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