2020-03-26 17:35:12 +08:00
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#include "librf.h"
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2019-04-21 09:05:04 +08:00
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#include <chrono>
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#include <iostream>
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#include <string>
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#include <thread>
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#include <future>
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2019-04-25 16:07:37 +08:00
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//原旨主义的异步函数,其回调写法大致如下
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2019-04-21 09:05:04 +08:00
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template<typename _Input_t, typename _Callable_t>
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2019-04-25 16:07:37 +08:00
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void tostring_async_originalism(_Input_t&& value, _Callable_t&& token)
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{
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std::thread([callback = std::move(token), value = std::forward<_Input_t>(value)]
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2019-04-21 09:05:04 +08:00
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{
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callback(std::to_string(value));
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}).detach();
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}
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2019-04-25 16:07:37 +08:00
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//使用原旨主义的方式扩展异步方法来支持future
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template<typename _Input_t>
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auto tostring_async_originalism_future(_Input_t&& value)
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{
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std::promise<std::string> _promise;
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std::future<std::string> _future = _promise.get_future();
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std::thread([_promise = std::move(_promise), value = std::forward<_Input_t>(value)]() mutable
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{
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_promise.set_value(std::to_string(value));
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}).detach();
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return std::move(_future);
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}
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//----------------------------------------------------------------------------------------------------------------------
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//以下演示如何通过现代回调(Modern Callback), 使用回调适配器模型,
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//将异步回调函数扩展到支持future模式,调用链模式,以及协程。
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//首先,准备modern_call_return_void_t和modern_callback_adapter_t给异步函数使用
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//通过一个间接的类来解决返回void的语法问题,以便于优化返回值
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struct modern_call_return_void_t
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{
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void get(){}
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};
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2019-04-21 09:05:04 +08:00
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//回调适配器的模板类
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//_Callable_t 要符合 _Signature_t 签名
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//这个类除了转移token外,不做任何有效的工作
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//有效工作等待特列化的类去做
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template<typename _Callable_t, typename _Signature_t>
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struct modern_callback_adapter_t
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{
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using callback_type = _Callable_t;
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using return_type = modern_call_return_void_t;
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static std::tuple<callback_type, return_type> traits(_Callable_t&& token)
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{
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return { std::forward<_Callable_t>(token), {} };
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}
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};
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2019-04-25 16:07:37 +08:00
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//一个使用回调处理结果的异步函数,会涉及以下概念:
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//_Input_t:异步函数的输入参数;
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//_Signature_t: 此异步回调的函数签名;应当满足‘void(_Exception_t, _Result_t...)’或者‘void(_Result_t...)’类型;
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//_Callable_t:回调函数或标记,如果是回调函数,则需要符合_Signature_t的签名类型。这个回调,必须调用一次,且只能调用一次;
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//_Return_t:异步函数的返回值;
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//_Result_t...:异步函数完成后的结果值,作为回调函数的入参部分;这个参数可以有零至多个;
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//_Exception_t:回调函数的异常, 如果不喜欢异常的则忽略这个部分,但就得异步代码将异常处置妥当;
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//
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//在回调适配器模型里,_Input_t/_Result_t/_Exception_t(可选)是异步函数提供的功能所固有的部分;_Callable_t/_Return_t
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//部分并不直接使用,而是通过适配器去另外处理。这样给予适配器一次扩展到future模式,调用链模式的机会,以及支持协程的机会。
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//
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//tostring_async 演示了在其他线程里,将_Input_t的输入值,转化为std::string类型的_Result_t。
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//然后调用_Signature_t为 ‘void(std::string &&)’ 类型的 _Callable_t。
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//忽视异常处理,故没有_Exception_t。
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//
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template<typename _Input_t, typename _Callable_t>
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auto tostring_async(_Input_t&& value, _Callable_t&& token)
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{
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//适配器类型
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using _Adapter_t = modern_callback_adapter_t<typename resumef::remove_cvref_t<_Callable_t>, void(std::string)>;
