[boost] Re: Windows MSVC thread exit handler for staticly linked Boost.Thread

From: Michael Glassford (glassfordm_at_[hidden])
Date: 2004-08-04 09:50:47

Roland wrote:

> On Wed, 04 Aug 2004 08:51:35 -0400 Michael Glassford <glassfordm_at_[hidden]> wrote:
> 
> 
>>Thanks, that did turn out to be the problem. It works fine, now, which 
>>is really good news.
> 
> 
> Fine.
> 
> I am currently trying to unify both versions (7 and 6). This also seems to be necessary,
> because Aarons code while paving the way yet has some minor problems (also on vc7):
> 
> While it is very interesting, that it is not mainCRTStartup which is the very first function
> of the executable that receives control, it may be problematic in our case.
> 
> I disbelieve that the threading library is prepared to be the very first in town (not
> even the EXE's entry point has been called yet!) and so I think it is much safer to 
> initalize everything after the runtime system is up, but before main.

Having experimented a bit and thought a bit, here's my take on how this 
could work:

1) Functions on_process_enter() and on_thread_enter() are unnecessary.

2) DllMain() and tls_callback() are needed only to call on_thread_exit().

3) Function at_thread_exit() schedules a tss cleanup task that needs to 
be run for a thread that uses tss. The first time it is executed it also 
calls:

     atexit(on_process_exit);
     atexit(on_thread_exit);

to schedule cleanup for the main thread before destructors of global 
objects are run and to schedule on_process_exit() (which calls TlsFree()).

4) In addition, to provide some cleanup support for compilers that don't 
yet have tls_callback() support, the thread class continues to call 
on_thread_exit() after the thread function exits for threads created by 
Boost.Threads.

This should make unification of the VC++ 7.1 and 6 versions easier; the 
only difference would be the startup code needed to call 
on_tls_prepare(), I believe.

Comments?

Also, I was wondering: has anyone tried this on VC++ 7.0?

Mike