Only expire tag cache once per push

Previously each tag in a push would invoke the Gitaly `FindAllTags` RPC
since the tag cache would be invalidated with every tag.

We can eliminate those extraneous calls by expiring the tag cache once
in `PostReceive` and taking advantage of the cached tags.

Relates to https://gitlab.com/gitlab-org/gitlab-ce/issues/65795

2 files changed, 11 insertions, 5 deletions

diff --git a/app/models/repository.rb b/app/models/repository.rb
index 58abfaef801..9d45a12fa6e 100644
--- a/app/models/repository.rb
+++ b/app/models/repository.rb
@@ -418,25 +418,29 @@ class Repository
   end
 
   # Runs code before pushing (= creating or removing) a tag.
+  #
+  # Note that this doesn't expire the tags. You may need to call
+  # expire_caches_for_tags or expire_tags_cache.
   def before_push_tag
+    repository_event(:push_tag)
+  end
+
+  def expire_caches_for_tags
     expire_statistics_caches
     expire_emptiness_caches
     expire_tags_cache
-
-    repository_event(:push_tag)
   end
 
   # Runs code before removing a tag.
   def before_remove_tag
-    expire_tags_cache
-    expire_statistics_caches
+    expire_caches_for_tags
 
     repository_event(:remove_tag)
   end
 
   # Runs code after removing a tag.
   def after_remove_tag
-    expire_tags_cache
+    expire_caches_for_tags
   end
 
   # Runs code after the HEAD of a repository is changed.
diff --git a/app/workers/post_receive.rb b/app/workers/post_receive.rb
index d8dfbc0faf7..675fa1a73ca 100644
--- a/app/workers/post_receive.rb
+++ b/app/workers/post_receive.rb
@@ -44,6 +44,8 @@ class PostReceive
 
     # Expire the branches cache so we have updated data for this push
     post_received.project.repository.expire_branches_cache if post_received.includes_branches?
+    # We only need to expire tags once per push
+    post_received.project.repository.expire_caches_for_tags if post_received.includes_tags?
 
     post_received.enum_for(:changes_refs).with_index do |(oldrev, newrev, ref), index|
       service_klass =