1 files changed, 67 insertions, 3 deletions

diff --git a/app/models/merge_request_diff_commit.rb b/app/models/merge_request_diff_commit.rb
index ed398e0d2e0..466d28301c0 100644
--- a/app/models/merge_request_diff_commit.rb
+++ b/app/models/merge_request_diff_commit.rb
@@ -9,21 +9,51 @@ class MergeRequestDiffCommit < ApplicationRecord
 
   belongs_to :merge_request_diff
 
+  # This relation is called `commit_author` and not `author`, as the project
+  # import/export logic treats relations named `author` as instances of the
+  # `User` class.
+  #
+  # NOTE: these columns are _not_ indexed, nor do they use foreign keys.
+  #
+  # This is deliberate, as creating these indexes on GitLab.com takes a _very_
+  # long time. In addition, there's no real need for them either based on how
+  # this data is used.
+  #
+  # For more information, refer to the following:
+  #
+  # - https://gitlab.com/gitlab-com/gl-infra/production/-/issues/5038#note_614592881
+  # - https://gitlab.com/gitlab-org/gitlab/-/merge_requests/63669
+  belongs_to :commit_author, class_name: 'MergeRequest::DiffCommitUser'
+  belongs_to :committer, class_name: 'MergeRequest::DiffCommitUser'
+
   sha_attribute :sha
   alias_attribute :id, :sha
 
   serialize :trailers, Serializers::Json # rubocop:disable Cop/ActiveRecordSerialize
   validates :trailers, json_schema: { filename: 'git_trailers' }
 
+  scope :with_users, -> { preload(:commit_author, :committer) }
+
+  # A list of keys of which their values need to be trimmed before they can be
+  # inserted into the merge_request_diff_commit_users table.
+  TRIM_USER_KEYS =
+    %i[author_name author_email committer_name committer_email].freeze
+
   # Deprecated; use `bulk_insert!` from `BulkInsertSafe` mixin instead.
   # cf. https://gitlab.com/gitlab-org/gitlab/issues/207989 for progress
   def self.create_bulk(merge_request_diff_id, commits)
-    rows = commits.map.with_index do |commit, index|
-      # See #parent_ids.
-      commit_hash = commit.to_hash.except(:parent_ids)
+    commit_hashes, user_tuples = prepare_commits_for_bulk_insert(commits)
+    users = MergeRequest::DiffCommitUser.bulk_find_or_create(user_tuples)
+
+    rows = commit_hashes.map.with_index do |commit_hash, index|
       sha = commit_hash.delete(:id)
+      author = users[[commit_hash[:author_name], commit_hash[:author_email]]]
+      committer =
+        users[[commit_hash[:committer_name], commit_hash[:committer_email]]]
 
       commit_hash.merge(
+        commit_author_id: author&.id,
+        committer_id: committer&.id,
         merge_request_diff_id: merge_request_diff_id,
         relative_order: index,
         sha: Gitlab::Database::ShaAttribute.serialize(sha), # rubocop:disable Cop/ActiveRecordSerialize
@@ -36,6 +66,24 @@ class MergeRequestDiffCommit < ApplicationRecord
     Gitlab::Database.bulk_insert(self.table_name, rows) # rubocop:disable Gitlab/BulkInsert
   end
 
+  def self.prepare_commits_for_bulk_insert(commits)
+    user_tuples = Set.new
+    hashes = commits.map do |commit|
+      hash = commit.to_hash.except(:parent_ids)
+
+      TRIM_USER_KEYS.each do |key|
+        hash[key] = MergeRequest::DiffCommitUser.prepare(hash[key])
+      end
+
+      user_tuples << [hash[:author_name], hash[:author_email]]
+      user_tuples << [hash[:committer_name], hash[:committer_email]]
+
+      hash
+    end
+
+    [hashes, user_tuples]
+  end
+
   def self.oldest_merge_request_id_per_commit(project_id, shas)
     # This method is defined here and not on MergeRequest, otherwise the SHA
     # values used in the WHERE below won't be encoded correctly.
@@ -54,4 +102,20 @@ class MergeRequestDiffCommit < ApplicationRecord
       )
       .group(:sha)
   end
+
+  def author_name
+    commit_author_id ? commit_author.name : super
+  end
+
+  def author_email
+    commit_author_id ? commit_author.email : super
+  end
+
+  def committer_name
+    committer_id ? committer.name : super
+  end
+
+  def committer_email
+    committer_id ? committer.email : super
+  end
 end