diff --git a/synapse/util/caches/dictionary_cache.py b/synapse/util/caches/dictionary_cache.py
index 588d2d49f2..b3b413b02c 100644
--- a/synapse/util/caches/dictionary_cache.py
+++ b/synapse/util/caches/dictionary_cache.py
@@ -15,26 +15,38 @@
import enum
import logging
import threading
-from collections import namedtuple
-from typing import Any
+from typing import Any, Dict, Generic, Iterable, Optional, Set, TypeVar
+
+import attr
from synapse.util.caches.lrucache import LruCache
logger = logging.getLogger(__name__)
-class DictionaryEntry(namedtuple("DictionaryEntry", ("full", "known_absent", "value"))):
+# The type of the cache keys.
+KT = TypeVar("KT")
+# The type of the dictionary keys.
+DKT = TypeVar("DKT")
+
+
+@attr.s(slots=True)
+class DictionaryEntry:
"""Returned when getting an entry from the cache
Attributes:
- full (bool): Whether the cache has the full or dict or just some keys.
+ full: Whether the cache has the full or dict or just some keys.
If not full then not all requested keys will necessarily be present
in `value`
- known_absent (set): Keys that were looked up in the dict and were not
+ known_absent: Keys that were looked up in the dict and were not
there.
- value (dict): The full or partial dict value
+ value: The full or partial dict value
"""
+ full = attr.ib(type=bool)
+ known_absent = attr.ib()
+ value = attr.ib()
+
def __len__(self):
return len(self.value)
@@ -45,21 +57,21 @@ class _Sentinel(enum.Enum):
sentinel = object()
-class DictionaryCache:
+class DictionaryCache(Generic[KT, DKT]):
"""Caches key -> dictionary lookups, supporting caching partial dicts, i.e.
fetching a subset of dictionary keys for a particular key.
"""
- def __init__(self, name, max_entries=1000):
+ def __init__(self, name: str, max_entries: int = 1000):
self.cache = LruCache(
max_size=max_entries, cache_name=name, size_callback=len
- ) # type: LruCache[Any, DictionaryEntry]
+ ) # type: LruCache[KT, DictionaryEntry]
self.name = name
self.sequence = 0
- self.thread = None
+ self.thread = None # type: Optional[threading.Thread]
- def check_thread(self):
+ def check_thread(self) -> None:
expected_thread = self.thread
if expected_thread is None:
self.thread = threading.current_thread()
@@ -69,12 +81,14 @@ class DictionaryCache:
"Cache objects can only be accessed from the main thread"
)
- def get(self, key, dict_keys=None):
+ def get(
+ self, key: KT, dict_keys: Optional[Iterable[DKT]] = None
+ ) -> DictionaryEntry:
"""Fetch an entry out of the cache
Args:
key
- dict_key(list): If given a set of keys then return only those keys
+ dict_key: If given a set of keys then return only those keys
that exist in the cache.
Returns:
@@ -95,7 +109,7 @@ class DictionaryCache:
return DictionaryEntry(False, set(), {})
- def invalidate(self, key):
+ def invalidate(self, key: KT) -> None:
self.check_thread()
# Increment the sequence number so that any SELECT statements that
@@ -103,19 +117,25 @@ class DictionaryCache:
self.sequence += 1
self.cache.pop(key, None)
- def invalidate_all(self):
+ def invalidate_all(self) -> None:
self.check_thread()
self.sequence += 1
self.cache.clear()
- def update(self, sequence, key, value, fetched_keys=None):
+ def update(
+ self,
+ sequence: int,
+ key: KT,
+ value: Dict[DKT, Any],
+ fetched_keys: Optional[Set[DKT]] = None,
+ ) -> None:
"""Updates the entry in the cache
Args:
sequence
- key (K)
- value (dict[X,Y]): The value to update the cache with.
- fetched_keys (None|set[X]): All of the dictionary keys which were
+ key
+ value: The value to update the cache with.
+ fetched_keys: All of the dictionary keys which were
fetched from the database.
If None, this is the complete value for key K. Otherwise, it
@@ -131,7 +151,9 @@ class DictionaryCache:
else:
self._update_or_insert(key, value, fetched_keys)
- def _update_or_insert(self, key, value, known_absent):
+ def _update_or_insert(
+ self, key: KT, value: Dict[DKT, Any], known_absent: Set[DKT]
+ ) -> None:
# We pop and reinsert as we need to tell the cache the size may have
# changed
@@ -140,5 +162,5 @@ class DictionaryCache:
entry.known_absent.update(known_absent)
self.cache[key] = entry
- def _insert(self, key, value, known_absent):
+ def _insert(self, key: KT, value: Dict[DKT, Any], known_absent: Set[DKT]) -> None:
self.cache[key] = DictionaryEntry(True, known_absent, value)
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