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
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 3 of the License, or
   7    (at your option) 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
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Bruno Haible <bruno@clisp.org>, 2005.  */
  18
  19 /* This file contains thread-local storage primitives for use with a given
  20    thread library.  It does not contain primitives for creating threads or
  21    for other multithreading primitives.
  22
  23    Type:                      gl_tls_key_t
  24    Initialization:            gl_tls_key_init (name, destructor);
  25    Getting per-thread value:  gl_tls_get (name)
  26    Setting per-thread value:  gl_tls_set (name, pointer);
  27    De-initialization:         gl_tls_key_destroy (name);
  28
  29    A per-thread value is of type 'void *'.
  30
  31    A destructor is a function pointer of type 'void (*) (void *)', called
  32    when a thread exits, and taking the last per-thread value as argument.  It
  33    is unspecified whether the destructor function is called when the last
  34    per-thread value is NULL.  On some platforms, the destructor function is
  35    not called at all.
  36 */
  37
  38
  39 #ifndef _TLS_H
  40 #define _TLS_H
  41
  42 /* ========================================================================= */
  43
  44 #if USE_POSIX_THREADS
  45
  46 /* Use the POSIX threads library.  */
  47
  48 # include <pthread.h>
  49 # include <stdlib.h>
  50
  51 # if PTHREAD_IN_USE_DETECTION_HARD
  52
  53 /* The pthread_in_use() detection needs to be done at runtime.  */
  54 #  define pthread_in_use() \
  55      glthread_in_use ()
  56 extern int glthread_in_use (void);
  57
  58 # endif
  59
  60 # if USE_POSIX_THREADS_WEAK
  61
  62 /* Use weak references to the POSIX threads library.  */
  63
  64 #  pragma weak pthread_key_create
  65 #  pragma weak pthread_getspecific
  66 #  pragma weak pthread_setspecific
  67 #  pragma weak pthread_key_delete
  68 #  ifndef pthread_self
  69 #   pragma weak pthread_self
  70 #  endif
  71
  72 #  if !PTHREAD_IN_USE_DETECTION_HARD
  73 #   pragma weak pthread_cancel
  74 #   define pthread_in_use() (pthread_cancel != NULL)
  75 #  endif
  76
  77 # else
  78
  79 #  if !PTHREAD_IN_USE_DETECTION_HARD
  80 #   define pthread_in_use() 1
  81 #  endif
  82
  83 # endif
  84
  85 /* ------------------------- gl_tls_key_t datatype ------------------------- */
  86
  87 typedef union
  88         {
  89           void *singlethread_value;
  90           pthread_key_t key;
  91         }
  92         gl_tls_key_t;
  93 # define gl_tls_key_init(NAME, DESTRUCTOR) \
  94     do                                                             \
  95       {                                                            \
  96         if (pthread_in_use ())                                     \
  97           {                                                        \
  98             if (pthread_key_create (&(NAME).key, DESTRUCTOR) != 0) \
  99               abort ();                                            \
 100           }                                                        \
 101         else                                                       \
 102           (NAME).singlethread_value = NULL;                        \
 103       }                                                            \
 104     while (0)
 105 # define gl_tls_get(NAME) \
 106     (pthread_in_use ()                  \
 107      ? pthread_getspecific ((NAME).key) \
 108      : (NAME).singlethread_value)
 109 # define gl_tls_set(NAME, POINTER) \
 110     do                                                            \
 111       {                                                           \
 112         if (pthread_in_use ())                                    \
 113           {                                                       \
 114             if (pthread_setspecific ((NAME).key, (POINTER)) != 0) \
 115               abort ();                                           \
 116           }                                                       \
 117         else                                                      \
 118           (NAME).singlethread_value = (POINTER);                  \
 119       }                                                           \
 120     while (0)
 121 # define gl_tls_key_destroy(NAME) \
 122     if (pthread_in_use () && pthread_key_delete ((NAME).key) != 0) \
 123       abort ()
 124
 125 #endif
 126
 127 /* ========================================================================= */
 128
 129 #if USE_PTH_THREADS
 130
 131 /* Use the GNU Pth threads library.  */
 132
 133 # include <pth.h>
 134 # include <stdlib.h>
 135
 136 # if USE_PTH_THREADS_WEAK
 137
 138 /* Use weak references to the GNU Pth threads library.  */
 139
 140 #  pragma weak pth_key_create
 141 #  pragma weak pth_key_getdata
 142 #  pragma weak pth_key_setdata
 143 #  pragma weak pth_key_delete
 144
 145 #  pragma weak pth_cancel
 146 #  define pth_in_use() (pth_cancel != NULL)
 147
 148 # else
 149
 150 #  define pth_in_use() 1
 151
 152 # endif
 153
 154 /* ------------------------- gl_tls_key_t datatype ------------------------- */
 155
 156 typedef union
 157         {
 158           void *singlethread_value;
 159           pth_key_t key;
 160         }
 161         gl_tls_key_t;
 162 # define gl_tls_key_init(NAME, DESTRUCTOR) \
 163     do                                                     \
 164       {                                                    \
 165         if (pth_in_use ())                                 \
 166           {                                                \
