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from collections.abc import Callable, Hashable
from functools import _make_key # noqa: PLC2701
from typing import Optional, cast
from django.core.cache import caches
from django.core.cache.backends.base import DEFAULT_TIMEOUT
from strawberry.extensions import SchemaExtension
from strawberry.types import ExecutionContext
class DjangoCacheBase(SchemaExtension):
"""Base for a Cache that uses Django built in cache instead of an in memory cache.
Arguments:
---------
`cache_name: str`
Name of the Django Cache to use, defaults to 'default'
`timeout: Optional[int]`
How long to hold items in the cache. See the Django Cache docs for details
https://docs.djangoproject.com/en/4.0/topics/cache/
`hash_fn: Optional[Callable[[Tuple, Dict], str]]`
A function to use to generate the cache keys
Defaults to the same key generator as functools.lru_cache
WARNING! The default function does NOT work with memcached
and will generate warnings
"""
def __init__(
self,
cache_name: str = "default",
timeout: Optional[int] = None,
hash_fn: Optional[Callable[[tuple, dict], Hashable]] = None,
*,
execution_context: Optional[ExecutionContext] = None,
):
super().__init__(execution_context=cast("ExecutionContext", execution_context))
self.cache = caches[cache_name]
self.timeout = timeout or DEFAULT_TIMEOUT
# Use same key generating function as functools.lru_cache as default
self.hash_fn = hash_fn or (lambda args, kwargs: _make_key(args, kwargs, False))
def execute_cached(self, func, *args, **kwargs):
hash_key = cast("str", self.hash_fn(args, kwargs))
cache_result = self.cache.get(hash_key)
if cache_result is not None:
return cache_result
func_result = func(*args, **kwargs)
self.cache.set(hash_key, func_result, timeout=self.timeout)
return func_result
|
