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| author | Sean Quah <8349537+squahtx@users.noreply.github.com> | 2021-11-30 16:28:02 +0000 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2021-11-30 16:28:02 +0000 |
| commit | 7ff22d6da41cd5ca80db95c18b409aea38e49fcd (patch) | |
| tree | 99dbc2a8eb19b7c1ecf23665970d706a995e7b91 /synapse/util/caches/lrucache.py | |
| parent | Eliminate a few `Any`s in `LruCache` type hints (#11453) (diff) | |
| download | synapse-7ff22d6da41cd5ca80db95c18b409aea38e49fcd.tar.xz | |
Fix `LruCache` corruption bug with a `size_callback` that can return 0 (#11454)
When all entries in an `LruCache` have a size of 0 according to the provided `size_callback`, and `drop_from_cache` is called on a cache node, the node would be unlinked from the LRU linked list but remain in the cache dictionary. An assertion would be later be tripped due to the inconsistency. Avoid unintentionally calling `__len__` and use a strict `is None` check instead when unwrapping the weak reference.
Diffstat (limited to 'synapse/util/caches/lrucache.py')
| -rw-r--r-- | synapse/util/caches/lrucache.py | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/synapse/util/caches/lrucache.py b/synapse/util/caches/lrucache.py index 05c4dcb062..eb96f7e665 100644 --- a/synapse/util/caches/lrucache.py +++ b/synapse/util/caches/lrucache.py @@ -271,7 +271,10 @@ class _Node(Generic[KT, VT]): removed from all lists. """ cache = self._cache() - if not cache or not cache.pop(self.key, None): + if ( + cache is None + or cache.pop(self.key, _Sentinel.sentinel) is _Sentinel.sentinel + ): # `cache.pop` should call `drop_from_lists()`, unless this Node had # already been removed from the cache. self.drop_from_lists() |