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Decide and apply a Toggle under one lock, so concurrent toggles each flip once [patch] - #31
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…flip once [patch] Toggle read IsActive, then called SetActive, then read IsActive again, each under its own acquisition of the gate. Two threads toggling an inactive controller could both read "off", both ask for "on", and both return true, leaving it on after two flips. SetActive now takes a function from the current state to the wanted one and runs it inside the lock that applies the change, returning the state it left. Toggle returns that instead of re-reading. Fixes #30. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_017vfJW4T6sUBiRNom98NuYi
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Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_017vfJW4T6sUBiRNom98NuYi
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This was referenced Nov 2, 2026
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Fixes #30
What was wrong
KeepAwakeController.Toggle()readIsActive, calledSetActive(!IsActive), and then readIsActiveagain, takinggateseparately each time. When two threads toggled an inactive controller, both could read "off" and both ask for "on". Both calls then returnedtrue, and the controller stayed on after two flips.Change
SetActivenow takes aFunc<bool, bool>from the current state to the state wanted. It evaluates that inside the lock that applies the change, and returns the state it left.Enable/Disablepass constant functions.Togglepassescurrent => !currentand returns the result, instead of re-readingIsActive.StateChangedis still raised after the lock is released.Tests
FakeSleepBlockergains anAcquireDelaythat widens the race window.Toggle_ConcurrentCallsEachFlipOnceAndReportTheirOwnResult: 200 trials of 4 threads released together by aBarrier. Each trial asserts the final state isN % 2 == 1, and that the return values contain exactly ⌈N/2⌉trueand ⌊N/2⌋false.Generated by Claude Code