Smarter refreshing of authorized projects

Prior to this commit the refreshing of authorized projects was done in
two steps:

1. Remove existing authorizations
2. Insert a new list of all authorizations

This can lead to a high amount of dead tuples as every time all rows are
being replaced. For example, if a user with 100 authorizations is given
access to a new project this would lead to:

* 100 rows being removed
* 101 new rows being inserted

This commit changes the way this system works so it only removes/inserts
what is necessary. Using the above example this would lead to only 1 new
row being inserted, with the initial 100 being left untouched.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/25257

1 files changed, 25 insertions, 0 deletions

diff --git a/spec/models/project_authorization_spec.rb b/spec/models/project_authorization_spec.rb
new file mode 100644
index 00000000000..33ef67f97a7
--- /dev/null
+++ b/spec/models/project_authorization_spec.rb
@@ -0,0 +1,25 @@
+require 'spec_helper'
+
+describe ProjectAuthorization do
+  let(:user) { create(:user) }
+  let(:project1) { create(:empty_project) }
+  let(:project2) { create(:empty_project) }
+
+  describe '.insert_authorizations' do
+    it 'inserts the authorizations' do
+      described_class.
+        insert_authorizations([[user.id, project1.id, Gitlab::Access::MASTER]])
+
+      expect(user.project_authorizations.count).to eq(1)
+    end
+
+    it 'inserts rows in batches' do
+      described_class.insert_authorizations([
+        [user.id, project1.id, Gitlab::Access::MASTER],
+        [user.id, project2.id, Gitlab::Access::MASTER],
+      ], 1)
+
+      expect(user.project_authorizations.count).to eq(2)
+    end
+  end
+end