fix: bound QuestionHistory size to prevent LAN-driven OOM#1733
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fix: bound QuestionHistory size to prevent LAN-driven OOM#1733bluetoothbot wants to merge 1 commit into
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QuestionHistory._history was unbounded between the 10s cache-cleanup ticks. A LAN peer streaming distinct questions could grow the dict (and the retained known_answers sets) for ~10s before async_expire ran, easily reaching hundreds of MB at line-rate. Cap _history at _MAX_QUESTION_HISTORY_ENTRIES (10000). When the cap is hit on insert, first call async_expire(now) opportunistically to drop entries past _DUPLICATE_QUESTION_INTERVAL; if the dict is still full, evict the oldest insertion (dict is ordered) until there is room. Match the existing DNSCache cap pattern. Fixes python-zeroconf#1723
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## master #1733 +/- ##
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Coverage 99.76% 99.76%
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Files 33 33
Lines 3440 3446 +6
Branches 473 475 +2
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+ Hits 3432 3438 +6
Misses 5 5
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Summary
QuestionHistory._historywas unbounded between the periodic 10sasync_expireticks driven by_CACHE_CLEANUP_INTERVAL. A LAN peer streaming distinct questions could grow the dict (and the retainedknown_answerssets) for ~10s before the next cleanup, easily reaching hundreds of MB at line-rate.Cap
_historyat a configurable upper bound, with opportunistic expiry on insert and oldest-first FIFO eviction as a fallback. Mirrors the_MAX_CACHE_RECORDSpattern from #1718.Fixes #1723
Changes
_MAX_QUESTION_HISTORY_ENTRIES = 10000toconst.py.QuestionHistory.add_question_at_time, when the cap would be exceeded by a new entry, first callasync_expire(now)to drop entries past_DUPLICATE_QUESTION_INTERVAL; if still full, evict the oldest insertion (Pythondictpreserves insertion order) until there is room._history.pxdto declare the new constant for the Cython hot path.Test plan
tests/test_history.pycases:test_question_history_bounded— flooding past the cap keeps_historysize ≤ cap.test_question_history_evicts_oldest_first— earliest-inserted entry is the first dropped at cap.test_question_history_opportunistic_expire— stale entries are reclaimed before fresh ones are evicted.SKIP_CYTHON=1 poetry run pytest --timeout=60 tests→ 361 passed, 2 skipped.poetry run cython -3 src/zeroconf/_history.pycompiles cleanly with the updated.pxd.Generated by Kōan /fix
Quality Report
Changes: 4 files changed, 70 insertions(+), 1 deletion(-)
Code scan: clean
Tests: passed (4 PASSED)
Branch hygiene: clean
Generated by Kōan post-mission quality pipeline