>class Router
>{
>    // std::map<int , co_event> m_cancellation; 
 std::map<int , async> m_cancellation;
>
>
>    awaitable<int> handle_message(session& sess)
>    {
>        auto& cancel = m_cancellation[sess->Id()];
>        defer(m_cancellation.erase(sess->id());
>
>
>        auto client = co_await g_client_pool.get();
>        defer(client.release(client));
>
>
>        co_task _task; 
>        auto request_id = _task << [](auto& client) -> awaitable<void> 
>        { 
>            // auto r = client.request(...); 
  auto r = co_await client.request(...); 
>            if (r == INVALID) 
>            { 
>                LOG(...); 
>            } 
>        }(client); 
>
>
>        auto cancel_id = _task << [](auto& cancel) -> awaitable<void> 
>       { 
>            co_await cancel.suspend(); 
>        }(cancel); 
>
>
>        auto ret_id = co_await _task.wait(); 
>        if (ret_id == cancel_id) 
>        { 
>            LOG("cancel"); 
>            co_return INVALID; 
>        } 
>
>
>        LOG("success"); 
>        // return 0; 
     co_return 0;
>    }
>     void cancel(int id)
>    {
>        if (auto it = m_cancellation.find(id); it != m_cancellation.end())
>        {
>            it->second.resume();
>        }
>    }
>};
>