Re: [Boost-users] Using boost::serialization in real-time without allocating memory

Subject: Re: [Boost-users] Using boost::serialization in real-time without allocating memory
From: Peter Soetens (peter.soetens_at_[hidden])
Date: 2009-09-17 10:33:16

On Thu, Sep 17, 2009 at 14:11, Stefan Strasser <strasser_at_[hidden]> wrote:
> Am Thursday 17 September 2009 15:10:11 schrieb Peter Soetens:
>> Hi,
>>
>> I'm trying to find out if boost::serialization can be used in
>> real-time applications to stream data into a fifo to another process.
>> It is mandatory that no memory allocations happen during the
>> serialization. I tested this with a std::vector<double> of 10 elements
>> in combination with the boost::iostreams library.
>>
>
>
>>
>> I'm guessing that the 2 allocations in the serialisation path come
>> from a temporay std::string object, when writing the
>> 'serialization::archive' string into the archive.
>
> you can supress that by passing no_header to the archive.
> however, that won't solve the problem.
> the archives internally use STL containers for type registration and object
> tracking (and maybe other things, I don't know all the details).
> so even if you can avoid those 2 allocations for a vector<double>, there is no
> way to avoid allocations in the general case, for any type, until
> boost.serialization accepts a custom allocator, or a traits class that
> handles the registration stuff.
> that code is statically linked right now so if you wanted to implement that
> you'd also have to refactor boost.serialization.
>
> also note that one archive can only be used for one serialization process -
> I'm guessing one object in your case. if you serialize 2 objects into 1
> archive they can only be read in that order from the stream.
> so you'd have to take the allocations of archive construction into account,
> too.
>
> the only simple way I see right now is using an own archive that doesn't
> derive from boost.serialization's common_?archive. but that comes close to an
> implementing an new serialization system.

Thanks for the detailed answer. I missed the point that an archive
could serialize only once. This is indeed incompatible with my design
requirements. By design, our serialisation requirements are  PODs and
std::vector<POD> since we only exchange 'pure' data structures (and
use std::vector in a limited way, almost similar to array<POD>). Much
of the features in boost::serialization aren't required for us.

I might do what you suggest or look for another serialization solution.

Peter