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//通过适配器获得兼容_Signature_t类型的真正的回调,以及返回值_Return_t
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auto adapter = _Adapter_t::traits(std::forward<_Callable_t>(token));
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2019-04-25 16:07:37 +08:00
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//callback与token未必是同一个变量,甚至未必是同一个类型
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std::thread([callback = std::move(std::get<0>(adapter)), value = std::forward<_Input_t>(value)]
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{
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using namespace std::literals;
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std::this_thread::sleep_for(0.1s);
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callback(std::to_string(value));
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}).detach();
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//返回适配器的_Return_t变量
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return std::move(std::get<1>(adapter)).get();
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}
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2019-04-25 16:07:37 +08:00
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//或者宏版本写法
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#define MODERN_CALLBACK_TRAITS(_Token_value, _Signature_t) \
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using _Adapter_t = modern_callback_adapter_t<typename resumef::remove_cvref_t<_Callable_t>, _Signature_t>; \
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auto _Adapter_value = _Adapter_t::traits(std::forward<_Callable_t>(_Token_value))
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#define MODERN_CALLBACK_CALL() std::move(std::get<0>(_Adapter_value))
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#define MODERN_CALLBACK_RETURN() return std::move(std::get<1>(_Adapter_value)).get()
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template<typename _Input_t, typename _Callable_t>
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auto tostring_async_macro(_Input_t&& value, _Callable_t&& token)
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{
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MODERN_CALLBACK_TRAITS(token, void(std::string));
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std::thread([callback = MODERN_CALLBACK_CALL(), value = std::forward<_Input_t>(value)]
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{
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callback(std::to_string(value));
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}).detach();
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MODERN_CALLBACK_RETURN();
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}
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2019-04-25 16:07:37 +08:00
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//----------------------------------------------------------------------------------------------------------------------
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//下面演示如何扩展tostring_async函数,以支持future模式
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2019-04-25 16:07:37 +08:00
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//future库有多种,但应当都提供遵循promise/future对,兼容std::promise/std::future用法
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//这样的话,可以做一个更加通用的支持future的callback类
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2019-04-25 16:07:37 +08:00
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//实现use_future_callback_t的基类,避免写一些重复代码
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template<typename _Promise_traits, typename _Result_t>
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struct use_future_callback_base_t
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{
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//回调函数的结果类型,已经排除掉了异常参数
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using result_type = _Result_t;
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//通过_Promise_traits获取真正的promise类型
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using promise_type = typename _Promise_traits::template promise_type<result_type>;
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//此类持有一个std::promise<_Result_t>,便于设置值和异常
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//而将与promise关联的future作为返回值_Return_t,让tostring_async返回。
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mutable promise_type _promise;
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auto get_future() const
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{
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return this->_promise.get_future();
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}
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};
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//此类的实例作为真正的callback,交给异步回调函数,替换token。
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//在实际应用中,需要针对是否有异常参数,结果值为0,1,多个等情况做特殊处理,故还需要通过更多的偏特化版本来支持。
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//具体的异常参数,需要根据实际应用去特里化。这里仅演示通过std::exception_ptr作为异常传递的情况。
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template<typename...>
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struct use_future_callback_t;
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//无异常,无结果的callback类型:void()
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template<typename _Promise_traits>
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struct use_future_callback_t<_Promise_traits> : public use_future_callback_base_t<_Promise_traits, void>
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{
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using use_future_callback_base_t<_Promise_traits, void>::use_future_callback_base_t;
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void operator()() const
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{
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this->_promise.set_value();
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}
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};
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//有异常,无结果的callback类型:void(exception_ptr)
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template<typename _Promise_traits>
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struct use_future_callback_t<_Promise_traits, std::exception_ptr> : public use_future_callback_base_t<_Promise_traits, void>
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{
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using use_future_callback_base_t<_Promise_traits, void>::use_future_callback_base_t;
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void operator()(std::exception_ptr eptr) const
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{
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if (!eptr)
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this->_promise.set_value();
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else
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this->_promise.set_exception(std::move(eptr));
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}
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};
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2019-04-25 16:07:37 +08:00
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//无异常,单结果的callback类型:void(_Result_t)
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template<typename _Promise_traits, typename _Result_t>
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struct use_future_callback_t<_Promise_traits, _Result_t> : public use_future_callback_base_t<_Promise_traits, _Result_t>
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{
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using use_future_callback_base_t<_Promise_traits, _Result_t>::use_future_callback_base_t;
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template<typename Arg>
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void operator()(Arg && arg) const
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{
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this->_promise.set_value(std::forward<Arg>(arg));
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}
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};
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2019-04-25 16:07:37 +08:00
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//有异常,单结果的callback类型:void(std::exception_ptr, _Result_t)
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template<typename _Promise_traits, typename _Result_t>
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struct use_future_callback_t<_Promise_traits, std::exception_ptr, _Result_t> : public use_future_callback_base_t<_Promise_traits, _Result_t>
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{
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using use_future_callback_base_t<_Promise_traits, _Result_t>::use_future_callback_base_t;
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2019-04-25 17:26:16 +08:00
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template<typename Arg>
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void operator()(std::exception_ptr eptr, Arg && arg) const
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{
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if (!eptr)
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this->_promise.set_value(std::forward<Arg>(arg));
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else
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this->_promise.set_exception(std::move(eptr));
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}
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};
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2019-04-25 17:48:42 +08:00
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//无异常,多结果的callback类型:void(_Result_t...)
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template<typename _Promise_traits, typename... _Result_t>
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struct use_future_callback_t<_Promise_traits, _Result_t...> : public use_future_callback_base_t<_Promise_traits, std::tuple<_Result_t...> >
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{
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using use_future_callback_base_t<_Promise_traits, std::tuple<_Result_t...> >::use_future_callback_base_t;
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template<typename... Args>
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void operator()(Args&&... args) const
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{
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static_assert(sizeof...(Args) == sizeof...(_Result_t), "");
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this->_promise.set_value(std::make_tuple(std::forward<Args>(args)...));
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}
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};
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//有异常,多结果的callback类型:void(std::exception_ptr, _Result_t...)
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template <typename _Promise_traits, typename... _Result_t>
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struct use_future_callback_t<_Promise_traits, std::exception_ptr, _Result_t...> : public use_future_callback_base_t<_Promise_traits, std::tuple<_Result_t...> >
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{
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using use_future_callback_base_t<_Promise_traits, std::tuple<_Result_t...> >::use_future_callback_base_t;
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template<typename... Args>
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void operator()(std::exception_ptr eptr, Args&&... args) const
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{
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static_assert(sizeof...(Args) == sizeof...(_Result_t), "");
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if (!eptr)
|
2020-02-29 01:11:21 +08:00
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this->_promise.set_value(std::make_tuple(std::forward<Args>(args)...));
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2019-04-25 17:48:42 +08:00
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else
|
2020-02-29 01:11:21 +08:00
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this->_promise.set_exception(std::move(eptr));
|
2019-04-25 17:48:42 +08:00
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}
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};
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2019-04-21 09:05:04 +08:00
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2019-04-25 16:07:37 +08:00
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//与use_future_callback_t配套的获得_Return_t的类
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2019-04-25 17:26:16 +08:00
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template<typename _Future_traits, typename _Result_t>
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2019-04-25 16:07:37 +08:00
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struct use_future_return_t
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2019-04-21 09:05:04 +08:00
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{
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2019-04-25 16:07:37 +08:00
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using result_type = _Result_t;
