diff --git a/synapse/util/caches/deferred_cache.py b/synapse/util/caches/deferred_cache.py
index da502aec11..377c9a282a 100644
--- a/synapse/util/caches/deferred_cache.py
+++ b/synapse/util/caches/deferred_cache.py
@@ -22,6 +22,7 @@ from typing import (
Iterable,
MutableMapping,
Optional,
+ Sized,
TypeVar,
Union,
cast,
@@ -104,7 +105,13 @@ class DeferredCache(Generic[KT, VT]):
max_size=max_entries,
cache_name=name,
cache_type=cache_type,
- size_callback=(lambda d: len(d) or 1) if iterable else None,
+ size_callback=(
+ (lambda d: len(cast(Sized, d)) or 1)
+ # Argument 1 to "len" has incompatible type "VT"; expected "Sized"
+ # We trust that `VT` is `Sized` when `iterable` is `True`
+ if iterable
+ else None
+ ),
metrics_collection_callback=metrics_cb,
apply_cache_factor_from_config=apply_cache_factor_from_config,
prune_unread_entries=prune_unread_entries,
@@ -289,7 +296,7 @@ class DeferredCache(Generic[KT, VT]):
callbacks = [callback] if callback else []
self.cache.set(key, value, callbacks=callbacks)
- def invalidate(self, key) -> None:
+ def invalidate(self, key: KT) -> None:
"""Delete a key, or tree of entries
If the cache is backed by a regular dict, then "key" must be of
|
