feat(multiplayer): add regional allocation budget

server/allocator/service.go

@@ -26,10 +26,15 @@ type RosterPublisher interface {
 	PublishRoster(context.Context, domain.Assignment, []domain.SignedJoinAuthorisation, func([]byte, []byte) bool) error
 }
 
+type AllocationBudget interface {
+	Allow(region string, now time.Time) error
+}
+
 type Service struct {
 	Provider Provider
 	Durable  Durable
 	Roster   RosterPublisher
+	Budget   AllocationBudget
 	Now      func() time.Time
 }
 
@@ -78,6 +83,11 @@ func (s Service) Allocate(ctx context.Context, request domain.AllocationRequest,
 		return agones.AllocatedServer{}, errNotConfigured
 	}
 	now := s.Now()
+	if s.Budget != nil {
+		if err := s.Budget.Allow(request.Region, now); err != nil {
+			return agones.AllocatedServer{}, err
+		}
+	}
 	result, err := s.Provider.Allocate(ctx, request, labels, now)
 	if err != nil {
 		return agones.AllocatedServer{}, err