = nil)
-      processor = Banzai::ReferenceParser[type]
-        .new(project, current_user)
+      context = RenderContext.new(project, current_user)
+      processor = Banzai::ReferenceParser[type].new(context)
 
       processor.process(html_documents)
     end
diff --git a/lib/banzai/reference_parser/base_parser.rb b/lib/banzai/reference_parser/base_parser.rb
index 279fca8d043..68752f5bb5a 100644
--- a/lib/banzai/reference_parser/base_parser.rb
+++ b/lib/banzai/reference_parser/base_parser.rb
@@ -45,9 +45,13 @@ module Banzai
         @data_attribute ||= "data-#{reference_type.to_s.dasherize}"
       end
 
-      def initialize(project = nil, current_user = nil)
-        @project = project
-        @current_user = current_user
+      # context - An instance of `Banzai::RenderContext`.
+      def initialize(context)
+        @context = context
+      end
+
+      def project_for_node(node)
+        context.project_for_node(node)
       end
 
       # Returns all the nodes containing references that the user can refer to.
@@ -224,7 +228,11 @@ module Banzai
 
       private
 
-      attr_reader :current_user, :project
+      attr_reader :context
+
+      def current_user
+        context.current_user
+      end
 
       # When a feature is disabled or visible only for
       # team members we should not allow team members
diff --git a/lib/banzai/reference_parser/issue_parser.rb b/lib/banzai/reference_parser/issue_parser.rb
index 230827129b6..6bee5ea15b9 100644
--- a/lib/banzai/reference_parser/issue_parser.rb
+++ b/lib/banzai/reference_parser/issue_parser.rb
@@ -5,15 +5,10 @@ module Banzai
 
       def nodes_visible_to_user(user, nodes)
         issues = records_for_nodes(nodes)
-        issues_to_check = issues.values
+        issues_to_check, cross_project_issues = partition_issues(issues, user)
 
-        unless can?(user, :read_cross_project)
-          issues_to_check, cross_project_issues = issues_to_check.partition do |issue|
-            issue.project == project
-          end
-        end
-
-        readable_issues = Ability.issues_readable_by_user(issues_to_check, user).to_set
+        readable_issues =
+          Ability.issues_readable_by_user(issues_to_check, user).to_set
 
         nodes.select do |node|
           issue_in_node = issues[node]
@@ -25,7 +20,7 @@ module Banzai
           # but not the issue.
           if readable_issues.include?(issue_in_node)
             true
-          elsif cross_project_issues&.include?(issue_in_node)
+          elsif cross_project_issues.include?(issue_in_node)
             can_read_reference?(user, issue_in_node)
           else
             false
@@ -33,6 +28,32 @@ module Banzai
         end
       end
 
+      # issues - A Hash mapping HTML nodes to their corresponding Issue
+      #          instances.
+      # user - The current User.
+      def partition_issues(issues, user)
+        return [issues.values, []] if can?(user, :read_cross_project)
+
+        issues_to_check = []
+        cross_project_issues = []
+
+        # We manually partition the data since our input is a Hash and our
+        # output has to be an Array of issues; not an Array of (node, issue)
+        # pairs.
+        issues.each do |node, issue|
+          target =
+            if issue.project == project_for_node(node)
+              issues_to_check
+            else
+              cross_project_issues
+            end
+
+          target << issue
+        end
+
+        [issues_to_check, cross_project_issues]
+      end
+
       def records_for_nodes(nodes)
         @issues_for_nodes ||= grouped_objects_for_nodes(
           nodes,
diff --git a/lib/banzai/reference_parser/user_parser.rb b/lib/banzai/reference_parser/user_parser.rb
index 8932d4f2905..ceb7f1d165c 100644
--- a/lib/banzai/reference_parser/user_parser.rb
+++ b/lib/banzai/reference_parser/user_parser.rb
@@ -58,7 +58,7 @@ module Banzai
       def can_read_project_reference?(node)
         node_id = node.attr('data-project').to_i
 
