Support Markdown rendering using multiple projectsrendering-markdown-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.

1 files changed, 11 insertions, 9 deletions

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