Use threadpool when building compute data model

Use the general purpose threadpool when building the nova compute
data model. Additionally, adds thorough explanation about theory of
operation.

Updates related test cases to better ensure the correct operation
of add_physical_layer.

Partially Implements: blueprint general-purpose-decision-engine-threadpool

Change-Id: I53ed32a4b2a089b05d1ffede629c9f4c5cb720c8

watcher/tests/decision_engine/cluster/test_nova_cdmc.py

@@ -291,6 +291,15 @@ class TestNovaModelBuilder(base.TestCase):
 
         self.assertEqual(set(['hostone', 'hosttwo']), result)
 
+    @mock.patch.object(nova_helper, 'NovaHelper')
+    def test_collect_aggregates_none(self, m_nova):
+        """Test collect_aggregates with host_aggregates None"""
+        result = set()
+        t_nova_cluster = nova.NovaModelBuilder(mock.Mock())
+        t_nova_cluster._collect_aggregates(None, result)
+
+        self.assertEqual(set(), result)
+
     @mock.patch.object(nova_helper, 'NovaHelper')
     def test_collect_zones(self, m_nova):
         """"""
@@ -310,8 +319,35 @@ class TestNovaModelBuilder(base.TestCase):
         self.assertEqual(set(['hostone']), result)
 
     @mock.patch.object(nova_helper, 'NovaHelper')
-    def test_add_physical_layer(self, m_nova):
-        """"""
+    def test_collect_zones_none(self, m_nova):
+        """Test collect_zones with availability_zones None"""
+        result = set()
+        t_nova_cluster = nova.NovaModelBuilder(mock.Mock())
+        t_nova_cluster._collect_zones(None, result)
+
+        self.assertEqual(set(), result)
+
+    @mock.patch.object(placement_helper, 'PlacementHelper')
+    @mock.patch.object(nova_helper, 'NovaHelper')
+    def test_add_physical_layer(self, m_nova, m_placement):
+        """Ensure all three steps of the physical layer are fully executed
+
+        First the return value for get_aggregate_list and get_service_list are
+        mocked. These return 3 hosts of which hostone is returned by both the
+        aggregate and service call. This will help verify the elimination of
+        duplicates. The scope is setup so that only hostone and hosttwo should
+        remain.
+
+        There will be 2 simulated compute nodes and 2 associated instances.
+        These will be returned by their matching calls in nova helper. The
+        calls to get_compute_node_by_name and get_instance_list are asserted
+        as to verify the correct operation of add_physical_layer.
+        """
+
+        mock_placement = mock.Mock(name="placement_helper")
+        mock_placement.get_inventories.return_value = dict()
+        mock_placement.get_usages_for_resource_provider.return_value = None
+        m_placement.return_value = mock_placement
 
         m_nova.return_value.get_aggregate_list.return_value = \
             [mock.Mock(id=1, name='example'),
@@ -321,7 +357,69 @@ class TestNovaModelBuilder(base.TestCase):
             [mock.Mock(zone='av_b', host='hostthree'),
              mock.Mock(zone='av_a', host='hostone')]
 
-        m_nova.return_value.get_compute_node_by_name.return_value = False
+        compute_node_one = mock.Mock(
+            id='796fee99-65dd-4262-aa-fd2a1143faa6',
+            hypervisor_hostname='hostone',
+            hypervisor_type='QEMU',
+            state='TEST_STATE',
+            status='TEST_STATUS',
+            memory_mb=333,
+            memory_mb_used=100,
+            free_disk_gb=222,
+            local_gb=111,
+            local_gb_used=10,
+            vcpus=4,
+            vcpus_used=0,
+            servers=[
+                {'name': 'fake_instance',
+                 'uuid': 'ef500f7e-dac8-470f-960c-169486fce71b'}
+            ],
+            service={'id': 123, 'host': 'hostone',
+                     'disabled_reason': ''},
+        )
+
+        compute_node_two = mock.Mock(
+            id='756fef99-65dd-4262-aa-fd2a1143faa6',
+            hypervisor_hostname='hosttwo',
+            hypervisor_type='QEMU',
+            state='TEST_STATE',
+            status='TEST_STATUS',
+            memory_mb=333,
+            memory_mb_used=100,
+            free_disk_gb=222,
+            local_gb=111,
+            local_gb_used=10,
+            vcpus=4,
+            vcpus_used=0,
+            servers=[
+                {'name': 'fake_instance2',
+                 'uuid': 'ef500f7e-dac8-47f0-960c-169486fce71b'}
+            ],
+            service={'id': 123, 'host': 'hosttwo',
+                     'disabled_reason': ''},
+        )
+
+        m_nova.return_value.get_compute_node_by_name.side_effect = [
+            [compute_node_one], [compute_node_two]
+        ]
+
+        fake_instance_one = mock.Mock(
+            id='796fee99-65dd-4262-aa-fd2a1143faa6',
+            name='fake_instance',
+            flavor={'ram': 333, 'disk': 222, 'vcpus': 4, 'id': 1},
+            metadata={'hi': 'hello'},
+            tenant_id='ff560f7e-dbc8-771f-960c-164482fce21b',
+        )
+        fake_instance_two = mock.Mock(
+            id='ef500f7e-dac8-47f0-960c-169486fce71b',
+            name='fake_instance2',
+            flavor={'ram': 333, 'disk': 222, 'vcpus': 4, 'id': 1},
+            metadata={'hi': 'hello'},
+            tenant_id='756fef99-65dd-4262-aa-fd2a1143faa6',
+        )
+        m_nova.return_value.get_instance_list.side_effect = [
+            [fake_instance_one], [fake_instance_two]
+        ]
 
         m_scope = [{"compute": [
             {"host_aggregates": [{"id": 5}]},
@@ -337,6 +435,13 @@ class TestNovaModelBuilder(base.TestCase):
         self.assertEqual(
             m_nova.return_value.get_compute_node_by_name.call_count, 2)
 
+        m_nova.return_value.get_instance_list.assert_any_call(
+            filters={'host': 'hostone'}, limit=1)
+        m_nova.return_value.get_instance_list.assert_any_call(
+            filters={'host': 'hosttwo'}, limit=1)
+        self.assertEqual(
+            m_nova.return_value.get_instance_list.call_count, 2)
+
     @mock.patch.object(placement_helper, 'PlacementHelper')
     @mock.patch.object(nova_helper, 'NovaHelper')
     def test_add_physical_layer_with_baremetal_node(self, m_nova,