PR #12558 was heavy for what the fix actually is — essay-length
comments, a dedicated helper method where a setdefault would do, and
a source-inspection test with no real behavior coverage. The
genuine code change is ~5 lines of new logic (1 field, 2 async with,
an on_ready wait block).
Trimmed:
- Replaced the 12-line _voice_lock_for helper with a setdefault
one-liner at each call site (join_voice_channel, leave_voice_channel).
- Collapsed the 12-line comment on on_message's _ready_event wait to
3 lines. Dropped the warning log on timeout — pass-on-timeout is
fine; if on_ready hangs that long, the bot is already broken and
the log wouldn't help.
- Dropped the source-inspection test (greps the module source for
expected substrings). It was low-value scaffolding; the
voice-serialization test covers actual behavior.
Net: -73 lines vs PR #12558. Same two guarantees preserved, same
test passes (verified by stashing the fix and confirming failure).
Two small races in gateway/platforms/discord.py, bundled together
since they're adjacent in the adapter and both narrow in impact.
1. on_message vs _resolve_allowed_usernames (startup window)
DISCORD_ALLOWED_USERS accepts both numeric IDs and raw usernames.
At connect-time, _resolve_allowed_usernames walks the bot's guilds
(fetch_members can take multiple seconds) to swap usernames for IDs.
on_message can fire during that window; _is_allowed_user compares
the numeric author.id against a set that may still contain raw
usernames — legitimate users get silently rejected for a few
seconds after every reconnect.
Fix: on_message awaits _ready_event (with a 30s timeout) when it
isn't already set. on_ready sets the event after the resolve
completes. In steady state this is a no-op (event already set);
only the startup / reconnect window ever blocks.
2. join_voice_channel check-and-connect
The existing-connection check at _voice_clients.get() and the
channel.connect() call straddled an await boundary with no lock.
Two concurrent /voice channel invocations could both see None and
both call connect(); discord.py raises ClientException
("Already connected") on the loser. Same race class for leave
running concurrently with _voice_timeout_handler.
Fix: per-guild asyncio.Lock (_voice_locks dict with lazy alloc via
_voice_lock_for). join_voice_channel and leave_voice_channel both
run their body under the lock. Sequential within a guild, still
fully concurrent across guilds.
Both: LOW severity. The first only affects username-based allowlists
on fast-follow-up messages at startup; the second is a narrow
exception on simultaneous voice commands. Bundled so the adapter
gets a single coherent polish pass.
Tests (tests/gateway/test_discord_race_polish.py): 2 regression cases.
- test_concurrent_joins_do_not_double_connect: two concurrent
join_voice_channel calls on the same guild result in exactly one
channel.connect() invocation.
- test_on_message_blocks_until_ready_event_set: asserts the expected
wait pattern is present in on_message (source inspection, since
full discord.py client setup isn't practical here).
Regression-guard validated: against unpatched gateway/platforms/discord.py
both tests fail. With the fix they pass. Full Discord suite (118
tests) green.
