Cache the number of forks of a projectforks-count-cache

The number of forks of a project doesn't change very frequently and
running a COUNT(*) every time this information is requested can be quite
expensive. We also end up running such a COUNT(*) query at least twice
on the homepage of a project.

By caching this data and refreshing it when necessary we can reduce
project homepage loading times by around 60 milliseconds (based on the
timings of https://gitlab.com/gitlab-org/gitlab-ce).

1 files changed, 8 insertions, 0 deletions

diff --git a/spec/requests/api/v3/projects_spec.rb b/spec/requests/api/v3/projects_spec.rb
index fca5b5b5d82..a514166274a 100644
--- a/spec/requests/api/v3/projects_spec.rb
+++ b/spec/requests/api/v3/projects_spec.rb
@@ -1004,6 +1004,14 @@ describe API::V3::Projects do
         expect(project_fork_target.forked?).to be_truthy
       end
 
+      it 'refreshes the forks count cachce' do
+        expect(project_fork_source.forks_count).to be_zero
+
+        post v3_api("/projects/#{project_fork_target.id}/fork/#{project_fork_source.id}", admin)
+
+        expect(project_fork_source.forks_count).to eq(1)
+      end
+
       it 'fails if forked_from project which does not exist' do
         post v3_api("/projects/#{project_fork_target.id}/fork/9999", admin)
         expect(response).to have_http_status(404)