fix(kqueue): preserve EV_CLEAR on EVFILT_USER notify and reset flag on EINTR#265
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fix(kqueue): preserve EV_CLEAR on EVFILT_USER notify and reset flag on EINTR#265paddor wants to merge 1 commit into
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Two bugs in the kqueue EVFILT_USER notification path:
notify()dropsEV_CLEAR: The trigger changelist usesEV_ADDwithoutEV_CLEAR. Since the filter was originally registered withEV_CLEAR(edge-triggered auto-reset), theEV_ADDinnotify()silently switches it to level-triggered mode. After the first notification, every subsequentkevent()wait returns the stale event immediately, causing a busy loop.EINTR swallows concurrent notification: When
kevent()returnsEINTR, the interrupted call may have already consumed theEVFILT_USERevent from a concurrentnotify(). The retry loop clears events but does not reset thenotifiedflag, sonotify()believes its event is still pending and skips re-triggering. The waiter never wakes.