Use dict as Table cache.

For both IPv4 and IPv6, use a dict instead of a weakref cache. This
makes the cache a permanent one, and avoids the overhead of
creating/freeing tables too often.

Author: ldx

iptc/ip4tc.py

@@ -1318,7 +1318,7 @@ class Table(object):
     ALL = ["filter", "mangle", "raw", "nat"]
     """This is the constant for all tables."""
 
-    _cache = weakref.WeakValueDictionary()
+    _cache = dict()
 
     def __new__(cls, name, autocommit=None):
         obj = Table._cache.get(name, None)

iptc/ip6tc.py

@@ -569,7 +569,7 @@ class Table6(Table):
     ALL = ["filter", "mangle", "raw", "security"]
     """This is the constant for all tables."""
 
-    _cache = weakref.WeakValueDictionary()
+    _cache = dict()
 
     def __new__(cls, name, autocommit=None):
         obj = Table6._cache.get(name, None)