-        project && project.id == node_id
+        project_for_node(node)&.id == node_id
       end
 
       def nodes_user_can_reference(current_user, nodes)
@@ -71,6 +71,7 @@ module Banzai
         nodes.select do |node|
           project_id = node.attr(project_attr)
           user_id = node.attr(author_attr)
+          project = project_for_node(node)
 
           if project && project_id && project.id == project_id.to_i
             true
diff --git a/lib/banzai/render_context.rb b/lib/banzai/render_context.rb
new file mode 100644
index 00000000000..e30fc9f469b
--- /dev/null
+++ b/lib/banzai/render_context.rb
@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+module Banzai
+  # Object storing the current user, project, and other details used when
+  # parsing Markdown references.
+  class RenderContext
+    attr_reader :current_user
+
+    # default_project - The default project to use for all documents, if any.
+    # current_user - The user viewing the document, if any.
+    def initialize(default_project = nil, current_user = nil)
+      @current_user = current_user
+      @projects = Hash.new(default_project)
+    end
+
+    # Associates an HTML document with a Project.
+    #
+    # document - The HTML document to map to a Project.
+    # object - The object that produced the HTML document.
+    def associate_document(document, object)
+      # XML nodes respond to "document" but will return a Document instance,
+      # even when they belong to a DocumentFragment.
+      document = document.document if document.fragment?
+
+      @projects[document] = object.project if object.respond_to?(:project)
+    end
+
+    def project_for_node(node)
+      @projects[node.document]
+    end
+  end
+end
diff --git a/spec/lib/banzai/commit_renderer_spec.rb b/spec/lib/banzai/commit_renderer_spec.rb
index e7ebb2a332f..1f53657c59c 100644
--- a/spec/lib/banzai/commit_renderer_spec.rb
+++ b/spec/lib/banzai/commit_renderer_spec.rb
@@ -6,7 +6,10 @@ describe Banzai::CommitRenderer do
       user = build(:user)
       project = create(:project, :repository)
 
-      expect(Banzai::ObjectRenderer).to receive(:new).with(project, user).and_call_original
+      expect(Banzai::ObjectRenderer)
+        .to receive(:new)
+        .with(user: user, default_project: project)
+        .and_call_original
 
       described_class::ATTRIBUTES.each do |attr|
         expect_any_instance_of(Banzai::ObjectRenderer).to receive(:render).with([project.commit], attr).once.and_call_original
diff --git a/spec/lib/banzai/issuable_extractor_spec.rb b/spec/lib/banzai/issuable_extractor_spec.rb
index 69763476dac..f42951d9781 100644
--- a/spec/lib/banzai/issuable_extractor_spec.rb
+++ b/spec/lib/banzai/issuable_extractor_spec.rb
@@ -3,7 +3,7 @@ require 'spec_helper'
 describe Banzai::IssuableExtractor do
   let(:project) { create(:project) }
   let(:user) { create(:user) }
-  let(:extractor) { described_class.new(project, user) }
+  let(:extractor) { described_class.new(Banzai::RenderContext.new(project, user)) }
   let(:issue) { create(:issue, project: project) }
   let(:merge_request) { create(:merge_request, source_project: project) }
   let(:issue_link) do
diff --git a/spec/lib/banzai/object_renderer_spec.rb b/spec/lib/banzai/object_renderer_spec.rb
index 074d521a5c6..1fe034ae9a2 100644
--- a/spec/lib/banzai/object_renderer_spec.rb
+++ b/spec/lib/banzai/object_renderer_spec.rb
@@ -3,7 +3,14 @@ require 'spec_helper'
 describe Banzai::ObjectRenderer do
   let(:project) { create(:project, :repository) }
   let(:user) { project.owner }
-  let(:renderer) { described_class.new(project, user, custom_value: 'value') }
+  let(:renderer) do
+    described_class.new(
+      default_project: project,
+      user: user,
+      redaction_context: { custom_value: 'value' }
+    )
+  end
+
   let(:object) { Note.new(note: 'hello', note_html: '<p dir="auto">hello</p>', cached_markdown_version: CacheMarkdownField::CACHE_VERSION) }
 
