Re: [Boost-users] Serialisation across libraries.

From: Hughes, James (jhughes_at_[hidden])
Date: 2007-05-08 11:24:05

Hi Robert,

I was worried there might not be enough information, so here goes. See
below.

> -----Original Message-----
> From: boost-users-bounces_at_[hidden] 
> [mailto:boost-users-bounces_at_[hidden]] On Behalf Of Robert Ramey
> Sent: 08 May 2007 15:57
> To: boost-users_at_[hidden]
> Subject: Re: [Boost-users] Serialisation across libraries.
> 
> A little extra information would be helpful.
> 
> a) what compiler/linker etc are you using

gcc 3.4.3  (Cross compiling to Arm)

> b) which version of boost serialization are you using.

A completely standard 1.33.1

> c) what kind of library: static, DLL, or?

All the libs involved are shared.

> d) Is this an issue related to shared_ptrs or more general?
> 

There are shared_ptr's involved. I will endeavour to describe the data
structure in the main library in more detail (limited to the Text case
which is all I am testing currently).

Message    - the basic data to be serialised
  contains some basic data and a vector of shared_ptrs to Panels (which
is a base class of a number of different panel types)

Panels    - Contains some basic member data

TextPanel - Derived from Panels, contains some member data and a
structure, PanelFieldsList 

PanelFieldsList contains a vector of shared_ptrs to Fields (which is a
base class to a number of different field types). 

Fields
 Base class contains a vector of raw pointers back to any panels which
reference them (but not currently serialised - trying to get the basics
working first - may add these in a post process of the loaded data to
save brain ache)

Now....The first area of problem, and the one described in my first
post, is that when I attempt to serialise a data structure that is
contained in an instance of Panels, it saves OK but on loading back in I
get this released twice/corruption error. The data structure is defined
in a header file from a different library (where is implementation is).
The header file for that DS contains the serialisation code, and a CPP
file in this other library contains a BOOST_SERIALIZATION_EXPORT_GUID
statement. Therefor this GUID is NOT available to the first library
until link time. I do wonder if this is where the problem arises. I
would like to keep the serialisation intrusive, in the appropriate
headers in the appropriate library rather than have to move to a
different location.

Now that I have described the DS in more detail, I can also add another
problem. Depending on which bits I attempt to serialise, on loading I
keep getting bus errors at various points, depending on which parts of
the DS I try to serialise. The save appears to work fine - I have
enclosed a dump of the saved DS.

I hope someone has some idea of what's going on, because I have been
staring at this all day to no avail.

Regards

James

Dump :::: Sorry about wrapping.....Is there any way I can reduce the
number of spaces output for indentation???

<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<!DOCTYPE boost_serialization>
<boost_serialization signature="serialization::archive" version="3">
<Message class_id="0" tracking_level="0" version="0">
        <Name>Message1</Name>
        <Filename class_id="1" tracking_level="0" version="0">
                <path>/home/jhughes/msg.xml</path>
        </Filename>
        <PanelList class_id="2" tracking_level="0" version="0">
                <count>1</count>
                <item class_id="3" tracking_level="0" version="1">
                        <px class_id="4" class_name="TextPanel"
tracking_level="1" version="0" object_id="_0">
                                <LCPanel class_id="5" tracking_level="0"
version="0">
                                        <RasterHeight>7</RasterHeight>
                                        <PanelWidth>0</PanelWidth>
                                        <PanelHeight>7</PanelHeight>
                                </LCPanel>
                                <TextPanelFields class_id="6"
tracking_level="1" version="0" object_id="_1">
                                        <LCPanelFields class_id="7"
tracking_level="1" version="0" object_id="_2">
                                                <LCPanelFieldsFacade
class_id="8" tracking_level="1" version="0"
object_id="_3"></LCPanelFieldsFacade>
                                                <Fields class_id="9"
tracking_level="0" version="0">
                                                        <count>1</count>
                                                        <item
class_id="10" tracking_level="0" version="1">
                                                                <px
class_id="12" class_name="StaticTextField" tracking_level="1"
version="0" object_id="_4">
 
<LCTextField class_id="13" tracking_level="1" version="0"
object_id="_5">
 
<LCField class_id="11" tracking_level="1" version="0"
object_id="_6"></LCField>
 
<Text></Text>
 
</LCTextField>
                                                                </px>
                                                        </item>
                                                </Fields>
                                        </LCPanelFields>
                                </TextPanelFields>
                        </px>
                </item>
        </PanelList>
</Message>
</boost_serialization>

> Robert Ramey
> 
> Hughes, James wrote:
> > Hello all,
> >
> > I am a bit stumped by a problem I am seeing with serialisation, and 
> > wondered whether it may be due to the way I sue some libraries.
> >
> > I have two libraries, one which contains the main code that uses 
> > serialisation, and another which contains some small 
> classes used by 
> > the main code.
> >
> > The main code serialises a tree like data structure containing some 
> > shared pointers, each node of the 'tree' contains member 
> data, and its 
> > one of these members that is causing a double free or 
> corruption error 
> > on loading. This particular member is a structure from the other 
> > library. It contains a serialisation template in the class header 
> > which appears to save correctly - the XML output all 
> appears correct.
> > However on loading the double free error occurs.
> >
> > I cannot see anything wrong with the code at all. The only 
> thing I can 
> > think of is that there are limitations in doing 
> serialisation across 
> > the library boundary. Perhaps I end up with two 
> instantiations of the 
> > template for serialisation? One in the main library, and one in the 
> > small library? Am I clutching at straws? DO I somehow have to force 
> > the instantiation of the serialisation for the class in the sub 
> > library to be in there, rather than being created again in the main 
> > library?
> >
> > Any thoughts?
> >
> > James
> >
> > This message (including any attachments) contains 
> confidential and/or 
> > proprietary information intended only for the addressee.
> > Any unauthorized disclosure, copying, distribution or 
> reliance on the 
> > contents of this information is strictly prohibited and may 
> constitute 
> > a violation of law.  If you are not the intended recipient, please 
> > notify the sender immediately by responding to this e-mail, 
> and delete 
> > the message from your system.  If you have any questions about this 
> > e-mail please notify the sender immediately.
> 
> 
> 
> _______________________________________________
> Boost-users mailing list
> Boost-users_at_[hidden]
> http://lists.boost.org/mailman/listinfo.cgi/boost-users
> 

This message (including any attachments) contains confidential 
and/or proprietary information intended only for the addressee.  
Any unauthorized disclosure, copying, distribution or reliance on 
the contents of this information is strictly prohibited and may 
constitute a violation of law.  If you are not the intended 
recipient, please notify the sender immediately by responding to 
this e-mail, and delete the message from your system.  If you 
have any questions about this e-mail please notify the sender 
immediately.