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fix: recalculate vote counts in a single atomic update - #1650
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ChangkeunJ wants to merge 1 commit into
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GetAndSaveVoteResult counted the active vote activities first and then saved the total as an absolute value. Any vote committed between the count and the write was lost when the slower request wrote last, so vote_count drifted away from the real number of votes (apache#1646). Recount the activities inside the UPDATE statement itself so the stored total always reflects the committed state at write time. The up/down counts returned to the caller keep using the existing count helpers.
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Fixes #1646
Proposed Changes
vote_countin a single atomicUPDATEthat recounts the active vote activities in subqueries, instead of counting first and writing the total as an absolute value. A slower request can no longer overwrite a newer total with a stale one.GetAndSaveVoteResultreturning the up/down counts from the existing count helpers, so the API response is unchanged.internal/repo/repo_test/vote_result_race_test.gowith a count test and a concurrent regression test (fresh question per round, 32 concurrent voters). Before this change the storedvote_countregularly ended up below the real count (e.g. 19 or 26 instead of 32); with this change every round stores the exact total.Note: the count and the write still see a statement-level snapshot, so a vote committing at the exact moment of the update can land after that update's recount. The next vote's recalculation heals the total, and the lost-update drift from the issue can no longer accumulate.