Re: [boost] [threads / signals2] Win events replace by boost signals (threadsafe)

Subject: Re: [boost] [threads / signals2] Win events replace by boost signals (threadsafe)
From: james (james_at_[hidden])
Date: 2015-03-26 03:26:07

On 25/03/2015 07:57, Fu ji wrote:
> I read about condition variable and it's also not the best idea, because we
> can receive signal only if we actually wait in this time. For example:
>
> void setcondvar()
> {
>      boost::this_thread::sleep_for(boost::chrono::milliseconds(200));
>      std::cout << "Set" << std::endl;
>      cond.notify_all();
>      std::cout << "After" << std::endl;
> }
>
> int main()
> {
>      boost::mutex CondMutex;
>
>      boost::thread t1(setcondvar);
>      t1.join();
>
>      std::cout << "Before wait" << std::endl;
>
>      boost::unique_lock<boost::mutex> lock(CondMutex);
>      bool result = cond.timed_wait(lock,
> boost::posix_time::milliseconds(1000));
>
>      std::cout << result;
>
> return 0;
> }
>
Code that looks like that is wrong.  Always have a flag protected by the 
mutex, always respond to the cond wait returning by checking the flag 
and waiting again unless timeout.