Re: [Boost-users] boost::bind memory leak

Subject: Re: [Boost-users] boost::bind memory leak
From: bit bit (g_rambot_at_[hidden])
Date: 2010-11-13 21:11:48

In general I follow the no-destr-throw rule. But i am trying to keep as much debugging information and if possible even recover. If it's impossible I just assert and terminate the appl. I repeat, it's just for this special case where I need all debugging inf. It's an API and I do not have control over code which is called inside ShutDown so that I can make it no-throw too.

  void CleanUp throw()
  {
       // do whatever
  };

  void ShutDown()
  {
      if (uncaught_exception())
      {
               try
               {
                     // do whatever
               }
               catch(...)
               {
                     assert("screwed");
               };
      }
      else
      {
               try

               {

                     // do whatever

               }

               catch(...)

               {

                     // recover code 
                     throw;

               };
      };
  };

    void func2()

    {
        try
        {
            shared_ptr<void> cleanup    (static_cast<void*>(0), bind(&A::CleanUp,    this));  // both need to be called

            shared_ptr<void> shutdown(static_cast<void*>(0), bind(&A::ShutDown, this)); // both need to be called

        }
        catch(...)
        {};
    };

Well maybe i just need to delete the uncaught_exception, keep the first if condition and call it a day. Angry API users after that. :D

From: nevin_at_[hidden]
Date: Sat, 13 Nov 2010 15:05:57 -0600
To: boost-users_at_[hidden]
Subject: Re: [Boost-users] boost::bind memory leak

2010/11/13 bit bit <g_rambot_at_[hidden]>

so you are saying that the leak cannot be prevented from inside the shared_ptr? 
I'm saying that throwing from a destructor is incredibly bad programming practice, and has been known to be bad programming practice for years (plenty of references on this from the writings of Herb Sutter and Scott Meyers).  The destructor for std::shared_ptr will (in all likelihood at this point) be marked noexcept under C++0X, which would terminate your program.

 I prefer not to make CleanupShit() a no-throw method so that it can report errors using exceptions.

Good luck with that.  Even assuming there is no memory leak, how would you make the following work:
    void func2()

    {
        try
        {
            int i;
            shared_ptr<void> shutdown(static_cast<void*>(0), bind(&A::func1, this));

            shared_ptr<void> goodluck(static_cast<void*>(0), bind(&A::func1, this));

        }
        catch(...)
        {};
    };
 

What I am trying to make a point at, is that shared_ptr should either prevent the leak in the first place using a second level of ra2 inside it, or at least assert that I am not supposed to throw inside the custom deleter.

The latter is obvious from the documentation:      ~shared_ptr(); // never throws
--  Nevin ":-)" Liber  <mailto:nevin_at_[hidden]>  [phone]

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