Fix high CPU usage when PostReceive receives refs/merge-requests/<id>

CHANGELOG

@@ -24,6 +24,7 @@ v 8.7.0 (unreleased)
   - API: Ability to filter milestones by state `active` and `closed` (Robert Schilling)
   - Implement 'Groups View' as an option for dashboard preferences !3379 (Elias W.)
   - Better errors handling when creating milestones inside groups
+  - Fix high CPU usage when PostReceive receives refs/merge-requests/<id>
   - Implement 'TODOs View' as an option for dashboard preferences !3379 (Elias W.)
   - Gracefully handle notes on deleted commits in merge requests (Stan Hu)
   - Fix creation of merge requests for orphaned branches (Stan Hu)

app/workers/post_receive.rb

@@ -40,7 +40,7 @@ class PostReceive
 
       if Gitlab::Git.tag_ref?(ref)
         GitTagPushService.new.execute(post_received.project, @user, oldrev, newrev, ref)
-      else
+      elsif Gitlab::Git.branch_ref?(ref)
         GitPushService.new(post_received.project, @user, oldrev: oldrev, newrev: newrev, ref: ref).execute
       end
     end

spec/workers/post_receive_spec.rb

@@ -4,6 +4,9 @@ describe PostReceive do
   let(:changes) { "123456 789012 refs/heads/tést\n654321 210987 refs/tags/tag" }
   let(:wrongly_encoded_changes) { changes.encode("ISO-8859-1").force_encoding("UTF-8") }
   let(:base64_changes) { Base64.encode64(wrongly_encoded_changes) }
+  let(:project) { create(:project) }
+  let(:key) { create(:key, user: project.owner) }
+  let(:key_id) { key.shell_id }
 
   context "as a resque worker" do
     it "reponds to #perform" do
@@ -11,11 +14,43 @@ describe PostReceive do
     end
   end
 
-  context "webhook" do
-    let(:project) { create(:project) }
-    let(:key) { create(:key, user: project.owner) }
-    let(:key_id) { key.shell_id }
+  describe "#process_project_changes" do
+    before do
+      allow_any_instance_of(Gitlab::GitPostReceive).to receive(:identify).and_return(project.owner)
+    end
 
+    context "branches" do
+      let(:changes) { "123456 789012 refs/heads/tést" }
+
+      it "should call GitTagPushService" do
+        expect_any_instance_of(GitPushService).to receive(:execute).and_return(true)
+        expect_any_instance_of(GitTagPushService).not_to receive(:execute)
+        PostReceive.new.perform(pwd(project), key_id, base64_changes)
+      end
+    end
+
+    context "tags" do
+      let(:changes) { "123456 789012 refs/tags/tag" }
+
+      it "should call GitTagPushService" do
+        expect_any_instance_of(GitPushService).not_to receive(:execute)
+        expect_any_instance_of(GitTagPushService).to receive(:execute).and_return(true)
+        PostReceive.new.perform(pwd(project), key_id, base64_changes)
+      end
+    end
+
+    context "merge-requests" do
+      let(:changes) { "123456 789012 refs/merge-requests/123" }
+
+      it "should not call any of the services" do
+        expect_any_instance_of(GitPushService).not_to receive(:execute)
+        expect_any_instance_of(GitTagPushService).not_to receive(:execute)
+        PostReceive.new.perform(pwd(project), key_id, base64_changes)
+      end
+    end
+  end
+
+  context "webhook" do
     it "fetches the correct project" do
       expect(Project).to receive(:find_with_namespace).with(project.path_with_namespace).and_return(project)
       PostReceive.new.perform(pwd(project), key_id, base64_changes)