Added a instance state update notification

Added a instance update notification (compute.instance.update) that
will report on changes to vm_state and task_state. The goal here is
to provide useful insight into instance state transitions.  (e.g.
BUILDING->ACTIVE)

The new notification has minimial dependencies and is intended for
wide use across the different layers/packages within nova.  Calls
in compute api/manager, scheduler, and the virt layer that modify
the instance state have been instrumented with this notification.

Change-Id: I223eb7eccc8aa079b782f6bb17727cd0b71d18ed

2 files changed, 12 insertions, 2 deletions

diff --git a/nova/scheduler/driver.py b/nova/scheduler/driver.py
index 82bba0ce4..8e49e5aa4 100644
--- a/nova/scheduler/driver.py
+++ b/nova/scheduler/driver.py
@@ -28,6 +28,7 @@ from nova import db
 from nova import exception
 from nova import flags
 from nova import log as logging
+from nova import notifications
 from nova.openstack.common import cfg
 from nova.openstack.common import importutils
 from nova.openstack.common import jsonutils
@@ -226,7 +227,11 @@ class Scheduler(object):
 
         # Changing instance_state.
         values = {"vm_state": vm_states.MIGRATING}
-        db.instance_update(context, instance_id, values)
+
+        # update instance state and notify
+        (old_ref, new_instance_ref) = db.instance_update_and_get_original(
+                context, instance_id, values)
+        notifications.send_update(context, old_ref, new_instance_ref)
 
         src = instance_ref['host']
         cast_to_compute_host(context, src, 'live_migration',
diff --git a/nova/scheduler/manager.py b/nova/scheduler/manager.py
index a2cef11a8..470368b03 100644
--- a/nova/scheduler/manager.py
+++ b/nova/scheduler/manager.py
@@ -29,6 +29,7 @@ from nova import exception
 from nova import flags
 from nova import log as logging
 from nova import manager
+from nova import notifications
 from nova.notifier import api as notifier
 from nova.openstack.common import cfg
 from nova.openstack.common import excutils
@@ -173,7 +174,11 @@ class SchedulerManager(manager.Manager):
             state = vm_state.upper()
             LOG.warning(_('Setting instance to %(state)s state.'), locals(),
                         instance_uuid=instance_uuid)
-            db.instance_update(context, instance_uuid, updates)
+
+            # update instance state and notify on the transition
+            (old_ref, new_ref) = db.instance_update_and_get_original(context,
+                    instance_uuid, updates)
+            notifications.send_update(context, old_ref, new_ref)
 
         payload = dict(request_spec=request_spec,
                        instance_properties=properties,