Use an exception to pass messages

app/controllers/projects_controller.rb

@@ -170,12 +170,17 @@ class ProjectsController < ApplicationController
   end
   def housekeeping
-    message = ::Projects::HousekeepingService.new(@project).execute
-    respond_to do |format|
-      flash[:notice] = message
-      format.html { redirect_to project_path(@project) }
-    end
+    ::Projects::HousekeepingService.new(@project).execute
+    redirect_to(
+      project_path(@project),
+      notice: "Housekeeping successfully started"
+    )
+  rescue ::Projects::HousekeepingService::LeaseTaken => ex
+    redirect_to(
+      edit_project_path(@project),
+      alert: ex.to_s
+    )
   end
   def toggle_star

app/services/git_push_service.rb

@@ -79,6 +79,7 @@ class GitPushService < BaseService
     housekeeping = Projects::HousekeepingService.new(@project)
     housekeeping.increment!
     housekeeping.execute if housekeeping.needed?
+  rescue Projects::HousekeepingService::LeaseTaken
   end
   def process_default_branch

app/services/projects/housekeeping_service.rb

@@ -11,20 +11,22 @@ module Projects
     LEASE_TIMEOUT = 3600
+    class LeaseTaken < StandardError
+      def to_s
+        "Somebody already triggered housekeeping for this project in the past #{LEASE_TIMEOUT / 60} minutes"
+      end
+    end
+
     def initialize(project)
       @project = project
     end
     def execute
-      if !try_obtain_lease
-        return "Housekeeping was already triggered in the past #{LEASE_TIMEOUT / 60} minutes"
-      end
+      raise LeaseTaken if !try_obtain_lease
       GitlabShellWorker.perform_async(:gc, @project.path_with_namespace)
-      @project.pushes_since_gc = 0
-      @project.save!
-
-      "Housekeeping successfully started"
+    ensure
+      @project.update_column(:pushes_since_gc, 0)
     end
     def needed?
@@ -32,8 +34,7 @@ module Projects
     end
     def increment!
-      @project.pushes_since_gc += 1
-      @project.save!
+      @project.increment!(:pushes_since_gc)
     end
     private

spec/services/git_push_service_spec.rb

@@ -402,7 +402,7 @@ describe GitPushService, services: true do
   end
   describe "housekeeping" do
-    let(:housekeeping) { instance_double('Projects::HousekeepingService', increment!: nil, needed?: false) }
+    let(:housekeeping) { Projects::HousekeepingService.new(project) }
     before do
       allow(Projects::HousekeepingService).to receive(:new).and_return(housekeeping)
@@ -414,16 +414,28 @@ describe GitPushService, services: true do
       execute_service(project, user, @oldrev, @newrev, @ref)
     end
-    it 'performs housekeeping when needed' do
-      expect(housekeeping).to receive(:needed?).and_return(true)
-      expect(housekeeping).to receive(:execute)
-      execute_service(project, user, @oldrev, @newrev, @ref)
+    context 'when housekeeping is needed' do
+      before do
+        allow(housekeeping).to receive(:needed?).and_return(true)
+      end
+      it 'performs housekeeping' do
+        expect(housekeeping).to receive(:execute)
+
+        execute_service(project, user, @oldrev, @newrev, @ref)
+      end
+
+      it 'does not raise an exception' do
+        allow(housekeeping).to receive(:try_obtain_lease).and_return(false)
+
+        execute_service(project, user, @oldrev, @newrev, @ref)
+      end
     end
+
     it 'increments the push counter' do
       expect(housekeeping).to receive(:increment!)
- 
+
       execute_service(project, user, @oldrev, @newrev, @ref)
     end
   end

spec/services/projects/housekeeping_service_spec.rb

@@ -14,7 +14,7 @@ describe Projects::HousekeepingService do
       expect(subject).to receive(:try_obtain_lease).and_return(true)
       expect(GitlabShellWorker).to receive(:perform_async).with(:gc, project.path_with_namespace)
-      expect(subject.execute).to include('successfully started')
+      subject.execute
       expect(project.pushes_since_gc).to eq(0)
     end
@@ -22,8 +22,8 @@ describe Projects::HousekeepingService do
       expect(subject).to receive(:try_obtain_lease).and_return(false)
       expect(GitlabShellWorker).not_to receive(:perform_async)
-      expect(subject.execute).to include('already triggered')
-      expect(project.pushes_since_gc).to eq(3)
+      expect { subject.execute }.to raise_error(Projects::HousekeepingService::LeaseTaken)
+      expect(project.pushes_since_gc).to eq(0)
     end
   end