lib/glthread/tls.h

   1 /* Thread-local storage in multithreaded situations.
   2    Copyright (C) 2005, 2007-2020 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 <https://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    Equivalent functions with control of error handling:
  29      Initialization:            err = glthread_tls_key_init (&name, destructor);
  30      Setting per-thread value:  err = glthread_tls_set (&name, pointer);
  31      De-initialization:         err = glthread_tls_key_destroy (&name);
  32
  33    A per-thread value is of type 'void *'.
  34
  35    A destructor is a function pointer of type 'void (*) (void *)', called
  36    when a thread exits, and taking the last per-thread value as argument.  It
  37    is unspecified whether the destructor function is called when the last
  38    per-thread value is NULL.  On some platforms, the destructor function is
  39    not called at all.
  40 */
  41
  42
  43 #ifndef _TLS_H
  44 #define _TLS_H
  45
  46 #include <errno.h>
  47 #include <stdlib.h>
  48
  49 #if !defined c11_threads_in_use
  50 # if HAVE_THREADS_H && USE_POSIX_THREADS_WEAK
  51 #  include <threads.h>
  52 #  pragma weak thrd_exit
  53 #  define c11_threads_in_use() (thrd_exit != NULL)
  54 # else
  55 #  define c11_threads_in_use() 0
  56 # endif
  57 #endif
  58
  59 /* ========================================================================= */
  60
  61 #if USE_ISOC_THREADS || USE_ISOC_AND_POSIX_THREADS
  62
  63 /* Use the ISO C threads library.  */
  64
  65 # include <threads.h>
  66
  67 /* ------------------------- gl_tls_key_t datatype ------------------------- */
  68
  69 typedef tss_t gl_tls_key_t;
  70 # define glthread_tls_key_init(KEY, DESTRUCTOR) \
  71     (tss_create (KEY, DESTRUCTOR) != thrd_success ? EAGAIN : 0)
  72 # define gl_tls_get(NAME) \
  73     tss_get (NAME)
  74 # define glthread_tls_set(KEY, POINTER) \
  75     (tss_set (*(KEY), (POINTER)) != thrd_success ? ENOMEM : 0)
  76 # define glthread_tls_key_destroy(KEY) \
  77     (tss_delete (*(KEY)), 0)
  78
  79 #endif
  80
  81 /* ========================================================================= */
  82
  83 #if USE_POSIX_THREADS
  84
  85 /* Use the POSIX threads library.  */
  86
  87 # include <pthread.h>
  88
  89 # if PTHREAD_IN_USE_DETECTION_HARD
  90
  91 /* The pthread_in_use() detection needs to be done at runtime.  */
  92 #  define pthread_in_use() \
  93      glthread_in_use ()
  94 extern int glthread_in_use (void);
  95
  96 # endif
  97
  98 # if USE_POSIX_THREADS_WEAK
  99
 100 /* Use weak references to the POSIX threads library.  */
 101
 102 #  pragma weak pthread_key_create
 103 #  pragma weak pthread_getspecific
 104 #  pragma weak pthread_setspecific
 105 #  pragma weak pthread_key_delete
 106 #  ifndef pthread_self
 107 #   pragma weak pthread_self
 108 #  endif
 109
 110 #  if !PTHREAD_IN_USE_DETECTION_HARD
 111 #   pragma weak pthread_mutexattr_gettype
 112 #   define pthread_in_use() \
 113       (pthread_mutexattr_gettype != NULL || c11_threads_in_use ())
 114 #  endif
 115
 116 # else
 117
 118 #  if !PTHREAD_IN_USE_DETECTION_HARD
 119 #   define pthread_in_use() 1
 120 #  endif
 121
 122 # endif
 123
 124 /* ------------------------- gl_tls_key_t datatype ------------------------- */
 125
 126 typedef union
 127         {
 128           void *singlethread_value;
 129           pthread_key_t key;
 130         }
 131         gl_tls_key_t;
 132 # define glthread_tls_key_init(KEY, DESTRUCTOR) \
 133     (pthread_in_use ()                              \
 134      ? pthread_key_create (&(KEY)->key, DESTRUCTOR) \
