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, 44 insertions, 1 deletions

diff --git a/spec/lib/gitlab/git_post_receive_spec.rb b/spec/lib/gitlab/git_post_receive_spec.rb
index 4c20d945585..f0df3794e29 100644
--- a/spec/lib/gitlab/git_post_receive_spec.rb
+++ b/spec/lib/gitlab/git_post_receive_spec.rb
@@ -3,7 +3,7 @@
 require 'spec_helper'
 
 describe ::Gitlab::GitPostReceive do
-  let(:project) { create(:project) }
+  set(:project) { create(:project, :repository) }
 
   subject { described_class.new(project, "project-#{project.id}", changes.dup, {}) }
 
@@ -92,4 +92,47 @@ describe ::Gitlab::GitPostReceive do
       end
     end
   end
+
+  describe '#includes_default_branch?' do
+    context 'with no default branch' do
+      let(:changes) do
+        <<~EOF
+          654321 210987 refs/heads/test1
+          654322 210986 refs/tags/#{project.default_branch}
+          654323 210985 refs/heads/test3
+        EOF
+      end
+
+      it 'returns false' do
+        expect(subject.includes_default_branch?).to be_falsey
+      end
+    end
+
+    context 'with a project with no default branch' do
+      let(:changes) do
+        <<~EOF
+          654321 210987 refs/heads/test1
+        EOF
+      end
+
+      it 'returns true' do
+        expect(project).to receive(:default_branch).and_return(nil)
+        expect(subject.includes_default_branch?).to be_truthy
+      end
+    end
+
+    context 'with default branch' do
+      let(:changes) do
+        <<~EOF
+          654322 210986 refs/heads/test1
+          654321 210987 refs/tags/test2
+          654323 210985 refs/heads/#{project.default_branch}
+        EOF
+      end
+
+      it 'returns true' do
+        expect(subject.includes_default_branch?).to be_truthy
+      end
+    end
+  end
 end