[Saga-devel] saga SVN commit 3324: /trunk/saga/saga/adaptors/utils/

['Andre Merzky']

Quoting [Hartmut Kaiser] (Jan 17 2009):
> 
> > User: amerzky
> > Date: 2009/01/17 10:37 AM
> > 
> > Modified:
> >  /trunk/saga/saga/adaptors/utils/
> >   utils.cpp
> > 
> > Log:
> >  don't optimize - C++ static initialization and threads  don't go
> >  along very well it seems
> 
> Thread safe initializations of statics is complex in any language. It's
> definitely not a C++ problem. C suffers from the same subtleties. All global
> data needs to be protected in multithreaded environments. And initialization
> of globals in multi threaded environments is tricky to say the best.

Don't take that personally :-)  I am not attacking C++ (this
time), just stating what you told me.  If we'd do C, I would
commented about C :-)

Take it easy..., Andre.


> But it is possible, you just have to know how to make it happen. Joao wrote
> a nice helper class based on Boosts init_once facility for doing exactly
> this
> (saga/external/boost/spirit/boost/spirit/core/non_terminal/impl/static.hpp).
> 
> Regards Hartmut
> 
> BTW: you don't need the 'bool have_localhosts' anymore. As every invocation
> of this functions get's its own copy of the vector anyways.
> 
> 
> >  A
> > 
> > File Changes:
> > 
> > Directory: /trunk/saga/saga/adaptors/utils/
> > ===========================================
> > 
> > File [modified]: utils.cpp
> > Delta lines: +2 -6
> > ===================================================================
> > --- trunk/saga/saga/adaptors/utils/utils.cpp	2009-01-17 16:08:08 UTC
> > (rev 3323)
> > +++ trunk/saga/saga/adaptors/utils/utils.cpp	2009-01-17 16:37:19 UTC
> > (rev 3324)
> > @@ -177,14 +177,10 @@
> >        // a '.' in its name.
> >        std::vector <std::string> get_localhosts (void)
> >        {
> > -        // scoped lock, to protect the static variables
> > -        boost::recursive_mutex              mtx_;
> > -        boost::recursive_mutex::scoped_lock lock (mtx_);
> > -
> >          // optimization: build this list only once - we assume that
> > host names
> >          // do not change during the runtime of the SAGA application.
> > -        static std::vector <std::string> localhosts;
> > -        static bool have_localhosts = false;
> > +        std::vector <std::string> localhosts;
> > +        bool have_localhosts = false;
> > 
> > 
> >          std::set    <std::string> initial_names;
> > 
> > _______________________________________________
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> > saga-devel at cct.lsu.edu
> > https://mail.cct.lsu.edu/mailman/listinfo/saga-devel
> 



-- 
Nothing is ever easy.