copr-matrix-synapse/python38_fix.patch
Kai A. Hiller c495426260 Fix Python 3.8 issues
Signed-off-by: Kai A. Hiller <V02460@gmail.com>
2019-10-31 21:19:29 +01:00

68 lines
2.5 KiB
Diff

diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index 5ac2530a6..bddadd629 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -17,8 +17,8 @@ import functools
import inspect
import logging
import threading
-from collections import namedtuple
from typing import Any, cast
+from weakref import WeakValueDictionary
from six import itervalues
@@ -430,7 +430,7 @@ class CacheDescriptor(_CacheDescriptorBase):
# Add our own `cache_context` to argument list if the wrapped function
# has asked for one
if self.add_cache_context:
- kwargs["cache_context"] = _CacheContext(cache, cache_key)
+ kwargs["cache_context"] = _CacheContext.get_instance(cache, cache_key)
try:
cached_result_d = cache.get(cache_key, callback=invalidate_callback)
@@ -625,14 +625,36 @@ class CacheListDescriptor(_CacheDescriptorBase):
return wrapped
-class _CacheContext(namedtuple("_CacheContext", ("cache", "key"))):
- # We rely on _CacheContext implementing __eq__ and __hash__ sensibly,
- # which namedtuple does for us (i.e. two _CacheContext are the same if
- # their caches and keys match). This is important in particular to
- # dedupe when we add callbacks to lru cache nodes, otherwise the number
- # of callbacks would grow.
+class _CacheContext:
+ """Holds cache information from the cached function higher in the calling order.
+
+ Can be used to invalidate the higher level cache entry if something changes
+ on a lower level.
+ """
+
+ _cache_context_objects = WeakValueDictionary()
+
+ def __init__(self, cache, cache_key):
+ self._cache = cache
+ self._cache_key = cache_key
+
def invalidate(self):
- self.cache.invalidate(self.key)
+ """Invalidates the cache entry referred to by the context."""
+ self._cache.invalidate(self._cache_key)
+
+ @classmethod
+ def get_instance(cls, cache, cache_key):
+ """Returns an instance constructed with the given arguments.
+
+ A new instance is only created if none already exists.
+ """
+
+ # We make sure there are no identical _CacheContext instances. This is
+ # important in particular to dedupe when we add callbacks to lru cache
+ # nodes, otherwise the number of callbacks would grow.
+ return cls._cache_context_objects.setdefault(
+ (cache, cache_key), cls(cache, cache_key)
+ )
def cached(