use make_weak_ref and resolve_ref from neutron-lib

The make_weak_ref and resolve_ref functions were rehomed into
neutron-lib with https://review.openstack.org/#/c/557809/
This patch consumes them by removing the functions and using lib's
version of them instead.

NeutronLibImpact

Change-Id: I41169ed0d93ea8caee530dcfc01a91271f02d538

neutron/common/utils.py

@@ -29,7 +29,6 @@ import sys
 import threading
 import time
 import uuid
-import weakref
 
 import eventlet
 from eventlet.green import subprocess
@@ -777,27 +776,6 @@ def get_related_rand_device_names(prefixes):
                                   max_length=n_const.DEVICE_NAME_MAX_LEN)
 
 
-try:
-    # PY3
-    weak_method = weakref.WeakMethod
-except AttributeError:
-    # PY2
-    import weakrefmethod
-    weak_method = weakrefmethod.WeakMethod
-
-
-def make_weak_ref(f):
-    """Make a weak reference to a function accounting for bound methods."""
-    return weak_method(f) if hasattr(f, '__self__') else weakref.ref(f)
-
-
-def resolve_ref(ref):
-    """Handles dereference of weakref."""
-    if isinstance(ref, weakref.ref):
-        ref = ref()
-    return ref
-
-
 def bytes_to_bits(value):
     return value * 8
 

neutron/db/_model_query.py

@@ -18,11 +18,11 @@ NOTE: This module shall not be used by external projects. It will be moved
 
 from neutron_lib.api import attributes
 from neutron_lib.db import utils as db_utils
+from neutron_lib.utils import helpers
 from oslo_db.sqlalchemy import utils as sa_utils
 from sqlalchemy import sql, or_, and_
 from sqlalchemy.ext import associationproxy
 
-from neutron.common import utils
 from neutron.db import _utils as ndb_utils
 from neutron.objects import utils as obj_utils
 
@@ -108,11 +108,11 @@ def register_hook(model, name, query_hook, filter_hook,
 
     """
     if callable(query_hook):
-        query_hook = utils.make_weak_ref(query_hook)
+        query_hook = helpers.make_weak_ref(query_hook)
     if callable(filter_hook):
-        filter_hook = utils.make_weak_ref(filter_hook)
+        filter_hook = helpers.make_weak_ref(filter_hook)
     if callable(result_filters):
-        result_filters = utils.make_weak_ref(result_filters)
+        result_filters = helpers.make_weak_ref(result_filters)
     _model_query_hooks.setdefault(model, {})[name] = {
         'query': query_hook,
         'filter': filter_hook,
@@ -153,11 +153,11 @@ def query_with_hooks(context, model):
             query_filter = (model.tenant_id == context.tenant_id)
     # Execute query hooks registered from mixins and plugins
     for hook in get_hooks(model):
-        query_hook = utils.resolve_ref(hook.get('query'))
+        query_hook = helpers.resolve_ref(hook.get('query'))
         if query_hook:
             query = query_hook(context, model, query)
 
-        filter_hook = utils.resolve_ref(hook.get('filter'))
+        filter_hook = helpers.resolve_ref(hook.get('filter'))
         if filter_hook:
             query_filter = filter_hook(context, model, query_filter)
 
@@ -245,7 +245,8 @@ def apply_filters(query, model, filters, context=None):
                     query = query.outerjoin(model.rbac_entries)
                 query = query.filter(is_shared)
         for hook in get_hooks(model):
-            result_filter = utils.resolve_ref(hook.get('result_filters', None))
+            result_filter = helpers.resolve_ref(
+                hook.get('result_filters', None))
             if result_filter:
                 query = result_filter(query, filters)
     return query

neutron/db/_resource_extend.py

@@ -18,7 +18,8 @@ NOTE: This module shall not be used by external projects. It will be moved
 import collections
 import inspect
 
-from neutron.common import utils
+from neutron_lib.utils import helpers
+
 
 # This dictionary will store methods for extending API resources.
 # Extensions can add their own methods by invoking register_funcs().
@@ -50,7 +51,7 @@ def register_funcs(resource, funcs):
             return foo_res
 
     """
-    funcs = [utils.make_weak_ref(f) if callable(f) else f
+    funcs = [helpers.make_weak_ref(f) if callable(f) else f
              for f in funcs]
     _resource_extend_functions.setdefault(resource, []).extend(funcs)
 
@@ -70,7 +71,7 @@ def get_funcs(resource):
 
 def apply_funcs(resource_type, response, db_object):
     for func in get_funcs(resource_type):
-        resolved_func = utils.resolve_ref(func)
+        resolved_func = helpers.resolve_ref(func)
         if resolved_func:
             resolved_func(response, db_object)