622 lines
21 KiB
Python
622 lines
21 KiB
Python
from collections import defaultdict
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from typing import Any, Dict, Iterable, List, Optional, Set, Tuple
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from django.apps import apps
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from typing_extensions import Protocol
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from .redis import use_redis
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from .utils import split_element_id, str_dict_to_bytes
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if use_redis:
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from .redis import get_connection, aioredis
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class ElementCacheProvider(Protocol):
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"""
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Base class for cache provider.
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See RedisCacheProvider as reverence implementation.
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"""
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async def clear_cache(self) -> None:
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...
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async def reset_full_cache(self, data: Dict[str, str]) -> None:
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...
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async def data_exists(self, user_id: Optional[int] = None) -> bool:
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...
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async def add_elements(self, elements: List[str]) -> None:
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...
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async def del_elements(
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self, elements: List[str], user_id: Optional[int] = None
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) -> None:
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...
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async def add_changed_elements(
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self, default_change_id: int, element_ids: Iterable[str]
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) -> int:
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...
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async def get_all_data(self, user_id: Optional[int] = None) -> Dict[bytes, bytes]:
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...
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async def get_collection_data(
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self, collection: str, user_id: Optional[int] = None
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) -> Dict[bytes, bytes]:
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...
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async def get_data_since(
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self, change_id: int, user_id: Optional[int] = None, max_change_id: int = -1
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) -> Tuple[Dict[str, List[bytes]], List[str]]:
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...
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async def get_element(
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self, element_id: str, user_id: Optional[int] = None
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) -> Optional[bytes]:
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...
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async def del_restricted_data(self, user_id: int) -> None:
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...
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async def set_lock(self, lock_name: str) -> bool:
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...
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async def get_lock(self, lock_name: str) -> bool:
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...
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async def del_lock(self, lock_name: str) -> None:
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...
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async def get_change_id_user(self, user_id: int) -> Optional[int]:
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...
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async def update_restricted_data(self, user_id: int, data: Dict[str, str]) -> None:
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...
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async def get_current_change_id(self) -> List[Tuple[str, int]]:
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...
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async def get_lowest_change_id(self) -> Optional[int]:
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...
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class RedisCacheProvider:
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"""
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Cache provider that loads and saves the data to redis.
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"""
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full_data_cache_key: str = "full_data"
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restricted_user_cache_key: str = "restricted_data:{user_id}"
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change_id_cache_key: str = "change_id"
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prefix: str = "element_cache_"
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def get_full_data_cache_key(self) -> str:
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return "".join((self.prefix, self.full_data_cache_key))
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def get_restricted_data_cache_key(self, user_id: int) -> str:
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return "".join(
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(self.prefix, self.restricted_user_cache_key.format(user_id=user_id))
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)
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def get_change_id_cache_key(self) -> str:
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return "".join((self.prefix, self.change_id_cache_key))
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async def clear_cache(self) -> None:
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"""
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Deleted all cache entries created with this element cache.
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"""
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async with get_connection() as redis:
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await redis.eval(
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"return redis.call('del', 'fake_key', unpack(redis.call('keys', ARGV[1])))",
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keys=[],
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args=[f"{self.prefix}*"],
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)
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async def reset_full_cache(self, data: Dict[str, str]) -> None:
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"""
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Deletes the full_data_cache and write new data in it.
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Also deletes the restricted_data_cache and the change_id_cache.
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"""
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async with get_connection() as redis:
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tr = redis.multi_exec()
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# like clear_cache but does not delete a lock
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tr.eval(
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"return redis.call('del', 'fake_key', unpack(redis.call('keys', ARGV[1])))",
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keys=[],
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args=[f"{self.prefix}{self.restricted_user_cache_key}*"],
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)
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tr.delete(self.get_change_id_cache_key())
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tr.delete(self.get_full_data_cache_key())
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tr.hmset_dict(self.get_full_data_cache_key(), data)
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await tr.execute()
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async def data_exists(self, user_id: Optional[int] = None) -> bool:
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"""
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Returns True, when there is data in the cache.