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2019-04-25 17:26:16 +08:00
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using future_type = typename _Future_traits::template future_type<result_type>;
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2019-04-25 16:07:37 +08:00
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future_type _future;
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2019-04-21 09:05:04 +08:00
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2019-04-25 16:07:37 +08:00
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use_future_return_t(future_type && ft)
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: _future(std::move(ft)) {}
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2019-04-21 09:05:04 +08:00
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2019-04-25 16:07:37 +08:00
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future_type get()
|
2019-04-21 09:05:04 +08:00
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{
|
2019-04-25 16:07:37 +08:00
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return std::move(_future);
|
2019-04-21 09:05:04 +08:00
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}
|
2019-04-25 16:07:37 +08:00
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};
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2019-04-25 17:48:42 +08:00
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//利用use_future_callback_t + use_future_return_t 实现的callback适配器
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template<typename _Token_as_callable_t, typename... _Result_t>
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struct modern_callback_adapter_impl_t
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{
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using traits_type = _Token_as_callable_t;
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using callback_type = use_future_callback_t<traits_type, _Result_t...>;
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using result_type = typename callback_type::result_type;
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using return_type = use_future_return_t<traits_type, result_type>;
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static std::tuple<callback_type, return_type> traits(const _Token_as_callable_t& /*没人关心这个变量*/)
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{
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callback_type callback{};
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auto future = callback.get_future();
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return { std::move(callback), std::move(future) };
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}
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};
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|
2019-04-25 16:07:37 +08:00
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//----------------------------------------------------------------------------------------------------------------------
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//一、做一个使用std::promise/std::future的辅助类。
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//这个类还负责萃取promise/future对的类型。
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struct std_future_t
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{
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template<typename _Result_t>
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using promise_type = std::promise<_Result_t>;
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template<typename _Result_t>
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using future_type = std::future<_Result_t>;
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};
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//二、申明这个辅助类的全局变量。不申明这个变量也行,就是每次要写use_future_t{},麻烦些。
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//以后就使用std_future,替代tostring_async的token参数了。
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|
//这个参数其实不需要实质传参,最后会被编译器优化没了。
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//仅仅是要指定_Callable_t的类型为std_future_t,
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|
//从而在tostring_async函数内,使用偏特化的modern_callback_adapter_t<std_future_t, ...>而已。
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|
constexpr std_future_t std_future{};
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|
2019-04-25 17:48:42 +08:00
|
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//三、偏特化_Callable_t为std_future_t类型的modern_callback_adapter_t
|
2019-04-25 16:07:37 +08:00
|
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|
//真正的回调类型是use_future_callback_t,返回类型_Return_t是use_future_return_t。
|
|
|
|
|
//配合use_future_callback_t的promise<result_type>,和use_future_return_t的future<result_type>,正好组成一对promise/future对。
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|
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|
//promise在真正的回调里设置结果值;
|
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|
|
|
//future返回给调用者获取结果值。
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|
|
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|
template<typename R, typename... _Result_t>
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|
struct modern_callback_adapter_t<std_future_t, R(_Result_t...)> : public modern_callback_adapter_impl_t<std_future_t, _Result_t...>
|
2019-04-21 09:05:04 +08:00
|
|
|
|
{
|
2019-04-25 16:07:37 +08:00
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
//----------------------------------------------------------------------------------------------------------------------
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|
|
|
//同理,可以制作支持C++20的协程的下列一系列类(其实,这才是我的最终目的)
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|
|
struct use_librf_t
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|
|
|
{
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|
template<typename _Result_t>
|
2020-02-16 12:03:51 +08:00
|
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|
|
using promise_type = resumef::awaitable_t<_Result_t>;
|
2019-04-21 09:05:04 +08:00
|
|
|
|
|
2019-04-25 16:07:37 +08:00
|
|
|
|
template<typename _Result_t>
|
|
|
|
|
using future_type = resumef::future_t<_Result_t>;
|
|
|
|
|
};
|
2019-04-25 17:26:16 +08:00
|
|
|
|
constexpr use_librf_t use_librf{};
|
2019-04-21 09:05:04 +08:00
|
|
|
|
|
2019-04-25 16:07:37 +08:00
|
|
|
|
template<typename R, typename... _Result_t>
|
|
|
|
|
struct modern_callback_adapter_t<use_librf_t, R(_Result_t...)> : public modern_callback_adapter_impl_t<use_librf_t, _Result_t...>
|
|
|
|
|
{
|
2019-04-21 09:05:04 +08:00
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
//所以,我现在的看法是,支持异步操作的库,尽可能如此设计回调。这样便于支持C++20的协程。以及future::then这样的任务链。
|
|
|
|
|
//这才是“摩登C++”!
