On Friday January 27 2012 10:11:07 Joachim Berdal Haga wrote: > On 26 January 2012 22:40, Anders Logg <l...@simula.no> wrote: > > On Wed, Jan 25, 2012 at 03:21:12PM +0100, Joachim Berdal Haga wrote: > >> This seems to be because of the instantiation of boost::shared_arrays. > >> The ownership of the array data is not transferred (the data will be > >> deleted by the caller of evaluate()), so this does not really add any > >> safety. > >> > >> I don't have a complete picture of how Array<> is used, does the > >> Python layer rely on the shared semantics (in other places)? If not, > >> it might be better to make them non-shared and create copies for use > >> in Python where needed. > > > > Would it help if we do this: > > > > 1. Make GenericFunction::evaluate an inline function that just calls > > a new version of GenericFunction::eval. > > > > 2. The new version of GenericFunction::eval has the same > > implementation as the current evaluate() function. > > > > The result would be that we get two eval() functions, one with plain > > pointers and one with Array(). A C++ user (and the JIT-compiled > > expressions) would use the plain pointer version, while the Array > > version gets wrapped for Python subclassing (where I assume the extra > > cost will not make a difference). > > I'm unsure about the details of how much of the call tree would have > to get dual signatures, but I guess it would be possible. However, it > doesn't add any safety for the Python layer because the data will be > deleted by the C++ layer even if Python holds a (shared) reference. > And as Johan says, the different interfaces are a maintenance problem. > > In my opinion, it would be best to make Array<T> a simple T*/len > container, and either subclass it or add a flag to decide if it owns > the data. Then, for sharing, use shared_ptr<Array>, and add some > safeguards that the shared_ptr actually holds an owned array.
Are you looking into this Joachim? Maybe you can try to implement a new storage pattern, and check the performance of that? Johan > -j. > > _______________________________________________ > Mailing list: https://launchpad.net/~dolfin > Post to : dolfin@lists.launchpad.net > Unsubscribe : https://launchpad.net/~dolfin > More help : https://help.launchpad.net/ListHelp _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : dolfin@lists.launchpad.net Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
