Cache & flush tag/branch counts

The methods used for this are Repository#tag_count and
Repository#branch_count which cache their output in Redis as well as
memoizing it in an instance variable. Both methods have a corresponding
methods/hooks to flush the caches at the right time.

app/models/repository.rb

@@ -160,7 +160,7 @@ class Repository
   end
   def rm_tag(tag_name)
-    expire_tags_cache
+    before_remove_tag
     gitlab_shell.rm_tag(path_with_namespace, tag_name)
   end
@@ -183,6 +183,14 @@ class Repository
     end
   end
+  def branch_count
+    @branch_count ||= cache.fetch(:branch_count) { raw_repository.branch_count }
+  end
+
+  def tag_count
+    @tag_count ||= cache.fetch(:tag_count) { raw_repository.rugged.tags.count }
+  end
+
   # Return repo size in megabytes
   # Cached in redis
   def size
@@ -278,6 +286,16 @@ class Repository
     @has_visible_content = nil
   end
+  def expire_branch_count_cache
+    cache.expire(:branch_count)
+    @branch_count = nil
+  end
+
+  def expire_tag_count_cache
+    cache.expire(:tag_count)
+    @tag_count = nil
+  end
+
   def rebuild_cache
     cache_keys.each do |key|
       cache.expire(key)
@@ -313,9 +331,16 @@ class Repository
     expire_root_ref_cache
   end
-  # Runs code before creating a new tag.
-  def before_create_tag
+  # Runs code before pushing (= creating or removing) a tag.
+  def before_push_tag
     expire_cache
+    expire_tag_count_cache
+  end
+
+  # Runs code before removing a tag.
+  def before_remove_tag
+    expire_tags_cache
+    expire_tag_count_cache
   end
   # Runs code after a repository has been forked/imported.
@@ -331,11 +356,13 @@ class Repository
   # Runs code after a new branch has been created.
   def after_create_branch
     expire_has_visible_content_cache
+    expire_branch_count_cache
   end
   # Runs code after an existing branch has been removed.
   def after_remove_branch
     expire_has_visible_content_cache
+    expire_branch_count_cache
   end
   def method_missing(m, *args, &block)

app/services/git_tag_push_service.rb

@@ -2,7 +2,7 @@ class GitTagPushService
   attr_accessor :project, :user, :push_data
   def execute(project, user, oldrev, newrev, ref)
-    project.repository.before_create_tag
+    project.repository.before_push_tag
     @project, @user = project, user
     @push_data = build_push_data(oldrev, newrev, ref)

app/views/projects/branches/destroy.js.haml

-$('.js-totalbranch-count').html("#{@repository.branches.size}")
+$('.js-totalbranch-count').html("#{@repository.branch_count}")

app/views/projects/commits/_head.html.haml

@@ -15,9 +15,9 @@
   = nav_link(html_options: {class: branches_tab_class}) do
     = link_to namespace_project_branches_path(@project.namespace, @project) do
       Branches
-      %span.badge.js-totalbranch-count= @repository.branches.size
+      %span.badge.js-totalbranch-count= @repository.branch_count
   = nav_link(controller: [:tags, :releases]) do
     = link_to namespace_project_tags_path(@project.namespace, @project) do
       Tags
-      %span.badge.js-totaltags-count= @repository.tags.length
+      %span.badge.js-totaltags-count= @repository.tag_count

spec/models/repository_spec.rb

@@ -405,7 +405,7 @@ describe Repository, models: true do
     end
   end
-  describe '#expire_branch_ache' do
+  describe '#expire_branch_cache' do
     # This method is private but we need it for testing purposes. Sadly there's
     # no other proper way of testing caching operations.
     let(:cache) { repository.send(:cache) }
@@ -556,11 +556,12 @@ describe Repository, models: true do
     end
   end
-  describe '#before_create_tag' do
+  describe '#before_push_tag' do
     it 'flushes the cache' do
       expect(repository).to receive(:expire_cache)
-      repository.before_create_tag
+      expect(repository).to receive(:expire_tag_count_cache)
+      repository.before_push_tag
     end
   end
@@ -607,4 +608,44 @@ describe Repository, models: true do
       expect(repository.main_language).to be_nil
     end
   end
+
+  describe '#before_remove_tag' do
+    it 'flushes the tag cache' do
+      expect(repository).to receive(:expire_tag_count_cache)
+
+      repository.before_remove_tag
+    end
+  end
+
+  describe '#branch_count' do
+    it 'returns the number of branches' do
+      expect(repository.branch_count).to be_an_instance_of(Fixnum)
+    end
+  end
+
+  describe '#tag_count' do
+    it 'returns the number of tags' do
+      expect(repository.tag_count).to be_an_instance_of(Fixnum)
+    end
+  end
+
+  describe '#expire_branch_count_cache' do
+    let(:cache) { repository.send(:cache) }
+
+    it 'expires the cache' do
+      expect(cache).to receive(:expire).with(:branch_count)
+
+      repository.expire_branch_count_cache
+    end
+  end
+
+  describe '#expire_tag_count_cache' do
+    let(:cache) { repository.send(:cache) }
+
+    it 'expires the cache' do
+      expect(cache).to receive(:expire).with(:tag_count)
+
+      repository.expire_tag_count_cache
+    end
+  end
 end

spec/services/delete_tag_service_spec.rb

+require 'spec_helper'
+
+describe DeleteTagService, services: true do
+  let(:project) { create(:project) }
+  let(:repository) { project.repository }
+  let(:user) { create(:user) }
+  let(:service) { described_class.new(project, user) }
+
+  let(:tag) { double(:tag, name: '8.5', target: 'abc123') }
+
+  describe '#execute' do
+    before do
+      allow(repository).to receive(:find_tag).and_return(tag)
+    end
+
+    it 'removes the tag' do
+      expect_any_instance_of(Gitlab::Shell).to receive(:rm_tag).
+        and_return(true)
+
+      expect(repository).to receive(:before_remove_tag)
+      expect(service).to receive(:success)
+
+      service.execute('8.5')
+    end
+  end
+end