Files
plm-lottery/app/rounds/service.py
T
davideandClaude Opus 5 daf66fd6bc Fix the round-open race, the advertised jackpot, and payout error handling
Round opening (B-09). open_new_round_if_needed now handles the IntegrityError
from ix_rounds_single_active (previous commit) by rolling back and using the
winner's round. Deviation from the plan in BUGS.md, which proposed making the
scheduler the only writer: that would mean the first bet after a cooldown
couldn't open a round, so both callers stay and a bounded retry was added
instead — a conflict where nothing is active yet just means the winner hadn't
committed, and a bet must not fail on that timing. get_active_round also logs
loudly if it ever sees more than one active round rather than silently picking
the newest.

The jackpot (B-11). It was participant_count * the *current* bet_amount_sats,
which overstated the pool (each stored bet is already net of that bet's network
fee) and silently rewrote the advertised jackpot of a round in progress whenever
an operator edited the bet amount. It now sums the participants' stored
bet_amount_sats. The remaining imprecision — the payout tx's own fee, deducted
from the winner's share and unknowable until the payout is built — is documented
in the code rather than promised away, since the comment there claimed exactness.

Payout (B-05, B-18). _trigger_payout is split into read / build+broadcast /
persist, so no DB session is held across a network call (on SQLite that meant
holding the write lock for two unbounded round-trips). That restructuring is also
what makes the error handling placeable: it now catches Exception around the
chain work and writes a payout_failed audit entry, where a malformed fee_address
used to raise EmbitError all the way to the scheduler's catch-all, leaving the
round stuck in paying_out with nothing recorded about why. Automatic payout retry
remains an open gap.

The scheduler also counts "building" participants as in-flight when deciding
whether a round may close, matching the two-phase bet write.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-07-27 00:32:22 +02:00

111 lines
5.2 KiB
Python

import logging
from datetime import datetime, timedelta, timezone
from sqlalchemy import select
from sqlalchemy.exc import IntegrityError
from sqlalchemy.ext.asyncio import AsyncSession
from app.db.models import Round
from app.rounds.config import get_round_config
from app.rounds.events import broadcaster
logger = logging.getLogger(__name__)
_ACTIVE_STATUSES = ("open", "closing", "drawing", "paying_out")
# Bounded: a conflict means someone else is opening a round right now, so a couple
# of retries is plenty. Unbounded retries could spin if the invariant were ever
# broken in a way we don't anticipate.
_OPEN_ROUND_ATTEMPTS = 3
async def get_active_round(session: AsyncSession) -> Round | None:
"""The round currently in progress (in any non-closed state), if any. Rounds
never overlap: a new round only opens once the previous one is fully closed
(payout confirmed, or no participants to pay out).
The database enforces "at most one active round" (ix_rounds_single_active, see
app/db/models.py), so the ordering below is belt-and-braces; if it ever does
see two, that's a broken invariant and worth a loud log rather than silently
picking one."""
active = (
await session.scalars(select(Round).where(Round.status.in_(_ACTIVE_STATUSES)).order_by(Round.id.desc()))
).all()
if len(active) > 1:
logger.error(
"invariant violated: %s rounds are active at once (ids=%s) — using the newest",
len(active),
[r.id for r in active],
)
return active[0] if active else None
def round_accepts_bets(round_: Round, round_duration_seconds: int) -> bool:
"""The authoritative "yellow light" check: once a round's timer has expired,
no new bet may be accepted, even though its DB status is still "open" (the
scheduler only flips it to "closing" on its next tick, up to
_TICK_INTERVAL_SECONDS later — see rounds/scheduler.py). Bets already placed
before the deadline are unaffected: the round still waits for them to confirm
before actually closing."""
if round_.status != "open":
return False
opened_at = round_.opened_at.replace(tzinfo=timezone.utc)
return datetime.now(timezone.utc) < opened_at + timedelta(seconds=round_duration_seconds)
async def open_new_round_if_needed(session: AsyncSession) -> Round | None:
"""Returns the active round if one exists (whatever its status). Otherwise
opens a fresh one, unless the last closed round's cooldown (ROUND_COOLDOWN_SECONDS)
hasn't elapsed yet, or the lottery is paused for maintenance — in either case
returns None. Callers that need to attach a bet must additionally check the
returned round's status == "open" — a round in closing/drawing/paying_out
isn't accepting new bets, but a new round can't open until it's done.
Pausing never touches a round already in progress: it only suppresses opening
the *next* one, so the current round still closes, draws, and pays out the
winner normally (see admin.py's /admin/pause and /admin/resume)."""
active = await get_active_round(session)
if active is not None:
return active
config = await get_round_config(session)
if config.paused:
return None
last_closed = await session.scalar(select(Round).where(Round.status == "closed").order_by(Round.id.desc()))
if last_closed is not None and last_closed.closed_at is not None:
closed_at = last_closed.closed_at.replace(tzinfo=timezone.utc)
if datetime.now(timezone.utc) < closed_at + timedelta(seconds=config.round_cooldown_seconds):
return None
for attempt in range(_OPEN_ROUND_ATTEMPTS):
round_ = Round(status="open")
session.add(round_)
try:
await session.flush()
except IntegrityError:
# Another caller (the scheduler tick, or a concurrent place_bet) got
# there first — ix_rounds_single_active turns what used to be two live
# rounds into a clean failure here. Roll our insert back and use theirs.
# Safe to roll back: this runs before its callers have written anything
# else in this session.
await session.rollback()
existing = await get_active_round(session)
if existing is not None:
logger.info("lost the race to open a round; using round %s", existing.id)
return existing
# Nothing active *and* the insert conflicted: the winner's transaction
# hadn't committed yet when we looked. Try again rather than failing the
# caller — a bet shouldn't 500 because of a scheduler tick's timing.
logger.info("round-open conflict with nothing active yet (attempt %s), retrying", attempt + 1)
continue
# Published pre-commit (the caller commits right after) — acceptable: this
# only tells subscribers "go refetch", and by the time an SSE client's
# refetch request actually lands, this in-process commit (microseconds
# away) has essentially always already happened.
broadcaster.publish()
return round_
logger.error("could not open a round after %s attempts", _OPEN_ROUND_ATTEMPTS)
return await get_active_round(session)