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Re: std::thread - DESPERATE NEED HELP!!!

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On 9/11/2019 11:16 AM, Szyk Cech wrote:
> Hi all!
> 
> [What I want]
> I want write reliable and modern Semaphore class.
> I want write unit test to validate it.
[...]

Here is a _very_ basic, bare bones semaphore:
__________________________
#include <iostream>
#include <mutex>
#include <condition_variable>

// Basic, bare bones C++ Semaphore
struct cpp_sem
{
     unsigned int m_count;
     std::mutex m_mutex;
     std::condition_variable m_cond;

     cpp_sem(unsigned int count = 0) : m_count(count)
     {

     }

     void dec() // wait
     {
         std::unique_lock<std::mutex> lock(m_mutex);
         while (m_count == 0) m_cond.wait(lock);
         --m_count;
     }

     void inc() // post
     {
         {
             std::unique_lock<std::mutex> lock(m_mutex);
             ++m_count;
         }

         m_cond.notify_one();
     }
};

int main() {

   std::cout << "p0\n";

   {
     cpp_sem sem(2);
     sem.dec();
     sem.dec();

     std::cout << "  a\n";

     sem.inc();
     sem.inc();
     sem.inc();

     std::cout << "  b\n";

     sem.dec();
     sem.dec();
     sem.dec();
     sem.inc();
     sem.dec();

     std::cout << "  c\n";

     // sem.dec(); // uncomment for deadlock!
   }

   std::cout << "p1\n";

   return 0;
}
__________________________


This can be improved upon.

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std::thread - DESPERATE NEED HELP!!! Szyk Cech <szykcech@spoko.pl> - 2019-09-11 20:16 +0200
  Re: std::thread - DESPERATE NEED HELP!!! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-09-11 23:01 -0700
  Re: std::thread - DESPERATE NEED HELP!!! Ralf Fassel <ralfixx@gmx.de> - 2019-09-12 11:14 +0200
  Re: std::thread - DESPERATE NEED HELP!!! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-09-13 12:53 -0700
  Re: std::thread - DESPERATE NEED HELP!!! Pavel <pauldontspamtolk@removeyourself.dontspam.yahoo> - 2019-09-13 23:38 -0400
    Re: std::thread - DESPERATE NEED HELP!!! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-09-13 22:07 -0700
      Re: std::thread - DESPERATE NEED HELP!!! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-09-13 22:17 -0700
        Re: std::thread - DESPERATE NEED HELP!!! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-09-13 23:01 -0700

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