Line data Source code
1 : /* Creating and controlling threads.
2 : Copyright (C) 2005-2020 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, 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
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 : Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-win32.h. */
19 :
20 : /* This file contains primitives for creating and controlling threads.
21 :
22 : Thread data type: gl_thread_t.
23 :
24 : Creating a thread:
25 : thread = gl_thread_create (func, arg);
26 : Or with control of error handling:
27 : err = glthread_create (&thread, func, arg);
28 : extern int glthread_create (gl_thread_t *result,
29 : void *(*func) (void *), void *arg);
30 :
31 : Querying and changing the signal mask of a thread (not supported on all
32 : platforms):
33 : gl_thread_sigmask (how, newmask, oldmask);
34 : Or with control of error handling:
35 : err = glthread_sigmask (how, newmask, oldmask);
36 : extern int glthread_sigmask (int how, const sigset_t *newmask, sigset_t *oldmask);
37 :
38 : Waiting for termination of another thread:
39 : gl_thread_join (thread, &return_value);
40 : Or with control of error handling:
41 : err = glthread_join (thread, &return_value);
42 : extern int glthread_join (gl_thread_t thread, void **return_value_ptr);
43 :
44 : Getting a reference to the current thread:
45 : current = gl_thread_self ();
46 : extern gl_thread_t gl_thread_self (void);
47 :
48 : Getting a reference to the current thread as a pointer, for debugging:
49 : ptr = gl_thread_self_pointer ();
50 : extern void * gl_thread_self_pointer (void);
51 :
52 : Terminating the current thread:
53 : gl_thread_exit (return_value);
54 : extern _Noreturn void gl_thread_exit (void *return_value);
55 :
56 : Requesting custom code to be executed at fork() time (not supported on all
57 : platforms):
58 : gl_thread_atfork (prepare_func, parent_func, child_func);
59 : Or with control of error handling:
60 : err = glthread_atfork (prepare_func, parent_func, child_func);
61 : extern int glthread_atfork (void (*prepare_func) (void),
62 : void (*parent_func) (void),
63 : void (*child_func) (void));
64 : Note that even on platforms where this is supported, use of fork() and
65 : threads together is problematic, see
66 : <https://lists.gnu.org/r/bug-gnulib/2008-08/msg00062.html>
67 : */
68 :
69 :
70 : #ifndef _GLTHREAD_THREAD_H
71 : #define _GLTHREAD_THREAD_H
72 :
73 : #include <errno.h>
74 : #include <stdlib.h>
75 :
76 : #if !defined c11_threads_in_use
77 : # if HAVE_THREADS_H && USE_POSIX_THREADS_WEAK
78 : # include <threads.h>
79 : # pragma weak thrd_exit
80 : # define c11_threads_in_use() (thrd_exit != NULL)
81 : # else
82 : # define c11_threads_in_use() 0
83 : # endif
84 : #endif
85 :
86 : #ifndef _GL_INLINE_HEADER_BEGIN
87 : #error "Please include config.h first."
88 : #endif
89 : _GL_INLINE_HEADER_BEGIN
90 : #ifndef _GLTHREAD_THREAD_INLINE
91 : # define _GLTHREAD_THREAD_INLINE _GL_INLINE
92 : #endif
93 :
94 : /* ========================================================================= */
95 :
96 : #if USE_ISOC_THREADS
97 :
98 : /* Use the ISO C threads library. */
99 :
100 : # include <threads.h>
101 :
102 : # ifdef __cplusplus
103 : extern "C" {
104 : # endif
105 :
106 : /* -------------------------- gl_thread_t datatype -------------------------- */
107 :
108 : typedef struct thrd_with_exitvalue *gl_thread_t;
109 : extern int glthread_create (gl_thread_t *threadp,
110 : void *(*func) (void *), void *arg);
111 : # define glthread_sigmask(HOW, SET, OSET) \
112 : pthread_sigmask (HOW, SET, OSET)
113 : extern int glthread_join (gl_thread_t thread, void **return_value_ptr);
114 : extern gl_thread_t gl_thread_self (void);
115 : # define gl_thread_self_pointer() \
116 : (void *) gl_thread_self ()
117 : extern _Noreturn void gl_thread_exit (void *return_value);
118 : # define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
