Refactor launch #173

4kangjc · 2022-10-29T04:35:21Z

Why

#171

What is changing

重构uthread::Launch，修改为enum class

Example

#171

CLAassistant · 2022-10-29T04:35:26Z

All committers have signed the CLA.

yanminhui · 2022-10-30T05:40:31Z

启动类型不必作为模板参数，这么做使得各个 async 重载变得复杂，需要长的模板参数判断（std::enable_if），调用者还要指定模板参数，可以参照标准库 std::async 类似做法，让它作为函数参数，实现看起来更简洁，调用者也不必指定模板参数。

4kangjc · 2022-10-30T07:46:01Z

启动类型不必作为模板参数，这么做使得各个 async 重载变得复杂，需要长的模板参数判断（std::enable_if），调用者还要指定模板参数，可以参照标准库 std::async 类似做法，让它作为函数参数，实现看起来更简洁，调用者也不必指定模板参数。

主要考虑到接口不变的情况下，如果接口改变的话，可以试试

4kangjc · 2022-10-30T08:29:48Z

启动类型不必作为模板参数，这么做使得各个 async 重载变得复杂，需要长的模板参数判断（std::enable_if），调用者还要指定模板参数，可以参照标准库 std::async 类似做法，让它作为函数参数，实现看起来更简洁，调用者也不必指定模板参数。

还有就是如果作为函数参数是运行期的，作为模板参数是编译期的

yanminhui · 2022-10-30T08:57:03Z

还有就是如果作为函数参数是运行期的，作为模板参数是编译期的

忽略不计，否则许多传递枚举类型的函数都得改成作为模板参数。

4kangjc · 2022-10-30T09:15:07Z

还有就是如果作为函数参数是运行期的，作为模板参数是编译期的

忽略不计，否则许多传递枚举类型的函数都得改成作为模板参数。

可是返回值得编译期确定，当Launch为Prompt类型时，返回值为Uthread，如何与其他类型区分呢？

yanminhui · 2022-10-30T10:35:10Z

可是返回值得编译期确定，当Launch为Prompt类型时，返回值为Uthread，如何与其他类型区分呢？

一般来说，重载的函数应具有相同的返回值类型，如果发现返回值类型可能不同，返回值可以作为出参，也就是说把返回值移到出参上，或者重新命名一个新的函数名进行区分。

4kangjc · 2022-10-30T11:34:12Z

可是返回值得编译期确定，当Launch为Prompt类型时，返回值为Uthread，如何与其他类型区分呢？

一般来说，重载的函数应具有相同的返回值类型，如果发现返回值类型可能不同，返回值可以作为出参，也就是说把返回值移到出参上，或者重新命名一个新的函数名进行区分。

这里并不适合，标准库那个可以做或运算，这里是互斥的，就算作为函数参数传递，调用者也得指定参数，并不比作为模版参数传递简洁，失去了最初的意义

yanminhui · 2022-10-30T12:44:43Z

这里并不适合，标准库那个可以做或运算，这里是互斥的，就算作为函数参数传递，调用者也得指定参数，并不比作为模版参数传递简洁，失去了最初的意义

按你这么说，std::async 也是互斥的，完全可以如下实现，也会是编译期。

// launch::async
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::async, int> = 0>
auto async(_Fp&& __f, _Args&&... __args) {
    // ...
}

// launch::deferred
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::deferred, int> = 0>
auto async(_Fp&& __f, _Args&&... __args) {
    // ...
}

// launch::async | launch::deferred
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::async|launch::deferred, int> = 0>
auto async(_Fp&& __f, _Args&&... __args) {
    return async<launch::async>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
    // or return async<launch::deferred>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
}

我们写模板函数为的是简洁，尽量能根据实参自动推导，不把显示实例化交给用户。

// compile-time
std::async<launch::deferred>(f, arg1, arg2);

// run-time
std::async(launch::deferred, f, arg1, arg2);

4kangjc · 2022-10-30T13:00:14Z

这里并不适合，标准库那个可以做或运算，这里是互斥的，就算作为函数参数传递，调用者也得指定参数，并不比作为模版参数传递简洁，失去了最初的意义

按你这么说，std::async 也是互斥的，完全可以如下实现，也会是编译期。

// launch::async
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::async, int> = 0>
auto async(_Fp&& __f, _Args&&... __args) {
    // ...
}

// launch::deferred
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::deferred, int> = 0>
auto async(_Fp&& __f, _Args&&... __args) {
    // ...
}

// launch::async | launch::deferred
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::async|launch::deferred, int> = 0>
auto async(_Fp&& __f, _Args&&... __args) {
    return async<launch::async>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
    // or return async<launch::deferred>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
}

我们写模板函数为的是简洁，尽量能根据实参自动推导，不把显示实例化交给用户。

// compile-time
std::async<launch::deferred>(f, arg1, arg2);

// run-time
std::async(launch::deferred, f, arg1, arg2);

launch::async和aunch::deferred并不互斥啊，他们可以同时存在，Launch::Prompt，Launch::Schedule，Launch::Current不行

4kangjc · 2022-10-30T13:05:49Z

这里并不适合，标准库那个可以做或运算，这里是互斥的，就算作为函数参数传递，调用者也得指定参数，并不比作为模版参数传递简洁，失去了最初的意义

按你这么说，std::async 也是互斥的，完全可以如下实现，也会是编译期。
// launch::async
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::async, int> = 0>
auto async(_Fp&& __f, _Args&&... __args) {
    // ...
}

// launch::deferred
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::deferred, int> = 0>
auto async(_Fp&& __f, _Args&&... __args) {
    // ...
}

// launch::async | launch::deferred
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::async|launch::deferred, int> = 0>
auto async(_Fp&& __f, _Args&&... __args) {
    return async<launch::async>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
    // or return async<launch::deferred>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
}
我们写模板函数为的是简洁，尽量能根据实参自动推导，不把显示实例化交给用户。
// compile-time
std::async<launch::deferred>(f, arg1, arg2);

// run-time
std::async(launch::deferred, f, arg1, arg2);
launch::async和aunch::deferred并不互斥啊，他们可以同时存在，Launch::Prompt，Launch::Schedule，Launch::Current不行

std::async<launch::async|launch::deferred>(f, arg1, arg2); 不等同于

async<launch::async>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...); 
async<launch::deferred>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);

所以如果通过模板参数的话，将来拓展也好，还是编写std::async<launch::async|launch::deferred>会有大量的冗余代码，所以标准库这个不适合使用模板参数传递async的类型，而async_simple是互斥的，并且返回值，函数的参数也不一样，例如Lauch::Schedule有两个版本，有一个和另外三个参数不一样，多一个C&& c，并不适合改写成函数参数传递

yanminhui · 2022-10-30T13:07:09Z

launch::async和aunch::deferred并不互斥啊，他们可以同时存在，Launch::Prompt，Launch::Schedule，Launch::Current不行

互斥的，当你指定 async|deferred 时，意思是由系统选择其中的某个，最终还是走向 async 或 deferred。

如果你觉得不互斥，可以看看上面的编译期声明会不会有问题。

4kangjc · 2022-10-30T13:10:33Z

launch::async和aunch::deferred并不互斥啊，他们可以同时存在，Launch::Prompt，Launch::Schedule，Launch::Current不行

互斥的，当你指定 async|deferred 时，意思是由系统选择其中的某个，最终还是走向 async 或 deferred。

如果你觉得不互斥，可以看看上面的编译期声明会不会有问题。

噢这样，没具体用过async，感觉怪怪的

yanminhui · 2022-10-30T13:38:07Z

你这里的实现编译通不过的，可以试着编译一下，得把模板写到返回值上

伪代码，若要编译如下：

#include <future>
#include <type_traits>

using namespace std;

// launch::async
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::async, int> = 0>
int async2(_Fp&& __f, _Args&&... __args) {
    // ...
    return 0;
}

// launch::deferred
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::deferred, int> = 0>
int async2(_Fp&& __f, _Args&&... __args) {
    // ...
    return 0;
}

// launch::async | launch::deferred
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == static_cast<launch>(launch::async|launch::deferred), int> = 0>
auto async2(_Fp&& __f, _Args&&... __args) {
    return async2<launch::async>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
    // or return async<launch::deferred>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
}

int main() {
    async2<launch::async>([](){});
    async2<launch::deferred>([](){});
    async2<launch::async|launch::deferred>([](){});
}

4kangjc · 2022-10-30T13:41:57Z

launch::async和aunch::deferred并不互斥啊，他们可以同时存在，Launch::Prompt，Launch::Schedule，Launch::Current不行

互斥的，当你指定 async|deferred 时，意思是由系统选择其中的某个，最终还是走向 async 或 deferred。
如果你觉得不互斥，可以看看上面的编译期声明会不会有问题。

噢这样，没具体用过async，感觉怪怪的

你这里的实现编译通不过的，可以试着编译一下，得把模板写到返回值上

伪代码，若要编译如下：

#include <future>
#include <type_traits>

using namespace std;

// launch::async
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::async, int> = 0>
int async2(_Fp&& __f, _Args&&... __args) {
    // ...
    return 0;
}

// launch::deferred
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::deferred, int> = 0>
int async2(_Fp&& __f, _Args&&... __args) {
    // ...
    return 0;
}

// launch::async | launch::deferred
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == static_cast<launch>(launch::async|launch::deferred), int> = 0>
auto async2(_Fp&& __f, _Args&&... __args) {
    return async2<launch::async>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
    // or return async<launch::deferred>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
}

int main() {
    async2<launch::async>([](){});
    async2<launch::deferred>([](){});
    async2<launch::async|launch::deferred>([](){});
}

编过了，我之前以为是

// launch::async
template <launch policy, class _Fp, class... _Args,
    typename = std::enable_if_t<policy == launch::async>>
int async2(_Fp&& __f, _Args&&... __args) {
    // ...
    return 0;
}

// launch::deferred
template <launch policy, class _Fp, class... _Args,
    typename = std::enable_if_t<policy == launch::deferred>>
int async2(_Fp&& __f, _Args&&... __args) {
    // ...
    return 0;
}

4kangjc · 2022-10-30T13:57:25Z

你这里的实现编译通不过的，可以试着编译一下，得把模板写到返回值上

伪代码，若要编译如下：

#include <future>
#include <type_traits>

using namespace std;

// launch::async
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::async, int> = 0>
int async2(_Fp&& __f, _Args&&... __args) {
    // ...
    return 0;
}

// launch::deferred
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::deferred, int> = 0>
int async2(_Fp&& __f, _Args&&... __args) {
    // ...
    return 0;
}

// launch::async | launch::deferred
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == static_cast<launch>(launch::async|launch::deferred), int> = 0>
auto async2(_Fp&& __f, _Args&&... __args) {
    return async2<launch::async>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
    // or return async<launch::deferred>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
}

int main() {
    async2<launch::async>([](){});
    async2<launch::deferred>([](){});
    async2<launch::async|launch::deferred>([](){});
}

其实可以这样写？

template <launch policy, class Fn, class... Args>
auto async(Fn&& f, Args&&... args) {
    if constexpr ((policy & launch::async) == launch::async) {
        //TODO
    }

    if constexpr ((policy & launch::deferred) == launch::deferred) {
        //TODO
    }
}

template<typename _Fn, typename... _Args>
auto async(_Fn&& __fn, _Args&&... __args) {
      return async<launch::async|launch::deferred>(
        std::forward<_Fn>(__fn),
		std::forward<_Args>(__args)...);
}


int main() {
    async<launch::async>([](){});
    async<launch::deferred>([](){});
    async([](){});
}

4kangjc · 2022-10-30T13:59:02Z

你这里的实现编译通不过的，可以试着编译一下，得把模板写到返回值上

伪代码，若要编译如下：

#include <future>
#include <type_traits>

using namespace std;

// launch::async
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::async, int> = 0>
int async2(_Fp&& __f, _Args&&... __args) {
    // ...
    return 0;
}

// launch::deferred
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::deferred, int> = 0>
int async2(_Fp&& __f, _Args&&... __args) {
    // ...
    return 0;
}

// launch::async | launch::deferred
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == static_cast<launch>(launch::async|launch::deferred), int> = 0>
auto async2(_Fp&& __f, _Args&&... __args) {
    return async2<launch::async>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
    // or return async<launch::deferred>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
}

int main() {
    async2<launch::async>([](){});
    async2<launch::deferred>([](){});
    async2<launch::async|launch::deferred>([](){});
}

其实可以这样写？

template <launch policy, class Fn, class... Args>
auto async(Fn&& f, Args&&... args) {
    if constexpr ((policy & launch::async) == launch::async) {
        //TODO
    }

    if constexpr ((policy & launch::deferred) == launch::deferred) {
        //TODO
    }
}

template<typename _Fn, typename... _Args>
auto async(_Fn&& __fn, _Args&&... __args) {
      return async<launch::async|launch::deferred>(
        std::forward<_Fn>(__fn),
		std::forward<_Args>(__args)...);
}


int main() {
    async<launch::async>([](){});
    async<launch::deferred>([](){});
    async([](){});
}

其实主要还是返回值和函数调用参数不一样的问题，不然async_simple也能像标准库那样去实现

4kangjc · 2022-10-30T14:26:53Z

你这里的实现编译通不过的，可以试着编译一下，得把模板写到返回值上

伪代码，若要编译如下：

#include <future>
#include <type_traits>

using namespace std;

// launch::async
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::async, int> = 0>
int async2(_Fp&& __f, _Args&&... __args) {
    // ...
    return 0;
}

// launch::deferred
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == launch::deferred, int> = 0>
int async2(_Fp&& __f, _Args&&... __args) {
    // ...
    return 0;
}

// launch::async | launch::deferred
template <launch policy, class _Fp, class... _Args,
    std::enable_if_t<policy == static_cast<launch>(launch::async|launch::deferred), int> = 0>
auto async2(_Fp&& __f, _Args&&... __args) {
    return async2<launch::async>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
    // or return async<launch::deferred>(std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
}

int main() {
    async2<launch::async>([](){});
    async2<launch::deferred>([](){});
    async2<launch::async|launch::deferred>([](){});
}

其实可以这样写？

template <launch policy, class Fn, class... Args>
auto async(Fn&& f, Args&&... args) {
    if constexpr ((policy & launch::async) == launch::async) {
        //TODO
    }

    if constexpr ((policy & launch::deferred) == launch::deferred) {
        //TODO
    }
}

template<typename _Fn, typename... _Args>
auto async(_Fn&& __fn, _Args&&... __args) {
      return async<launch::async|launch::deferred>(
        std::forward<_Fn>(__fn),
		std::forward<_Args>(__args)...);
}


int main() {
    async<launch::async>([](){});
    async<launch::deferred>([](){});
    async([](){});
}

其实主要还是返回值和函数调用参数不一样的问题，不然async_simple也能像标准库那样去实现

暂时只想到将Exector提前这么一个办法

template <Launch T, class F, class C = std::nullptr_t>
inline std::conditional_t<T == Launch::Prompt, Uthread, void>
async(Executor* ex, F&& f, C&& c = nullptr) {
    if constexpr (T == Launch::Schedule) {
        if (!ex)
            AS_UNLIKELY { return; }
        ex->schedule([f = std::move(f), c = std::move(c), ex]() {
            Uthread uth(Attribute{ex}, std::move(f));
            if (c) {
                uth.join(std::move(c));
            } else {
                uth.detach();
            }
        });
    } else if constexpr (T == Launch::Prompt) {
        return Uthread(Attribute{ex}, std::forward<F>(f)); 
    } else if constexpr (T == Launch::Current) {
        Uthread uth(Attribute{ex}, std::forward<F>(f));
        uth.detach();
    } else {
        // Invalid Launch
    }
    
}

ChuanqiXu9

当前的接口设计确实不那么连贯，不过从解决眼下问题的角度以及保持接口的角度出发，我觉得现在这个 patch 也可以接受的

ChuanqiXu9 · 2022-10-31T02:31:50Z

async_simple/uthread/Async.h

-                                  T>::type* = nullptr>
-inline Uthread async(F&& f, Executor* ex) {
+template <Launch T, class F>
+inline std::enable_if_t<T == Launch::Prompt, Uthread> async(F&& f,


这些 enable if 改成 requires 会好一些

这些 enable if 改成 requires 会好一些

OK

RainMark · 2022-10-31T07:09:01Z

当时确实主要是返回值和参数类型不一样，不然是可以把policy放到参数上的。考虑到换个函数名字给使用者带来不便利性所以先用模板参数来区分了。

RainMark · 2022-10-31T11:39:35Z

感觉是不是可以删掉Prompt那种？而且Prompt貌似更符合sync execution语义

4kangjc · 2022-10-31T14:02:20Z

Why

#171

What is changing

修改了ReadFile.bench.cpp下无符号整数与有符号整数比较产生的编译错误重构uthread::Launch，修改为enum class

Example

#171

我发现clang下不会触发报错，难怪，你们用的是clang

ChuanqiXu9 · 2022-11-01T02:35:30Z

触发报错，难怪，你们用的

对，像这种不同的修改最好放到不同的 PR里比较好

ChuanqiXu9

这个 Patch 本身应该是好的；接口设计属于历史遗留问题了

ChuanqiXu9 reviewed Oct 31, 2022

View reviewed changes

4kangjc force-pushed the refactor-Launch branch from 941e6a0 to a4a3e14 Compare November 2, 2022 05:50

refactor uthread::Launch

85d1ab1

4kangjc force-pushed the refactor-Launch branch from a4a3e14 to 85d1ab1 Compare November 2, 2022 05:54

ChuanqiXu9 approved these changes Nov 3, 2022

View reviewed changes

ChuanqiXu9 merged commit 789a3e0 into alibaba:main Nov 3, 2022

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Refactor launch #173

Refactor launch #173

4kangjc commented Oct 29, 2022 •

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Refactor launch #173

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