   describe '#render' do
diff --git a/spec/lib/banzai/redactor_spec.rb b/spec/lib/banzai/redactor_spec.rb
index 441f3725985..aaeec953e4b 100644
--- a/spec/lib/banzai/redactor_spec.rb
+++ b/spec/lib/banzai/redactor_spec.rb
@@ -3,7 +3,7 @@ require 'spec_helper'
 describe Banzai::Redactor do
   let(:user) { create(:user) }
   let(:project) { build(:project) }
-  let(:redactor) { described_class.new(project, user) }
+  let(:redactor) { described_class.new(Banzai::RenderContext.new(project, user)) }
 
   describe '#redact' do
     context 'when reference not visible to user' do
@@ -54,7 +54,7 @@ describe Banzai::Redactor do
 
     context 'when project is in pending delete' do
       let!(:issue) { create(:issue, project: project) }
-      let(:redactor) { described_class.new(project, user) }
+      let(:redactor) { described_class.new(Banzai::RenderContext.new(project, user)) }
 
       before do
         project.update(pending_delete: true)
diff --git a/spec/lib/banzai/reference_parser/base_parser_spec.rb b/spec/lib/banzai/reference_parser/base_parser_spec.rb
index 6175d4c4ca9..4e6e8eca38a 100644
--- a/spec/lib/banzai/reference_parser/base_parser_spec.rb
+++ b/spec/lib/banzai/reference_parser/base_parser_spec.rb
@@ -5,13 +5,14 @@ describe Banzai::ReferenceParser::BaseParser do
 
   let(:user) { create(:user) }
   let(:project) { create(:project, :public) }
+  let(:context) { Banzai::RenderContext.new(project, user) }
 
   subject do
     klass = Class.new(described_class) do
       self.reference_type = :foo
     end
 
-    klass.new(project, user)
+    klass.new(context)
   end
 
   describe '.reference_type=' do
@@ -23,6 +24,19 @@ describe Banzai::ReferenceParser::BaseParser do
     end
   end
 
+  describe '#project_for_node' do
+    it 'returns the Project for a node' do
+      document = instance_double('document', fragment?: false)
+      project = instance_double('project')
+      object = instance_double('object', project: project)
+      node = instance_double('node', document: document)
+
+      context.associate_document(document, object)
+
+      expect(subject.project_for_node(node)).to eq(project)
+    end
+  end
+
   describe '#nodes_visible_to_user' do
     let(:link) { empty_html_link }
 
@@ -164,7 +178,7 @@ describe Banzai::ReferenceParser::BaseParser do
         self.reference_type = :test
       end
 
-      instance = dummy.new(project, user)
+      instance = dummy.new(Banzai::RenderContext.new(project, user))
       document = Nokogiri::HTML.fragment('<a class="gfm"></a><a class="gfm" data-reference-type="test"></a>')
 
       expect(instance).to receive(:gather_references)
diff --git a/spec/lib/banzai/reference_parser/commit_parser_spec.rb b/spec/lib/banzai/reference_parser/commit_parser_spec.rb
index 3505659c2c3..cca53a8b9b9 100644
--- a/spec/lib/banzai/reference_parser/commit_parser_spec.rb
+++ b/spec/lib/banzai/reference_parser/commit_parser_spec.rb
@@ -5,7 +5,7 @@ describe Banzai::ReferenceParser::CommitParser do
 
   let(:project) { create(:project, :public) }
   let(:user) { create(:user) }
-  subject { described_class.new(project, user) }
+  subject { described_class.new(Banzai::RenderContext.new(project, user)) }
   let(:link) { empty_html_link }
 
