Function bthread_once_task

test/bthread_once_unittest.cpp:38–42

}

void bthread_once_task() {
    bthread_once(&g_bthread_once_control, init_routine);
    //  `init_routine' only be called once.
    ASSERT_EQ(1, g_bthread_once_count.load(butil::memory_order_relaxed));
}

void* first_bthread_once_task(void*) {
    g_bthread_once_started = true;