Method wakeup

test/bthread_timer_thread_unittest.cpp:65–73

    }

    void wakeup() {
        if (_sleep_ms != 0) {
            _sleep_ms = 0;
            bthread::futex_wake_private(&_sleep_ms, 1);
        } else {
            LOG(ERROR) << "No need to wakeup "
                       << (_name ? _name : "") << " task_id=" << _task_id;
        }
    }

    // verify the first run is in specified time range.
    void expect_first_run()