Allow subclasses to modify dict_extend hooks

Partial-Bug 1219991

This change modifies the hook processing for dict_extend routines
to call the method on the instance if a hook is registered as a string.
Otherwise, the callable hook is directly invoked as an unbound method.

This patch fixes hook registration for all extensions except port_binding.
This is because some plugins are currently working around this limitation
by invoking both the global hook and another dict_extend function,
which might either be registered as another hook, or invoked explicitly
before returning the response.
Fixing this would go beyong the scope of this patch.

Change-Id: Ibe78433e6554aa7fdf5156fc75b8339254876e78

neutron/db/db_base_plugin_v2.py

@@ -154,6 +154,19 @@ class CommonDbMixin(object):
                     query = result_filter(query, filters)
         return query
 
+    def _apply_dict_extend_functions(self, resource_type,
+                                     response, db_object):
+        for func in self._dict_extend_functions.get(
+            resource_type, []):
+            args = (response, db_object)
+            if isinstance(func, basestring):
+                func = getattr(self, func, None)
+            else:
+                # must call unbound method - use self as 1st argument
+                args = (self,) + args
+            if func:
+                func(*args)
+
     def _get_collection_query(self, context, model, filters=None,
                               sorts=None, limit=None, marker_obj=None,
                               page_reverse=False):
@@ -865,9 +878,8 @@ class NeutronDbPluginV2(neutron_plugin_base_v2.NeutronPluginBaseV2,
                            for subnet in network['subnets']]}
         # Call auxiliary extend functions, if any
         if process_extensions:
-            for func in self._dict_extend_functions.get(attributes.NETWORKS,
-                                                        []):
-                func(self, res, network)
+            self._apply_dict_extend_functions(
+                attributes.NETWORKS, res, network)
         return self._fields(res, fields)
 
     def _make_subnet_dict(self, subnet, fields=None):
@@ -907,9 +919,8 @@ class NeutronDbPluginV2(neutron_plugin_base_v2.NeutronPluginBaseV2,
                "device_owner": port["device_owner"]}
         # Call auxiliary extend functions, if any
         if process_extensions:
-            for func in self._dict_extend_functions.get(attributes.PORTS,
-                                                        []):
-                func(self, res, port)
+            self._apply_dict_extend_functions(
+                attributes.PORTS, res, port)
         return self._fields(res, fields)
 
     def _create_bulk(self, resource, context, request_items):

neutron/db/extradhcpopt_db.py

@@ -128,4 +128,4 @@ class ExtraDhcpOptMixin(object):
         return res
 
     db_base_plugin_v2.NeutronDbPluginV2.register_dict_extend_funcs(
-        attributes.PORTS, [_extend_port_dict_extra_dhcp_opt])
+        attributes.PORTS, ['_extend_port_dict_extra_dhcp_opt'])

neutron/db/extraroute_db.py

@@ -63,7 +63,7 @@ class ExtraRoute_db_mixin(l3_db.L3_NAT_db_mixin):
                                 ))
 
     db_base_plugin_v2.NeutronDbPluginV2.register_dict_extend_funcs(
-        l3.ROUTERS, [_extend_router_dict_extraroute])
+        l3.ROUTERS, ['_extend_router_dict_extraroute'])
 
     def update_router(self, context, id, router):
         r = router['router']

neutron/db/l3_db.py

@@ -143,9 +143,12 @@ class L3_NAT_db_mixin(l3.RouterPluginBase):
         if router['gw_port_id']:
             nw_id = router.gw_port['network_id']
             res[EXTERNAL_GW_INFO] = {'network_id': nw_id}
+        # NOTE(salv-orlando): The following assumes this mixin is used in a
+        # class inheriting from CommonDbMixin, which is true for all existing
+        # plugins.
         if process_extensions:
-            for func in self._dict_extend_functions.get(l3.ROUTERS, []):
-                func(self, res, router)
+            self._apply_dict_extend_functions(
+                l3.ROUTERS, res, router)
         return self._fields(res, fields)
 
     def create_router(self, context, router):
@@ -792,7 +795,7 @@ class L3_NAT_db_mixin(l3.RouterPluginBase):
 
     # Register dict extend functions for networks
     db_base_plugin_v2.NeutronDbPluginV2.register_dict_extend_funcs(
-        attributes.NETWORKS, [_extend_network_dict_l3])
+        attributes.NETWORKS, ['_extend_network_dict_l3'])
 
     def _process_l3_create(self, context, net_data, req_data):
         external = req_data.get(l3.EXTERNAL)

neutron/db/portsecurity_db.py

@@ -177,6 +177,6 @@ class PortSecurityDbMixin(object):
 
     # Register dict extend functions for ports and networks
     db_base_plugin_v2.NeutronDbPluginV2.register_dict_extend_funcs(
-        attrs.NETWORKS, [_extend_port_security_dict])
+        attrs.NETWORKS, ['_extend_port_security_dict'])
     db_base_plugin_v2.NeutronDbPluginV2.register_dict_extend_funcs(
-        attrs.PORTS, [_extend_port_security_dict])
+        attrs.PORTS, ['_extend_port_security_dict'])

neutron/db/securitygroups_db.py

@@ -444,7 +444,7 @@ class SecurityGroupDbMixin(ext_sg.SecurityGroupPluginBase):
 
     # Register dict extend functions for ports
     db_base_plugin_v2.NeutronDbPluginV2.register_dict_extend_funcs(
-        attr.PORTS, [_extend_port_dict_security_group])
+        attr.PORTS, ['_extend_port_dict_security_group'])
 
     def _process_port_create_security_group(self, context, port,
                                             security_group_ids):

neutron/plugins/nicira/dbexts/distributedrouter.py

@@ -66,4 +66,4 @@ class DistributedRouter_mixin(object):
 
     # Register dict extend functions for ports
     db_base_plugin_v2.NeutronDbPluginV2.register_dict_extend_funcs(
-        l3.ROUTERS, [_extend_router_dict_distributed])
+        l3.ROUTERS, ['_extend_router_dict_distributed'])

neutron/plugins/nicira/dbexts/maclearning.py

@@ -59,7 +59,7 @@ class MacLearningDbMixin(object):
 
     # Register dict extend functions for ports
     db_base_plugin_v2.NeutronDbPluginV2.register_dict_extend_funcs(
-        attributes.PORTS, [_extend_port_mac_learning_state])
+        attributes.PORTS, ['_extend_port_mac_learning_state'])
 
     def _update_mac_learning_state(self, context, port_id, enabled):
         try: