Avoid db lookup in info_from_instance().

The method info_from_instance() in nova.notifications was doing a db
lookup for the system_metadata for an instance.  This patch updates that
code to get that data from the instance that's passed in instead.  The
rest of the patch are related changes to make that happen.

metadata_to_dict() was needed here.  It lived in nova.compute.utils.
nova.compute.utils already imported nova.notifications, so using it from
there would have created a circular import.  Move the method to
nova.utils instead and update the tree to use it from its new location.

I also noticed that the xen driver had a copy of metdata_to_dict().
This patch removes it and uses the common implementation in nova.utils.

'system_metadata' was added to _extra_keys of the Instance db model so
that it would show up in a serialized instance.  Tests failed without it
as the result of getting instances via the conductor API did not include
system_metadata.  Now it's there.

Part of bp no-db-compute.

Change-Id: I451355fb26ae29f13b71438f7896c448b59f97b0

9 files changed, 31 insertions, 40 deletions

diff --git a/nova/compute/manager.py b/nova/compute/manager.py
index d1cffea7d..275611cdf 100644
--- a/nova/compute/manager.py
+++ b/nova/compute/manager.py
@@ -1132,8 +1132,7 @@ class ComputeManager(manager.SchedulerDependentManager):
                                          vm_state=vm_states.DELETED,
                                          task_state=None,
                                          terminated_at=timeutils.utcnow())
-        system_meta = compute_utils.metadata_to_dict(
-            instance['system_metadata'])
+        system_meta = utils.metadata_to_dict(instance['system_metadata'])
         self.conductor_api.instance_destroy(context, instance)
 
         # ensure block device mappings are not leaked
@@ -1675,8 +1674,7 @@ class ComputeManager(manager.SchedulerDependentManager):
 
     def _get_rescue_image_ref(self, context, instance):
         """Determine what image should be used to boot the rescue VM."""
-        system_meta = compute_utils.metadata_to_dict(
-            instance['system_metadata'])
+        system_meta = utils.metadata_to_dict(instance['system_metadata'])
 
         rescue_image_ref = system_meta.get('image_base_image_ref')
 
diff --git a/nova/compute/utils.py b/nova/compute/utils.py
index 2b1286e16..1874e886f 100644
--- a/nova/compute/utils.py
+++ b/nova/compute/utils.py
@@ -37,13 +37,6 @@ CONF.import_opt('host', 'nova.netconf')
 LOG = log.getLogger(__name__)
 
 
-def metadata_to_dict(metadata):
-    result = {}
-    for item in metadata:
-        result[item['key']] = item['value']
-    return result
-
-
 def add_instance_fault_from_exc(context, instance, fault, exc_info=None):
     """Adds the specified fault to the database."""
 
@@ -159,7 +152,8 @@ def notify_usage_exists(context, instance_ref, current_period=False,
             ignore_missing_network_data)
 
     if system_metadata is None:
-        system_metadata = metadata_to_dict(instance_ref['system_metadata'])
+        system_metadata = utils.metadata_to_dict(
+                instance_ref['system_metadata'])
 
     # add image metadata to the notification:
     image_meta = notifications.image_meta(system_metadata)
diff --git a/nova/db/sqlalchemy/models.py b/nova/db/sqlalchemy/models.py
index 14c651020..80bbe9512 100644
--- a/nova/db/sqlalchemy/models.py
+++ b/nova/db/sqlalchemy/models.py
@@ -221,7 +221,7 @@ class Instance(BASE, NovaBase):
         return base_name
 
     def _extra_keys(self):
-        return ['name']
+        return ['name', 'system_metadata']
 
     user_id = Column(String(255))
     project_id = Column(String(255))
diff --git a/nova/notifications.py b/nova/notifications.py
index f399ac55d..65428d03f 100644
--- a/nova/notifications.py
+++ b/nova/notifications.py
@@ -283,12 +283,8 @@ def info_from_instance(context, instance_ref, network_info,
     instance_type_name = instance_ref.get('instance_type', {}).get('name', '')
 
     if system_metadata is None:
-        try:
-            system_metadata = db.instance_system_metadata_get(
-                    context, instance_ref['uuid'])
-
-        except exception.NotFound:
-            system_metadata = {}
+        system_metadata = utils.metadata_to_dict(
+                instance_ref['system_metadata'])
 
     instance_info = dict(
         # Owner properties
diff --git a/nova/tests/compute/test_compute.py b/nova/tests/compute/test_compute.py
index b8212848c..38dcd5521 100644
--- a/nova/tests/compute/test_compute.py
+++ b/nova/tests/compute/test_compute.py
@@ -5287,7 +5287,7 @@ class ComputeAPITestCase(BaseTestCase):
 
