1 /* Thread-local storage in multithreaded situations.
2 Copyright (C) 2005, 2007-2021 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 */