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If user_id is None, the method tests for full_data. If user_id is an int, it tests
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for the restricted_data_cache for the user with the user_id. 0 is for anonymous.
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"""
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async with get_connection() as redis:
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if user_id is None:
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cache_key = self.get_full_data_cache_key()
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else:
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cache_key = self.get_restricted_data_cache_key(user_id)
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return await redis.exists(cache_key)
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async def add_elements(self, elements: List[str]) -> None:
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"""
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Add or change elements to the cache.
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elements is a list with an even len. the odd values are the element_ids and the even
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values are the elements. The elements have to be encoded, for example with json.
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"""
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async with get_connection() as redis:
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await redis.hmset(self.get_full_data_cache_key(), *elements)
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async def del_elements(
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self, elements: List[str], user_id: Optional[int] = None
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) -> None:
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"""
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Deletes elements from the cache.
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elements has to be a list of element_ids.
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If user_id is None, the elements are deleted from the full_data cache. If user_id is an
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int, the elements are deleted one restricted_data_cache. 0 is for anonymous.
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"""
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async with get_connection() as redis:
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if user_id is None:
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cache_key = self.get_full_data_cache_key()
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else:
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cache_key = self.get_restricted_data_cache_key(user_id)
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await redis.hdel(cache_key, *elements)
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async def add_changed_elements(
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self, default_change_id: int, element_ids: Iterable[str]
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) -> int:
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"""
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Saves which elements are change with a change_id.
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Generates and returns the change_id.
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"""
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async with get_connection() as redis:
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return int(
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await redis.eval(
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lua_script_change_data,
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keys=[self.get_change_id_cache_key()],
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args=[default_change_id, *element_ids],
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)
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)
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async def get_all_data(self, user_id: Optional[int] = None) -> Dict[bytes, bytes]:
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"""
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Returns all data from a cache.
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if user_id is None, then the data is returned from the full_data_cache. If it is and
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int, it is returned from a restricted_data_cache. 0 is for anonymous.
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"""
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if user_id is None:
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cache_key = self.get_full_data_cache_key()
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else:
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cache_key = self.get_restricted_data_cache_key(user_id)
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async with get_connection() as redis:
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return await redis.hgetall(cache_key)
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async def get_collection_data(
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self, collection: str, user_id: Optional[int] = None
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) -> Dict[bytes, bytes]:
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"""
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Returns all elements for a collection from the cache.
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"""
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if user_id is None:
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cache_key = self.get_full_data_cache_key()
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else:
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cache_key = self.get_restricted_data_cache_key(user_id)
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async with get_connection() as redis:
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out = {}
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async for k, v in redis.ihscan(cache_key, match=f"{collection}:*"):
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out[k] = v
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return out
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async def get_element(
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self, element_id: str, user_id: Optional[int] = None
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) -> Optional[bytes]:
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"""
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Returns one element from the cache.
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Returns None, when the element does not exist.
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"""
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if user_id is None:
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cache_key = self.get_full_data_cache_key()
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else:
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cache_key = self.get_restricted_data_cache_key(user_id)
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async with get_connection() as redis:
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return await redis.hget(cache_key, element_id)
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async def get_data_since(
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self, change_id: int, user_id: Optional[int] = None, max_change_id: int = -1
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) -> Tuple[Dict[str, List[bytes]], List[str]]:
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"""
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Returns all elements since a change_id.
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The returend value is a two element tuple. The first value is a dict the elements where
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the key is the collection_string and the value a list of (json-) encoded elements. The
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second element is a list of element_ids, that have been deleted since the change_id.
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if user_id is None, the full_data is returned. If user_id is an int, the restricted_data
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for an user is used. 0 is for the anonymous user.
