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, 38 insertions, 14 deletions

diff --git a/nova/virt/baremetal/proxy.py b/nova/virt/baremetal/proxy.py
index 90011f28b..ba8296127 100644
--- a/nova/virt/baremetal/proxy.py
+++ b/nova/virt/baremetal/proxy.py
@@ -42,6 +42,7 @@ 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 import utils
 from nova.virt.baremetal import dom
@@ -253,14 +254,20 @@ class ProxyConnection(driver.ComputeDriver):
             try:
                 LOG.debug(_("Key is injected but instance is not running yet"),
                           instance=instance)
-                db.instance_update(context, instance['id'],
-                    {'vm_state': vm_states.BUILDING})
+                (old_ref, new_ref) = db.instance_update_and_get_original(
+                        context, instance['id'],
+                        {'vm_state': vm_states.BUILDING})
+                notifications.send_update(context, old_ref, new_ref)
+
                 state = self._conn.create_domain(xml_dict, bpath)
                 if state == power_state.RUNNING:
                     LOG.debug(_('instance %s: booted'), instance['name'],
                               instance=instance)
-                    db.instance_update(context, instance['id'],
+                    (old_ref, new_ref) = db.instance_update_and_get_original(
+                            context, instance['id'],
                             {'vm_state': vm_states.ACTIVE})
+                    notifications.send_update(context, old_ref, new_ref)
+
                     LOG.debug(_('~~~~~~ current state = %s ~~~~~~'), state,
                               instance=instance)
                     LOG.debug(_("instance %s spawned successfully"),
@@ -271,9 +278,12 @@ class ProxyConnection(driver.ComputeDriver):
             except Exception as Exn:
                 LOG.debug(_("Bremetal assignment is overcommitted."),
                           instance=instance)
-                db.instance_update(context, instance['id'],
-                           {'vm_state': vm_states.OVERCOMMIT,
-                            'power_state': power_state.SUSPENDED})
+                (old_ref, new_ref) = db.instance_update_and_get_original(
+                        context, instance['id'],
+                        {'vm_state': vm_states.OVERCOMMIT,
+                         'power_state': power_state.SUSPENDED})
+                notifications.send_update(context, old_ref, new_ref)
+
             timer.stop()
         timer.f = _wait_for_boot
 
diff --git a/nova/virt/xenapi/host.py b/nova/virt/xenapi/host.py
index cceca0da0..d5f568360 100644
--- a/nova/virt/xenapi/host.py
+++ b/nova/virt/xenapi/host.py
@@ -26,6 +26,7 @@ from nova.compute import vm_states
 from nova import context
 from nova import db
 from nova import exception
+from nova import notifications
 from nova.virt.xenapi import vm_utils
 
 LOG = logging.getLogger(__name__)
@@ -74,21 +75,34 @@ class Host(object):
                         vm_counter = vm_counter + 1
 
                         dest = _host_find(ctxt, self._session, host, host_ref)
-                        db.instance_update(ctxt, instance.id,
-                                           {'host': dest,
-                                            'vm_state': vm_states.MIGRATING})
+                        (old_ref, new_ref) = \
+                                db.instance_update_and_get_original(ctxt,
+                                        instance.id,
+                                        {'host': dest,
+                                         'vm_state': vm_states.MIGRATING})
+                        notifications.send_update(ctxt, old_ref, new_ref)
+
                         self._session.call_xenapi('VM.pool_migrate',
                                                   vm_ref, host_ref, {})
                         migrations_counter = migrations_counter + 1
-                        db.instance_update(ctxt, instance.id,
-                                           {'vm_state': vm_states.ACTIVE})
+
+                        (old_ref, new_ref) = \
+                            db.instance_update_and_get_original(ctxt,
+                                    instance.id,
+                                    {'vm_state': vm_states.ACTIVE})
+                        notifications.send_update(ctxt, old_ref, new_ref)
+
                         break
                     except self.XenAPI.Failure:
                         LOG.exception('Unable to migrate VM %(vm_ref)s'
                                       'from %(host)s' % locals())
-                        db.instance_update(ctxt, instance.id,
-                                           {'host': host,
-                                            'vm_state': vm_states.ACTIVE})
+                        (old_ref, new_ref) = \
+                            db.instance_update_and_get_original(ctxt,
+                                    instance.id,
+                                    {'hosts': host,
+                                     'vm_state': vm_states.ACTIVE})
+                        notifications.send_update(ctxt, old_ref, new_ref)
+
             if vm_counter == migrations_counter:
                 return 'on_maintenance'
             else: