Re: Thread local storage

[Ken Raeburn]

On Oct 4, 2009, at 10:03, Ludovic Courtès wrote:
> I looked again at how/whether we could improve thread-local storage
> access, using compiler support (the ‘__thread’ storage class).

For the most part I think the wip-tls changes look good.  In the non- 
__thread case, though, you've eliminated the pthread_key_create call,  
making it not work on my Mac.  (In addition to the still-present  
i18n.c compilation problem.)  Assuming that __thread variables are by  
default initialized to 0 (or NULL or whatever we specify), we also  
don't need anything in init_thread_key when we have __thread support.   
I suggest something like the patch below.  I haven't tried it on a  
system *with* the __thread support though.

Ken

--- a/libguile/threads.c
+++ b/libguile/threads.c
@@ -538,11 +538,13 @@ on_thread_exit (void *v)

 static scm_i_pthread_once_t init_thread_key_once =  
SCM_I_PTHREAD_ONCE_INIT;

+#ifndef SCM_HAVE_THREAD_STORAGE_CLASS
 static void
 init_thread_key (void)
 {
-  SET_CURRENT_THREAD (NULL);
+  scm_i_pthread_key_create (&scm_i_thread_key, NULL);
 }
+#endif

 /* Perform any initializations necessary to bring the current thread
    into guile mode, initializing Guile itself, if necessary.
@@ -561,7 +563,9 @@ scm_i_init_thread_for_guile (SCM_STACKITEM *base,  
SCM parent)
 {
   scm_i_thread *t;

+#ifndef SCM_HAVE_THREAD_STORAGE_CLASS
   scm_i_pthread_once (&init_thread_key_once, init_thread_key);
+#endif

   t = SCM_I_CURRENT_THREAD;
   if (t == NULL)