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"""
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changed_elements: Dict[str, List[bytes]] = defaultdict(list)
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deleted_elements: List[str] = []
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if user_id is None:
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cache_key = self.get_full_data_cache_key()
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else:
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cache_key = self.get_restricted_data_cache_key(user_id)
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# Convert max_change_id to a string. If its negative, use the string '+inf'
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redis_max_change_id = "+inf" if max_change_id < 0 else str(max_change_id)
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async with get_connection() as redis:
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# lua script that returns gets all element_ids from change_id_cache_key
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# and then uses each element_id on full_data or restricted_data.
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# It returns a list where the odd values are the change_id and the
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# even values the element as json. The function wait_make_dict creates
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# a python dict from the returned list.
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elements: Dict[bytes, Optional[bytes]] = await aioredis.util.wait_make_dict(
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redis.eval(
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"""
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-- Get change ids of changed elements
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local element_ids = redis.call('zrangebyscore', KEYS[1], ARGV[1], ARGV[2])
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-- Save elements in array. Rotate element_id and element_json
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local elements = {}
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for _, element_id in pairs(element_ids) do
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table.insert(elements, element_id)
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table.insert(elements, redis.call('hget', KEYS[2], element_id))
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end
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return elements
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""",
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keys=[self.get_change_id_cache_key(), cache_key],
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args=[change_id, redis_max_change_id],
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)
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)
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for element_id, element_json in elements.items():
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if element_id.startswith(b"_config"):
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# Ignore config values from the change_id cache key
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continue
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if element_json is None:
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# The element is not in the cache. It has to be deleted.
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deleted_elements.append(element_id.decode())
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else:
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collection_string, id = split_element_id(element_id)
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changed_elements[collection_string].append(element_json)
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return changed_elements, deleted_elements
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async def del_restricted_data(self, user_id: int) -> None:
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"""
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Deletes all restricted_data for an user. 0 is for the anonymous user.
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"""
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async with get_connection() as redis:
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await redis.delete(self.get_restricted_data_cache_key(user_id))
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async def set_lock(self, lock_name: str) -> bool:
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"""
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Tries to sets a lock.
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Returns True when the lock could be set.
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Returns False when the lock was already set.
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"""
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# TODO: Improve lock. See: https://redis.io/topics/distlock
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async with get_connection() as redis:
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return await redis.setnx(f"{self.prefix}lock_{lock_name}", 1)
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async def get_lock(self, lock_name: str) -> bool:
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"""
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Returns True, when the lock for the restricted_data of an user is set. Else False.
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"""
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async with get_connection() as redis:
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return await redis.get(f"{self.prefix}lock_{lock_name}")
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async def del_lock(self, lock_name: str) -> None:
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"""
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Deletes the lock for the restricted_data of an user. Does nothing when the
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lock is not set.
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"""
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async with get_connection() as redis:
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await redis.delete(f"{self.prefix}lock_{lock_name}")
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async def get_change_id_user(self, user_id: int) -> Optional[int]:
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"""
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Get the change_id for the restricted_data of an user.
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This is the change_id where the restricted_data was last calculated.
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"""
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async with get_connection() as redis:
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return await redis.hget(
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self.get_restricted_data_cache_key(user_id), "_config:change_id"
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)
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async def update_restricted_data(self, user_id: int, data: Dict[str, str]) -> None:
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"""
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Updates the restricted_data for an user.
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data has to be a dict where the key is an element_id and the value the (json-) encoded
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element.
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"""
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async with get_connection() as redis:
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await redis.hmset_dict(self.get_restricted_data_cache_key(user_id), data)
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async def get_current_change_id(self) -> List[Tuple[str, int]]:
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"""
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Get the highest change_id from redis.
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"""
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async with get_connection() as redis:
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return await redis.zrevrangebyscore(
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self.get_change_id_cache_key(), withscores=True, count=1, offset=0
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)
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async def get_lowest_change_id(self) -> Optional[int]:
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"""
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Get the lowest change_id from redis.
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Returns None if lowest score does not exist.
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"""
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async with get_connection() as redis:
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return await redis.zscore(
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self.get_change_id_cache_key(), "_config:lowest_change_id"
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)
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class MemmoryCacheProvider:
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"""
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CacheProvider for the ElementCache that uses only the memory.
