diff options
Diffstat (limited to '_posts')
| -rw-r--r-- | _posts/2015-07-03-std-call-once-bug-in-visual-studio-2012-2013.md | 22 |
1 files changed, 10 insertions, 12 deletions
diff --git a/_posts/2015-07-03-std-call-once-bug-in-visual-studio-2012-2013.md b/_posts/2015-07-03-std-call-once-bug-in-visual-studio-2012-2013.md index 5570979..19f6224 100644 --- a/_posts/2015-07-03-std-call-once-bug-in-visual-studio-2012-2013.md +++ b/_posts/2015-07-03-std-call-once-bug-in-visual-studio-2012-2013.md @@ -4,8 +4,6 @@ layout: post excerpt: > In this post, I will describe a neat bug I've stumbled upon in C++ Standard Library implementation shipped with Microsoft Visual Studio 2012/2013. -custom_css: - - syntax.css --- ### Abstract @@ -46,7 +44,7 @@ C++11 and singletons Anyway, the story begins with me trying to implement the singleton pattern using C++11 facilities like this: -{% highlight c++ %} +``` #include <mutex> template <typename DerivedT> @@ -83,13 +81,13 @@ private: template <typename DerivedT> std::once_flag Singleton<DerivedT>::initialized_flag; -{% endhighlight %} +``` Neat, huh? Now other classes can inherit from `Singleton`, implementing the singleton pattern effortlessly: -{% highlight c++ %} +``` class Logger : public Singleton<Logger> { private: @@ -98,7 +96,7 @@ private: friend class Singleton<Logger>; }; -{% endhighlight %} +``` Note that the [N2660] standard proposal isn't/wasn't implemented in the compilers shipped with Visual Studio 2012/2013. @@ -106,7 +104,7 @@ If it was, I wouldn't, of course, need to employ this `std::call_once` trickery, and the implementation would be much simpler, i.e. something like this: -{% highlight c++ %} +``` class Logger { public: @@ -120,7 +118,7 @@ private: Logger() = default; ~Logger() = default; }; -{% endhighlight %} +``` <div class="alert alert-info"> <p>The point is that the <code>Logger::get_instance</code> routine above wasn't @@ -156,7 +154,7 @@ logging to be done. OK, I thought, I will simply call `Logger::get_instance` inside `Duke`s constructor, and everything would be fine. -{% highlight c++ %} +``` #include <chrono> #include <thread> @@ -195,13 +193,13 @@ private: friend class Singleton<Duke>; }; -{% endhighlight %} +``` What would happen if I had two threads, one to do something with the `Duke` instance, and the other to do something else, logging in process? Like this: -{% highlight c++ %} +``` #include <ctime> #include <iostream> @@ -249,7 +247,7 @@ int main() t2.join(); return 0; } -{% endhighlight %} +``` The first thread is supposed to have to total running time of about 13 seconds, right? |