Introduce VirtAPI to nova/virt

This patch introduces a VirtAPI class which will house
callbacks provided by the manager to the virt drivers, allowing
things such as direct database accesses to be pulled out of
the virt drivers and delegated to another service.

As a first step, this introduces an instance_update() method
and makes all the virt drivers use it instead of direct calls
to db.instance_update.*().

Change-Id: I2e40831f5cfb20a03b304097d84d592aab035ef1

nova/compute/manager.py

@@ -73,6 +73,7 @@
 from nova.scheduler import rpcapi as scheduler_rpcapi
 from nova import utils
 from nova.virt import driver
+from nova.virt import virtapi
 from nova import volume
 
 
@@ -209,6 +210,17 @@ def _get_image_meta(context, image_ref):
     return image_service.show(context, image_id)
 
 
+class ComputeVirtAPI(virtapi.VirtAPI):
+    def __init__(self, compute):
+        super(ComputeVirtAPI, self).__init__()
+        self._compute = compute
+
+    def instance_update(self, context, instance_uuid, updates):
+        return self._compute.db.instance_update_and_get_original(context,
+                                                                 instance_uuid,
+                                                                 updates)
+
+
 class ComputeManager(manager.SchedulerDependentManager):
     """Manages the running instances from creation to destruction."""
 
@@ -225,10 +237,13 @@ def __init__(self, compute_driver=None, *args, **kwargs):
             LOG.error(_("Compute driver option required, but not specified"))
             sys.exit(1)
 
+        self.virtapi = ComputeVirtAPI(self)
+
         LOG.info(_("Loading compute driver '%s'") % compute_driver)
         try:
             self.driver = utils.check_isinstance(
-                    importutils.import_object_ns('nova.virt', compute_driver),
+                    importutils.import_object_ns('nova.virt', compute_driver,
+                                                 self.virtapi),
                     driver.ComputeDriver)
         except ImportError as e:
             LOG.error(_("Unable to load the virtualization driver: %s") % (e))

nova/tests/baremetal/test_proxy_bare_metal.py

@@ -257,7 +257,7 @@ def test_get_info(self):
         self.mox.ReplayAll()
 
         # Code under test
-        conn = driver.BareMetalDriver(True)
+        conn = driver.BareMetalDriver(None, True)
         # TODO(mikalstill): this is not a very good fake instance
         info = conn.get_info({'name': 'instance-00000001'})
 

nova/tests/compute/test_resource_tracker.py

@@ -42,7 +42,7 @@ def get_available_resource(self):
 
 class FakeVirtDriver(driver.ComputeDriver):
 
-    def __init__(self):
+    def __init__(self, virtapi):
         self.memory_mb = 5
         self.local_gb = 6
         self.vcpus = 1
@@ -148,9 +148,9 @@ def _tracker(self, unsupported=False):
         host = "fakehost"
 
         if unsupported:
-            driver = UnsupportedVirtDriver()
+            driver = UnsupportedVirtDriver(None)
         else:
-            driver = FakeVirtDriver()
+            driver = FakeVirtDriver(None)
 
         tracker = resource_tracker.ResourceTracker(host, driver)
         return tracker
@@ -293,12 +293,12 @@ def testUpdateUseOnlyForTracked(self):
         self.assertEqual(1, self.tracker.compute_node['current_workload'])
 
     def testFreeRamResourceValue(self):
-        driver = FakeVirtDriver()
+        driver = FakeVirtDriver(None)
         mem_free = driver.memory_mb - driver.memory_mb_used
         self.assertEqual(mem_free, self.tracker.compute_node['free_ram_mb'])
 
     def testFreeDiskResourceValue(self):
-        driver = FakeVirtDriver()
+        driver = FakeVirtDriver(None)
         mem_free = driver.local_gb - driver.local_gb_used
         self.assertEqual(mem_free, self.tracker.compute_node['free_disk_gb'])
 

nova/tests/test_hypervapi.py

@@ -66,7 +66,7 @@ def setUp(self):
                         vswitch_name='external')
 
         self._hypervutils = hypervutils.HyperVUtils()
-        self._conn = driver_hyperv.HyperVDriver()
+        self._conn = driver_hyperv.HyperVDriver(None)
 
     def _setup_stubs(self):
         db_fakes.stub_out_db_instance_api(self.stubs)