On Fri, Jan 9, 2009 at 5:29 PM, Roy Stogner <royst...@ices.utexas.edu> wrote: > > To enable a bit more modularity, automatic multithreading, etc., as > I've mentioned before, I'd like to change the DiffSystem/FEMSystem > interface. > > Right now, the library has methods like: > > DiffSystem::element_residual() > > Which, overridden by the user, can access DiffSystem member variables > with state information (like time) and solution information (like > elem_solution) to fill residual information (like elem_residual and > elem_jacobian). This is general enough that we could write structured > finite difference methods on top of it if we wanted to. > > But for now, we all use the only important subclass, FEMSystem, which > adds more member variables with FEM (or if you wanted, cell-centered > FVM) specific information - the FE, Quadrature rule, and Elem classes, > for example. > > > That's fine, but now I'd like to move all those member variables into > a method argument: > > DiffSystem::element_residual(DiffContext&) > > So that, in particular, different threads can work on different > DiffContext objects at the same time without creating multiple > systems. We'd then move FEMSystem-specific member variables into a > FEMContext subclass of DiffContext, and users whose FEMSystem > subclasses add new member variables would add them to > "CahnHilliardContext" or some such. > > > People with more C++ intuition than I are already seeing the problem > that arises? > > If BSys subclasses ASys, and BCon subclasses ACon, then > BSys::method(BCon&) is not an implementation of ASys::method(ACon&), > and for our purposes BSys::method() won't work with just an ACon&. > Worse: if ASys is FEMSystem and BSys is UserInventedSystem, then > there's no way for ASys to even create a BCon to pass in.
How low-level do users of BSys::method() need to get? I mean, is it imperative that they be able to provide the context, or is the library going to be smart enough to do it for them? When you first described the multithreading idea, I thought OK cool, I still just call element_residual() and then DiffSystem/FEMSystem worries about creating the separate data for separate threads, etc etc. In derived systems classes, the user might be required to implement a build_context() function, callable by the base class. The base class then manages all the contexts while the threads operate on them and cleans them up when the assembly is finished. But, I suspect I am just not understanding the bigger picture of how you want to multithread DiffSystem, so maybe I could use a little enlightenment on that point... -- John ------------------------------------------------------------------------------ Check out the new SourceForge.net Marketplace. It is the best place to buy or sell services for just about anything Open Source. http://p.sf.net/sfu/Xq1LFB _______________________________________________ Libmesh-devel mailing list Libmesh-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-devel
