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import hashlib, time, typing, uuid
class Cache(object):
def __init__(self):
self._items = {}
def cache_key(self, key: str):
return "sha1:%s" % hashlib.sha1(key.encode("utf8")).hexdigest()
def cache(self, key: str, value: typing.Any) -> str:
return self._cache(key, value, None)
def temporary_cache(self, key: str, value: typing.Any, timeout: float
)-> str:
return self._cache(key, value, time.monotonic()+timeout)
def _cache(self, key: str, value: typing.Any,
expiration: typing.Optional[float]) -> str:
id = self.cache_key(key)
self._items[id] = [key, value, expiration]
return id
def next_expiration(self) -> typing.Optional[float]:
expirations = [value[-1] for value in self._items.values()]
expirations = list(filter(None, expirations))
if not expirations:
return None
now = time.monotonic()
expirations = [e-now for e in expirations]
return max(min(expirations), 0)
def expire(self):
now = time.monotonic()
expired = []
for id in self._items.keys():
key, value, expiration = self._items[id]
if expiration and expiration <= now:
expired.append(id)
for id in expired:
del self._items[id]
def has_item(self, key: typing.Any) -> bool:
return self.cache_key(key) in self._items
def get(self, key: str) -> typing.Any:
key, value, expiration = self._items[self.cache_key(key)]
return value
def remove(self, key: str):
del self._items[self.cache_key(key)]
def get_expiration(self, key: typing.Any) -> float:
key, value, expiration = self._items[self.cache_key(key)]
return expiration
def until_expiration(self, key: typing.Any) -> float:
expiration = self.get_expiration(key)
return expiration-time.monotonic()
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