Re: [boost] [variant] static_visitor deadlock

Subject: Re: [boost] [variant] static_visitor deadlock
From: Andrew Hundt (athundt_at_[hidden])
Date: 2011-05-17 17:40:12

Apologies, the deadlock was my fault.

Cheers!
Andrew Hundt

On Tue, May 17, 2011 at 1:06 PM, Andrew Hundt <athundt_at_[hidden]> wrote:

> I believe I may have found a way to create a deadlock in static_visitor,
> but it may be my own mistake.
>
> It seems if I apply one static visitor within another with an extra call to
> operator() that I use for shared_ptr objects, the program deadlocks in
> apply_visitor_binary_invoke::internal_visit(). The template in my class
> below is another static visitor object, so in essence I am creating an
> effect similar to a java decorator using visitors. Here is a stripped down
> version of the class with which the deadlock occurs:
>
> /**
>  * @class VisitorDecorator
>  *
>  * @brief decorates (wraps) a normal visitor
>  */
> template <typename T>
> class VisitorDecorator : public  boost::static_visitor<typename
> T::result_type> {
>   typedef typename T::result_type t_result_type;
> public:
>   VisitorDecorator(boost::shared_ptr<T> deviceCommandVisitor, std::string
> filename):
>     m_visitor(deviceCommandVisitor),
>     m_filename(filename)
>     {}
>
>   /**
>    * @brief strip shared pointers and handle the object itself
>    */
>   template <typename U, typename V>
>   inline t_result_type operator()( boost::shared_ptr<U>& deviceP,
> boost::shared_ptr<V>& commandP){
>
>     return operator()(*deviceP,*commandP);
>   }
>
>    /**
>    * @brief Connect the specified struct types to the log file
>    */
>   template<typename U, typename V>
>   t_result_type operator()(U& device, V& command){
>
>     return (*m_visitor)(device,command);
>   }
> private:
>   boost::shared_ptr<T> m_visitor;
>   std::string m_filename;
> };
>
>
>
> Does anyone have thoughts or suggestions, be it my fault or a bug in the
> library?
>
> Cheers!
> Andrew Hundt
>
>