402 lines
9.3 KiB
Python
402 lines
9.3 KiB
Python
from abc import ABC, abstractmethod
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from collections import OrderedDict
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from dataclasses import dataclass
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from enum import Enum
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from typing import Any, List, Optional, Union
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class CacheEntryStatus(Enum):
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VALID = "VALID"
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IN_PROGRESS = "IN_PROGRESS"
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class EvictionPolicyType(Enum):
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time_based = "time_based"
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frequency_based = "frequency_based"
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@dataclass(frozen=True)
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class CacheKey:
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command: str
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redis_keys: tuple
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class CacheEntry:
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def __init__(
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self,
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cache_key: CacheKey,
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cache_value: bytes,
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status: CacheEntryStatus,
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connection_ref,
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):
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self.cache_key = cache_key
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self.cache_value = cache_value
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self.status = status
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self.connection_ref = connection_ref
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def __hash__(self):
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return hash(
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(self.cache_key, self.cache_value, self.status, self.connection_ref)
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)
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def __eq__(self, other):
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return hash(self) == hash(other)
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class EvictionPolicyInterface(ABC):
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@property
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@abstractmethod
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def cache(self):
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pass
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@cache.setter
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def cache(self, value):
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pass
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@property
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@abstractmethod
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def type(self) -> EvictionPolicyType:
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pass
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@abstractmethod
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def evict_next(self) -> CacheKey:
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pass
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@abstractmethod
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def evict_many(self, count: int) -> List[CacheKey]:
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pass
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@abstractmethod
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def touch(self, cache_key: CacheKey) -> None:
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pass
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class CacheConfigurationInterface(ABC):
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@abstractmethod
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def get_cache_class(self):
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pass
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@abstractmethod
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def get_max_size(self) -> int:
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pass
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@abstractmethod
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def get_eviction_policy(self):
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pass
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@abstractmethod
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def is_exceeds_max_size(self, count: int) -> bool:
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pass
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@abstractmethod
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def is_allowed_to_cache(self, command: str) -> bool:
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pass
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class CacheInterface(ABC):
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@property
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@abstractmethod
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def collection(self) -> OrderedDict:
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pass
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@property
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@abstractmethod
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def config(self) -> CacheConfigurationInterface:
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pass
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@property
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@abstractmethod
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def eviction_policy(self) -> EvictionPolicyInterface:
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pass
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@property
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@abstractmethod
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def size(self) -> int:
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pass
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@abstractmethod
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def get(self, key: CacheKey) -> Union[CacheEntry, None]:
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pass
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@abstractmethod
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def set(self, entry: CacheEntry) -> bool:
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pass
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@abstractmethod
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def delete_by_cache_keys(self, cache_keys: List[CacheKey]) -> List[bool]:
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pass
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@abstractmethod
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def delete_by_redis_keys(self, redis_keys: List[bytes]) -> List[bool]:
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pass
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@abstractmethod
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def flush(self) -> int:
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pass
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@abstractmethod
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def is_cachable(self, key: CacheKey) -> bool:
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pass
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class DefaultCache(CacheInterface):
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def __init__(
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self,
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cache_config: CacheConfigurationInterface,
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) -> None:
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self._cache = OrderedDict()
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self._cache_config = cache_config
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self._eviction_policy = self._cache_config.get_eviction_policy().value()
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self._eviction_policy.cache = self
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@property
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def collection(self) -> OrderedDict:
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return self._cache
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@property
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def config(self) -> CacheConfigurationInterface:
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return self._cache_config
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@property
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def eviction_policy(self) -> EvictionPolicyInterface:
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return self._eviction_policy
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@property
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def size(self) -> int:
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return len(self._cache)
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def set(self, entry: CacheEntry) -> bool:
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if not self.is_cachable(entry.cache_key):
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return False
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self._cache[entry.cache_key] = entry
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self._eviction_policy.touch(entry.cache_key)
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if self._cache_config.is_exceeds_max_size(len(self._cache)):
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self._eviction_policy.evict_next()
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return True
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def get(self, key: CacheKey) -> Union[CacheEntry, None]:
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entry = self._cache.get(key, None)
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if entry is None:
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return None
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self._eviction_policy.touch(key)
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return entry
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def delete_by_cache_keys(self, cache_keys: List[CacheKey]) -> List[bool]:
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response = []
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for key in cache_keys:
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if self.get(key) is not None:
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self._cache.pop(key)
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response.append(True)
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else:
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response.append(False)
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return response
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def delete_by_redis_keys(self, redis_keys: List[bytes]) -> List[bool]:
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response = []
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keys_to_delete = []
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for redis_key in redis_keys:
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if isinstance(redis_key, bytes):
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redis_key = redis_key.decode()
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for cache_key in self._cache:
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if redis_key in cache_key.redis_keys:
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keys_to_delete.append(cache_key)
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response.append(True)
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for key in keys_to_delete:
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self._cache.pop(key)
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return response
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def flush(self) -> int:
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elem_count = len(self._cache)
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self._cache.clear()
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return elem_count
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def is_cachable(self, key: CacheKey) -> bool:
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return self._cache_config.is_allowed_to_cache(key.command)
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class LRUPolicy(EvictionPolicyInterface):
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def __init__(self):
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self.cache = None
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@property
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def cache(self):
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return self._cache
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@cache.setter
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def cache(self, cache: CacheInterface):
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self._cache = cache
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@property
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def type(self) -> EvictionPolicyType:
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return EvictionPolicyType.time_based
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def evict_next(self) -> CacheKey:
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self._assert_cache()
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popped_entry = self._cache.collection.popitem(last=False)
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return popped_entry[0]
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def evict_many(self, count: int) -> List[CacheKey]:
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self._assert_cache()
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if count > len(self._cache.collection):
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raise ValueError("Evictions count is above cache size")
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popped_keys = []
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for _ in range(count):
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popped_entry = self._cache.collection.popitem(last=False)
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popped_keys.append(popped_entry[0])
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return popped_keys
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def touch(self, cache_key: CacheKey) -> None:
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self._assert_cache()
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if self._cache.collection.get(cache_key) is None:
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raise ValueError("Given entry does not belong to the cache")
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self._cache.collection.move_to_end(cache_key)
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def _assert_cache(self):
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if self.cache is None or not isinstance(self.cache, CacheInterface):
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raise ValueError("Eviction policy should be associated with valid cache.")