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See the RedisCacheProvider for a description of the methods.
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This provider supports only one process. It saves the data into the memory.
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When you use different processes they will use diffrent data.
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"""
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def __init__(self) -> None:
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self.set_data_dicts()
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def set_data_dicts(self) -> None:
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self.full_data: Dict[str, str] = {}
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self.restricted_data: Dict[int, Dict[str, str]] = {}
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self.change_id_data: Dict[int, Set[str]] = {}
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self.locks: Dict[str, str] = {}
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async def clear_cache(self) -> None:
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self.set_data_dicts()
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async def reset_full_cache(self, data: Dict[str, str]) -> None:
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self.full_data = data
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async def data_exists(self, user_id: Optional[int] = None) -> bool:
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if user_id is None:
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cache_dict = self.full_data
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else:
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cache_dict = self.restricted_data.get(user_id, {})
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return bool(cache_dict)
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async def add_elements(self, elements: List[str]) -> None:
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if len(elements) % 2:
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raise ValueError(
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"The argument elements of add_elements has to be a list with an even number of elements."
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)
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for i in range(0, len(elements), 2):
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self.full_data[elements[i]] = elements[i + 1]
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async def del_elements(
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self, elements: List[str], user_id: Optional[int] = None
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) -> None:
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if user_id is None:
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cache_dict = self.full_data
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else:
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cache_dict = self.restricted_data.get(user_id, {})
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for element in elements:
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try:
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del cache_dict[element]
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except KeyError:
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pass
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async def add_changed_elements(
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self, default_change_id: int, element_ids: Iterable[str]
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) -> int:
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element_ids = list(element_ids)
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try:
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change_id = (await self.get_current_change_id())[0][1] + 1
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except IndexError:
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change_id = default_change_id
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for element_id in element_ids:
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if change_id in self.change_id_data:
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self.change_id_data[change_id].add(element_id)
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else:
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self.change_id_data[change_id] = {element_id}
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return change_id
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async def get_all_data(self, user_id: Optional[int] = None) -> Dict[bytes, bytes]:
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if user_id is None:
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cache_dict = self.full_data
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else:
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cache_dict = self.restricted_data.get(user_id, {})
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return str_dict_to_bytes(cache_dict)
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async def get_collection_data(
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self, collection: str, user_id: Optional[int] = None
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) -> Dict[bytes, bytes]:
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if user_id is None:
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cache_dict = self.full_data
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else:
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cache_dict = self.restricted_data.get(user_id, {})
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out = {}
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for key, value in cache_dict.items():