 167             if (!pth_key_create (&(NAME).key, DESTRUCTOR)) \
 168               abort ();                                    \
 169           }                                                \
 170         else                                               \
 171           (NAME).singlethread_value = NULL;                \
 172       }                                                    \
 173     while (0)
 174 # define gl_tls_get(NAME) \
 175     (pth_in_use ()                  \
 176      ? pth_key_getdata ((NAME).key) \
 177      : (NAME).singlethread_value)
 178 # define gl_tls_set(NAME, POINTER) \
 179     do                                                    \
 180       {                                                   \
 181         if (pth_in_use ())                                \
 182           {                                               \
 183             if (!pth_key_setdata ((NAME).key, (POINTER))) \
 184               abort ();                                   \
 185           }                                               \
 186         else                                              \
 187           (NAME).singlethread_value = (POINTER);          \
 188       }                                                   \
 189     while (0)
 190 # define gl_tls_key_destroy(NAME) \
 191     if (pth_in_use () && !pth_key_delete ((NAME).key)) \
 192       abort ()
 193
 194 #endif
 195
 196 /* ========================================================================= */
 197
 198 #if USE_SOLARIS_THREADS
 199
 200 /* Use the old Solaris threads library.  */
 201
 202 # include <thread.h>
 203 # include <stdlib.h>
 204
 205 # if USE_SOLARIS_THREADS_WEAK
 206
 207 /* Use weak references to the old Solaris threads library.  */
 208
 209 #  pragma weak thr_keycreate
 210 #  pragma weak thr_getspecific
 211 #  pragma weak thr_setspecific
 212
 213 #  pragma weak thr_suspend
 214 #  define thread_in_use() (thr_suspend != NULL)
 215
 216 # else
 217
 218 #  define thread_in_use() 1
 219
 220 # endif
 221
 222 /* ------------------------- gl_tls_key_t datatype ------------------------- */
 223
 224 typedef union
 225         {
 226           void *singlethread_value;
 227           thread_key_t key;
 228         }
 229         gl_tls_key_t;
 230 # define gl_tls_key_init(NAME, DESTRUCTOR) \
 231     do                                                        \
 232       {                                                       \
 233         if (thread_in_use ())                                 \
 234           {                                                   \
 235             if (thr_keycreate (&(NAME).key, DESTRUCTOR) != 0) \
 236               abort ();                                       \
 237           }                                                   \
 238         else                                                  \
 239           (NAME).singlethread_value = NULL;                   \
 240       }                                                       \
 241     while (0)
 242 # define gl_tls_get(NAME) \
 243     (thread_in_use ()                \
 244      ? glthread_tls_get ((NAME).key) \
 245      : (NAME).singlethread_value)
 246 extern void *glthread_tls_get (thread_key_t key);
 247 # define gl_tls_set(NAME, POINTER) \
 248     do                                                        \
 249       {                                                       \
 250         if (thread_in_use ())                                 \
 251           {                                                   \
 252             if (thr_setspecific ((NAME).key, (POINTER)) != 0) \
 253               abort ();                                       \
 254           }                                                   \
 255         else                                                  \
 256           (NAME).singlethread_value = (POINTER);              \
 257       }                                                       \
 258     while (0)
 259 # define gl_tls_key_destroy(NAME) \
 260     /* Unsupported.  */ \
 261     (void)0
 262
 263 #endif
 264
 265 /* ========================================================================= */
 266
 267 #if USE_WIN32_THREADS
 268
 269 # include <windows.h>
 270
 271 /* ------------------------- gl_tls_key_t datatype ------------------------- */
 272
 273 typedef DWORD gl_tls_key_t;
 274 # define gl_tls_key_init(NAME, DESTRUCTOR) \
 275     /* The destructor is unsupported.  */    \
 276     if (((NAME) = TlsAlloc ()) == (DWORD)-1) \
 277       abort ()
 278 # define gl_tls_get(NAME) \
 279     TlsGetValue (NAME)
 280 # define gl_tls_set(NAME, POINTER) \
 281     if (!TlsSetValue (NAME, POINTER)) \
 282       abort ()
 283 # define gl_tls_key_destroy(NAME) \
 284     if (!TlsFree (NAME)) \
 285       abort ()
 286
 287 #endif
 288
 289 /* ========================================================================= */
 290
 291 #if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_SOLARIS_THREADS || USE_WIN32_THREADS)
 292
 293 /* Provide dummy implementation if threads are not supported.  */
 294
 295 /* ------------------------- gl_tls_key_t datatype ------------------------- */
 296
 297 typedef struct
 298         {
 299           void *singlethread_value;
 300         }
 301         gl_tls_key_t;
 302 # define gl_tls_key_init(NAME, DESTRUCTOR) \
 303     (NAME).singlethread_value = NULL
 304 # define gl_tls_get(NAME) \
 305     (NAME).singlethread_value
 306 # define gl_tls_set(NAME, POINTER) \
 307     (NAME).singlethread_value = (POINTER)
 308 # define gl_tls_key_destroy(NAME) \
 309     (void)0
 310
 311 #endif
 312
 313 /* ========================================================================= */
 314
 315 #endif /* _TLS_H */