The `FindCommit` RPC is one of the most popular ones: https://log.gprd.gitlab.net/goto/2690d5a0-5f4d-11ed-b0ec-930003e0679c. Let's investigate whether is possible to cache it for the root ref. If we decide that it's reasonable to introduce this optimization, it makes sense to do it behind a feature flag. The changes may look something like: ```diff diff --git a/app/models/repository.rb b/app/models/repository.rb index 3413b3e34249..8b3644385425 100644 --- a/app/models/repository.rb +++ b/app/models/repository.rb @@ -52,7 +52,7 @@ class Repository gitlab_ci_yml branch_names tag_names branch_count tag_count avatar exists? root_ref merged_branch_names has_visible_content? issue_template_names_hash merge_request_template_names_hash - user_defined_metrics_dashboard_paths xcode_project? has_ambiguous_refs?).freeze + user_defined_metrics_dashboard_paths xcode_project? has_ambiguous_refs? root_ref_commit).freeze # Certain method caches should be refreshed when certain types of files are # changed. This Hash maps file types (as returned by Gitlab::FileDetector) to @@ -361,6 +361,10 @@ def expire_statistics_caches expire_method_caches(%i(size commit_count)) end + def expire_root_ref_commit_cache + expire_method_caches(%i(root_ref_commit)) + end + def expire_all_method_caches expire_method_caches(CACHED_METHODS) end @@ -407,7 +411,7 @@ def expire_branch_cache(branch_name = nil) end def expire_root_ref_cache - expire_method_caches(%i(root_ref)) + expire_method_caches(%i(root_ref root_ref_commit)) end # Expires the cache(s) used to determine if a repository is empty or not. @@ -430,6 +434,7 @@ def expire_content_cache expire_emptiness_caches expire_exists_cache expire_statistics_caches + expire_root_ref_commit_cache end def expire_status_cache @@ -498,6 +503,7 @@ def after_change_head # Runs code after a new commit has been pushed. def after_push_commit(branch_name) + expire_root_ref_commit_cache expire_statistics_caches expire_branch_cache(branch_name) @@ -1203,6 +1209,8 @@ def remove_prohibited_branches # TODO Genericize finder, later split this on finders by Ref or Oid # https://gitlab.com/gitlab-org/gitlab/issues/19877 def find_commit(oid_or_ref) + return ::Commit.from_hash(root_ref_commit, container) if oid_or_ref == root_ref + commit = if oid_or_ref.is_a?(Gitlab::Git::Commit) oid_or_ref else @@ -1212,6 +1220,11 @@ def find_commit(oid_or_ref) ::Commit.new(commit, container) if commit end + def root_ref_commit + Gitlab::Git::Commit.find(raw_repository, root_ref).to_hash + end + cache_method_asymmetrically :root_ref_commit + def redis_set_cache @redis_set_cache ||= Gitlab::RepositorySetCache.new(self) end ```