Fail forking when source has lots of LFS objects

Also use `pluck` instead of loading all objects in memory.

app/models/project.rb

@@ -1388,6 +1388,14 @@ class Project < ApplicationRecord
       .where(lfs_objects_projects: { project_id: [self, lfs_storage_project] })
   end
 
+  # TODO: Call `#lfs_objects` instead once all LfsObjectsProject records are
+  # backfilled. At that point, projects can look at their own `lfs_objects`.
+  #
+  # See https://gitlab.com/gitlab-org/gitlab/issues/122002 for more info.
+  def lfs_objects_oids
+    all_lfs_objects.pluck(:oid)
+  end
+
   def personal?
     !group
   end

app/workers/repository_fork_worker.rb

@@ -30,11 +30,13 @@ class RepositoryForkWorker
     result = gitlab_shell.fork_repository(source_project, target_project)
 
     if result
-      Projects::LfsPointers::LfsLinkService
-        .new(target_project)
-        .execute(lfs_pointers(source_project))
+      link_lfs_objects(source_project, target_project)
     else
-      raise "Unable to fork project #{target_project.id} for repository #{source_project.disk_path} -> #{target_project.disk_path}"
+      raise_fork_failure(
+        source_project,
+        target_project,
+        'Failed to create fork repository'
+      )
     end
 
     target_project.after_import
@@ -47,7 +49,19 @@ class RepositoryForkWorker
     false
   end
 
-  def lfs_pointers(project)
-    project.lfs_objects.map(&:oid)
+  def link_lfs_objects(source_project, target_project)
+    Projects::LfsPointers::LfsLinkService
+        .new(target_project)
+        .execute(source_project.lfs_objects_oids)
+  rescue Projects::LfsPointers::LfsLinkService::TooManyOidsError
+    raise_fork_failure(
+      source_project,
+      target_project,
+      'Source project has too many LFS objects'
+    )
+  end
+
+  def raise_fork_failure(source_project, target_project, reason)
+    raise "Unable to fork project #{target_project.id} for repository #{source_project.disk_path} -> #{target_project.disk_path}: #{reason}"
   end
 end

spec/models/project_spec.rb

@@ -5547,6 +5547,31 @@ describe Project do
     end
   end
 
+  describe '#lfs_objects_oids' do
+    let(:project) { create(:project) }
+    let(:lfs_object) { create(:lfs_object) }
+    let(:another_lfs_object) { create(:lfs_object) }
+
+    subject { project.lfs_objects_oids }
+
+    context 'when project has associated LFS objects' do
+      before do
+        create(:lfs_objects_project, lfs_object: lfs_object, project: project)
+        create(:lfs_objects_project, lfs_object: another_lfs_object, project: project)
+      end
+
+      it 'returns OIDs of LFS objects' do
+        expect(subject).to match_array([lfs_object.oid, another_lfs_object.oid])
+      end
+    end
+
+    context 'when project has no associated LFS objects' do
+      it 'returns empty array' do
+        expect(subject).to be_empty
+      end
+    end
+  end
+
   def rugged_config
     rugged_repo(project.repository).config
   end

spec/workers/repository_fork_worker_spec.rb

@@ -72,8 +72,8 @@ describe RepositoryForkWorker do
         perform!
       end
 
-      it "handles bad fork" do
-        error_message = "Unable to fork project #{forked_project.id} for repository #{project.disk_path} -> #{forked_project.disk_path}"
+      it 'handles bad fork' do
+        error_message = "Unable to fork project #{forked_project.id} for repository #{project.disk_path} -> #{forked_project.disk_path}: Failed to create fork repository"
 
         expect_fork_repository.and_return(false)
 
@@ -83,11 +83,22 @@ describe RepositoryForkWorker do
       it 'calls Projects::LfsPointers::LfsLinkService#execute with OIDs of source project LFS objects' do
         expect_fork_repository.and_return(true)
         expect_next_instance_of(Projects::LfsPointers::LfsLinkService) do |service|
-          expect(service).to receive(:execute).with(project.lfs_objects.map(&:oid))
+          expect(service).to receive(:execute).with(project.lfs_objects_oids)
         end
 
         perform!
       end
+
+      it "handles LFS objects link failure" do
+        error_message = "Unable to fork project #{forked_project.id} for repository #{project.disk_path} -> #{forked_project.disk_path}: Source project has too many LFS objects"
+
+        expect_fork_repository.and_return(true)
+        expect_next_instance_of(Projects::LfsPointers::LfsLinkService) do |service|
+          expect(service).to receive(:execute).and_raise(Projects::LfsPointers::LfsLinkService::TooManyOidsError)
+        end
+
+        expect { perform! }.to raise_error(StandardError, error_message)
+      end
     end
 
     context 'only project ID passed' do