Private
Public Access
ksmithandClaude Sonnet 5
5527b25e52
Root cause, confirmed live against Postgres and reproduced end-to-end through two real WebSocket connections: ws/chat.py shares one AsyncSession for a whole connection's lifetime. A read-only action (e.g. a "join" frame's membership check) can leave a transaction open with nothing to commit it until the next write. Postgres's now()/CURRENT_TIMESTAMP returns that transaction's *start* time in that case, not the actual statement's -- so a reply sent after any idle/reading period got timestamped to when the idle period started, sorting it before messages that were genuinely sent earlier. This is independent of the two earlier #45 fixes (missing ORDER BY tiebreakers, a stale-response race on reload) -- both were real bugs, but this was the actual mechanism behind "my message appears before theirs even though theirs was sent first." Switched Message.created_at and MessageReaction.created_at from func.now() to func.clock_timestamp(), which always reflects the actual moment of execution regardless of how long the transaction has been open. Migration is a plain column-default change -- no table rewrite, no lock risk, round-trips cleanly. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
32 lines
1.2 KiB
Python
32 lines
1.2 KiB
Python
import uuid
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from datetime import datetime
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from sqlalchemy import DateTime, ForeignKey, String, UniqueConstraint, func
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from sqlalchemy.orm import Mapped, mapped_column, relationship
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from app.models.base import Base
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class MessageReaction(Base):
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__tablename__ = "message_reactions"
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__table_args__ = (
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UniqueConstraint(
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"message_id", "user_id", "emoji",
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name="uq_message_reactions_message_user_emoji",
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),
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)
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id: Mapped[uuid.UUID] = mapped_column(primary_key=True, default=uuid.uuid4)
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message_id: Mapped[uuid.UUID] = mapped_column(ForeignKey("messages.id"), index=True, nullable=False)
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user_id: Mapped[uuid.UUID] = mapped_column(ForeignKey("users.id"), nullable=False)
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emoji: Mapped[str] = mapped_column(String(32), nullable=False)
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# clock_timestamp(), not now() -- same transaction-pinning hazard as
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# Message.created_at (see that column's comment); toggle_reaction runs
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# through the same long-lived, shared WS session.
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created_at: Mapped[datetime] = mapped_column(
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DateTime(timezone=True), server_default=func.clock_timestamp(), nullable=False
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)
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message = relationship("Message")
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user = relationship("User")
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