Hello Stuart, hello Robert, since a while I am using a specialised version of boost::archive::details::heap_allocator<> for deserialization of my objects. The reason I do this is preformance: I have a bunch of small objects that I read in one by one, use it and discard it. The custom allocator simply tells the serialization library to place it always at the same address. This works fine using boost 1.33.1. Regards, -- Christian Pfligersdorffer Software Engineering http://www.eos.info Robert Ramey on Sunday, June 22, 2008 2:37 AM:

which allocator are we talking about?

If one use STL containers, the allocators associated with the container type are used so if specify particular allocators for your own collections, those allocators will be used when data is recovered and rebuilt.

The library uses a couple of STL containers for tracking objects and class ids. The currently would not be accessible. No one has ever asked about this before. We are only now starting to profile serialization performance tests so we will know for the first time ever if there is anything to be gained in this area. Its possible that a future version might permit one to specify an allocator when the archive is instantiated - but for now, usage of the standard allocator is built in.

Robert Ramey

Stuart Reynolds wrote:

...

I'm interested in using Boost's serialization for a middleware library that receives allocators from the application that uses it. Is it possible to specify which allocators for the serialization library to uses?

I can't override global new/delete -- the application reserves the right to do this.

Cheers, - Stuart

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-- Christian Pfligersdorffer Software Engineering http://www.eos.info

Stuart Reynolds wrote:

For our own interrnal uses of STL we provide our own STL allocators, which resolve to malloc/free callback functions provided to our library through its public interface. However, without recompiling the source to the serialization library, I don't think I can make the library use these allocators. (Right?)

Right

Generally speaking, because I work on embedded systems, we need to monitor and control memory usage very carefully. We can't have any dependencies on libraries that make naked calls to malloc/free or global new/delete since on many of the platforms we target the OS does not provide a heap, or must use a particular one of manys available heaps each of which may reference physically different memory.

If all allocations went to boost::archive::details::heap_allocator<>,

they don't. heap allocator is used only for resurrection objects saved through pointers.

So, for now it looks like I need to modify the the serialization library for boost and incorporate it into my build system. (Right?)

Right Robert Ramey

I can't override the global allocators because application code reserves the right do that. I'm making a library. If a library overrides new and delete, the application that links against it cannot (multiply defined linker references will result as the error). Often, in embedded applications, it is not safe to ever call the global allocator -- allocations must be routed to specific heaps for particular purposes. For example, if you have a solid state hard drive, portions of it may be reserved to function as a heap. You want certain pieces of memory to allocated there (where accesses are slow and made infrequently), and certain other pieces to be allocated in the main RAM (where accesses are frequent and fast.) Or, as another example, if you use a library you may want to be able to profile the memory used by it (for example to provide high-speed pools for frequent allocation sizes, or to see how close you are to running up against the limits of the memory available in a particular heap). This is only really straightforward to do if the library is provided allocators through which all its allocations are made. - Stuart On Tue, Jun 24, 2008 at 11:12 AM, Emil Dotchevski wrote:

On Mon, Jun 23, 2008 at 10:34 AM, Stuart Reynolds wrote:

...

So, for now it looks like I need to modify the the serialization library for boost and incorporate it into my build system. (Right?)

Can't you override global new/delete? This will catch all STL allocations as well as anything from Boost.

Emil Dotchevski Reverge Studios, Inc. http://www.revergestudios.com/reblog/index.php?n=ReCode _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users