1 /* Thread-local storage in multithreaded situations.
2 Copyright (C) 2005, 2007-2021 Free Software Foundation, Inc.
3
4 This file is free software: you can redistribute it and/or modify
5 it under the terms of the GNU Lesser General Public License as
6 published by the Free Software Foundation; either version 2.1 of the
7 License, or (at your option) any later version.
8
9 This file 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 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser 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_FROM_LIBC
51 # define c11_threads_in_use() 1
52 # elif HAVE_THREADS_H && USE_POSIX_THREADS_WEAK
53 # include <threads.h>
54 # pragma weak thrd_exit
55 # define c11_threads_in_use() (thrd_exit != NULL)
56 # else
57 # define c11_threads_in_use() 0
58 # endif
59 #endif
60
61 /* ========================================================================= */
62
63 #if USE_ISOC_THREADS || USE_ISOC_AND_POSIX_THREADS
64
65 /* Use the ISO C threads library. */
66
67 # include <threads.h>
68
69 /* ------------------------- gl_tls_key_t datatype ------------------------- */
70
71 typedef tss_t gl_tls_key_t;
72 # define glthread_tls_key_init(KEY, DESTRUCTOR) \
73 (tss_create (KEY, DESTRUCTOR) != thrd_success ? EAGAIN : 0)
74 # define gl_tls_get(NAME) \
75 tss_get (NAME)
76 # define glthread_tls_set(KEY, POINTER) \
77 (tss_set (*(KEY), (POINTER)) != thrd_success ? ENOMEM : 0)
78 # define glthread_tls_key_destroy(KEY) \
79 (tss_delete (*(KEY)), 0)
80
81 #endif
82
83 /* ========================================================================= */
84
85 #if USE_POSIX_THREADS
86
87 /* Use the POSIX threads library. */
88
89 # include <pthread.h>
90
91 # if PTHREAD_IN_USE_DETECTION_HARD
92
93 /* The pthread_in_use() detection needs to be done at runtime. */
94 # define pthread_in_use() \
95 glthread_in_use ()
96 extern int glthread_in_use (void);
97
98 # endif
99
100 # if USE_POSIX_THREADS_WEAK
101
102 /* Use weak references to the POSIX threads library. */
103
104 # pragma weak pthread_key_create
105 # pragma weak pthread_getspecific
106 # pragma weak pthread_setspecific
107 # pragma weak pthread_key_delete
108 # ifndef pthread_self
109 # pragma weak pthread_self
110 # endif
111
112 # if !PTHREAD_IN_USE_DETECTION_HARD
113 # pragma weak pthread_mutexattr_gettype
114 # define pthread_in_use() \
115 (pthread_mutexattr_gettype != NULL || c11_threads_in_use ())
116 # endif
117
118 # else
119
120 # if !PTHREAD_IN_USE_DETECTION_HARD
121 # define pthread_in_use() 1
122 # endif
123
124 # endif
125
126 /* ------------------------- gl_tls_key_t datatype ------------------------- */
127
128 typedef union
129 {
130 void *singlethread_value;
131 pthread_key_t key;
132 }
133 gl_tls_key_t;
134 # define glthread_tls_key_init(KEY, DESTRUCTOR) \
135 (pthread_in_use () \
136 ? pthread_key_create (&(KEY)->key, DESTRUCTOR) \
137 : ((KEY)->singlethread_value = NULL, 0))
138 # define gl_tls_get(NAME) \
139 (pthread_in_use () \
140 ? pthread_getspecific ((NAME).key) \
141 : (NAME).singlethread_value)
142 # define glthread_tls_set(KEY, POINTER) \
143 (pthread_in_use () \
144 ? pthread_setspecific ((KEY)->key, (POINTER)) \
145 : ((KEY)->singlethread_value = (POINTER), 0))
146 # define glthread_tls_key_destroy(KEY) \
147 (pthread_in_use () ? pthread_key_delete ((KEY)->key) : 0)
148
149 #endif
150
151 /* ========================================================================= */
152
153 #if USE_WINDOWS_THREADS
154
155 # define WIN32_LEAN_AND_MEAN /* avoid including junk */
156 # include <windows.h>
157
158 # include "windows-tls.h"
159
160 /* ------------------------- gl_tls_key_t datatype ------------------------- */
161
162 typedef glwthread_tls_key_t gl_tls_key_t;
163 # define glthread_tls_key_init(KEY, DESTRUCTOR) \
164 glwthread_tls_key_create (KEY, DESTRUCTOR)
165 # define gl_tls_get(NAME) \
166 TlsGetValue (NAME)
167 # define glthread_tls_set(KEY, POINTER) \
168 (!TlsSetValue (*(KEY), POINTER) ? EINVAL : 0)
169 # define glthread_tls_key_destroy(KEY) \
170 glwthread_tls_key_delete (*(KEY))
171
172 #endif
173
174 /* ========================================================================= */
175
176 #if !(USE_ISOC_THREADS || USE_POSIX_THREADS || USE_ISOC_AND_POSIX_THREADS || USE_WINDOWS_THREADS)
177
178 /* Provide dummy implementation if threads are not supported. */
179
180 /* ------------------------- gl_tls_key_t datatype ------------------------- */
181
182 typedef struct
183 {
184 void *singlethread_value;
185 }
186 gl_tls_key_t;
187 # define glthread_tls_key_init(KEY, DESTRUCTOR) \
188 ((KEY)->singlethread_value = NULL, \
189 (void) (DESTRUCTOR), \
190 0)
191 # define gl_tls_get(NAME) \
192 (NAME).singlethread_value
193 # define glthread_tls_set(KEY, POINTER) \
194 ((KEY)->singlethread_value = (POINTER), 0)
195 # define glthread_tls_key_destroy(KEY) \
196 0
197
198 #endif
199
200 /* ========================================================================= */
201
202 /* Macros with built-in error handling. */
203
204 /* ------------------------- gl_tls_key_t datatype ------------------------- */
205
206 #define gl_tls_key_init(NAME, DESTRUCTOR) \
207 do \
208 { \
209 if (glthread_tls_key_init (&NAME, DESTRUCTOR)) \
210 abort (); \
211 } \
212 while (0)
213 #define gl_tls_set(NAME, POINTER) \
214 do \
215 { \
216 if (glthread_tls_set (&NAME, POINTER)) \
217 abort (); \
218 } \
219 while (0)
220 #define gl_tls_key_destroy(NAME) \
221 do \
222 { \
223 if (glthread_tls_key_destroy (&NAME)) \
224 abort (); \
225 } \
226 while (0)
227
228 /* ========================================================================= */
229
230 #endif /* _TLS_H */