Merge branch 'master' into ce-to-ee-2017-12-12

app/models/merge_request.rb

@@ -9,6 +9,7 @@ class MergeRequest < ActiveRecord::Base
   include ManualInverseAssociation
   include EachBatch
   include ThrottledTouch
+  include Gitlab::Utils::StrongMemoize
 
   ignore_column :locked_at,
                 :ref_fetched
@@ -56,6 +57,7 @@ class MergeRequest < ActiveRecord::Base
   serialize :merge_params, Hash # rubocop:disable Cop/ActiveRecordSerialize
 
   after_create :ensure_merge_request_diff, unless: :importing?
+  after_update :clear_memoized_shas
   after_update :reload_diff_if_branch_changed
 
   # When this attribute is true some MR validation is ignored
@@ -404,14 +406,18 @@ class MergeRequest < ActiveRecord::Base
   end
 
   def source_branch_head
-    return unless source_project
-
-    source_project.repository.commit(source_branch_ref) if source_branch_ref
+    strong_memoize(:source_branch_head) do
+      if source_project && source_branch_ref
+        source_project.repository.commit(source_branch_ref)
+      end
+    end
   end
 
   def target_branch_head
+    strong_memoize(:target_branch_head) do
       target_project.repository.commit(target_branch_ref)
     end
+  end
 
   def branch_merge_base_commit
     start_sha = target_branch_sha
@@ -558,6 +564,13 @@ class MergeRequest < ActiveRecord::Base
     end
   end
 
+  def clear_memoized_shas
+    @target_branch_sha = @source_branch_sha = nil
+
+    clear_memoization(:source_branch_head)
+    clear_memoization(:target_branch_head)
+  end
+
   def reload_diff_if_branch_changed
     if (source_branch_changed? || target_branch_changed?) &&
         (source_branch_head && target_branch_head)

app/models/merge_request_diff.rb

@@ -104,19 +104,19 @@ class MergeRequestDiff < ActiveRecord::Base
   def base_commit
     return unless base_commit_sha
 
-    project.commit(base_commit_sha)
+    project.commit_by(oid: base_commit_sha)
   end
 
   def start_commit
     return unless start_commit_sha
 
-    project.commit(start_commit_sha)
+    project.commit_by(oid: start_commit_sha)
   end
 
   def head_commit
     return unless head_commit_sha
 
-    project.commit(head_commit_sha)
+    project.commit_by(oid: head_commit_sha)
   end
 
   def commit_shas

changelogs/unreleased/zj-memoization-mr-commits.yml

+---
+title: Cache commits for MergeRequest diffs
+merge_request:
+author:
+type: performance

config/application.rb

@@ -51,6 +51,10 @@ module Gitlab
       #{config.root}/ee/app/helpers
     ])
 
+    # Rake tasks ignore the eager loading settings, so we need to set the
+    # autoload paths explicitly
+    config.autoload_paths = config.eager_load_paths.dup
+
     # Only load the plugins named here, in the order given (default is alphabetical).
     # :all can be used as a placeholder for all plugins not explicitly named.
     # config.plugins = [ :exception_notification, :ssl_requirement, :all ]