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class EvictionPolicy(Enum):
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LRU = LRUPolicy
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class CacheConfig(CacheConfigurationInterface):
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DEFAULT_CACHE_CLASS = DefaultCache
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DEFAULT_EVICTION_POLICY = EvictionPolicy.LRU
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DEFAULT_MAX_SIZE = 10000
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DEFAULT_ALLOW_LIST = [
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"BITCOUNT",
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"BITFIELD_RO",
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"BITPOS",
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"EXISTS",
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"GEODIST",
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"GEOHASH",
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"GEOPOS",
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"GEORADIUSBYMEMBER_RO",
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"GEORADIUS_RO",
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"GEOSEARCH",
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"GET",
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"GETBIT",
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"GETRANGE",
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"HEXISTS",
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"HGET",
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"HGETALL",
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"HKEYS",
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"HLEN",
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"HMGET",
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"HSTRLEN",
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"HVALS",
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"JSON.ARRINDEX",
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"JSON.ARRLEN",
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"JSON.GET",
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"JSON.MGET",
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"JSON.OBJKEYS",
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"JSON.OBJLEN",
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"JSON.RESP",
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"JSON.STRLEN",
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"JSON.TYPE",
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"LCS",
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"LINDEX",
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"LLEN",
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"LPOS",
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"LRANGE",
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"MGET",
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"SCARD",
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"SDIFF",
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"SINTER",
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"SINTERCARD",
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"SISMEMBER",
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"SMEMBERS",
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"SMISMEMBER",
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"SORT_RO",
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"STRLEN",
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"SUBSTR",
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"SUNION",
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"TS.GET",
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"TS.INFO",
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"TS.RANGE",
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"TS.REVRANGE",
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"TYPE",
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"XLEN",
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"XPENDING",
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"XRANGE",
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"XREAD",
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"XREVRANGE",
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"ZCARD",
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"ZCOUNT",
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"ZDIFF",
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"ZINTER",
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"ZINTERCARD",
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"ZLEXCOUNT",
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"ZMSCORE",
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"ZRANGE",
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"ZRANGEBYLEX",
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"ZRANGEBYSCORE",
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"ZRANK",
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"ZREVRANGE",
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"ZREVRANGEBYLEX",
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"ZREVRANGEBYSCORE",
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"ZREVRANK",
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"ZSCORE",
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"ZUNION",
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]
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def __init__(
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self,
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max_size: int = DEFAULT_MAX_SIZE,
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cache_class: Any = DEFAULT_CACHE_CLASS,
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eviction_policy: EvictionPolicy = DEFAULT_EVICTION_POLICY,
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):
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self._cache_class = cache_class
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self._max_size = max_size
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self._eviction_policy = eviction_policy
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def get_cache_class(self):
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return self._cache_class
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def get_max_size(self) -> int:
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return self._max_size
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def get_eviction_policy(self) -> EvictionPolicy:
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return self._eviction_policy
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def is_exceeds_max_size(self, count: int) -> bool:
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return count > self._max_size
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def is_allowed_to_cache(self, command: str) -> bool:
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return command in self.DEFAULT_ALLOW_LIST
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class CacheFactoryInterface(ABC):
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@abstractmethod
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def get_cache(self) -> CacheInterface:
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pass
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class CacheFactory(CacheFactoryInterface):
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def __init__(self, cache_config: Optional[CacheConfig] = None):
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self._config = cache_config
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if self._config is None:
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self._config = CacheConfig()
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def get_cache(self) -> CacheInterface:
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cache_class = self._config.get_cache_class()
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return cache_class(cache_config=self._config)
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