Correct cache key for proxy_owner, with_context_options

Fixed issue in subquery loader strategy which prevented caching from
working correctly. This would have been seen in the logs as a "generated"
message instead of "cached" for all subqueryload SQL emitted, which by
saturating the cache with new keys would degrade overall performance; it
also would produce "LRU size alert" warnings.

In this issue we also observe that the local LRU cache for lazyloader
and selectinloader will get used for all subsequent loads as well,
which makes it more likely to hit the limit of 30.   However rather than
trying to work this out, it would be better if we removed the
loader-local LRU caches altogether once we are confident these
are working well.

Fixes: #6459
Change-Id: Id953e8f75536bb87f7e3315929cebcd8f84a5a50

1 files changed, 18 insertions, 0 deletions

diff --git a/lib/sqlalchemy/sql/traversals.py b/lib/sqlalchemy/sql/traversals.py
index e8a805285..e64eff6a4 100644
--- a/lib/sqlalchemy/sql/traversals.py
+++ b/lib/sqlalchemy/sql/traversals.py
@@ -310,6 +310,12 @@ class CacheKey(namedtuple("CacheKey", ["key", "bindparams"])):
     def __eq__(self, other):
         return self.key == other.key
 
+    @classmethod
+    def _diff_tuples(cls, left, right):
+        ck1 = CacheKey(left, [])
+        ck2 = CacheKey(right, [])
+        return ck1._diff(ck2)
+
     def _whats_different(self, other):
 
         k1 = self.key
@@ -413,6 +419,11 @@ class _CacheKey(ExtendedInternalTraversal):
 
     visit_propagate_attrs = PROPAGATE_ATTRS
 
+    def visit_with_context_options(
+        self, attrname, obj, parent, anon_map, bindparams
+    ):
+        return tuple((fn.__code__, c_key) for fn, c_key in obj)
+
     def visit_inspectable(self, attrname, obj, parent, anon_map, bindparams):
         return (attrname, inspect(obj)._gen_cache_key(anon_map, bindparams))
 
@@ -1209,6 +1220,13 @@ class TraversalComparatorStrategy(InternalTraversal, util.MemoizedSlots):
         else:
             return left == right
 
+    def visit_with_context_options(
+        self, attrname, left_parent, left, right_parent, right, **kw
+    ):
+        return tuple((fn.__code__, c_key) for fn, c_key in left) == tuple(
+            (fn.__code__, c_key) for fn, c_key in right
+        )
+
     def visit_plain_obj(
         self, attrname, left_parent, left, right_parent, right, **kw
     ):