Re: [Boost-users] Boost serialization : Stream error exception

From: Bill Lear (rael_at_[hidden])
Date: 2006-08-24 12:35:37

On Thursday, August 24, 2006 at 07:33:01 (-0700) smith smithson writes:
>I'm trying to use boost serialization to
>serialize/deserialize data to and from a mmap'd file.
>I have my own ostream/istream classes that essentially
>read/write bytes from a mmap'd file. The process works
>fine except on some rare occasions (With different
>objects/number of objects), in which case boost throws
>a "stream error" exception. Any ideas what could
>trigger this? A search of the Boost archives indicated
>other people had the same problem, where the solution
>was "use binary mode when you open the file"... but
>I'm not using a file on disk, I'm using a mmap'd file.
>(As a side note, the mmap file is large enough to hold
>all my data and does not need to be expanded or
>remmap'd etc) 
>
>The OS i'm using is Linux. 
>
>Thanks for any suggestions...

I don't use my own mmap classes, I use boost's, under Linux:

        boost::iostreams::stream<boost::iostreams::mapped_file_source>
            ifs(filename);

        if (compress) {
            boost::iostreams::filtering_istream in;
            in.push(boost::iostreams::zlib_decompressor());
            in.push(ifs);

            Archive ia(in);
            ia >> BOOST_SERIALIZATION_NVP(obj);
        } else {
            Archive ia(ifs);
            ia >> BOOST_SERIALIZATION_NVP(obj);
        }

And it works fine.  I do not use it for the write side, as I don't
know in advance how large the object will be, etc.  I would suggest
a few runs with standard streams to see if you still get the error.
Boost is independent (should be) of the stream used, so that would
be a good test.

Bill