Cache graph log

app/controllers/projects/graphs_controller.rb

@@ -8,10 +8,18 @@ class Projects::GraphsController < Projects::ApplicationController
     respond_to do |format|
       format.html
       format.js do
-        @repo = @project.repository
-        @stats = Gitlab::Git::GitStats.new(@repo.raw, @repo.root_ref)
-        @log = @stats.parsed_log.to_json rescue []
+        fetch_graph
       end
     end
   end
+
+  private
+
+  def fetch_graph
+    @log = @project.repository.graph_log.to_json
+    @success = true
+  rescue => ex
+    @log = []
+    @success = false
+  end
 end

app/models/repository.rb

@@ -61,6 +61,14 @@ class Repository
     Rails.cache.delete(cache_key(:size))
     Rails.cache.delete(cache_key(:branch_names))
     Rails.cache.delete(cache_key(:tag_names))
+    Rails.cache.delete(cache_key(:graph_log))
+  end
+
+  def graph_log
+    Rails.cache.fetch(cache_key(:graph)) do
+      stats = Gitlab::Git::GitStats.new(raw, root_ref)
+      stats.parsed_log
+    end
   end
 
   def cache_key(type)

app/views/projects/graphs/show.js.haml

-:plain
+- if @success
+  :plain
     controller = new ContributorsStatGraph
     controller.init(#{@log})
 
@@ -13,4 +14,6 @@
       controller.change_date_header()
       controller.redraw_authors()
     })
-
+- else
+  :plain
+    $('.stat-graph').replaceWith('<div class="alert alert-error">Failed to load graph</div>')