sysdeps/htl/pt-key-create.c

   1 /* pthread_key_create.  Hurd version.
   2    Copyright (C) 2002-2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library;  if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <pthread.h>
  20 #include <stdlib.h>
  21 #include <assert.h>
  22
  23 #include <pt-internal.h>
  24 #include <pthreadP.h>
  25
  26 pthread_mutex_t __pthread_key_lock;
  27 pthread_once_t __pthread_key_once = PTHREAD_ONCE_INIT;
  28
  29 void (**__pthread_key_destructors) (void *arg);
  30 int __pthread_key_size;
  31 int __pthread_key_count;
  32 int __pthread_key_invalid_count;
  33
  34 int
  35 __pthread_key_create (pthread_key_t *key, void (*destructor) (void *))
  36 {
  37   /* Where to look for the next key slot.  */
  38   static int index;
  39
  40   __pthread_key_lock_ready ();
  41
  42   __pthread_mutex_lock (&__pthread_key_lock);
  43
  44 do_search:
  45   /* Use the search hint and try to find a free slot.  */
  46   for (; index < __pthread_key_count
  47        && __pthread_key_destructors[index] != PTHREAD_KEY_INVALID; index++)
  48     ;
  49
  50   /* See if we actually found a free element.  */
  51   if (index < __pthread_key_count)
  52     {
  53       assert (__pthread_key_destructors[index] == PTHREAD_KEY_INVALID);
  54       assert (__pthread_key_invalid_count > 0);
  55
  56       __pthread_key_invalid_count--;
  57       __pthread_key_destructors[index] = destructor;
  58       *key = index++;
  59
  60       __pthread_mutex_unlock (&__pthread_key_lock);
  61       return 0;
  62     }
  63
  64   assert (index == __pthread_key_count);
  65
  66   /* No space at the end.  */
  67   if (__pthread_key_size == __pthread_key_count)
  68     {
  69       /* See if it is worth looking for a free element.  */
  70       if (__pthread_key_invalid_count > 4
  71           && __pthread_key_invalid_count > __pthread_key_size / 8)
  72         {
  73           index = 0;
  74           goto do_search;
  75         }
  76
  77
  78       /* Resize the array.  */
  79       {
  80         void *t;
  81         int newsize;
  82
  83         if (__pthread_key_size == 0)
  84           newsize = 8;
  85         else
  86           newsize = __pthread_key_size * 2;
  87
  88         t = realloc (__pthread_key_destructors,
  89                      newsize * sizeof (*__pthread_key_destructors));
  90         if (t == NULL)
  91           {
  92             __pthread_mutex_unlock (&__pthread_key_lock);
  93             return ENOMEM;
  94           }
  95
  96         __pthread_key_size = newsize;
  97         __pthread_key_destructors = t;
  98       }
  99     }
 100
 101   __pthread_key_destructors[index] = destructor;
 102   *key = index;
 103
 104   index++;
 105   __pthread_key_count++;
 106
 107   __pthread_mutex_unlock (&__pthread_key_lock);
 108   return 0;
 109 }
 110 weak_alias (__pthread_key_create, pthread_key_create)
 111 hidden_def (__pthread_key_create)