Re: Clarification on Glib Thread-Safe Operation

[David Judkovics <djudkovi us ibm com>]

Owen Taylor wrote:

> On Thu, 2003-10-02 at 10:43, David Judkovics wrote:
>  
>
> > My project makes extensive use of what I believe are glibs non thread
> > related functions and types.  The wording of the documentation
> > concerning glib thread safe operation has left me confused.
> >
> > The documentation states glib must be compiled with the macro
> > 'G_THREADS_ENABLED' defined for thread safe operation.
> >
> > ..."This macro is defined, if GLib was compiled with thread support.
> > This does not necessarily mean, that there is a thread implementation
> > available, but the infrastructure is in place and once you provide a
> > thread implementation to g_thread_init(), GLib will be multi-thread
> > safe. It isn't and cannot be, if G_THREADS_ENABLED is not defined."...
> >    
>
> Not that all that G_THREAD_ENABLED being defined means is that
> you didn't pass
>
> --disable-threads
>
> to GLib's configure. Thread support is the default.

Owen,

Thats the corollary to my question, I think.  I have the default 
configuration for glib and 'G_THREADS_ENABLED' is not defined.  
If 'G_THREADS_ENABLED' is not defined does that mean '--disable-threads' 
was passed to configure?  

Or is the fact I'm using the default build mean this is a thread safe 
lib with or without 'G_THREADS_ENABLED' defined?

>  
>
> > Later on the documentation for 'g_thread_init()'  states, 
> >
> > ..."Before you use a thread related function in GLib, you should
> > initialize the thread system. This is done by calling g_thread_init().
> > Most of the time you will only have to call g_thread_init(NULL)."...
> >
> > To me thread safe operation and the use of glib thread related
> > functions are two distinct configuration issues.  The documentation
> > seems to mix them.
> > This is my confusion.
> >    
>
> How do you think GLib achieves thread-safe operation? It uses the
> glib thread related functions.
>
>  
>
> > My project is a library that uses the 'g_slist_' calls extensively,
> > calls I believe that are not thread related.  My project library must
> > be thread safe.  The version of glib we are using does not have
> > 'G_THREADS_ENABLED' defined.  Is my project library thread safe within
> > the context of its use of glib's 'g_slist_' calls?
> >    
>
>  
>
> > Put another way,  is glibs 'g_slist_' calls thread safe without
> > 'G_THREADS_ENABLED' defined?
> >    
>
> If you disabled thread support when compiling GLib, you
> cannot use it from a threaded application.
>
> Regards,
> 					Owen
>
>
>
>