diff --git a/synapse/util/caches/ttlcache.py b/synapse/util/caches/ttlcache.py
index 6ce2a3d12b..96a8274940 100644
--- a/synapse/util/caches/ttlcache.py
+++ b/synapse/util/caches/ttlcache.py
@@ -15,6 +15,7 @@
import logging
import time
+from typing import Any, Callable, Dict, Generic, Tuple, TypeVar, Union
import attr
from sortedcontainers import SortedList
@@ -23,15 +24,19 @@ from synapse.util.caches import register_cache
logger = logging.getLogger(__name__)
-SENTINEL = object()
+SENTINEL = object() # type: Any
+T = TypeVar("T")
+KT = TypeVar("KT")
+VT = TypeVar("VT")
-class TTLCache:
+
+class TTLCache(Generic[KT, VT]):
"""A key/value cache implementation where each entry has its own TTL"""
- def __init__(self, cache_name, timer=time.time):
+ def __init__(self, cache_name: str, timer: Callable[[], float] = time.time):
# map from key to _CacheEntry
- self._data = {}
+ self._data = {} # type: Dict[KT, _CacheEntry]
# the _CacheEntries, sorted by expiry time
self._expiry_list = SortedList() # type: SortedList[_CacheEntry]
@@ -40,26 +45,27 @@ class TTLCache:
self._metrics = register_cache("ttl", cache_name, self, resizable=False)
- def set(self, key, value, ttl):
+ def set(self, key: KT, value: VT, ttl: float) -> None:
"""Add/update an entry in the cache
Args:
key: key for this entry
value: value for this entry
- ttl (float): TTL for this entry, in seconds
+ ttl: TTL for this entry, in seconds
"""
expiry = self._timer() + ttl
self.expire()
e = self._data.pop(key, SENTINEL)
- if e != SENTINEL:
+ if e is not SENTINEL:
+ assert isinstance(e, _CacheEntry)
self._expiry_list.remove(e)
entry = _CacheEntry(expiry_time=expiry, ttl=ttl, key=key, value=value)
self._data[key] = entry
self._expiry_list.add(entry)
- def get(self, key, default=SENTINEL):
+ def get(self, key: KT, default: T = SENTINEL) -> Union[VT, T]:
"""Get a value from the cache
Args:
@@ -72,23 +78,23 @@ class TTLCache:
"""
self.expire()
e = self._data.get(key, SENTINEL)
- if e == SENTINEL:
+ if e is SENTINEL:
self._metrics.inc_misses()
- if default == SENTINEL:
+ if default is SENTINEL:
raise KeyError(key)
return default
+ assert isinstance(e, _CacheEntry)
self._metrics.inc_hits()
return e.value
- def get_with_expiry(self, key):
+ def get_with_expiry(self, key: KT) -> Tuple[VT, float, float]:
"""Get a value, and its expiry time, from the cache
Args:
key: key to look up
Returns:
- Tuple[Any, float, float]: the value from the cache, the expiry time
- and the TTL
+ A tuple of the value from the cache, the expiry time and the TTL
Raises:
KeyError if the entry is not found
@@ -102,7 +108,7 @@ class TTLCache:
self._metrics.inc_hits()
return e.value, e.expiry_time, e.ttl
- def pop(self, key, default=SENTINEL):
+ def pop(self, key: KT, default: T = SENTINEL) -> Union[VT, T]: # type: ignore
"""Remove a value from the cache
If key is in the cache, remove it and return its value, else return default.
@@ -118,29 +124,30 @@ class TTLCache:
"""
self.expire()
e = self._data.pop(key, SENTINEL)
- if e == SENTINEL:
+ if e is SENTINEL:
self._metrics.inc_misses()
- if default == SENTINEL:
+ if default is SENTINEL:
raise KeyError(key)
return default
+ assert isinstance(e, _CacheEntry)
self._expiry_list.remove(e)
self._metrics.inc_hits()
return e.value
- def __getitem__(self, key):
+ def __getitem__(self, key: KT) -> VT:
return self.get(key)
- def __delitem__(self, key):
+ def __delitem__(self, key: KT) -> None:
self.pop(key)
- def __contains__(self, key):
+ def __contains__(self, key: KT) -> bool:
return key in self._data
- def __len__(self):
+ def __len__(self) -> int:
self.expire()
return len(self._data)
- def expire(self):
+ def expire(self) -> None:
"""Run the expiry on the cache. Any entries whose expiry times are due will
be removed
"""
@@ -158,7 +165,7 @@ class _CacheEntry:
"""TTLCache entry"""
# expiry_time is the first attribute, so that entries are sorted by expiry.
- expiry_time = attr.ib()
- ttl = attr.ib()
+ expiry_time = attr.ib(type=float)
+ ttl = attr.ib(type=float)
key = attr.ib()
value = attr.ib()
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