Merge branch 'run-pipeline-for-merge-train-at-train-ref-ce' into 'master'

CE Port: Fix race condition of `refs/merge` competing overwrite

See merge request gitlab-org/gitlab-ce!30308

2 files changed, 17 insertions, 0 deletions

diff --git a/app/models/merge_request.rb b/app/models/merge_request.rb
index e96e26cc773..53977748c30 100644
--- a/app/models/merge_request.rb
+++ b/app/models/merge_request.rb
@@ -1127,6 +1127,19 @@ class MergeRequest < ApplicationRecord
     "refs/#{Repository::REF_MERGE_REQUEST}/#{iid}/merge"
   end
 
+  def train_ref_path
+    "refs/#{Repository::REF_MERGE_REQUEST}/#{iid}/train"
+  end
+
+  def cleanup_refs(only: :all)
+    target_refs = []
+    target_refs << ref_path       if %i[all head].include?(only)
+    target_refs << merge_ref_path if %i[all merge].include?(only)
+    target_refs << train_ref_path if %i[all train].include?(only)
+
+    project.repository.delete_refs(*target_refs)
+  end
+
   def self.merge_request_ref?(ref)
     ref.start_with?("refs/#{Repository::REF_MERGE_REQUEST}/")
   end
diff --git a/app/models/repository.rb b/app/models/repository.rb
index a408db7ebbe..a25d5abfa64 100644
--- a/app/models/repository.rb
+++ b/app/models/repository.rb
@@ -845,6 +845,10 @@ class Repository
     raw.merge_to_ref(user, source_sha, branch, target_ref, message, first_parent_ref)
   end
 
+  def delete_refs(*ref_names)
+    raw.delete_refs(*ref_names)
+  end
+
   def ff_merge(user, source, target_branch, merge_request: nil)
     their_commit_id = commit(source)&.id
     raise 'Invalid merge source' if their_commit_id.nil?