Merge two methods.

app/models/repository.rb

@@ -654,20 +654,17 @@ class Repository
   end
 
   def last_commit_for_path(sha, path)
-    sha = cache_last_commit_id_for_path(sha, path)
+    sha = last_commit_id_for_path(sha, path)
     commit(sha)
   end
 
   def last_commit_id_for_path(sha, path)
+    key = path.blank? ? "last_commit_id_for_path:#{sha}" : "last_commit_id_for_path:#{sha}:#{Digest::SHA1.hexdigest(path)}"
+
+    cache.fetch(key) do
       args = %W(#{Gitlab.config.git.bin_path} rev-list --max-count=1 #{sha} -- #{path})
       Gitlab::Popen.popen(args, path_to_repo).first.strip
     end
-
-  def cache_last_commit_id_for_path(sha, path)
-    key = path.blank? ? "last_commit_id_for_path:#{sha}" : "last_commit_id_for_path:#{sha}:#{Digest::SHA1.hexdigest(path)}"
-    cache.fetch(key) do
-      last_commit_id_for_path(sha, path)
-    end
   end
 
   def next_branch(name, opts = {})

lib/api/files.rb

@@ -70,7 +70,7 @@ module API
           ref: params[:ref],
           blob_id: blob.id,
           commit_id: commit.id,
-          last_commit_id: repo.cache_last_commit_id_for_path(commit.sha, params[:file_path])
+          last_commit_id: repo.last_commit_id_for_path(commit.sha, params[:file_path])
         }
       end
 

spec/models/repository_spec.rb

@@ -142,16 +142,16 @@ describe Repository, models: true do
   describe '#last_commit_id_for_path' do
     subject { repository.last_commit_id_for_path(sample_commit.id, '.gitignore') }
 
-    it { is_expected.to eq('c1acaa58bbcbc3eafe538cb8274ba387047b69f8') }
+    it "returns last commit id for a given path" do
+      is_expected.to eq('c1acaa58bbcbc3eafe538cb8274ba387047b69f8')
     end
 
-  describe '#cache_last_commit_id_for_path' do
-    it "caches #last_commit_id_for_path" do
+    it "caches last commit id for a given path" do
       cache = repository.send(:cache)
       key = "last_commit_id_for_path:#{sample_commit.id}:#{Digest::SHA1.hexdigest('.gitignore')}"
 
       expect(cache).to receive(:fetch).with(key).and_return('c1acaa5')
-      expect(repository.cache_last_commit_id_for_path(sample_commit.id, '.gitignore')).to eq('c1acaa5')
+      is_expected.to eq('c1acaa5')
     end
   end