Expire project caches once per push instead of once per ref

Previously `ProjectCacheWorker` would be scheduled once per ref, which
would generate unnecessary I/O and load on Sidekiq, especially if many
tags or branches were pushed at once. `ProjectCacheWorker` would expire
three items:

1. Repository size: This only needs to be updated once per push.
2. Commit count: This only needs to be updated if the default branch
   is updated.
3. Project method caches: This only needs to be updated if the default
   branch changes, but only if certain files change (e.g. README,
   CHANGELOG, etc.).

Because the third item requires looking at the actual changes in the
commit deltas, we schedule one `ProjectCacheWorker` to handle the first
two cases, and schedule a separate `ProjectCacheWorker` for the third
case if it is needed. As a result, this brings down the number of
`ProjectCacheWorker` jobs from N to 2.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/52046

1 files changed, 66 insertions, 5 deletions

diff --git a/spec/workers/post_receive_spec.rb b/spec/workers/post_receive_spec.rb
index 3b69b81f12e..c8a0c22b0e8 100644
--- a/spec/workers/post_receive_spec.rb
+++ b/spec/workers/post_receive_spec.rb
@@ -37,6 +37,29 @@ describe PostReceive do
   end
 
   describe "#process_project_changes" do
+    context 'with an empty project' do
+      let(:empty_project) { create(:project, :empty_repo) }
+      let(:changes) { "123456 789012 refs/heads/tést1\n" }
+
+      before do
+        allow_any_instance_of(Gitlab::GitPostReceive).to receive(:identify).and_return(empty_project.owner)
+        allow(Gitlab::GlRepository).to receive(:parse).and_return([empty_project, Gitlab::GlRepository::PROJECT])
+      end
+
+      it 'expire the status cache' do
+        expect(empty_project.repository).to receive(:expire_status_cache)
+
+        perform
+      end
+
+      it 'schedules a cache update for commit count and size' do
+        expect(ProjectCacheWorker).to receive(:perform_async)
+                                        .with(empty_project.id, [], [:repository_size, :commit_count], true)
+
+        perform
+      end
+    end
+
     context 'empty changes' do
       it "does not call any PushService but runs after project hooks" do
         expect(Git::BranchPushService).not_to receive(:new)
@@ -67,15 +90,22 @@ describe PostReceive do
       context "branches" do
         let(:changes) do
           <<~EOF
-            '123456 789012 refs/heads/tést1'
-            '123456 789012 refs/heads/tést2'
+            123456 789012 refs/heads/tést1
+            123456 789012 refs/heads/tést2
           EOF
         end
 
         it 'expires the branches cache' do
           expect(project.repository).to receive(:expire_branches_cache).once
 
-          described_class.new.perform(gl_repository, key_id, base64_changes)
+          perform
+        end
+
+        it 'expires the status cache' do
+          expect(project).to receive(:empty_repo?).and_return(true)
+          expect(project.repository).to receive(:expire_status_cache)
+
+          perform
         end
 
         it 'calls Git::BranchPushService' do
@@ -87,6 +117,30 @@ describe PostReceive do
 
           perform
         end
+
+        it 'schedules a cache update for repository size only' do
+          expect(ProjectCacheWorker).to receive(:perform_async)
+                                          .with(project.id, [], [:repository_size], true)
+
+          perform
+        end
+
+        context 'with a default branch' do
+          let(:changes) do
+            <<~EOF
+              123456 789012 refs/heads/tést1
+              123456 789012 refs/heads/tést2
+              678912 123455 refs/heads/#{project.default_branch}
+            EOF
+          end
+
+          it 'schedules a cache update for commit count and size' do
+            expect(ProjectCacheWorker).to receive(:perform_async)
+                                            .with(project.id, [], [:repository_size, :commit_count], true)
+
+            perform
+          end
+        end
       end
 
       context "tags" do
@@ -107,7 +161,7 @@ describe PostReceive do
         it 'does not expire branches cache' do
           expect(project.repository).not_to receive(:expire_branches_cache)
 
-          described_class.new.perform(gl_repository, key_id, base64_changes)
+          perform
         end
 
         it "only invalidates tags once" do
@@ -115,7 +169,7 @@ describe PostReceive do
           expect(project.repository).to receive(:expire_caches_for_tags).once.and_call_original
           expect(project.repository).to receive(:expire_tags_cache).once.and_call_original
 
-          described_class.new.perform(gl_repository, key_id, base64_changes)
+          perform
         end
 
         it "calls Git::TagPushService" do
@@ -129,6 +183,13 @@ describe PostReceive do
 
           perform
         end
+
+        it 'schedules a single ProjectCacheWorker update' do
+          expect(ProjectCacheWorker).to receive(:perform_async)
+                                          .with(project.id, [], [:repository_size], true)
+
+          perform
+        end
       end
 
       context "merge-requests" do