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glibc  2.9
pthread_key_create.c
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00001 /* Copyright (C) 2002, 2003, 2006 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <errno.h>
00021 #include "pthreadP.h"
00022 #include <atomic.h>
00023 
00024 
00025 int
00026 __pthread_key_create (key, destr)
00027      pthread_key_t *key;
00028      void (*destr) (void *);
00029 {
00030   /* Find a slot in __pthread_kyes which is unused.  */
00031   for (size_t cnt = 0; cnt < PTHREAD_KEYS_MAX; ++cnt)
00032     {
00033       uintptr_t seq = __pthread_keys[cnt].seq;
00034 
00035       if (KEY_UNUSED (seq) && KEY_USABLE (seq)
00036          /* We found an unused slot.  Try to allocate it.  */
00037          && ! atomic_compare_and_exchange_bool_acq (&__pthread_keys[cnt].seq,
00038                                                seq + 1, seq))
00039        {
00040          /* Remember the destructor.  */
00041          __pthread_keys[cnt].destr = destr;
00042 
00043          /* Return the key to the caller.  */
00044          *key = cnt;
00045 
00046          /* The call succeeded.  */
00047          return 0;
00048        }
00049     }
00050 
00051   return EAGAIN;
00052 }
00053 strong_alias (__pthread_key_create, pthread_key_create)
00054 strong_alias (__pthread_key_create, __pthread_key_create_internal)