 135      : ((KEY)->singlethread_value = NULL, 0))
 136 # define gl_tls_get(NAME) \
 137     (pthread_in_use ()                  \
 138      ? pthread_getspecific ((NAME).key) \
 139      : (NAME).singlethread_value)
 140 # define glthread_tls_set(KEY, POINTER) \
 141     (pthread_in_use ()                             \
 142      ? pthread_setspecific ((KEY)->key, (POINTER)) \
 143      : ((KEY)->singlethread_value = (POINTER), 0))
 144 # define glthread_tls_key_destroy(KEY) \
 145     (pthread_in_use () ? pthread_key_delete ((KEY)->key) : 0)
 146
 147 #endif
 148
 149 /* ========================================================================= */
 150
 151 #if USE_WINDOWS_THREADS
 152
 153 # define WIN32_LEAN_AND_MEAN  /* avoid including junk */
 154 # include <windows.h>
 155
 156 # include "windows-tls.h"
 157
 158 /* ------------------------- gl_tls_key_t datatype ------------------------- */
 159
 160 typedef glwthread_tls_key_t gl_tls_key_t;
 161 # define glthread_tls_key_init(KEY, DESTRUCTOR) \
 162     glwthread_tls_key_create (KEY, DESTRUCTOR)
 163 # define gl_tls_get(NAME) \
 164     TlsGetValue (NAME)
 165 # define glthread_tls_set(KEY, POINTER) \
 166     (!TlsSetValue (*(KEY), POINTER) ? EINVAL : 0)
 167 # define glthread_tls_key_destroy(KEY) \
 168     glwthread_tls_key_delete (*(KEY))
 169
 170 #endif
 171
 172 /* ========================================================================= */
 173
 174 #if !(USE_ISOC_THREADS || USE_POSIX_THREADS || USE_ISOC_AND_POSIX_THREADS || USE_WINDOWS_THREADS)
 175
 176 /* Provide dummy implementation if threads are not supported.  */
 177
 178 /* ------------------------- gl_tls_key_t datatype ------------------------- */
 179
 180 typedef struct
 181         {
 182           void *singlethread_value;
 183         }
 184         gl_tls_key_t;
 185 # define glthread_tls_key_init(KEY, DESTRUCTOR) \
 186     ((KEY)->singlethread_value = NULL, \
 187      (void) (DESTRUCTOR),              \
 188      0)
 189 # define gl_tls_get(NAME) \
 190     (NAME).singlethread_value
 191 # define glthread_tls_set(KEY, POINTER) \
 192     ((KEY)->singlethread_value = (POINTER), 0)
 193 # define glthread_tls_key_destroy(KEY) \
 194     0
 195
 196 #endif
 197
 198 /* ========================================================================= */
 199
 200 /* Macros with built-in error handling.  */
 201
 202 /* ------------------------- gl_tls_key_t datatype ------------------------- */
 203
 204 #define gl_tls_key_init(NAME, DESTRUCTOR) \
 205    do                                                 \
 206      {                                                \
 207        if (glthread_tls_key_init (&NAME, DESTRUCTOR)) \
 208          abort ();                                    \
 209      }                                                \
 210    while (0)
 211 #define gl_tls_set(NAME, POINTER) \
 212    do                                         \
 213      {                                        \
 214        if (glthread_tls_set (&NAME, POINTER)) \
 215          abort ();                            \
 216      }                                        \
 217    while (0)
 218 #define gl_tls_key_destroy(NAME) \
 219    do                                        \
 220      {                                       \
 221        if (glthread_tls_key_destroy (&NAME)) \
 222          abort ();                           \
 223      }                                       \
 224    while (0)
 225
 226 /* ========================================================================= */
 227
 228 #endif /* _TLS_H */