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import collections
import datetime
from datetime import timedelta, timezone
from typing import Any, Optional
from pydantic import BaseModel, Field
class CachedItem(BaseModel):
timestamp: datetime.datetime = Field(
default_factory=lambda: datetime.datetime.now(tz=timezone.utc)
)
value: Any
class LRUCache:
def __init__(self, capacity: int, expiration_time: timedelta):
self.capacity: int = capacity
self.expiration_time: timedelta = expiration_time
self.cache: collections.OrderedDict = collections.OrderedDict()
def get(self, key) -> Optional[CachedItem]:
try:
item: CachedItem = self.cache.pop(key)
if (
datetime.datetime.now(tz=timezone.utc) - item.timestamp
> self.expiration_time
):
return None
self.cache[key] = item
return item.value
except KeyError:
return None
def set(self, key, value) -> None:
try:
self.cache.pop(key)
except KeyError:
if len(self.cache) >= self.capacity:
self.cache.popitem(last=False)
self.cache[key] = CachedItem(value=value)
@staticmethod
def create_key(*args):
return str(args) # TODO think about this
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