   describe '#nodes_visible_to_user' do
diff --git a/spec/lib/banzai/reference_parser/commit_range_parser_spec.rb b/spec/lib/banzai/reference_parser/commit_range_parser_spec.rb
index 21813177deb..23e16fe0213 100644
--- a/spec/lib/banzai/reference_parser/commit_range_parser_spec.rb
+++ b/spec/lib/banzai/reference_parser/commit_range_parser_spec.rb
@@ -5,7 +5,7 @@ describe Banzai::ReferenceParser::CommitRangeParser do
 
   let(:project) { create(:project, :public) }
   let(:user) { create(:user) }
-  subject { described_class.new(project, user) }
+  subject { described_class.new(Banzai::RenderContext.new(project, user)) }
   let(:link) { empty_html_link }
 
   describe '#nodes_visible_to_user' do
diff --git a/spec/lib/banzai/reference_parser/external_issue_parser_spec.rb b/spec/lib/banzai/reference_parser/external_issue_parser_spec.rb
index 25969b65168..1cb31e57114 100644
--- a/spec/lib/banzai/reference_parser/external_issue_parser_spec.rb
+++ b/spec/lib/banzai/reference_parser/external_issue_parser_spec.rb
@@ -5,7 +5,7 @@ describe Banzai::ReferenceParser::ExternalIssueParser do
 
   let(:project) { create(:project, :public) }
   let(:user) { create(:user) }
-  subject { described_class.new(project, user) }
+  subject { described_class.new(Banzai::RenderContext.new(project, user)) }
   let(:link) { empty_html_link }
 
   describe '#nodes_visible_to_user' do
diff --git a/spec/lib/banzai/reference_parser/issue_parser_spec.rb b/spec/lib/banzai/reference_parser/issue_parser_spec.rb
index cb7f8b20dda..77c2064caba 100644
--- a/spec/lib/banzai/reference_parser/issue_parser_spec.rb
+++ b/spec/lib/banzai/reference_parser/issue_parser_spec.rb
@@ -7,7 +7,7 @@ describe Banzai::ReferenceParser::IssueParser do
   let(:user)    { create(:user) }
   let(:issue)   { create(:issue, project: project) }
   let(:link)    { empty_html_link }
-  subject       { described_class.new(project, user) }
+  subject       { described_class.new(Banzai::RenderContext.new(project, user)) }
 
   describe '#nodes_visible_to_user' do
     context 'when the link has a data-issue attribute' do
diff --git a/spec/lib/banzai/reference_parser/label_parser_spec.rb b/spec/lib/banzai/reference_parser/label_parser_spec.rb
index b700161d6c2..e4df2533821 100644
--- a/spec/lib/banzai/reference_parser/label_parser_spec.rb
+++ b/spec/lib/banzai/reference_parser/label_parser_spec.rb
@@ -6,7 +6,7 @@ describe Banzai::ReferenceParser::LabelParser do
   let(:project) { create(:project, :public) }
   let(:user) { create(:user) }
   let(:label) { create(:label, project: project) }
-  subject { described_class.new(project, user) }
+  subject { described_class.new(Banzai::RenderContext.new(project, user)) }
   let(:link) { empty_html_link }
 
   describe '#nodes_visible_to_user' do
diff --git a/spec/lib/banzai/reference_parser/merge_request_parser_spec.rb b/spec/lib/banzai/reference_parser/merge_request_parser_spec.rb
index 14542342cf6..5417b1f00be 100644
--- a/spec/lib/banzai/reference_parser/merge_request_parser_spec.rb
+++ b/spec/lib/banzai/reference_parser/merge_request_parser_spec.rb
@@ -6,7 +6,7 @@ describe Banzai::ReferenceParser::MergeRequestParser do
   let(:user) { create(:user) }
   let(:project) { create(:project, :public) }
   let(:merge_request) { create(:merge_request, source_project: project) }
-  subject { described_class.new(project, user) }
+  subject { described_class.new(Banzai::RenderContext.new(merge_request.target_project, user)) }
   let(:link) { empty_html_link }
 
