lib/tls.h

   1 /* Thread-local storage in multithreaded situations.
   2    Copyright (C) 2005 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify it
   5    under the terms of the GNU Library General Public License as published
   6    by the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with this program; if not, write to the Free Software
  16    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  17    USA.  */
  18
  19 /* Written by Bruno Haible <bruno@clisp.org>, 2005.  */
  20
  21 /* This file contains thread-local storage primitives for use with a given
  22    thread library.  It does not contain primitives for creating threads or
  23    for other multithreading primitives.
  24
  25    Type:                      gl_tls_key_t
  26    Initialization:            gl_tls_key_init (name, destructor);
  27    Getting per-thread value:  gl_tls_get (name)
  28    Setting per-thread value:  gl_tls_set (name, pointer);
  29    De-initialization:         gl_tls_key_destroy (name);
  30
  31    A per-thread value is of type 'void *'.
  32
  33    A destructor is a function pointer of type 'void (*) (void *)', called
  34    when a thread exits, and taking the last per-thread value as argument.  It
  35    is unspecified whether the destructor function is called when the last
  36    per-thread value is NULL.  On some platforms, the destructor function is
  37    not called at all.
  38 */
  39
  40
  41 /* ========================================================================= */
  42
  43 #if USE_POSIX_THREADS
  44
  45 /* Use the POSIX threads library.  */
  46
  47 # include <pthread.h>
  48 # include <stdlib.h>
  49
  50 # if PTHREAD_IN_USE_DETECTION_HARD
  51
  52 /* The pthread_in_use() detection needs to be done at runtime.  */
  53 #  define pthread_in_use() \
  54      glthread_in_use ()
  55 extern int glthread_in_use (void);
  56
  57 # endif
  58
  59 # if USE_POSIX_THREADS_WEAK
  60
  61 /* Use weak references to the POSIX threads library.  */
  62
  63 #  pragma weak pthread_key_create
  64 #  pragma weak pthread_getspecific
  65 #  pragma weak pthread_setspecific
  66 #  pragma weak pthread_key_delete
  67 #  ifndef pthread_self
  68 #   pragma weak pthread_self
  69 #  endif
  70
  71 #  if !PTHREAD_IN_USE_DETECTION_HARD
  72 #   pragma weak pthread_cancel
  73 #   define pthread_in_use() (pthread_cancel != NULL)
  74 #  endif
  75
  76 # else
  77
  78 #  if !PTHREAD_IN_USE_DETECTION_HARD
  79 #   define pthread_in_use() 1
  80 #  endif
  81
  82 # endif
  83
  84 /* ------------------------- gl_tls_key_t datatype ------------------------- */
  85
  86 typedef union
  87         {
  88           void *singlethread_value;
  89           pthread_key_t key;
  90         }
  91         gl_tls_key_t;
  92 # define gl_tls_key_init(NAME, DESTRUCTOR) \
  93     if (pthread_in_use ())                                     \
  94       {                                                        \
  95         if (pthread_key_create (&(NAME).key, DESTRUCTOR) != 0) \
  96           abort ();                                            \
  97       }                                                        \
  98     else                                                       \
  99       (NAME).singlethread_value = NULL
 100 # define gl_tls_get(NAME) \
 101     (pthread_in_use ()                  \
 102      ? pthread_getspecific ((NAME).key) \
 103      : (NAME).singlethread_value)
 104 # define gl_tls_set(NAME, POINTER) \
 105     if (pthread_in_use ())                                    \
 106       {                                                       \
 107         if (pthread_setspecific ((NAME).key, (POINTER)) != 0) \
 108           abort ();                                           \
 109       }                                                       \
 110     else                                                      \
 111       (NAME).singlethread_value = (POINTER)
 112 # define gl_tls_key_destroy(NAME) \
 113     if (pthread_in_use () && pthread_key_delete ((NAME).key) != 0) \
 114       abort ()
 115
 116 #endif
 117
 118 /* ========================================================================= */
 119
 120 #if USE_PTH_THREADS
 121
 122 /* Use the GNU Pth threads library.  */
 123
 124 # include <pth.h>
 125 # include <stdlib.h>
 126
 127 # if USE_PTH_THREADS_WEAK
 128
 129 /* Use weak references to the GNU Pth threads library.  */
 130
 131 #  pragma weak pth_key_create
 132 #  pragma weak pth_key_getdata
 133 #  pragma weak pth_key_setdata
 134 #  pragma weak pth_key_delete
 135
 136 #  pragma weak pth_cancel
 137 #  define pth_in_use() (pth_cancel != NULL)
 138
 139 # else
 140
 141 #  define pth_in_use() 1
 142
 143 # endif
 144
 145 /* ------------------------- gl_tls_key_t datatype ------------------------- */
 146
 147 typedef union
 148         {
 149           void *singlethread_value;
 150           pth_key_t key;
