Merge branch 'optimise-extractsref-when-there-is-no-path' into 'master'

Optimise ExtractsRef when there is no slash

See merge request gitlab-org/gitlab!38343

changelogs/unreleased/optimise-extractsref-when-there-is-no-path.yml

+---
+title: Remove some unnecessary Redis calls on commit lists
+merge_request: 38343
+author:
+type: performance

lib/extracts_ref.rb

@@ -47,6 +47,10 @@ module ExtractsRef
     if id =~ /^(\h{40})(.+)/
       # If the ref appears to be a SHA, we're done, just split the string
       pair = $~.captures
+    elsif id.exclude?('/')
+      # If the ID contains no slash, we must have a ref and no path, so
+      # we can skip the Redis calls below
+      pair = [id, '']
     else
       # Otherwise, attempt to detect the ref using a list of the repository_container's
       # branches and tags
@@ -71,12 +75,10 @@ module ExtractsRef
       end
     end
 
-    pair[0] = pair[0].strip
-
-    # Remove ending slashes from path
-    pair[1].gsub!(%r{^/|/$}, '')
-
-    pair
+    [
+      pair[0].strip,
+      pair[1].gsub(%r{^/|/$}, '') # Remove leading and trailing slashes from path
+    ]
   end
 
   # Assigns common instance variables for views working with Git tree-ish objects

spec/support/shared_examples/path_extraction_shared_examples.rb

@@ -88,9 +88,16 @@ RSpec.shared_examples 'extracts refs' do
         expect(extract_ref('stable')).to eq(['stable', ''])
       end
 
-      it 'extracts the longest matching ref' do
-        expect(extract_ref('release/app/v1.0.0/README.md')).to eq(
-          ['release/app/v1.0.0', 'README.md'])
+      it 'does not fetch ref names when there is no slash' do
+        expect(self).not_to receive(:ref_names)
+
+        extract_ref('master')
+      end
+
+      it 'fetches ref names when there is a slash' do
+        expect(self).to receive(:ref_names).and_call_original
+
+        extract_ref('release/app/v1.0.0')
       end
     end
 
@@ -113,6 +120,11 @@ RSpec.shared_examples 'extracts refs' do
       it 'falls back to a primitive split for an invalid ref' do
         expect(extract_ref('stable/CHANGELOG')).to eq(%w(stable CHANGELOG))
       end
+
+      it 'extracts the longest matching ref' do
+        expect(extract_ref('release/app/v1.0.0/README.md')).to eq(
+          ['release/app/v1.0.0', 'README.md'])
+      end
     end
   end
 end