Add oslo db retry decorator to the RPC handlers

The decorator was previously added at the API layer
(commit 4e77442d52,
commit d04335c448).
However some RPC handlers are also dealing with port
create/update/delete operations, like dhcp ports for example.
We need to cover these cases too.

Also remove db retry from ml2 plugin delete_port()
as it's not needed once we retry at the API and RPC layers.
(there is already a unit test on this)

The patch also adds a unit test for checking deadlock
handling during port creation at API layer.
Though it's not directly related to the current fix,
I decided to leave it for regression preventing purposes.

Closes-Bug: #1479738
Change-Id: I7793a8f7c37ca542b8bc12372168aaaa0826ac4c

neutron/api/rpc/handlers/dhcp_rpc.py

@@ -26,6 +26,7 @@ from neutron.api.v2 import attributes
 from neutron.common import constants
 from neutron.common import exceptions as n_exc
 from neutron.common import utils
+from neutron.db import api as db_api
 from neutron.extensions import portbindings
 from neutron.i18n import _LW
 from neutron import manager
@@ -157,6 +158,7 @@ class DhcpRpcCallback(object):
         network['ports'] = plugin.get_ports(context, filters=filters)
         return network
 
+    @db_api.retry_db_errors
     def release_dhcp_port(self, context, **kwargs):
         """Release the port currently being used by a DHCP agent."""
         host = kwargs.get('host')
@@ -169,6 +171,7 @@ class DhcpRpcCallback(object):
         plugin = manager.NeutronManager.get_plugin()
         plugin.delete_ports_by_device_id(context, device_id, network_id)
 
+    @db_api.retry_db_errors
     def release_port_fixed_ip(self, context, **kwargs):
         """Release the fixed_ip associated the subnet on a port."""
         host = kwargs.get('host')
@@ -203,6 +206,7 @@ class DhcpRpcCallback(object):
         LOG.warning(_LW('Updating lease expiration is now deprecated. Issued  '
                         'from host %s.'), host)
 
+    @db_api.retry_db_errors
     @resource_registry.mark_resources_dirty
     def create_dhcp_port(self, context, **kwargs):
         """Create and return dhcp port information.
@@ -224,6 +228,7 @@ class DhcpRpcCallback(object):
         plugin = manager.NeutronManager.get_plugin()
         return self._port_action(plugin, context, port, 'create_port')
 
+    @db_api.retry_db_errors
     def update_dhcp_port(self, context, **kwargs):
         """Update the dhcp port."""
         host = kwargs.get('host')

neutron/api/rpc/handlers/l3_rpc.py

@@ -23,6 +23,7 @@ from neutron.common import constants
 from neutron.common import exceptions
 from neutron.common import utils
 from neutron import context as neutron_context
+from neutron.db import api as db_api
 from neutron.extensions import l3
 from neutron.extensions import portbindings
 from neutron.i18n import _LE
@@ -58,6 +59,7 @@ class L3RpcCallback(object):
                 plugin_constants.L3_ROUTER_NAT]
         return self._l3plugin
 
+    @db_api.retry_db_errors
     def sync_routers(self, context, **kwargs):
         """Sync routers according to filters to a specific agent.
 
@@ -196,6 +198,7 @@ class L3RpcCallback(object):
         filters = {'fixed_ips': {'subnet_id': [subnet_id]}}
         return self.plugin.get_ports(context, filters=filters)
 
+    @db_api.retry_db_errors
     def get_agent_gateway_port(self, context, **kwargs):
         """Get Agent Gateway port for FIP.
 

neutron/plugins/ml2/plugin.py

@@ -1276,8 +1276,6 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
                 raise e.errors[0].error
             raise exc.ServicePortInUse(port_id=port_id, reason=e)
 
-    @oslo_db_api.wrap_db_retry(max_retries=db_api.MAX_RETRIES,
-                               retry_on_deadlock=True)
     def delete_port(self, context, id, l3_port_check=True):
         self._pre_delete_port(context, id, l3_port_check)
         # TODO(armax): get rid of the l3 dependency in the with block

neutron/tests/unit/plugins/ml2/test_plugin.py

@@ -617,6 +617,20 @@ class TestMl2PortsV2(test_plugin.TestPortsV2, Ml2PluginV2TestCase):
             # by the called method
             self.assertIsNone(l3plugin.disassociate_floatingips(ctx, port_id))
 
+    def test_create_port_tolerates_db_deadlock(self):
+        ctx = context.get_admin_context()
+        with self.network() as net:
+            with self.subnet(network=net) as subnet:
+                segments = ml2_db.get_network_segments(ctx.session,
+                                                       net['network']['id'])
+                with mock.patch('neutron.plugins.ml2.plugin.'
+                                'db.get_network_segments') as get_seg_mock:
+                    get_seg_mock.side_effect = [db_exc.DBDeadlock, segments,
+                                                segments, segments]
+                    with self.port(subnet=subnet) as port:
+                        self.assertTrue(port['port']['id'])
+                        self.assertEqual(4, get_seg_mock.call_count)
+
     def test_delete_port_tolerates_db_deadlock(self):
         ctx = context.get_admin_context()
         plugin = manager.NeutronManager.get_plugin()
@@ -627,7 +641,9 @@ class TestMl2PortsV2(test_plugin.TestPortsV2, Ml2PluginV2TestCase):
                             'db.get_locked_port_and_binding') as lock:
                 lock.side_effect = [db_exc.DBDeadlock,
                                     (port_db, binding)]
-                plugin.delete_port(ctx, port['port']['id'])
+                req = self.new_delete_request('ports', port['port']['id'])
+                res = req.get_response(self.api)
+                self.assertEqual(204, res.status_int)
                 self.assertEqual(2, lock.call_count)
                 self.assertRaises(
                     exc.PortNotFound, plugin.get_port, ctx, port['port']['id'])