c1b87356ce
Not totally sure if this is necessary, but I feel like it makes more sense to err on the side of more data correctness, rather than hypothesizing about performance
37 lines
1.1 KiB
Python
37 lines
1.1 KiB
Python
from sqlalchemy import func, sql, Interval, and_, or_
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from contextlib import contextmanager
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from atst.database import db
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from atst.domain.exceptions import ClaimFailedException
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@contextmanager
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def claim_for_update(resource, minutes=30):
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Model = resource.__class__
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claim_until = func.now() + func.cast(
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sql.functions.concat(minutes, " MINUTES"), Interval
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)
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rows_updated = (
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db.session.query(Model)
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.filter(
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and_(
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Model.id == resource.id,
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or_(Model.claimed_until == None, Model.claimed_until < func.now()),
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)
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)
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.update({"claimed_until": claim_until}, synchronize_session="fetch")
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)
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if rows_updated < 1:
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raise ClaimFailedException(resource)
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claimed = db.session.query(Model).filter_by(id=resource.id).one()
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try:
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yield claimed
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finally:
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db.session.query(Model).filter(Model.id == resource.id).filter(
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Model.claimed_until != None
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).update({"claimed_until": sql.null()}, synchronize_session="fetch")
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