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eb5624233d
* fix log buffer idle polling * log_buffer: document notificationHealthCheckInterval tradeoffs Explain that notifyChan is the primary wakeup path and this interval only bounds the fallback / state-recheck cadence, so future maintainers don't tune it without understanding the implications for client-disconnect detection latency. * log_buffer: rename waitForNotification to awaitNotificationOrTimeout The helper returns after either a notification or the health-check timeout; the old name read like it blocked indefinitely. No behavior change. * log_buffer: wake blocked subscribers on shutdown awaitNotificationOrTimeout previously only returned on notifyChan or the health-check timeout, so ShutdownLogBuffer on an idle buffer (where copyToFlush returns nil and loopFlush never fires the post-flush notification) would leave subscribers parked for up to 250ms before they noticed IsStopping. Add an internal shutdownCh closed by ShutdownLogBuffer and select on it from awaitNotificationOrTimeout, which is now a method on *LogBuffer. Subscribers wake immediately, re-check IsStopping, and exit. No change to LoopProcessLogData signatures or any caller (filer metadata subscribers, MQ broker, local partition subscribe). * log_buffer: regression tests for flush-notify wake-up TestLoopFlush_NotifiesSubscribersAfterFlush directly verifies that loopFlush calls notifySubscribers after processing a flush, so a reader parked on notifyChan wakes promptly when a flush lands. Verified to fail if that notification is removed. TestLoopProcessLogDataWithOffset_WakesOnDataArrival is the end-to-end counterpart: a real LoopProcessLogDataWithOffset reader parks on notifyChan via the ResumeFromDiskError branch, then wakes and processes the entry well under the 250ms fallback once data arrives. * log_buffer: keep notification-timeout logs at V(4) Revert the V(4)->V(5) demotion. Now that the shutdown wake-up path exists and (with the follow-up fix) idle-polling CPU churn is bounded by the 250ms health check, these timeout logs no longer flood at V=4 the way they did on the 10ms fallback, so the previous verbosity is appropriate again. * log_buffer: exit reader loops cleanly on shutdown awaitNotificationOrTimeout returns true on both data notifications and shutdown (shutdownCh closed). Without an explicit IsStopping() guard, the ResumeFromDiskError, offset-based no-data, empty-buffer, and timestamp-wait paths would either tight-spin against a closed shutdownCh or, in the offset-based case, return ResumeFromDiskError to the caller instead of exiting. Add an IsStopping() check after each awaitNotificationOrTimeout call that previously continued or returned ResumeFromDiskError, so subscribers exit promptly with isDone=true and err=nil when ShutdownLogBuffer is called. * log_buffer: regression test for shutdown wake-up Park a real LoopProcessLogDataWithOffset reader on notifyChan via the ResumeFromDiskError branch, call ShutdownLogBuffer, and assert the reader exits with isDone=true and err=nil well under the 250ms fallback. Verified to fail (timeout) if the IsStopping() guards added in the prior commit are removed. * log_buffer: bump reader-park sleep to 50ms with rationale Both wake-path tests use a sleep to give the goroutine time to reach awaitNotificationOrTimeout before the test triggers the wake-up. Bump from 20ms to 50ms and document the timing assumption to reduce flakiness on slow CI. Both paths are race-free either way (a buffered notification or a closed shutdownCh stays valid until consumed), so this is purely about exercising the park-then-wake path rather than the already-pending fast path.