84 lines
2.0 KiB
Python
84 lines
2.0 KiB
Python
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from typing import Dict
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from typing_extensions import Protocol
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from .redis import use_redis
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if use_redis:
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from .redis import get_connection
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class LockProtocol(Protocol):
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async def set(self, lock_name: str) -> bool:
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...
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async def get(self, lock_name: str) -> bool:
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...
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async def delete(self, lock_name: str) -> None:
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...
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class RedisLockProvider:
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lock_prefix = "lock_"
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async def set(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 and False, if it 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.lock_prefix}{lock_name}", 1)
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async def get(self, lock_name: str) -> bool:
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"""
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Returns True, when the lock 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.lock_prefix}{lock_name}")
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async def delete(self, lock_name: str) -> None:
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"""
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Deletes the lock. Does nothing when the 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.lock_prefix}{lock_name}")
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class MemoryLockProvider:
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def __init__(self) -> None:
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self.locks: Dict[str, str] = {}
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async def set(self, lock_name: str) -> bool:
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if lock_name in self.locks:
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return False
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self.locks[lock_name] = "1"
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return True
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async def get(self, lock_name: str) -> bool:
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return lock_name in self.locks
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async def delete(self, lock_name: str) -> None:
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try:
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del self.locks[lock_name]
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except KeyError:
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pass
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def load_lock_provider() -> LockProtocol:
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"""
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Generates an lock provider singleton.
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"""
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if use_redis:
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lock_provider: LockProtocol = RedisLockProvider()
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else:
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lock_provider = MemoryLockProvider()
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return lock_provider
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locking = load_lock_provider()
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