Add latest changes from gitlab-org/gitlab@master

1 files changed, 130 insertions, 0 deletions

diff --git a/app/services/merge_requests/create_ref_service.rb b/app/services/merge_requests/create_ref_service.rb
new file mode 100644
index 00000000000..7aa27e57405
--- /dev/null
+++ b/app/services/merge_requests/create_ref_service.rb
@@ -0,0 +1,130 @@
+# frozen_string_literal: true
+
+module MergeRequests
+  # CreateRefService creates or overwrites a ref under "refs/merge-requests/"
+  # with a commit for the merged result.
+  class CreateRefService
+    include Gitlab::Utils::StrongMemoize
+
+    CreateRefError = Class.new(StandardError)
+
+    def initialize(
+      current_user:, merge_request:, target_ref:, first_parent_ref:,
+      source_sha: nil, merge_commit_message: nil)
+
+      @current_user = current_user
+      @merge_request = merge_request
+      @initial_source_sha = source_sha
+      @target_ref = target_ref
+      @merge_commit_message = merge_commit_message
+      @first_parent_sha = target_project.commit(first_parent_ref)&.sha
+    end
+
+    def execute
+      commit_sha = initial_source_sha # the SHA to be at HEAD of target_ref
+      source_sha = initial_source_sha # the SHA to be the merged result of the source (minus the merge commit)
+      expected_old_oid = ""           # the SHA we expect target_ref to be at prior to an update (an optimistic lock)
+
+      # TODO: Update this message with the removal of FF merge_trains_create_ref_service and update tests
+      # This is for compatibility with MergeToRefService during the rollout.
+      return ServiceResponse.error(message: '3:Invalid merge source') unless first_parent_sha.present?
+
+      commit_sha, source_sha, expected_old_oid = maybe_squash!(commit_sha, source_sha, expected_old_oid)
+      commit_sha, source_sha, expected_old_oid = maybe_rebase!(commit_sha, source_sha, expected_old_oid)
+      commit_sha, source_sha = maybe_merge!(commit_sha, source_sha, expected_old_oid)
+
+      ServiceResponse.success(
+        payload: {
+          commit_sha: commit_sha,
+          target_sha: first_parent_sha,
+          source_sha: source_sha
+        }
+      )
+    rescue CreateRefError => error
+      ServiceResponse.error(message: error.message)
+    end
+
+    private
+
+    attr_reader :current_user, :merge_request, :target_ref, :first_parent_sha, :initial_source_sha
+
+    delegate :target_project, to: :merge_request
+    delegate :repository, to: :target_project
+
+    def maybe_squash!(commit_sha, source_sha, expected_old_oid)
+      if merge_request.squash_on_merge?
+        squash_result = MergeRequests::SquashService.new(
+          merge_request: merge_request,
+          current_user: current_user,
+          commit_message: squash_commit_message
+        ).execute
+        raise CreateRefError, squash_result[:message] if squash_result[:status] == :error
+
+        commit_sha = squash_result[:squash_sha]
+        source_sha = commit_sha
+      end
+
+      # squash does not overwrite target_ref, so expected_old_oid remains the same
+      [commit_sha, source_sha, expected_old_oid]
+    end
+
+    def maybe_rebase!(commit_sha, source_sha, expected_old_oid)
+      if target_project.ff_merge_must_be_possible?
+        commit_sha = safe_gitaly_operation do
+          repository.rebase_to_ref(
+            current_user,
+            source_sha: source_sha,
+            target_ref: target_ref,
+            first_parent_ref: first_parent_sha
+          )
+        end
+
+        source_sha = commit_sha
+        expected_old_oid = commit_sha
+      end
+
+      [commit_sha, source_sha, expected_old_oid]
+    end
+
+    def maybe_merge!(commit_sha, source_sha, expected_old_oid)
+      unless target_project.merge_requests_ff_only_enabled
+        source_sha = safe_gitaly_operation do
+          repository.merge_to_ref(
+            current_user,
+            source_sha: source_sha,
+            target_ref: target_ref,
+            message: merge_commit_message,
+            first_parent_ref: first_parent_sha,
+            branch: nil,
+            expected_old_oid: expected_old_oid
+          )
+        end
+        commit = target_project.commit(commit_sha)
+        _, source_sha = commit.parent_ids
+      end
+
+      [commit_sha, source_sha]
+    end
+
+    def safe_gitaly_operation
+      yield
+    rescue Gitlab::Git::PreReceiveError, Gitlab::Git::CommandError, ArgumentError => error
+      raise CreateRefError, error.message
+    end
+
+    def squash_commit_message
+      merge_request.merge_params['squash_commit_message'].presence ||
+        merge_request.default_squash_commit_message(user: current_user)
+    end
+    strong_memoize_attr :squash_commit_message
+
+    def merge_commit_message
+      return @merge_commit_message if @merge_commit_message.present?
+
+      @merge_commit_message = (
+        merge_request.merge_params['commit_message'].presence ||
+        merge_request.default_merge_commit_message(user: current_user)
+      )
+    end
+  end
+end