119 :
120 : # ifdef __cplusplus
121 : }
122 : # endif
123 :
124 : #endif
125 :
126 : /* ========================================================================= */
127 :
128 : #if USE_POSIX_THREADS || USE_ISOC_AND_POSIX_THREADS
129 :
130 : /* Use the POSIX threads library. */
131 :
132 : # include <pthread.h>
133 :
134 : /* On IRIX, pthread_atfork is declared in <unistd.h>, not in <pthread.h>. */
135 : # if defined __sgi
136 : # include <unistd.h>
137 : # endif
138 :
139 : # if USE_POSIX_THREADS_WEAK
140 : /* Compilers other than GCC need to see the declaration of pthread_sigmask
141 : before the "#pragma weak pthread_sigmask" below. */
142 : # include <signal.h>
143 : # endif
144 :
145 : # ifdef __cplusplus
146 : extern "C" {
147 : # endif
148 :
149 : # if PTHREAD_IN_USE_DETECTION_HARD
150 :
151 : /* The pthread_in_use() detection needs to be done at runtime. */
152 : # define pthread_in_use() \
153 : glthread_in_use ()
154 : extern int glthread_in_use (void);
155 :
156 : # endif
157 :
158 : # if USE_POSIX_THREADS_WEAK
159 :
160 : /* Use weak references to the POSIX threads library. */
161 :
162 : /* Weak references avoid dragging in external libraries if the other parts
163 : of the program don't use them. Here we use them, because we don't want
164 : every program that uses libintl to depend on libpthread. This assumes
165 : that libpthread would not be loaded after libintl; i.e. if libintl is
166 : loaded first, by an executable that does not depend on libpthread, and
167 : then a module is dynamically loaded that depends on libpthread, libintl
168 : will not be multithread-safe. */
169 :
170 : /* The way to test at runtime whether libpthread is present is to test
171 : whether a function pointer's value, such as &pthread_mutex_init, is
172 : non-NULL. However, some versions of GCC have a bug through which, in
173 : PIC mode, &foo != NULL always evaluates to true if there is a direct
174 : call to foo(...) in the same function. To avoid this, we test the
175 : address of a function in libpthread that we don't use. */
176 :
177 : # ifndef pthread_sigmask /* Do not declare rpl_pthread_sigmask weak. */
178 : # pragma weak pthread_sigmask
179 : # endif
180 :
181 : # pragma weak pthread_join
182 : # ifndef pthread_self
183 : # pragma weak pthread_self
184 : # endif
185 : # pragma weak pthread_exit
186 : # if HAVE_PTHREAD_ATFORK
187 : # pragma weak pthread_atfork
188 : # endif
189 :
190 : # if !PTHREAD_IN_USE_DETECTION_HARD
191 : # pragma weak pthread_mutexattr_gettype
192 : # define pthread_in_use() \
193 : (pthread_mutexattr_gettype != NULL || c11_threads_in_use ())
194 : # endif
195 :
196 : # else
197 :
198 : # if !PTHREAD_IN_USE_DETECTION_HARD
199 : # define pthread_in_use() 1
200 : # endif
201 :
202 : # endif
203 :
204 : /* -------------------------- gl_thread_t datatype -------------------------- */
205 :
206 : /* This choice of gl_thread_t assumes that
207 : pthread_equal (a, b) is equivalent to ((a) == (b)).
208 : This is the case on all platforms in use in 2008. */
209 : typedef pthread_t gl_thread_t;
210 : # define glthread_create(THREADP, FUNC, ARG) \
211 : (pthread_in_use () ? pthread_create (THREADP, NULL, FUNC, ARG) : ENOSYS)
212 : # define glthread_sigmask(HOW, SET, OSET) \
213 : (pthread_in_use () ? pthread_sigmask (HOW, SET, OSET) : 0)
214 : # define glthread_join(THREAD, RETVALP) \
215 : (pthread_in_use () ? pthread_join (THREAD, RETVALP) : 0)
216 : # ifdef PTW32_VERSION
217 : /* In pthreads-win32, pthread_t is a struct with a pointer field 'p' and
218 : other fields. */
219 : # define gl_thread_self() \
220 : (pthread_in_use () ? pthread_self () : gl_null_thread)
221 : # define gl_thread_self_pointer() \
222 : (pthread_in_use () ? pthread_self ().p : NULL)
223 : extern const gl_thread_t gl_null_thread;
224 : # elif defined __MVS__
225 : /* On IBM z/OS, pthread_t is a struct with an 8-byte '__' field.
