Banzai - avoid redis if attr is in DB cachebanzai-avoid-redis-if-db-cache

When cache_collection_render runs we end up reading and writing
things to redis even if we already have the rendered field cached
in the DB. This commit avoids using redis at all whenever we have
the field already rendered in the DB cache.

3 files changed, 39 insertions, 5 deletions

diff --git a/spec/models/commit_range_spec.rb b/spec/models/commit_range_spec.rb
index b96ca89c893..4a524b585e1 100644
--- a/spec/models/commit_range_spec.rb
+++ b/spec/models/commit_range_spec.rb
@@ -139,8 +139,8 @@ describe CommitRange do
   end
 
   describe '#has_been_reverted?' do
-    let(:issue) { create(:issue) }
-    let(:user) { issue.author }
+    let(:user) { create(:user) }
+    let(:issue) { create(:issue, author: user, project: project) }
 
     it 'returns true if the commit has been reverted' do
       create(:note_on_issue,
@@ -149,9 +149,11 @@ describe CommitRange do
              note: commit1.revert_description(user),
              project: issue.project)
 
-      expect_any_instance_of(Commit).to receive(:reverts_commit?)
-        .with(commit1, user)
-        .and_return(true)
+      expect_next_instance_of(Commit) do |commit|
+        expect(commit).to receive(:reverts_commit?)
+          .with(commit1, user)
+          .and_return(true)
+      end
 
       expect(commit1.has_been_reverted?(user, issue.notes_with_associations)).to eq(true)
     end
diff --git a/spec/models/concerns/cache_markdown_field_spec.rb b/spec/models/concerns/cache_markdown_field_spec.rb
index 0e5fb2b5153..9a12c3d6965 100644
--- a/spec/models/concerns/cache_markdown_field_spec.rb
+++ b/spec/models/concerns/cache_markdown_field_spec.rb
@@ -198,6 +198,36 @@ describe CacheMarkdownField, :clean_gitlab_redis_cache do
         end
       end
     end
+
+    describe '#updated_cached_html_for' do
+      let(:thing) { klass.new(description: markdown, description_html: html, cached_markdown_version: cache_version) }
+
+      context 'when the markdown cache is outdated' do
+        before do
+          thing.cached_markdown_version += 1
+        end
+
+        it 'calls #refresh_markdown_cache' do
+          expect(thing).to receive(:refresh_markdown_cache)
+
+          expect(thing.updated_cached_html_for(:description)).to eq(html)
+        end
+      end
+
+      context 'when the markdown field does not exist' do
+        it 'returns nil' do
+          expect(thing.updated_cached_html_for(:something)).to eq(nil)
+        end
+      end
+
+      context 'when the markdown cache is up to date' do
+        it 'does not call #refresh_markdown_cache' do
+          expect(thing).not_to receive(:refresh_markdown_cache)
+
+          expect(thing.updated_cached_html_for(:description)).to eq(html)
+        end
+      end
+    end
   end
 
   context 'for Active record classes' do
diff --git a/spec/models/note_spec.rb b/spec/models/note_spec.rb
index 7a1ab20186a..03003e3dd7d 100644
--- a/spec/models/note_spec.rb
+++ b/spec/models/note_spec.rb
@@ -177,6 +177,7 @@ describe Note do
             pipeline: :note,
             cache_key: [note1, "note"],
             project: note1.project,
+            rendered: note1.note_html,
             author: note1.author
           }
         }]).and_call_original
@@ -189,6 +190,7 @@ describe Note do
             pipeline: :note,
             cache_key: [note2, "note"],
             project: note2.project,
+            rendered: note2.note_html,
             author: note2.author
           }
         }]).and_call_original