         _context = context.get_admin_context()
         instance = self._create_fake_instance({'metadata': {'key1': 'value1'}})
-        instance = dict(instance)
+        instance = dict(instance.iteritems())
 
         metadata = self.compute_api.get_instance_metadata(_context, instance)
         self.assertEqual(metadata, {'key1': 'value1'})
diff --git a/nova/tests/compute/test_compute_utils.py b/nova/tests/compute/test_compute_utils.py
index 6e7227d4c..4372039e0 100644
--- a/nova/tests/compute/test_compute_utils.py
+++ b/nova/tests/compute/test_compute_utils.py
@@ -359,6 +359,9 @@ class UsageInfoTestCase(test.TestCase):
         extra_usage_info = {'image_name': 'fake_name'}
         db.instance_system_metadata_update(self.context, instance['uuid'],
                 sys_metadata, False)
+        # NOTE(russellb) Make sure our instance has the latest system_metadata
+        # in it.
+        instance = db.instance_get(self.context, instance_id)
         compute_utils.notify_about_instance_usage(self.context, instance,
         'create.start', extra_usage_info=extra_usage_info)
         self.assertEquals(len(test_notifier.NOTIFICATIONS), 1)
@@ -382,14 +385,3 @@ class UsageInfoTestCase(test.TestCase):
         image_ref_url = "%s/images/1" % glance.generate_glance_url()
         self.assertEquals(payload['image_ref_url'], image_ref_url)
         self.compute.terminate_instance(self.context, instance)
-
-
-class MetadataToDictTestCase(test.TestCase):
-    def test_metadata_to_dict(self):
-        self.assertEqual(compute_utils.metadata_to_dict(
-                [{'key': 'foo1', 'value': 'bar'},
-                 {'key': 'foo2', 'value': 'baz'}]),
-                         {'foo1': 'bar', 'foo2': 'baz'})
-
-    def test_metadata_to_dict_empty(self):
-        self.assertEqual(compute_utils.metadata_to_dict([]), {})
diff --git a/nova/tests/test_utils.py b/nova/tests/test_utils.py
index 9eab72c5b..84d56cadf 100644
--- a/nova/tests/test_utils.py
+++ b/nova/tests/test_utils.py
@@ -778,3 +778,14 @@ class IntLikeTestCase(test.TestCase):
         self.assertFalse(
             utils.is_int_like("0cc3346e-9fef-4445-abe6-5d2b2690ec64"))
         self.assertFalse(utils.is_int_like("a1"))
+
+
+class MetadataToDictTestCase(test.TestCase):
+    def test_metadata_to_dict(self):
+        self.assertEqual(utils.metadata_to_dict(
+                [{'key': 'foo1', 'value': 'bar'},
+                 {'key': 'foo2', 'value': 'baz'}]),
+                         {'foo1': 'bar', 'foo2': 'baz'})
+
+    def test_metadata_to_dict_empty(self):
+        self.assertEqual(utils.metadata_to_dict([]), {})
diff --git a/nova/utils.py b/nova/utils.py
index f9e08fd80..97091e42c 100644
--- a/nova/utils.py
+++ b/nova/utils.py
@@ -1261,3 +1261,10 @@ def last_bytes(file_like_object, num):
 
     remaining = file_like_object.tell()
     return (file_like_object.read(), remaining)
+
+
+def metadata_to_dict(metadata):
+    result = {}
+    for item in metadata:
+        result[item['key']] = item['value']
+    return result
diff --git a/nova/virt/xenapi/vm_utils.py b/nova/virt/xenapi/vm_utils.py
index 52a5f37b2..582a9320a 100644
--- a/nova/virt/xenapi/vm_utils.py
+++ b/nova/virt/xenapi/vm_utils.py
@@ -196,13 +196,6 @@ class ImageType(object):
         }.get(image_type_id)
 
 
-def _system_metadata_to_dict(system_metadata):
-    result = {}
-    for item in system_metadata:
-        result[item['key']] = item['value']
-    return result
-
-
 def create_vm(session, instance, name_label, kernel, ramdisk,
               use_pv_kernel=False):
     """Create a VM record.  Returns new VM reference.
@@ -994,7 +987,7 @@ def _create_image(context, session, instance, name_label, image_id,
     elif cache_images == 'all':
         cache = True
     elif cache_images == 'some':
-        sys_meta = _system_metadata_to_dict(instance['system_metadata'])
+        sys_meta = utils.metadata_to_dict(instance['system_metadata'])
         try:
             cache = utils.bool_from_str(sys_meta['image_cache_in_nova'])
         except KeyError:
@@ -1087,7 +1080,7 @@ def _image_uses_bittorrent(context, instance):
     if xenapi_torrent_images == 'all':
         bittorrent = True
     elif xenapi_torrent_images == 'some':
-        sys_meta = _system_metadata_to_dict(instance['system_metadata'])
+        sys_meta = utils.metadata_to_dict(instance['system_metadata'])
         try:
             bittorrent = utils.bool_from_str(sys_meta['image_bittorrent'])
         except KeyError: