是否足够声明一个函数为transaction_safe，所以他们可以使用线程安全？ [英] Is it enough to declare a function as transaction_safe, so they can be used thread-safe?

问题描述

只要在我的一个类中声明所有的函数为 transaction_safe ，就可以在事务中使用线程安全 atomic_noexcept ，atomic_cancel，atomic_commit 来自实验性事务内存TS？

Is enough just to declare all of the functions as transaction_safe in some my class, so its can be used as thread-safe in transactions atomic_noexcept, atomic_cancel, atomic_commit from Experimental Transactional Memory TS?

已知的事务内存TS（ISO / IEC TS 19841：2015）实验C ++标准库。简单示例如下： http://en.cppreference.com/w/cpp/language/ transactional_memory

As known there are Transactional Memory TS (ISO/IEC TS 19841:2015) in the Experimental C++ standard libraries. Simple examples are here: http://en.cppreference.com/w/cpp/language/transactional_memory

另外还有针对
的C ++扩展的技术规范事务内存： http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4514 .pdf

第34页：

23.4 Associative containers [associative]
23.4.4 Class template map [map]
23.4.4.1 Class template map overview [map.overview]

In 23.4.4.1 [map.overview], add "transaction_safe" to the declarations of all
variants of the begin and end member functions and to
the declarations of size, max_size, and empty.

如果事务内存将提交到C ++标准，那么我们可以这样做，并且线程安全？

I.e. if Transactional Memory will commit to the C++ Standard, then can we simply do something like this and will it thread-safe?

#include<map>
#include<thread>

std::map<int, int> m;

int main() {

 std::thread t1([&m]() {
  atomic_cancel
  {
   m[1] = 1;    // thread-safe
  }
 } );

 t1.join();

 return 0;
}

$ b <即使使用GCC 6.1上的 -fgnu-tm 键： https://godbolt.org/g/UcV4wI

只要将所有函数声明为 transaction_safe 在一些我的类，所以它可以用作线程安全 - 如果我将调用它的作用域： atomic_cancel {obj.func（）; }

And will enough just to declare all of the functions as transaction_safe in some my class, so its can be used as thread-safe - if I will call its in scope: atomic_cancel { obj.func(); }?

推荐答案

原子块中的复合语句不允许执行
任何表达式或语句或调用不是$ b的任何函数$ b transaction_safe

The compound-statement in an atomic block is not allowed to execute any expression or statement or call any function that isn't transaction_safe

std :: map 不会是 transaction_safe 方法， t在atomic_cancel中调用它。这将是一个编译时错误。

std::map<int, int>::operator[] wouldn't be a transaction_safe method, so you couldn't call it in atomic_cancel. It would be a compile time error.

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