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if key.startswith(f"{collection}:"):
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out[key] = value
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return str_dict_to_bytes(out)
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async def get_element(
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self, element_id: str, user_id: Optional[int] = None
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) -> Optional[bytes]:
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if user_id is None:
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cache_dict = self.full_data
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else:
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cache_dict = self.restricted_data.get(user_id, {})
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value = cache_dict.get(element_id, None)
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return value.encode() if value is not None else None
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async def get_data_since(
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self, change_id: int, user_id: Optional[int] = None, max_change_id: int = -1
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) -> Tuple[Dict[str, List[bytes]], List[str]]:
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changed_elements: Dict[str, List[bytes]] = defaultdict(list)
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deleted_elements: List[str] = []
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if user_id is None:
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cache_dict = self.full_data
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else:
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cache_dict = self.restricted_data.get(user_id, {})
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all_element_ids: Set[str] = set()
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for data_change_id, element_ids in self.change_id_data.items():
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if data_change_id >= change_id and (
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max_change_id == -1 or data_change_id <= max_change_id
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):
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all_element_ids.update(element_ids)
|
|
|
|
for element_id in all_element_ids:
|
|
element_json = cache_dict.get(element_id, None)
|
|
if element_json is None:
|
|
deleted_elements.append(element_id)
|
|
else:
|
|
collection_string, id = split_element_id(element_id)
|
|
changed_elements[collection_string].append(element_json.encode())
|
|
return changed_elements, deleted_elements
|
|
|
|
async def del_restricted_data(self, user_id: int) -> None:
|
|
try:
|
|
del self.restricted_data[user_id]
|
|
except KeyError:
|
|
pass
|
|
|
|
async def set_lock(self, lock_name: str) -> bool:
|
|
if lock_name in self.locks:
|
|
return False
|
|
self.locks[lock_name] = "1"
|
|
return True
|
|
|
|
async def get_lock(self, lock_name: str) -> bool:
|
|
return lock_name in self.locks
|
|
|
|
async def del_lock(self, lock_name: str) -> None:
|
|
try:
|
|
del self.locks[lock_name]
|
|
except KeyError:
|
|
pass
|
|
|
|
async def get_change_id_user(self, user_id: int) -> Optional[int]:
|
|
data = self.restricted_data.get(user_id, {})
|
|
change_id = data.get("_config:change_id", None)
|
|
return int(change_id) if change_id is not None else None
|
|
|
|
async def update_restricted_data(self, user_id: int, data: Dict[str, str]) -> None:
|
|
redis_data = self.restricted_data.setdefault(user_id, {})
|
|
redis_data.update(data)
|
|
|
|
async def get_current_change_id(self) -> List[Tuple[str, int]]:
|
|
change_data = self.change_id_data
|
|
if change_data:
|
|
return [("no_usefull_value", max(change_data.keys()))]
|
|
return []
|
|
|
|
async def get_lowest_change_id(self) -> Optional[int]:
|
|
change_data = self.change_id_data
|
|
if change_data:
|
|
return min(change_data.keys())
|
|
return None
|
|
|
|
|
|
class Cachable(Protocol):
|
|
"""
|
|
A Cachable is an object that returns elements that can be cached.
|
|
|
|
It needs at least the methods defined here.
|
|
"""
|
|
|
|
def get_collection_string(self) -> str:
|
|
"""
|
|
Returns the string representing the name of the cachable.
|
|
"""
|
|
|
|
def get_elements(self) -> List[Dict[str, Any]]:
|
|
"""
|
|
Returns all elements of the cachable.
|
|
"""
|
|
|
|
async def restrict_elements(
|
|
self, user_id: int, elements: List[Dict[str, Any]]
|
|
) -> List[Dict[str, Any]]:
|
|
"""
|
|
Converts full_data to restricted_data.
|
|
|
|
elements can be an empty list, a list with some elements of the cachable or with all
|
|
elements of the cachable.
|
|
"""
|
|
|
|
|
|
def get_all_cachables() -> List[Cachable]:
|
|
"""
|
|
Returns all element of OpenSlides.
|
|
"""
|
|
out: List[Cachable] = []
|
|
for app in apps.get_app_configs():
|
|
try:
|
|
# Get the method get_startup_elements() from an app.
|
|
# This method has to return an iterable of Cachable objects.
|
|
get_startup_elements = app.get_startup_elements
|
|
except AttributeError:
|
|
# Skip apps that do not implement get_startup_elements.
|
|
continue
|
|
out.extend(get_startup_elements())
|
|
return out
|
|
|
|
|
|
lua_script_change_data = """
|
|
-- Generate a new change_id
|
|
local tmp = redis.call('zrevrangebyscore', KEYS[1], '+inf', '-inf', 'WITHSCORES', 'LIMIT', 0, 1)
|
|
local change_id
|
|
if next(tmp) == nil then
|
|
-- The key does not exist
|
|
change_id = ARGV[1]
|
|
else
|
|
change_id = tmp[2] + 1
|
|
end
|
|
|
|
-- Add elements to sorted set
|
|
local count = 2
|
|
while ARGV[count] do
|
|
redis.call('zadd', KEYS[1], change_id, ARGV[count])
|
|
count = count + 1
|
|
end
|
|
|
|
-- Set lowest_change_id if it does not exist
|
|
redis.call('zadd', KEYS[1], 'NX', change_id, '_config:lowest_change_id')
|
|
|
|
return change_id
|
|
"""
|