fix crash for static ThreadPool

}// namespace future_detail

static ThreadPool g_default_thread_pool;

TaskQueueBase *g_default_scheduler = &g_default_thread_pool;

static std::atomic<TaskQueueBase *> g_default_scheduler{nullptr};

// static ThreadPool default_thread_pool;

static std::unique_ptr<Thread> g_default_thread;

void

SetDefaultScheduler(TaskQueueBase *scheduler) noexcept

{

    if (scheduler == nullptr) {

        g_default_scheduler = &g_default_thread_pool;

    } else {

        g_default_scheduler = scheduler;

    }

    SLED_ASSERT(scheduler, "scheduler is nullptr");

    g_default_scheduler.store(scheduler, std::memory_order_release);

}

TaskQueueBase *

GetDefaultScheduler() noexcept

{

    return g_default_scheduler;

    static std::once_flag flag;

    std::call_once(flag, [&] {

        g_default_thread = sled::Thread::Create();

        g_default_thread->Start();

        TaskQueueBase *null_scheduler = nullptr;

        while (g_default_scheduler.load() == nullptr) {

            g_default_scheduler.compare_exchange_weak(null_scheduler, g_default_thread.get());

        }

    });

    return g_default_scheduler.load(std::memory_order_acquire);

}

}// namespace sled