|
|
|
|
|
|
2019-04-25 16:07:37 +08:00
|
|
|
|
//----------------------------------------------------------------------------------------------------------------------
|
2019-04-21 09:05:04 +08:00
|
|
|
|
//使用范例
|
2019-04-25 16:07:37 +08:00
|
|
|
|
|
2019-04-25 17:26:16 +08:00
|
|
|
|
//演示异步库有多个异步回调函数,只要按照Modern Callback范式去做回调,就不再需要写额外的代码,就可以适配到future+librf,以及更多的其他库
|
|
|
|
|
template<typename _Ty1, typename _Ty2, typename _Callable_t>
|
|
|
|
|
auto add_async(_Ty1&& val1, _Ty2&& val2, _Callable_t&& token)
|
|
|
|
|
{
|
2019-04-25 17:56:51 +08:00
|
|
|
|
MODERN_CALLBACK_TRAITS(token, void(decltype(val1 + val2)));
|
2019-04-25 17:26:16 +08:00
|
|
|
|
|
2019-04-25 17:56:51 +08:00
|
|
|
|
std::thread([=, callback = MODERN_CALLBACK_CALL()]
|
2019-04-25 17:26:16 +08:00
|
|
|
|
{
|
|
|
|
|
using namespace std::literals;
|
|
|
|
|
std::this_thread::sleep_for(0.1s);
|
|
|
|
|
callback(val1 + val2);
|
|
|
|
|
}).detach();
|
|
|
|
|
|
|
|
|
|
MODERN_CALLBACK_RETURN();
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
//演示异步库有多个异步回调函数,只要按照Modern Callback范式去做回调,就不再需要写额外的代码,就可以适配到future+librf,以及更多的其他库
|
|
|
|
|
template<typename _Ty1, typename _Ty2, typename _Callable_t>
|
|
|
|
|
auto muldiv_async(_Ty1&& val1, _Ty2&& val2, _Callable_t&& token)
|
|
|
|
|
{
|
2019-04-25 17:56:51 +08:00
|
|
|
|
MODERN_CALLBACK_TRAITS(token, void(std::exception_ptr, decltype(val1 * val2), decltype(val1 / val2)));
|
2019-04-25 17:26:16 +08:00
|
|
|
|
|
2019-04-25 17:56:51 +08:00
|
|
|
|
std::thread([=, callback = MODERN_CALLBACK_CALL()]
|
2019-04-25 17:26:16 +08:00
|
|
|
|
{
|
|
|
|
|
using namespace std::literals;
|
|
|
|
|
std::this_thread::sleep_for(0.1s);
|
|
|
|
|
|
|
|
|
|
auto v1 = val1 * val2;
|
|
|
|
|
|
|
|
|
|
if (val2 == 0)
|
|
|
|
|
callback(std::make_exception_ptr(std::logic_error("divided by zero")), v1, 0);
|
|
|
|
|
else
|
|
|
|
|
callback(nullptr, v1, val1 / val2);
|
|
|
|
|
}).detach();
|
|
|
|
|
|
|
|
|
|
MODERN_CALLBACK_RETURN();
|
|
|
|
|
}
|
|
|
|
|
|
2019-04-21 09:05:04 +08:00
|
|
|
|
void resumable_main_modern_cb()
|
|
|
|
|
{
|
|
|
|
|
using namespace std::literals;
|
|
|
|
|
|
|
|
|
|
//使用lambda作为异步回调函数,传统用法
|
2019-04-25 16:07:37 +08:00
|
|
|
|
tostring_async_originalism(-1.0, [](std::string && value)
|
