Combine `LruCache.invalidate` and `invalidate_many` (#9973)

* Make `invalidate` and `invalidate_many` do the same thing

... so that we can do either over the invalidation replication stream, and also
because they always confused me a bit.

* Kill off `invalidate_many`

* changelog

1 files changed, 6 insertions, 2 deletions

diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py

index 2ac24a2f25..d77e8edeea 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -48,7 +48,6 @@ F = TypeVar("F", bound=Callable[..., Any])
 class _CachedFunction(Generic[F]):
     invalidate = None  # type: Any
     invalidate_all = None  # type: Any
-    invalidate_many = None  # type: Any
     prefill = None  # type: Any
     cache = None  # type: Any
     num_args = None  # type: Any
@@ -262,6 +261,11 @@ class DeferredCacheDescriptor(_CacheDescriptorBase):
     ):
         super().__init__(orig, num_args=num_args, cache_context=cache_context)
 
+        if tree and self.num_args < 2:
+            raise RuntimeError(
+                "tree=True is nonsensical for cached functions with a single parameter"
+            )
+
         self.max_entries = max_entries
         self.tree = tree
         self.iterable = iterable
@@ -302,11 +306,11 @@ class DeferredCacheDescriptor(_CacheDescriptorBase):
         wrapped = cast(_CachedFunction, _wrapped)
 
         if self.num_args == 1:
+            assert not self.tree
             wrapped.invalidate = lambda key: cache.invalidate(key[0])
             wrapped.prefill = lambda key, val: cache.prefill(key[0], val)
         else:
             wrapped.invalidate = cache.invalidate
-            wrapped.invalidate_many = cache.invalidate_many
             wrapped.prefill = cache.prefill
 
         wrapped.invalidate_all = cache.invalidate_all