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>
47 lines
2.3 KiB
Python
47 lines
2.3 KiB
Python
import uuid
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from datetime import datetime
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from sqlalchemy import CheckConstraint, DateTime, ForeignKey, Text, 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 Message(Base):
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__tablename__ = "messages"
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__table_args__ = (
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CheckConstraint(
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"content IS NOT NULL OR image_id IS NOT NULL OR file_id IS NOT NULL",
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name="messages_content_or_attachment_required",
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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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room_id: Mapped[uuid.UUID] = mapped_column(ForeignKey("rooms.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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# Nullable since Phase "image uploads": a message can be an image with
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# no caption. The CheckConstraint above still requires at least one of
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# content/image_id/file_id.
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content: Mapped[str | None] = mapped_column(Text)
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image_id: Mapped[uuid.UUID | None] = mapped_column(ForeignKey("message_images.id"))
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file_id: Mapped[uuid.UUID | None] = mapped_column(ForeignKey("message_files.id"))
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# clock_timestamp(), not now()/func.now() -- the WS handler (ws/chat.py)
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# shares one AsyncSession for a whole connection's lifetime, and a
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# read-only op (e.g. a "join" frame's membership check) can leave a
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# transaction open with nothing to commit it until the next write.
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# Postgres's now()/CURRENT_TIMESTAMP returns the *transaction's* start
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# time in that case, not the actual INSERT's -- confirmed live to be the
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# actual cause of #45 (a reply sent well after an idle read-only period
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# got timestamped to when that period started, sorting it before
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# messages that were genuinely sent earlier). clock_timestamp() always
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# reflects the real moment of execution regardless of transaction age.
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created_at: Mapped[datetime] = mapped_column(
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DateTime(timezone=True), server_default=func.clock_timestamp(), index=True, nullable=False
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)
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edited_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
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deleted_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
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user = relationship("User")
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image = relationship("MessageImage")
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file = relationship("MessageFile")
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