|
|
|
|
{
|
|
|
|
|
std::cout << value << std::endl;
|
|
|
|
|
});
|
2019-04-25 17:26:16 +08:00
|
|
|
|
std::this_thread::sleep_for(0.5s);
|
2019-04-21 09:05:04 +08:00
|
|
|
|
|
|
|
|
|
tostring_async(1.0, [](std::string && value)
|
|
|
|
|
{
|
|
|
|
|
std::cout << value << std::endl;
|
|
|
|
|
});
|
2019-04-25 16:07:37 +08:00
|
|
|
|
|
2019-04-25 17:26:16 +08:00
|
|
|
|
std::this_thread::sleep_for(0.5s);
|
2019-04-21 09:05:04 +08:00
|
|
|
|
std::cout << "......" << std::endl;
|
|
|
|
|
|
|
|
|
|
//支持future的用法
|
2019-04-25 16:07:37 +08:00
|
|
|
|
std::future<std::string> f1 = tostring_async_originalism_future(5);
|
2019-04-21 09:05:04 +08:00
|
|
|
|
std::cout << f1.get() << std::endl;
|
|
|
|
|
|
2019-04-25 16:07:37 +08:00
|
|
|
|
std::future<std::string> f2 = tostring_async(6.0f, std_future);
|
2019-04-21 09:05:04 +08:00
|
|
|
|
std::cout << f2.get() << std::endl;
|
|
|
|
|
|
|
|
|
|
//支持librf的用法
|
|
|
|
|
GO
|
|
|
|
|
{
|
2020-03-01 12:13:41 +08:00
|
|
|
|
#ifndef __clang__
|
2019-04-25 17:26:16 +08:00
|
|
|
|
try
|
2020-03-01 12:13:41 +08:00
|
|
|
|
#endif
|
2019-04-25 17:26:16 +08:00
|
|
|
|
{
|
|
|
|
|
int val = co_await add_async(1, 2, use_librf);
|
2020-02-16 12:03:51 +08:00
|
|
|
|
std::cout << val << std::endl;
|
2019-04-25 17:26:16 +08:00
|
|
|
|
|
|
|
|
|
//muldiv_async函数可能会抛异常,取决于val是否是0
|
|
|
|
|
//异常将会带回到本协程里的代码,所以需要try-catch
|
|
|
|
|
auto ab = co_await muldiv_async(9, val, use_librf);
|
|
|
|
|
//C++17:
|
|
|
|
|
//auto [a, b] = co_await muldiv_async(9, val, use_librf);
|
|
|
|
|
|
|
|
|
|
std::string result = co_await tostring_async(std::get<0>(ab) + std::get<1>(ab), use_librf);
|
|
|
|
|
|
|
|
|
|
std::cout << result << std::endl;
|
|
|
|
|
}
|
2020-03-01 12:13:41 +08:00
|
|
|
|
#ifndef __clang__
|
2019-04-25 17:26:16 +08:00
|
|
|
|
catch (const std::exception& e)
|
|
|
|
|
{
|
|
|
|
|
std::cout << "exception signal : " << e.what() << std::endl;
|
|
|
|
|
}
|
|
|
|
|
catch (...)
|
|
|
|
|
{
|
|
|
|
|
std::cout << "exception signal : who knows?" << std::endl;
|
|
|
|
|
}
|
2020-03-01 12:13:41 +08:00
|
|
|
|
#endif
|
2019-04-21 09:05:04 +08:00
|
|
|
|
};
|
2019-04-25 17:26:16 +08:00
|
|
|
|
|
2019-04-21 09:05:04 +08:00
|
|
|
|
resumef::this_scheduler()->run_until_notask();
|
|
|
|
|
}
|