Sync the changes to LFS when locking/unlocking files in the UI

app/services/lfs/unlock_file_service.rb

@@ -20,7 +20,6 @@ module Lfs
 
     def unlock_file
       forced = params[:force] == true
-      lock = project.lfs_file_locks.find(params[:id])
 
       if lock.can_be_unlocked_by?(current_user, forced)
         lock.destroy!
@@ -32,5 +31,15 @@ module Lfs
         error("#{lock.path} is locked by GitLab User #{lock.user_id}", 403)
       end
     end
+
+    def lock
+      return @lock if defined?(@lock)
+
+      @lock = if params[:id].present?
+                project.lfs_file_locks.find(params[:id])
+              elsif params[:path].present?
+                project.lfs_file_locks.find_by!(path: params[:path])
+              end
+    end
   end
 end

changelogs/unreleased-ee/1830-implement-lfs-file-locking.yml

+---
+title: Add support for LFS File Locking API
+merge_request: 4091
+author:
+type: added

ee/app/controllers/projects/path_locks_controller.rb

 class Projects::PathLocksController < Projects::ApplicationController
   include PathLocksHelper
+  include ExtractsPath
 
   # Authorize
   before_action :require_non_empty_project
   before_action :authorize_push_code!, only: [:toggle]
 
   before_action :check_license
+  before_action :assign_ref_vars, only: :toggle
+  before_action :lfs_blob_ids, only: :toggle
 
   def index
     @path_locks = @project.path_locks.page(params[:page])
@@ -15,9 +18,9 @@ class Projects::PathLocksController < Projects::ApplicationController
     path_lock = @project.path_locks.find_by(path: params[:path])
 
     if path_lock
-      PathLocks::UnlockService.new(project, current_user).execute(path_lock)
+      unlock_file(path_lock)
     else
-      PathLocks::LockService.new(project, current_user).execute(params[:path])
+      lock_file
     end
 
     head :ok
@@ -50,4 +53,35 @@ class Projects::PathLocksController < Projects::ApplicationController
       redirect_to admin_license_path
     end
   end
+
+  def lock_file
+    path_lock = PathLocks::LockService.new(project, current_user).execute(params[:path])
+
+    if path_lock.persisted? && sync_with_lfs?
+      Lfs::LockFileService.new(project, current_user, path: params[:path]).execute
+    end
+  end
+
+  def unlock_file(path_lock)
+    PathLocks::UnlockService.new(project, current_user).execute(path_lock)
+
+    if sync_with_lfs?
+      Lfs::UnlockFileService.new(project, current_user, path: path_lock.path, force: true).execute
+    end
+  end
+
+  # Override get_id from ExtractsPath in this case is just the root of the default branch.
+  def get_id
+    @ref ||= project.repository.root_ref
+  end
+
+  def lfs_file?
+    blob = project.repository.blob_at_branch(get_id, params[:path])
+
+    @lfs_blob_ids.include?(blob.id)
+  end
+
+  def sync_with_lfs?
+    project.lfs_enabled? && lfs_file?
+  end
 end

spec/ee/requests/projects/path_locks_spec.rb

+require 'rails_helper'
+
+describe Projects::PathLocksController, type: :request do
+  let(:project) { create(:project, :repository) }
+  let(:user)    { project.owner }
+  let(:viewer)  { user }
+
+  before do
+    login_as(viewer)
+  end
+
+  describe 'POST #toggle' do
+    context 'when locking a file' do
+      context 'when LFS is enabled' do
+        before do
+          allow_any_instance_of(Projects::PathLocksController).to receive(:sync_with_lfs?).and_return(true)
+        end
+
+        it 'locks the file' do
+          expect { toggle_lock('README.md') }.to change { PathLock.count }.to(1)
+
+          expect(response).to have_gitlab_http_status(200)
+        end
+
+        it "locks the file in LFS" do
+          expect { toggle_lock('README.md') }.to change { LfsFileLock.count }.to(1)
+        end
+      end
+
+      context 'when LFS is not enabled' do
+        it 'locks the file' do
+          expect { toggle_lock('README.md') }.to change { PathLock.count }.to(1)
+
+          expect(response).to have_gitlab_http_status(200)
+        end
+
+        it "doesn't lock the file in LFS" do
+          expect { toggle_lock('README.md') }.not_to change { LfsFileLock.count }
+        end
+      end
+    end
+
+    context 'when unlocking a file' do
+      context 'when LFS is enabled' do
+        before do
+          allow_any_instance_of(Projects::PathLocksController).to receive(:sync_with_lfs?).and_return(true)
+
+          toggle_lock('README.md')
+        end
+
+        it 'unlocks the file' do
+          expect { toggle_lock('README.md') }.to change { PathLock.count }.to(0)
+
+          expect(response).to have_gitlab_http_status(200)
+        end
+
+        it "unlocks the file in LFS" do
+          expect { toggle_lock('README.md') }.to change { LfsFileLock.count }.to(0)
+        end
+      end
+    end
+
+    context 'when LFS is not enabled' do
+      before do
+        toggle_lock('README.md')
+      end
+
+      it 'unlocks the file' do
+        expect { toggle_lock('README.md') }.to change { PathLock.count }.to(0)
+
+        expect(response).to have_gitlab_http_status(200)
+      end
+    end
+  end
+
+  def toggle_lock(path)
+    post toggle_project_path_locks_path(project), path: path
+  end
+end