Threading libsmbclient - a proposal.

[Jeremy Allison]

On Wed, Apr 08, 2009 at 12:41:23AM +0000, simo wrote:
> 
> No, you have barriers in the include:
> #ifndef _smb_threads_h_
> #define _smb_threads_h_
> 
> So multiple inclusion shouldn't really happen.

Multiple includes in the same module can't happen,
but inclusion in *different* modules can.

> I am trying to understand in which case this would make a difference.

Imagine we have module a.c which #define SMB_USE_THREADS
and includes smb_threads.h, and then module b.c which
also (by accident in an include header) also defines
SMB_USE_THREADS and includes smb_threads.h. In your
methed we get duplicate definitions of the sample
functions.

With the instantiation macro method you can
include "smb_threads.h" as many times as you
like but the implementation only gets defined
in the module where you have :

SMB_THREADS_DEF_PTHREAD_IMPLEMENTATION(var);

That's defined in a .c file, not in or before 
a header, so it's much easier for a user of 
the library to control and remember.

Jeremy.