add support for commit (in mr) to reference filter

app/controllers/concerns/renders_notes.rb

@@ -3,7 +3,7 @@ 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, @project, noteable_context(noteable))
 
     notes
   end
@@ -26,4 +26,13 @@ module RendersNotes
 
     notes.each {|n| n.specialize_for_first_contribution!(noteable)}
   end
+
+  def noteable_context(noteable)
+    case noteable
+    when MergeRequest
+      { merge_request: noteable }
+    else
+      {}
+    end
+  end
 end

app/models/merge_request.rb

@@ -1042,4 +1042,13 @@ class MergeRequest < ActiveRecord::Base
 
     project.merge_requests.merged.where(author_id: author_id).empty?
   end
+
+  def banzai_render_context(field)
+    # this will be used to reference these commit in the context of the MR
+    # the URL are built differently
+    {
+      merge_request: self,
+      mr_commit_shas: all_commit_shas
+    }
+  end
 end

app/models/note.rb

@@ -379,6 +379,42 @@ class Note < ActiveRecord::Base
     Gitlab::EtagCaching::Store.new.touch(key)
   end
 
+  def touch(*args)
+    # We're not using an explicit transaction here because this would in all
+    # cases result in all future queries going to the primary, even if no writes
+    # are performed.
+    #
+    # We touch the noteable first so its SELECT query can run before our writes,
+    # ensuring it runs on a secondary (if no prior write took place).
+    touch_noteable
+    super
+  end
+
+  # By default Rails will issue an "SELECT *" for the relation, which is
+  # overkill for just updating the timestamps. To work around this we manually
+  # touch the data so we can SELECT only the columns we need.
+  def touch_noteable
+    # Commits are not stored in the DB so we can't touch them.
+    return if for_commit?
+
+    assoc = association(:noteable)
+
+    noteable_object =
+      if assoc.loaded?
+        noteable
+      else
+        # If the object is not loaded (e.g. when notes are loaded async) we
+        # _only_ want the data we actually need.
+        assoc.scope.select(:id, :updated_at).take
+      end
+
+    noteable_object&.touch
+  end
+
+  def banzai_render_context(field)
+    super.merge(noteable: noteable)
+  end
+
   private
 
   def keep_around_commit

app/views/projects/commits/_commit.html.haml

@@ -4,7 +4,7 @@
 - ref = local_assigns.fetch(:ref) { merge_request&.source_branch }
 - link = commit_path(project, commit, merge_request: merge_request)
 
-- cache_key = [project.full_path, commit.id, current_application_settings, @path.presence, current_controller?(:commits), merge_request.iid, view_details, I18n.locale]
+- cache_key = [project.full_path, commit.id, current_application_settings, @path.presence, current_controller?(:commits), merge_request&.iid, view_details, I18n.locale]
 - cache_key.push(commit.status(ref)) if commit.status(ref)
 
 -# EE-only

lib/banzai/filter/commit_reference_filter.rb

@@ -24,8 +24,18 @@ module Banzai
 
       def url_for_object(commit, project)
         h = Gitlab::Routing.url_helpers
-        h.project_commit_url(project, commit,
-                                        only_path: context[:only_path])
+        noteable = context[:merge_request] || context[:noteable]
+
+        if noteable.is_a?(MergeRequest) &&
+           noteable.all_commit_shas.include?(commit.id)
+
+          # the internal shas are in the context?
+          # why not preload in the object?, just make sure we have the same ref
+          # in all the rendering
+          h.diffs_project_merge_request_url(project, noteable, commit_id: commit.id)
+        else
+          h.project_commit_url(project, commit, only_path: context[:only_path])
+        end
       end
 
       def object_link_text_extras(object, matches)

lib/banzai/object_renderer.rb

@@ -18,10 +18,10 @@ module Banzai
     # project - A Project to use for redacting Markdown.
     # user - The user viewing the Markdown/HTML documents, if any.
     # context - A Hash containing extra attributes to use during redaction
-    def initialize(project, user = nil, redaction_context = {})
+    def initialize(project, user = nil, context = {})
       @project = project
       @user = user
-      @redaction_context = redaction_context
+      @context = base_context.merge(context)
     end
 
     # Renders and redacts an Array of objects.
@@ -48,7 +48,8 @@ module Banzai
       pipeline = HTML::Pipeline.new([])
 
       objects.map do |object|
-        pipeline.to_document(Banzai.render_field(object, attribute))
+        context = context_for(object, attribute)
+        pipeline.to_document(Banzai.render_field(object, attribute, context))
       end
     end
 
@@ -73,20 +74,19 @@ module Banzai
 
     # Returns a Banzai context for the given object and attribute.
     def context_for(object, attribute)
-      base_context.merge(object.banzai_render_context(attribute))
+      @context.merge(object.banzai_render_context(attribute))
     end
 
     def base_context
-      @base_context ||= @redaction_context.merge(
+      {
         current_user: user,
         project: project,
         skip_redaction: true
-      )
+      }
     end
 
     def save_options
-      return {} unless base_context[:xhtml]
-
+      return {} unless @context[:xhtml]
       { save_with: Nokogiri::XML::Node::SaveOptions::AS_XHTML }
     end
   end