   describe '#nodes_visible_to_user' do
diff --git a/spec/lib/banzai/reference_parser/milestone_parser_spec.rb b/spec/lib/banzai/reference_parser/milestone_parser_spec.rb
index 7dacdf8d629..751d042ffde 100644
--- a/spec/lib/banzai/reference_parser/milestone_parser_spec.rb
+++ b/spec/lib/banzai/reference_parser/milestone_parser_spec.rb
@@ -6,7 +6,7 @@ describe Banzai::ReferenceParser::MilestoneParser do
   let(:project) { create(:project, :public) }
   let(:user) { create(:user) }
   let(:milestone) { create(:milestone, project: project) }
-  subject { described_class.new(project, user) }
+  subject { described_class.new(Banzai::RenderContext.new(project, user)) }
   let(:link) { empty_html_link }
 
   describe '#nodes_visible_to_user' do
diff --git a/spec/lib/banzai/reference_parser/snippet_parser_spec.rb b/spec/lib/banzai/reference_parser/snippet_parser_spec.rb
index 69ec3f66aa8..d410bd4c164 100644
--- a/spec/lib/banzai/reference_parser/snippet_parser_spec.rb
+++ b/spec/lib/banzai/reference_parser/snippet_parser_spec.rb
@@ -9,7 +9,7 @@ describe Banzai::ReferenceParser::SnippetParser do
   let(:external_user) { create(:user, :external) }
   let(:project_member) { create(:user) }
 
-  subject { described_class.new(project, user) }
+  subject { described_class.new(Banzai::RenderContext.new(project, user)) }
   let(:link) { empty_html_link }
 
   def visible_references(snippet_visibility, user = nil)
diff --git a/spec/lib/banzai/reference_parser/user_parser_spec.rb b/spec/lib/banzai/reference_parser/user_parser_spec.rb
index b079a3be029..112447f098e 100644
--- a/spec/lib/banzai/reference_parser/user_parser_spec.rb
+++ b/spec/lib/banzai/reference_parser/user_parser_spec.rb
@@ -6,7 +6,7 @@ describe Banzai::ReferenceParser::UserParser do
   let(:group) { create(:group) }
   let(:user) { create(:user) }
   let(:project) { create(:project, :public, group: group, creator: user) }
-  subject { described_class.new(project, user) }
+  subject { described_class.new(Banzai::RenderContext.new(project, user)) }
   let(:link) { empty_html_link }
 
   describe '#referenced_by' do
diff --git a/spec/lib/banzai/render_context_spec.rb b/spec/lib/banzai/render_context_spec.rb
new file mode 100644
index 00000000000..ad17db11613
--- /dev/null
+++ b/spec/lib/banzai/render_context_spec.rb
@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Banzai::RenderContext do
+  let(:document) { Nokogiri::HTML.fragment('<p>hello</p>') }
+
+  describe '#project_for_node' do
+    it 'returns the default project if no associated project was found' do
+      project = instance_double('project')
+      context = described_class.new(project)
+
+      expect(context.project_for_node(document)).to eq(project)
+    end
+
+    it 'returns the associated project if one was associated explicitly' do
+      project = instance_double('project')
+      obj = instance_double('object', project: project)
+      context = described_class.new
+
+      context.associate_document(document, obj)
+
+      expect(context.project_for_node(document)).to eq(project)
+    end
+
+    it 'returns the project associated with a DocumentFragment when using a node' do
+      project = instance_double('project')
+      obj = instance_double('object', project: project)
+      context = described_class.new
+      node = document.children.first
+
+      context.associate_document(document, obj)
+
+      expect(context.project_for_node(node)).to eq(project)
+    end
+  end
+end
diff --git a/spec/services/events/render_service_spec.rb b/spec/services/events/render_service_spec.rb
index b4a4a44d07b..075cb45e46c 100644
--- a/spec/services/events/render_service_spec.rb
+++ b/spec/services/events/render_service_spec.rb
@@ -9,9 +9,7 @@ describe Events::RenderService do
     context 'when the request format is atom' do
       it 'renders the note inside events' do
         expect(Banzai::ObjectRenderer).to receive(:new)
-          .with(event.project, user,
-                only_path: false,
-                xhtml: true)
+          .with(user: user, redaction_context: { only_path: false, xhtml: true })
           .and_call_original
 
