42 lines
1.0 KiB
Python
42 lines
1.0 KiB
Python
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"""Small Redis lock helpers for background tasks."""
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from dataclasses import dataclass
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import uuid
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import redis
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from app.core.config import settings
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@dataclass(frozen=True)
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class RedisLockHandle:
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client: redis.Redis
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key: str
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token: bytes
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def acquire_redis_lock(key: str, *, ttl_seconds: int) -> RedisLockHandle | None:
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"""Acquire a single-owner Redis lock or return None when unavailable."""
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client = redis.from_url(settings.redis_url, decode_responses=False)
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token = uuid.uuid4().hex.encode("utf-8")
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if not client.set(key, token, nx=True, ex=ttl_seconds):
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return None
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return RedisLockHandle(client=client, key=key, token=token)
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def release_redis_lock(handle: RedisLockHandle | None) -> None:
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"""Release the lock only if we still own it."""
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if handle is None:
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return
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handle.client.eval(
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"""
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if redis.call("GET", KEYS[1]) == ARGV[1] then
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return redis.call("DEL", KEYS[1])
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end
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return 0
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""",
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1,
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handle.key,
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handle.token,
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)
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