Properly synchronize status for ports deleted from backend

Ensure that the status for a port is properly synchronized even
when the port itself does not exist anymore in the backend, avoiding
raising exceptions due to missing results in the NVP query.

This patch also adjusts a comment and improves exception handling
in _nvp_get_port_id

Bug 1229331

Change-Id: Ibaa581006c994a543c1795dd3f1d50086583b953

neutron/plugins/nicira/NeutronPlugin.py

@@ -741,16 +741,16 @@ class NvpPluginV2(addr_pair_db.AllowedAddressPairsMixin,
                 cluster,
                 neutron_port['network_id'],
                 neutron_port['id'])
-            if nvp_port:
-                nicira_db.add_neutron_nvp_port_mapping(
-                    context.session,
-                    neutron_port['id'],
-                    nvp_port['uuid'])
-                return nvp_port['uuid']
-        except Exception:
+        except NvpApiClient.NvpApiException:
             LOG.exception(_("Unable to find NVP uuid for Neutron port %s"),
                           neutron_port['id'])
 
+        if nvp_port:
+            nicira_db.add_neutron_nvp_port_mapping(
+                context.session, neutron_port['id'],
+                nvp_port['uuid'])
+            return nvp_port['uuid']
+
     def _extend_fault_map(self):
         """Extends the Neutron Fault Map.
 

neutron/plugins/nicira/common/sync.py

@@ -381,17 +381,19 @@ class NvpSynchronizer():
                     lswitchport = nvplib.get_port(
                         self._cluster, neutron_port_data['network_id'],
                         lp_uuid, relations='LogicalPortStatus')
-            except exceptions.PortNotFoundOnNetwork:
+            except (exceptions.PortNotFoundOnNetwork):
                 # NOTE(salv-orlando): We should be catching
-                # NvpApiClient.ResourceNotFound here
-                # The logical switch port was not found
+                # NvpApiClient.ResourceNotFound here instead
+                # of PortNotFoundOnNetwork when the id exists but
+                # the logical switch port was not found
                 LOG.warning(_("Logical switch port for neutron port %s "
                               "not found on NVP."), neutron_port_data['id'])
                 lswitchport = None
             else:
-                # Update the cache
+                # If lswitchport is not None, update the cache.
+                # It could be none if the port was deleted from the backend
+                if lswitchport:
                     self._nvp_cache.update_lswitchport(lswitchport)
-
         # Note(salv-orlando): It might worth adding a check to verify neutron
         # resource tag in nvp entity matches Neutron id.
         # By default assume things go wrong