[API] Fix race in load balancer deletion

A PENDING_DELETE status may not be written to the DB before the gearman
thread executes.  This means an exception is fired in send_delete().

This patch causes the DB data to be committed before the gearman thread
is executed.  It also makes sure that the remaining LBs don't include the
one getting deleted.

Change-Id: I17618af2709535c525ff99bd03958891d61f5624

libra/api/controllers/load_balancers.py

@@ -573,11 +573,12 @@ class LoadBalancersController(RestController):
                     filter(Node.lbid == lb.id).delete()
                 session.query(HealthMonitor).\
                     filter(HealthMonitor.lbid == lb.id).delete()
+                session.commit()
             else:
+                session.commit()
                 submit_job(
                     'DELETE', device.name, device.id, lb.id
                 )
-            session.commit()
             return None
 
     def usage(self, load_balancer_id):

libra/common/api/gearman_client.py

@@ -228,6 +228,7 @@ class GearmanClientThread(object):
                 LoadBalancer
             ).join(LoadBalancer.devices).\
                 filter(Device.id == data).\
+                filter(LoadBalancer.id != self.lbid).\
                 filter(LoadBalancer.status != 'DELETED').\
                 filter(LoadBalancer.status != 'PENDING_DELETE').\
                 count()