dekun
42 lines
1.3 KiB
Python
42 lines
1.3 KiB
Python
"""多实例定时任务互斥。锁有过期时间，持有进程异常退出后其他实例仍能继续。"""
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from __future__ import annotations
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import os
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import socket
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from datetime import timedelta
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from sqlalchemy import update
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from sqlalchemy.exc import IntegrityError
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from app.clock import utcnow
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from app.database import session_scope
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from app.models import SchedulerLock
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OWNER = f"{socket.gethostname()}:{os.getpid()}"
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def acquire_lock(name: str, ttl: timedelta) -> bool:
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now = utcnow()
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until = now + ttl
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try:
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with session_scope() as session:
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lock = session.get(SchedulerLock, name)
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if lock is None:
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session.add(SchedulerLock(name=name, locked_until=until, owner=OWNER))
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try:
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session.flush()
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except IntegrityError:
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session.rollback()
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return False
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return True
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updated = session.execute(
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update(SchedulerLock)
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.where(SchedulerLock.name == name)
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.where(SchedulerLock.locked_until <= now)
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.values(locked_until=until, owner=OWNER)
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)
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return updated.rowcount == 1
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except IntegrityError:
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return False
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