Method usleep

src/bthread/task_group.cpp:1010–1041

To be consistent with sys_usleep, set errno and return -1 on error.

// To be consistent with sys_usleep, set errno and return -1 on error.
int TaskGroup::usleep(TaskGroup** pg, uint64_t timeout_us) {
    if (0 == timeout_us) {
        yield(pg);
        return 0;
    }
    TaskGroup* g = *pg;
    // We have to schedule timer after we switched to next bthread otherwise
    // the timer may wake up(jump to) current still-running context.
    SleepArgs e = { timeout_us, g->current_tid(), g->current_task(), g };
    g->set_remained(_add_sleep_event, &e);
    sched(pg);
    g = *pg;
    if (e.meta->sleep_failed) {
        // Fail to schedule timer, return error.
        e.meta->sleep_failed = false;
        errno = ESTOP;
        return -1;
    }
    e.meta->current_sleep = 0;
    if (e.meta->interrupted) {
        // Race with set and may consume multiple interruptions, which are OK.
        e.meta->interrupted = false;
        // NOTE: setting errno to ESTOP is not necessary from bthread's
        // pespective, however many RPC code expects bthread_usleep to set
        // errno to ESTOP when the thread is stopping, and print FATAL
        // otherwise. To make smooth transitions, ESTOP is still set instead
        // of EINTR when the thread is stopping.
        errno = (e.meta->stop ? ESTOP : EINTR);
        return -1;
    }
    return 0;
}

// Defined in butex.cpp
bool erase_from_butex_because_of_interruption(ButexWaiter* bw);