Remove boottime from quark times#368
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Times derived from quark.boottime were computed once and stored, so a system clock step after quark_init() (say NTP correcting a clock that was wrong at boot) left every stored and emitted timestamp shifted by the step size until restart. Nothing computed with quark.boottime is stored or handed out anymore: qev->time, proc_time_boot and exit_time_event are raw ns since boot, translated at the last moment with the new quark_time_to_wallclock(). Since quark has no event loop, keeping the epoch honest is the user's job: detect a step (a CLOCK_REALTIME timerfd with TFD_TIMER_CANCEL_ON_SET, or polling the CLOCK_REALTIME - CLOCK_BOOTTIME delta, which only moves on steps) and call the new quark_update_boottime(). Corrections then apply retroactively to any raw time, including events that predate the step. This also makes proc_entity_id immune to clock changes, as it now hashes the raw start time. Breaking change: consumers that treated qev->time, proc_time_boot or exit_time_event as wallclock epoch ns (endpoint, go-quark) must translate via quark_time_to_wallclock().
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Times derived from quark.boottime were computed once and stored, so a system clock step after quark_init() (say NTP correcting a clock that was wrong at boot) left every stored and emitted timestamp shifted by the step size until restart.
Nothing computed with quark.boottime is stored or handed out anymore: qev->time, proc_time_boot and exit_time_event are raw ns since boot, translated at the last moment with the new quark_time_to_wallclock(). Since quark has no event loop, keeping the epoch honest is the user's job: detect a step (a CLOCK_REALTIME timerfd with TFD_TIMER_CANCEL_ON_SET, or polling the CLOCK_REALTIME - CLOCK_BOOTTIME delta, which only moves on steps) and call the new quark_update_boottime(). Corrections then apply retroactively to any raw time, including events that predate the step.
This also makes proc_entity_id immune to clock changes, as it now hashes the raw start time.
Breaking change: consumers that treated qev->time, proc_time_boot or exit_time_event as wallclock epoch ns must translate via quark_time_to_wallclock().