Merge branch 'project-cache-worker-without-diverging' into 'master'

Removed diverging commit count calculation from Repository#build_cache

Using a repository with 1000 branches the old `Repository#build_cache` method would take around 180 seconds to complete. Without calculating the diverging commit counts this method "only" takes around 60 seconds. 

See commit 28cc2413eb5ddf920ce0b5eed803121f8b884754 for more details. This fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/14058

cc @rspeicher 

See merge request !3274

app/models/repository.rb

@@ -227,12 +227,6 @@ class Repository
         send(key)
       end
     end
-
-    branches.each do |branch|
-      unless cache.exist?(:"diverging_commit_counts_#{branch.name}")
-        send(:diverging_commit_counts, branch)
-      end
-    end
   end
 
   def expire_tags_cache
@@ -301,18 +295,6 @@ class Repository
     @tag_count = nil
   end
 
-  def rebuild_cache
-    cache_keys.each do |key|
-      cache.expire(key)
-      send(key)
-    end
-
-    branches.each do |branch|
-      cache.expire(:"diverging_commit_counts_#{branch.name}")
-      diverging_commit_counts(branch)
-    end
-  end
-
   def lookup_cache
     @lookup_cache ||= {}
   end

spec/models/repository_spec.rb

@@ -780,4 +780,34 @@ describe Repository, models: true do
       end
     end
   end
+
+  describe '#build_cache' do
+    let(:cache) { repository.send(:cache) }
+
+    it 'builds the caches if they do not already exist' do
+      expect(cache).to receive(:exist?).
+        exactly(repository.cache_keys.length).
+        times.
+        and_return(false)
+
+      repository.cache_keys.each do |key|
+        expect(repository).to receive(key)
+      end
+
+      repository.build_cache
+    end
+
+    it 'does not build any caches that already exist' do
+      expect(cache).to receive(:exist?).
+        exactly(repository.cache_keys.length).
+        times.
+        and_return(true)
+
+      repository.cache_keys.each do |key|
+        expect(repository).to_not receive(key)
+      end
+
+      repository.build_cache
+    end
+  end
 end