 151         }
 152         gl_tls_key_t;
 153 # define gl_tls_key_init(NAME, DESTRUCTOR) \
 154     if (pth_in_use ())                                 \
 155       {                                                \
 156         if (!pth_key_create (&(NAME).key, DESTRUCTOR)) \
 157           abort ();                                    \
 158       }                                                \
 159     else                                               \
 160       (NAME).singlethread_value = NULL
 161 # define gl_tls_get(NAME) \
 162     (pth_in_use ()                  \
 163      ? pth_key_getdata ((NAME).key) \
 164      : (NAME).singlethread_value)
 165 # define gl_tls_set(NAME, POINTER) \
 166     if (pth_in_use ())                                \
 167       {                                               \
 168         if (!pth_key_setdata ((NAME).key, (POINTER))) \
 169           abort ();                                   \
 170       }                                               \
 171     else                                              \
 172       (NAME).singlethread_value = (POINTER)
 173 # define gl_tls_key_destroy(NAME) \
 174     if (pth_in_use () && !pth_key_delete ((NAME).key)) \
 175       abort ()
 176
 177 #endif
 178
 179 /* ========================================================================= */
 180
 181 #if USE_SOLARIS_THREADS
 182
 183 /* Use the old Solaris threads library.  */
 184
 185 # include <thread.h>
 186 # include <stdlib.h>
 187
 188 # if USE_SOLARIS_THREADS_WEAK
 189
 190 /* Use weak references to the old Solaris threads library.  */
 191
 192 #  pragma weak thr_keycreate
 193 #  pragma weak thr_getspecific
 194 #  pragma weak thr_setspecific
 195
 196 #  pragma weak thr_suspend
 197 #  define thread_in_use() (thr_suspend != NULL)
 198
 199 # else
 200
 201 #  define thread_in_use() 1
 202
 203 # endif
 204
 205 /* ------------------------- gl_tls_key_t datatype ------------------------- */
 206
 207 typedef union
 208         {
 209           void *singlethread_value;
 210           thread_key_t key;
 211         }
 212         gl_tls_key_t;
 213 # define gl_tls_key_init(NAME, DESTRUCTOR) \
 214     if (thread_in_use ())                                 \
 215       {                                                   \
 216         if (thr_keycreate (&(NAME).key, DESTRUCTOR) != 0) \
 217           abort ();                                       \
 218       }                                                   \
 219     else                                                  \
 220       (NAME).singlethread_value = NULL
 221 # define gl_tls_get(NAME) \
 222     (thread_in_use ()                \
 223      ? glthread_tls_get ((NAME).key) \
 224      : (NAME).singlethread_value)
 225 extern void *glthread_tls_get (thread_key_t key);
 226 # define gl_tls_set(NAME, POINTER) \
 227     if (thread_in_use ())                                 \
 228       {                                                   \
 229         if (thr_setspecific ((NAME).key, (POINTER)) != 0) \
 230           abort ();                                       \
 231       }                                                   \
 232     else                                                  \
 233       (NAME).singlethread_value = (POINTER)
 234 # define gl_tls_key_destroy(NAME) \
 235     /* Unsupported.  */ \
 236     (void)0
 237
 238 #endif
 239
 240 /* ========================================================================= */
 241
 242 #if USE_WIN32_THREADS
 243
 244 # include <windows.h>
 245
 246 /* ------------------------- gl_tls_key_t datatype ------------------------- */
 247
 248 typedef DWORD gl_tls_key_t;
 249 # define gl_tls_key_init(NAME, DESTRUCTOR) \
 250     /* The destructor is unsupported.  */    \
 251     if (((NAME) = TlsAlloc ()) == (DWORD)-1) \
 252       abort ()
 253 # define gl_tls_get(NAME) \
 254     TlsGetValue (NAME)
 255 # define gl_tls_set(NAME, POINTER) \
 256     if (!TlsSetValue (NAME, POINTER)) \
 257       abort ()
 258 # define gl_tls_key_destroy(NAME) \
 259     if (!TlsFree (NAME)) \
 260       abort ()
 261
 262 #endif
 263
 264 /* ========================================================================= */
 265
 266 #if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_SOLARIS_THREADS || USE_WIN32_THREADS)
 267
 268 /* Provide dummy implementation if threads are not supported.  */
 269
 270 /* ------------------------- gl_tls_key_t datatype ------------------------- */
 271
 272 typedef struct
 273         {
 274           void *singlethread_value;
 275         }
 276         gl_tls_key_t;
 277 # define gl_tls_key_init(NAME, DESTRUCTOR) \
 278     (NAME).singlethread_value = NULL
 279 # define gl_tls_get(NAME) \
 280     (NAME).singlethread_value
 281 # define gl_tls_set(NAME, POINTER) \
 282     (NAME).singlethread_value = (POINTER)
 283 # define gl_tls_key_destroy(NAME) \
 284     (void)0
 285
 286 #endif