objects: add ComputeNode.get_by_uuid method

The HostAPI is going to use this to uniquely identify a host
across cells.

Depends-On: I940979d85fc105c9733ae19c406e85debe8fdffb

Part of blueprint service-hyper-uuid-in-api

Change-Id: I21f4b18e4554e9e912496e623461129196c72852

nova/objects/compute_node.py

@@ -49,7 +49,8 @@ class ComputeNode(base.NovaPersistentObject, base.NovaObject):
     # Version 1.15: Added uuid
     # Version 1.16: Added disk_allocation_ratio
     # Version 1.17: Added mapped
-    VERSION = '1.17'
+    # Version 1.18: Added get_by_uuid().
+    VERSION = '1.18'
 
     fields = {
         'id': fields.IntegerField(read_only=True),
@@ -239,6 +240,14 @@ class ComputeNode(base.NovaPersistentObject, base.NovaObject):
         db_compute = db.compute_node_get(context, compute_id)
         return cls._from_db_object(context, cls(), db_compute)
 
+    @base.remotable_classmethod
+    def get_by_uuid(cls, context, compute_uuid):
+        nodes = ComputeNodeList.get_all_by_uuids(context, [compute_uuid])
+        # We have a unique index on the uuid column so we can get back 0 or 1.
+        if not nodes:
+            raise exception.ComputeHostNotFound(host=compute_uuid)
+        return nodes[0]
+
     # NOTE(hanlind): This is deprecated and should be removed on the next
     # major version bump
     @base.remotable_classmethod

nova/tests/unit/objects/test_compute_node.py

@@ -164,6 +164,27 @@ class _TestComputeNodeObject(object):
         self.assertNotIn('uuid', compute.obj_what_changed())
         get_mock.assert_called_once_with(self.context, 123)
 
+    @mock.patch.object(compute_node.ComputeNodeList, 'get_all_by_uuids')
+    def test_get_by_uuid(self, get_all_by_uuids):
+        fake_node = copy.copy(fake_compute_node)
+        fake_node['stats'] = None
+        get_all_by_uuids.return_value = objects.ComputeNodeList(
+            objects=[objects.ComputeNode(**fake_node)])
+        compute = compute_node.ComputeNode.get_by_uuid(
+            self.context, uuidsentinel.fake_compute_node)
+        self.assertEqual(uuidsentinel.fake_compute_node, compute.uuid)
+        get_all_by_uuids.assert_called_once_with(
+            self.context, [uuidsentinel.fake_compute_node])
+
+    @mock.patch.object(compute_node.ComputeNodeList, 'get_all_by_uuids')
+    def test_get_by_uuid_not_found(self, get_all_by_uuids):
+        get_all_by_uuids.return_value = objects.ComputeNodeList()
+        self.assertRaises(exception.ComputeHostNotFound,
+                          compute_node.ComputeNode.get_by_uuid,
+                          self.context, uuidsentinel.fake_compute_node)
+        get_all_by_uuids.assert_called_once_with(
+            self.context, [uuidsentinel.fake_compute_node])
+
     @mock.patch.object(db, 'compute_node_get')
     def test_get_without_mapped(self, get_mock):
         fake_node = copy.copy(fake_compute_node)

nova/tests/unit/objects/test_objects.py

@@ -1072,7 +1072,7 @@ object_data = {
     'BuildRequestList': '1.0-cd95608eccb89fbc702c8b52f38ec738',
     'CellMapping': '1.0-7f1a7e85a22bbb7559fc730ab658b9bd',
     'CellMappingList': '1.0-4ee0d9efdfd681fed822da88376e04d2',
-    'ComputeNode': '1.17-abc222ef5a707dcd3e3d32b48197c9e7',
+    'ComputeNode': '1.18-431fafd8ac4a5f3559bd9b1f1332cc22',
     'ComputeNodeList': '1.17-52f3b0962b1c86b98590144463ebb192',
     'DNSDomain': '1.0-7b0b2dab778454b6a7b6c66afe163a1a',
     'DNSDomainList': '1.0-4ee0d9efdfd681fed822da88376e04d2',