         expect_any_instance_of(Banzai::ObjectRenderer)
@@ -24,7 +22,7 @@ describe Events::RenderService do
     context 'when the request format is not atom' do
       it 'renders the note inside events' do
         expect(Banzai::ObjectRenderer).to receive(:new)
-          .with(event.project, user, {})
+          .with(user: user, redaction_context: {})
           .and_call_original
 
         expect_any_instance_of(Banzai::ObjectRenderer)
diff --git a/spec/services/notes/render_service_spec.rb b/spec/services/notes/render_service_spec.rb
index faac498037f..f771620bc0d 100644
--- a/spec/services/notes/render_service_spec.rb
+++ b/spec/services/notes/render_service_spec.rb
@@ -4,23 +4,28 @@ describe Notes::RenderService do
   describe '#execute' do
     it 'renders a Note' do
       note = double(:note)
-      project = double(:project)
       wiki = double(:wiki)
       user = double(:user)
 
-      expect(Banzai::ObjectRenderer).to receive(:new)
-        .with(project, user,
-             requested_path: 'foo',
-             project_wiki: wiki,
-             ref: 'bar',
-             only_path: nil,
-             xhtml: false)
+      expect(Banzai::ObjectRenderer)
+        .to receive(:new)
+        .with(
+          user: user,
+          redaction_context: {
+              requested_path: 'foo',
+              project_wiki: wiki,
+              ref: 'bar',
+              only_path: nil,
+              xhtml: false
+          }
+        )
         .and_call_original
 
       expect_any_instance_of(Banzai::ObjectRenderer)
-        .to receive(:render).with([note], :note)
+        .to receive(:render)
+        .with([note], :note)
 
-      described_class.new(user).execute([note], project,
+      described_class.new(user).execute([note],
                                         requested_path: 'foo',
                                         project_wiki: wiki,
                                         ref: 'bar',
diff --git a/spec/support/filter_spec_helper.rb b/spec/support/filter_spec_helper.rb
index b871b7ffc90..721d359c2ee 100644
--- a/spec/support/filter_spec_helper.rb
+++ b/spec/support/filter_spec_helper.rb
@@ -18,6 +18,11 @@ module FilterSpecHelper
       context.reverse_merge!(project: project)
     end
 
+    render_context = Banzai::RenderContext
+      .new(context[:project], context[:current_user])
+
+    context = context.merge(render_context: render_context)
+
     described_class.call(html, context)
   end
 
diff --git a/spec/support/reference_parser_helpers.rb b/spec/support/reference_parser_helpers.rb
index 5d5e80851e6..c01897ed1a1 100644
--- a/spec/support/reference_parser_helpers.rb
+++ b/spec/support/reference_parser_helpers.rb
@@ -5,9 +5,11 @@ module ReferenceParserHelpers
 
   shared_examples 'no N+1 queries' do
     it 'avoids N+1 queries in #nodes_visible_to_user', :request_store do
+      context = Banzai::RenderContext.new(project, user)
+
       record_queries = lambda do |links|
         ActiveRecord::QueryRecorder.new do
-          described_class.new(project, user).nodes_visible_to_user(user, links)
+          described_class.new(context).nodes_visible_to_user(user, links)
         end
       end
 
@@ -19,9 +21,11 @@ module ReferenceParserHelpers
     end
 
     it 'avoids N+1 queries in #records_for_nodes', :request_store do
+      context = Banzai::RenderContext.new(project, user)
+
       record_queries = lambda do |links|
         ActiveRecord::QueryRecorder.new do
-          described_class.new(project, user).records_for_nodes(links)
+          described_class.new(context).records_for_nodes(links)
         end
       end