Cache `Repository#exists?` false in RequestStore

* Only truthy values are cached in Redis.
* All values are cached in RequestStore and in an instance variable.

1 files changed, 85 insertions, 0 deletions

diff --git a/spec/lib/gitlab/repository_cache_spec.rb b/spec/lib/gitlab/repository_cache_spec.rb
index fc259cf1208..741ee12633f 100644
--- a/spec/lib/gitlab/repository_cache_spec.rb
+++ b/spec/lib/gitlab/repository_cache_spec.rb
@@ -47,4 +47,89 @@ describe Gitlab::RepositoryCache do
       expect(backend).to have_received(:fetch).with("baz:#{namespace}", &p)
     end
   end
+
+  describe '#fetch_without_caching_false', :use_clean_rails_memory_store_caching do
+    let(:key) { :foo }
+    let(:backend) { Rails.cache }
+
+    it 'requires a block' do
+      expect do
+        cache.fetch_without_caching_false(key)
+      end.to raise_error(LocalJumpError)
+    end
+
+    context 'when the key does not exist in the cache' do
+      context 'when the result of the block is truthy' do
+        it 'returns the result of the block' do
+          result = cache.fetch_without_caching_false(key) { true }
+
+          expect(result).to be true
+        end
+
+        it 'caches the value' do
+          expect(backend).to receive(:write).with("#{key}:#{namespace}", true)
+
+          cache.fetch_without_caching_false(key) { true }
+        end
+      end
+
+      context 'when the result of the block is falsey' do
+        let(:p) { -> { false } }
+
+        it 'returns the result of the block' do
+          result = cache.fetch_without_caching_false(key, &p)
+
+          expect(result).to be false
+        end
+
+        it 'does not cache the value' do
+          expect(backend).not_to receive(:write).with("#{key}:#{namespace}", true)
+
+          cache.fetch_without_caching_false(key, &p)
+        end
+      end
+    end
+
+    context 'when the cached value is truthy' do
+      before do
+        backend.write("#{key}:#{namespace}", true)
+      end
+
+      it 'returns the cached value' do
+        result = cache.fetch_without_caching_false(key) { 'block result' }
+
+        expect(result).to be true
+      end
+
+      it 'does not execute the block' do
+        expect do |b|
+          cache.fetch_without_caching_false(key, &b)
+        end.not_to yield_control
+      end
+
+      it 'does not write to the cache' do
+        expect(backend).not_to receive(:write)
+
+        cache.fetch_without_caching_false(key) { 'block result' }
+      end
+    end
+
+    context 'when the cached value is falsey' do
+      before do
+        backend.write("#{key}:#{namespace}", false)
+      end
+
+      it 'returns the result of the block' do
+        result = cache.fetch_without_caching_false(key) { 'block result' }
+
+        expect(result).to eq 'block result'
+      end
+
+      it 'writes the truthy value to the cache' do
+        expect(backend).to receive(:write).with("#{key}:#{namespace}", 'block result')
+
+        cache.fetch_without_caching_false(key) { 'block result' }
+      end
+    end
+  end
 end