Use dedicated method for counting commits, branches, and tags and cache the output

Currently the view app/views/projects/commits/_head.html.haml counts the amount of commits, branches, and tags using the following 3 snippets of code respectively:

• @repository.commit_count
• @repostiory.branches.size
• @repository.tags.length

For each case a dedicated method should be added that basically does the above but caches the output. The cache in turn should be flushed whenever new tags/branches/commits are pushed or existing ones are removed.

When navigating to the branches page of my local GitLab CE clone the time used for counting tags is already around 500 ms (when using my slow FS). The timings for commits/branches may vary, but in general there's no point in counting this live.

mentioned in issue #12443 (moved)

mentioned in issue #12619 (moved)

Adding a dedicated method for counting branches (with a cache) also means we can remove the cache for Repository#has_visible_content? as the method would become nothing more than:

def has_visible_content?
  branch_count > 0
end

From the top of my head, this method would be something like:

def branch_count
  cache.fetch(:branch_count) { raw_repository.branch_count }
end

Milestone changed to 8.6

Added repository label

Reassigned to @yorickpeterse

Currently I have the following changes:

diff --git a/app/models/repository.rb b/app/models/repository.rb
index c135ab6..46fa0f6 100644
--- a/app/models/repository.rb
+++ b/app/models/repository.rb
@@ -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)
diff --git a/app/views/projects/commits/_head.html.haml b/app/views/projects/commits/_head.html.haml
index 498c5e0..7a5b0d9 100644
--- a/app/views/projects/commits/_head.html.haml
+++ b/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

Using these changes visiting the branches page of GitLab CE locally takes around 4.6 seconds on average (after an initial load to build the caches), opposed to around 6.65 seconds on average (an improvement of ~1.45x).

Next I'll add some tests and make sure the caches are flushed whenever needed.

mentioned in merge request !3128 (merged)

Status changed to closed by commit e8cd04e8

Mentioned in commit pfjason/gitlab-ce@e8cd04e8

mentioned in commit test-nick/gitlab-ce@569021be