Hi, Giuseppe Corbelli <giuseppe.corbe...@copanitalia.com> wrote on 08.04.2013 11:29:10:
> On 03/04/2013 10:08, Holger Joukl wrote: > > Hi Giuseppe, > > > > thanks for answering and sorry for the delayed response. Easter > > holidays :-) > > To punish you here's another late reply. ;-) > >>> However, on Linux compiled with GCC, if an exception gets raised in the > >>> Python callback the > >>> program segfaults. Obviously the C part of the vendor library has not > >>> been compiled with > >>> (GCC-) exception support for Linux. > >>> > >>> Unfortunately this isn't under my control and the library provider > >>> seems not to be willing > >>> to make the library robust against exceptions in user callback code. > >>> > >>> So I need to keep the Boost C++ exception that "signals" the Python > >>> exception from passing > >>> through the C parts. > >> > >> How does the library handle callbacks? An event loop in a separate > >> thread? Do you have to explicitly call some blocking function to run the > >> event loop? > > > > Yes. There's a separate thread that schedules events to a queue being > > dispatch in the main loop, in the main thread. > > And yes, there's a blocking call to a dispatch method with the possibility > > of a timeout or alternatively a non-blocking poll call (we make > sure to properly > > release& reacquire the Python GIL during blocking). > > > >> If it's a C lib likely the callbacks are just function pointers. Being > >> called inside a C object I'd say you assumption is correct: no C++ > >> exceptions to be > >> raised inside callbacks (the lib is gcc-compiled, it has no knowledge of > >> exceptions). > > > > Correct, the callbacks are function pointers from the C libs point of view. > > > >> If you could recompile with g++ the exception would raise from the > >> event loop, > >> unless catched while calling the callback function pointer. > > > > While I do have the C++ sources (to be able to recompile for different C++ > > compilers) > > I don't have the C sources so I unfortunately I can't recompile the C-lib > > parts with > > exceptions support. > > Sidenote: For Oracle/Sun Solaris Studio compilers this isn't a problem as > > you basically can't > > and don't need to switch the exception support of the compiler for mixing C > > and C++ code > > (http://www.oracle.com/technetwork/articles/servers-storage-dev/ > mixingcandcpluspluscode-305840.html) > > I have found a couple of references. > http://gcc.gnu.org/onlinedocs/gcc/Link-Options.html (see static-libgcc) > http://gcc.gnu.org/wiki/Visibility Thanks, I'll need to look into these. > The proprietary lib is shared, right? linked to? shared? static? Shared C lib, we compile a shared C++ lib linked to the C lib from the vendor C++ sources, which we shared-link the (shared) Boost.Python wrapper to. > >> Sidenote: how does the C++ exception mechanism work under the hood? What > >> happens if it's called inside a C compiled function? > > > > Not sure if I understand your question correctly, but: > > - Solaris Studio compilers: An exception raised in a C++ compiled function > > that got called > > from a C compiled function called from a C++ main will properly propagate > > to the main caller > > - GCC: An exception raised in a C++ compiled function that got called > > from a C compiled function called from a C++ main will > > - segfault if the C compiled function hasn't been compiled withexception > > support (-fexceptions) > > - properly propagate to the main caller if the C compiled function has > > been compiled with exception support > > Well, I was thinking about ASM level :-) No clue whatsoever. Regards Holger Landesbank Baden-Wuerttemberg Anstalt des oeffentlichen Rechts Hauptsitze: Stuttgart, Karlsruhe, Mannheim, Mainz HRA 12704 Amtsgericht Stuttgart _______________________________________________ Cplusplus-sig mailing list Cplusplus-sig@python.org http://mail.python.org/mailman/listinfo/cplusplus-sig
