c++ - 如何在源代码中强制执行单线程构建

Question

背景:我为一些非常专业的数据处理创建了许多小型实用程序。通常，我是唯一的用户。我什至不考虑多线程编程，因为运行时性能对于我的用例来说已经足够了。关键资源是我的编程时间。所以我想避免多线程编程所需的任何额外工作。

但是，当我将来重用我的代码时，似乎存在一个风险，即我的源代码会在多线程上下文中执行。

根据 CppCoreGuidelines :

Be careful: there are many examples where code that was “known” to never run in a multi-threaded program was run as part of a multi-threaded program. Often years later. Typically, such programs lead to a painful effort to remove data races. Therefore, code that is never intended to run in a multi-threaded environment should be clearly labeled as such and ideally come with compile or run-time enforcement mechanisms to catch those usage bugs early.

同一来源中的大多数建议实际上让我开始了多线程编程。我更愿意遵循的一个建议是:

Refuse to build and/or run in a multi-threaded environment.

所以我的问题是，我该怎么做？例如。是否有包含文件、#pragma 等来确保源文件中所有内容的单线程构建/执行？

Answer 1

与 g++/gcc编译和链接多线程代码需要使用 -pthread编译器和链接器选项。此选项设置 _REENTRANT您可以在编译时检查的宏:

$ c="g++ -E -dD -xc++ /dev/null"
$ diff <($c) <($c -pthread)
389a390
> #define _REENTRANT 1

与流行的看法相反，using -lpthread linker option is unnecessary and insufficient to correctly build a multi-threaded program .

---

Microsoft Visual Studio 集 _MT用于多线程构建的宏，IIRC。

---

Boost 库执行以下操作:

// Turn on threading support if the compiler thinks that it's in
// multithreaded mode.  We put this here because there are only a
// limited number of macros that identify this (if there's any missing
// from here then add to the appropriate compiler section):
//
#if (defined(__MT__) || defined(_MT) || defined(_REENTRANT) \
    || defined(_PTHREADS) || defined(__APPLE__) || defined(__DragonFly__)) \
    && !defined(BOOST_HAS_THREADS)
#  define BOOST_HAS_THREADS
#endif

这样你就可以#include <boost/config.hpp>然后检查 BOOST_HAS_THREADS 的值宏。

---

如果在多线程模式下构建，下面会导致编译错误:

#if defined(BOOST_HAS_THREADS) || defined(_REENTRANT) || defined(_MT)
#error This code is single-threaded only.
#endif