Re: [Boost-users] serialization gives memory leaks due to throwingconstructors

From: Robert Ramey (ramey_at_[hidden])
Date: 2007-03-02 11:27:24

I don't think this case needs two layers of try/catch.

This thread started with a concern about throwing
an exception while in a constructor.

If an exception is thrown during construction, there are
no pointers created.  So calling "delete created pointers"
is a no-op and does no harm if it is called.  If an exception
is thrown during loading, then "delete_created_pointers" will
becalled with the desired effect.

This is not to say that I know for a fact that that an
exception thrown during construction can in fact create
a memory leak.  To be honest, I never considered that when
I wrote the code so it might be possible.  I would have
to look into it.

Robert Ramey

gast128 wrote:
> Robert Ramey <ramey <at> rrsd.com> writes:
>
>> Note: the function of 'delete_created_pointers'  is to delete any
>> pointer created during the process of loading.  Construction
>> of an archive creates no such pointers.  So not calling
>> 'delete_created_pointers' in this case will have no effect and
>> does not need to be called.
>
> Ok 3 things:
> 1) I think a throwing ctor should not create memory leaks. I believe
> Sutter has comments about this in his book
> 2) The loaded XML file can be altered by users. Therfore the load can
> fail and I want it to be guarded. But now I have to add a double
> guard:
>
> bool Load(const std::string& cr)
> {
>    std::fstream fstr(cr);
>
>    try
>    {
>        boost::archive::xml_iarchive ia(fstr);
>
>        try
>        {
>           ia >> ...;
>           return true;
>        }
>        catch (boost::archive::archive_exception& re)
>        {
>            ia.delete_created_pointers();
>        }
>    }
>    catch (boost::archive::archive_exception& re)
>    {
>    }
>
>    return false;
> }