Re: [boost] asio forcing the use of handlers?

From: Christopher Kohlhoff (chris_at_[hidden])
Date: 2007-09-11 06:57:09

Roland Schwarz wrote:
> 
> Christopher Kohlhoff wrote:
>> http://article.gmane.org/gmane.comp.lib.boost.devel/155402
> 
> I was traveling along this post, but now have another question:
> 
> While my thread is waiting in the futures:
> 
> T get() const
>    {
>      boost::mutex::scoped_lock lock(mutex_);
>      while (!value_.get() && !exception_.get())
>        condition_.wait(lock);
>      if (exception_.get())
>        exception_->raise();
>      return *value_;
>    }
> 
> it will not react to a    io_service_.stop(); request.
>
> While I do understand why this is so, I wonder if there is a way to let 
> the future also check for the demuxers stop flag and exit the wait by 
> possibly throwing an error?

A stop() may only be a temporary condition for the io_service. You can 
subsequently reset the io_service and call run() again. I.e. the 
stopping of the io_service is a separate issue to whether the future is 
ultimately fulfilled.

It might be more appropriate to use the destruction of the io_service 
object, since the io_service destructor cleans up all unfinished handler 
objects. If the handlers in turn hold the associated promise objects 
then the destruction of all promises can be used to indicate that the 
future has been abandoned.

Cheers,
Chris