Remove use of service_* conductor calls from xenapi host.py

This removes use of some service calls in the conductor by xenapi's
host.py module and replaces them with object usage. Existing tests
are sufficient to confirm the same behavior remains.

Related to blueprint virt-objects-juno

Change-Id: I908cca4fa1d297c5c9b1d84ae7ebe7452a30ba12

nova/virt/xenapi/host.py

@@ -21,11 +21,11 @@ import re
 
 from nova.compute import task_states
 from nova.compute import vm_states
-from nova import conductor
 from nova import context
 from nova import exception
 from nova.objects import aggregate as aggregate_obj
 from nova.objects import instance as instance_obj
+from nova.objects import service as service_obj
 from nova.openstack.common.gettextutils import _
 from nova.openstack.common import jsonutils
 from nova.openstack.common import log as logging
@@ -41,7 +41,6 @@ class Host(object):
     def __init__(self, session, virtapi):
         self._session = session
         self._virtapi = virtapi
-        self._conductor_api = conductor.API()
 
     def host_power_action(self, _host, action):
         """Reboots or shuts down the host."""
@@ -118,18 +117,11 @@ class Host(object):
         """Sets the specified host's ability to accept new instances."""
         # Since capabilities are gone, use service table to disable a node
         # in scheduler
-        status = {'disabled': not enabled,
-                'disabled_reason': 'set by xenapi host_state'
-                }
         cntxt = context.get_admin_context()
-        service = self._conductor_api.service_get_by_args(
-                cntxt,
-                host,
-                'nova-compute')
-        self._conductor_api.service_update(
-                cntxt,
-                service,
-                status)
+        service = service_obj.Service.get_by_args(cntxt, host, 'nova-compute')
+        service.disabled = not enabled
+        service.disabled_reason = 'set by xenapi host_state'
+        service.save()
 
         args = {"enabled": jsonutils.dumps(enabled)}
         response = call_xenhost(self._session, "set_host_enabled", args)