Per-checksum score submission locks to prevent score duplicates #557
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cmyui
requested review from
skrungly,
NiceAesth,
tsunyoku and
7mochi
as code owners
|
cc @minisbett |
cmyui
changed the title
cmyui
commented
Feb 3, 2024
tsunyoku
approved these changes
Feb 3, 2024
cmyui
commented
Feb 3, 2024
| score.acc = score.calculate_accuracy() | ||
| # hold a lock around (check if submitted, submission) to ensure no duplicates | ||
| # are submitted to the database, and potentially award duplicate score/pp/etc. | ||
| async with app.state.score_submission_locks[score.client_checksum]: |
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Hmm I wonder if I could put a lifespan on the lock objects -- like a timeout in redis, to avoid holding the memory until shutdown
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Doesn't seem like a release blocker imo given
$ python3
Python 3.11.7 (main, Dec 8 2023, 18:56:58) [GCC 11.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> import asyncio
>>> sys.getsizeof(asyncio.Lock())
56Assuming 100,000 scores that means 56 * 100_000 / 1024 ** 2 = 5.34 MB
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Describe your changes
There is an ongoing issue due to this TOCTOU bug where scores (with identical checksums) may submit more than a single time (and award duplicate pp/score/etc.) if multiple get between the start and end conditions simultaneously.
This change adds a concurrency lock around the affected area to ensure only one runs at a time.
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