Re: [dbus-cplusplus-devel] Ref counter system not thread safe?

[P. D. <sh...@gm...>]

Hi Nicolas,

On Thu, Nov 20, 2008 at 10:22 AM, Nicolas Parcollet
<npa...@wy...> wrote:
> I everybody. I m occasionnaly working with DBus C++ and pushing it to its
> highest limits.
>
that's very much needed and very appreciated, thanks

> The following traces show a failure condition that happens sometime when I ran
> a very long test making heavy use of DBus C++. The program contains one
> adaptor and several proxies. It is a threaded environment.
>
> Program received signal SIGBUS, Bus error.
> [Switching to thread 1546]
> 0x004178c8 in DBus::RefCnt::noref (this=0x45c4a8)
> at /usr/targets/081119-1.1.13-debug/root/usr/include/dbus-c++-1/dbus-c++/util.h:72
> 72                      return (*__ref) == 0;
> (gdb)
> Continuing.
> Program terminated with signal SIGBUS, Bus error.
> The program no longer exists.
> (gdb)
>
> It seems the the ref counter is broken. This is probably due to a race
> condition between unref/noref but it is still quite blur for me. From what i
> saw the ref counting sytem is not thread safe. Any idea how this could be
> solved?
>
off the top of my head, the reference counting variable should be
declared 'volatile', after that the compiler should be smart enough to
use atomic intrinsics when incrementing/decrementing the counter, i'll
change that now

> I am working with version 0.5 (AC_INIT([libdbus-c++], 0.5.0,
> [sh...@gm...])). Since the ChangeLog is not up to date i can't figure
> out if something like that was fixed or not, so I need your help.
>
due to lack of active maintainership (blame me), there has never been
an official release, 0.5.0 could refer to any git snapshot taken in
the past months, I recommend using the latest source from freedesktop
git clone git://anongit.freedesktop.org/git/dbus/dbus-c++/

> Thanks a lot.
>
> Nico P.
thank you,
Paolo