226 : The first three bytes of this field appear to uniquely identify a
227 : pthread_t, though not necessarily representing a pointer. */
228 : # define gl_thread_self() \
229 : (pthread_in_use () ? pthread_self () : gl_null_thread)
230 : # define gl_thread_self_pointer() \
231 : (pthread_in_use () ? *((void **) pthread_self ().__) : NULL)
232 : extern const gl_thread_t gl_null_thread;
233 : # else
234 : # define gl_thread_self() \
235 : (pthread_in_use () ? pthread_self () : (pthread_t) NULL)
236 : # define gl_thread_self_pointer() \
237 : (pthread_in_use () ? (void *) pthread_self () : NULL)
238 : # endif
239 : # define gl_thread_exit(RETVAL) \
240 : (void) (pthread_in_use () ? (pthread_exit (RETVAL), 0) : 0)
241 :
242 : # if HAVE_PTHREAD_ATFORK
243 : # define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) \
244 : (pthread_in_use () ? pthread_atfork (PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) : 0)
245 : # else
246 : # define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
247 : # endif
248 :
249 : # ifdef __cplusplus
250 : }
251 : # endif
252 :
253 : #endif
254 :
255 : /* ========================================================================= */
256 :
257 : #if USE_WINDOWS_THREADS
258 :
259 : # define WIN32_LEAN_AND_MEAN /* avoid including junk */
260 : # include <windows.h>
261 :
262 : # include "windows-thread.h"
263 :
264 : # ifdef __cplusplus
265 : extern "C" {
266 : # endif
267 :
268 : /* -------------------------- gl_thread_t datatype -------------------------- */
269 :
270 : typedef glwthread_thread_t gl_thread_t;
271 : # define glthread_create(THREADP, FUNC, ARG) \
272 : glwthread_thread_create (THREADP, 0, FUNC, ARG)
273 : # define glthread_sigmask(HOW, SET, OSET) \
274 : /* unsupported */ 0
275 : # define glthread_join(THREAD, RETVALP) \
276 : glwthread_thread_join (THREAD, RETVALP)
277 : # define gl_thread_self() \
278 : glwthread_thread_self ()
279 : # define gl_thread_self_pointer() \
280 : gl_thread_self ()
281 : # define gl_thread_exit(RETVAL) \
282 : glwthread_thread_exit (RETVAL)
283 : # define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
284 :
285 : # ifdef __cplusplus
286 : }
287 : # endif
288 :
289 : #endif
290 :
291 : /* ========================================================================= */
292 :
293 : #if !(USE_ISOC_THREADS || USE_POSIX_THREADS || USE_ISOC_AND_POSIX_THREADS || USE_WINDOWS_THREADS)
294 :
295 : /* Provide dummy implementation if threads are not supported. */
296 :
297 : typedef int gl_thread_t;
298 : # define glthread_create(THREADP, FUNC, ARG) ENOSYS
299 : # define glthread_sigmask(HOW, SET, OSET) 0
300 : # define glthread_join(THREAD, RETVALP) 0
301 : # define gl_thread_self() 0
302 : # define gl_thread_self_pointer() \
303 : ((void *) gl_thread_self ())
304 : # define gl_thread_exit(RETVAL) (void)0
305 : # define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
306 :
307 : #endif
308 :
309 : /* ========================================================================= */
310 :
311 : /* Macros with built-in error handling. */
312 :
313 : #ifdef __cplusplus
314 : extern "C" {
315 : #endif
316 :
317 : _GLTHREAD_THREAD_INLINE gl_thread_t
318 52 : gl_thread_create (void *(*func) (void *arg), void *arg)
319 : {
320 : gl_thread_t thread;
321 : int ret;
322 :
323 52 : ret = glthread_create (&thread, func, arg);
324 52 : if (ret != 0)
325 0 : abort ();
326 52 : return thread;
327 : }
328 : #define gl_thread_sigmask(HOW, SET, OSET) \
329 : do \
330 : { \
331 : if (glthread_sigmask (HOW, SET, OSET)) \
332 : abort (); \
333 : } \
334 : while (0)
335 : #define gl_thread_join(THREAD, RETVAL) \
336 : do \
337 : { \
338 : if (glthread_join (THREAD, RETVAL)) \
339 : abort (); \
340 : } \
341 : while (0)
342 : #define gl_thread_atfork(PREPARE, PARENT, CHILD) \
343 : do \
344 : { \
345 : if (glthread_atfork (PREPARE, PARENT, CHILD)) \
346 : abort (); \
347 : } \
348 : while (0)
349 :
350 : #ifdef __cplusplus
351 : }
352 : #endif
353 :
354 : _GL_INLINE_HEADER_END
355 :
356 : #endif /* _GLTHREAD_THREAD_H */
|
