Expire caches after forking/importing a repository

This ensures the caches for Repository#empty? and
Repository#has_visible_content? are flushed after a repository has been
imported or forked.

Fixes gitlab-org/gitlab-ce#13505

app/models/repository.rb

@@ -258,6 +258,14 @@ class Repository
     @root_ref = nil
   end
+  # Expires the cache(s) used to determine if a repository is empty or not.
+  def expire_emptiness_caches
+    cache.expire(:empty?)
+    @empty = nil
+
+    expire_has_visible_content_cache
+  end
+
   def expire_has_visible_content_cache
     cache.expire(:has_visible_content?)
     @has_visible_content = nil

app/workers/repository_fork_worker.rb

@@ -27,6 +27,7 @@ class RepositoryForkWorker
       return
     end
+    project.repository.expire_emptiness_caches
     project.import_finish
   end
 end

app/workers/repository_import_worker.rb

@@ -18,6 +18,7 @@ class RepositoryImportWorker
       return
     end
+    project.repository.expire_emptiness_caches
     project.import_finish
   end
 end

spec/models/repository_spec.rb

@@ -355,6 +355,17 @@ describe Repository, models: true do
     end
   end
+  describe '#expire_emptiness_caches' do
+    let(:cache) { repository.send(:cache) }
+
+    it 'expires the caches' do
+      expect(cache).to receive(:expire).with(:empty?)
+      expect(repository).to receive(:expire_has_visible_content_cache)
+
+      repository.expire_emptiness_caches
+    end
+  end
+
   describe :skip_merged_commit do
     subject { repository.commits(Gitlab::Git::BRANCH_REF_PREFIX + "'test'", nil, 100, 0, true).map{ |k| k.id } }

spec/workers/repository_fork_worker_spec.rb

@@ -19,6 +19,18 @@ describe RepositoryForkWorker do
         fork_project.namespace.path)
     end
+    it 'flushes the empty caches' do
+      expect_any_instance_of(Gitlab::Shell).to receive(:fork_repository).
+        with(project.path_with_namespace, fork_project.namespace.path).
+        and_return(true)
+
+      expect_any_instance_of(Repository).to receive(:expire_emptiness_caches).
+        and_call_original
+
+      subject.perform(project.id, project.path_with_namespace,
+                      fork_project.namespace.path)
+    end
+
     it "handles bad fork" do
       expect_any_instance_of(Gitlab::Shell).to receive(:fork_repository).and_return(false)
       subject.perform(

spec/workers/repository_import_worker_spec.rb

+require 'spec_helper'
+
+describe RepositoryImportWorker do
+  let(:project) { create(:project) }
+
+  subject { described_class.new }
+
+  describe '#perform' do
+    it 'imports a project' do
+      expect_any_instance_of(Projects::ImportService).to receive(:execute).
+        and_return({ status: :ok })
+
+      expect_any_instance_of(Repository).to receive(:expire_emptiness_caches)
+      expect_any_instance_of(Project).to receive(:import_finish)
+
+      subject.perform(project.id)
+    end
+  end
+end