1 /* Creating and controlling threads.
2 Copyright (C) 2005-2008 Free Software Foundation, Inc.
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 2, or (at your option)
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.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software Foundation,
16 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
18 /* Written by Bruno Haible <bruno@clisp.org>, 2005.
19 Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-solaris.h,
22 /* This file contains primitives for creating and controlling threads.
24 Thread data type: gl_thread_t.
27 thread = gl_thread_create (func, arg);
28 Or with control of error handling:
29 err = glthread_create (&thread, func, arg);
30 extern int glthread_create (gl_thread_t *result,
31 void *(*func) (void *), void *arg);
33 Querying and changing the signal mask of a thread (not supported on all
35 gl_thread_sigmask (how, newmask, oldmask);
36 Or with control of error handling:
37 err = glthread_sigmask (how, newmask, oldmask);
38 extern int glthread_sigmask (int how, const sigset_t *newmask, sigset_t *oldmask);
40 Waiting for termination of another thread:
41 gl_thread_join (thread, &return_value);
42 Or with control of error handling:
43 err = glthread_join (thread, &return_value);
44 extern int glthread_join (gl_thread_t thread, void **return_value_ptr);
46 Getting a reference to the current thread:
47 current = gl_thread_self ();
48 extern gl_thread_t gl_thread_self (void);
50 Terminating the current thread:
51 gl_thread_exit (return_value);
52 extern void gl_thread_exit (void *return_value) __attribute__ ((noreturn));
54 Requesting custom code to be executed at fork() time(not supported on all
56 gl_thread_atfork (prepare_func, parent_func, child_func);
57 Or with control of error handling:
58 err = glthread_atfork (prepare_func, parent_func, child_func);
59 extern int glthread_atfork (void (*prepare_func) (void),
60 void (*parent_func) (void),
61 void (*child_func) (void));
62 Note that even on platforms where this is supported, use of fork() and
63 threads together is problematic, see
64 <http://lists.gnu.org/archive/html/bug-gnulib/2008-08/msg00062.html>
68 #ifndef _GLTHREAD_THREAD_H
69 #define _GLTHREAD_THREAD_H
74 /* ========================================================================= */
78 /* Use the POSIX threads library. */
86 # if PTHREAD_IN_USE_DETECTION_HARD
88 /* The pthread_in_use() detection needs to be done at runtime. */
89 # define pthread_in_use() \
91 extern int glthread_in_use (void);
95 # if USE_POSIX_THREADS_WEAK
97 /* Use weak references to the POSIX threads library. */
99 /* Weak references avoid dragging in external libraries if the other parts
100 of the program don't use them. Here we use them, because we don't want
101 every program that uses libintl to depend on libpthread. This assumes
102 that libpthread would not be loaded after libintl; i.e. if libintl is
103 loaded first, by an executable that does not depend on libpthread, and
104 then a module is dynamically loaded that depends on libpthread, libintl
105 will not be multithread-safe. */
107 /* The way to test at runtime whether libpthread is present is to test
108 whether a function pointer's value, such as &pthread_mutex_init, is
109 non-NULL. However, some versions of GCC have a bug through which, in
110 PIC mode, &foo != NULL always evaluates to true if there is a direct
111 call to foo(...) in the same function. To avoid this, we test the
112 address of a function in libpthread that we don't use. */
114 # pragma weak pthread_create
115 # pragma weak pthread_sigmask
116 # pragma weak pthread_join
117 # ifndef pthread_self
118 # pragma weak pthread_self
120 # pragma weak pthread_exit
121 # if HAVE_PTHREAD_ATFORK
122 # pragma weak pthread_atfork
125 # if !PTHREAD_IN_USE_DETECTION_HARD
126 # pragma weak pthread_cancel
127 # define pthread_in_use() (pthread_cancel != NULL)
132 # if !PTHREAD_IN_USE_DETECTION_HARD
133 # define pthread_in_use() 1
138 /* -------------------------- gl_thread_t datatype -------------------------- */
140 typedef pthread_t gl_thread_t;
141 # define glthread_create(THREADP, FUNC, ARG) \
142 (pthread_in_use () ? pthread_create (THREADP, NULL, FUNC, ARG) : ENOSYS)
143 # define glthread_sigmask(HOW, SET, OSET) \
144 (pthread_in_use () ? pthread_sigmask (HOW, SET, OSET) : 0)
145 # define glthread_join(THREAD, RETVALP) \
146 (pthread_in_use () ? pthread_join (THREAD, RETVALP) : 0)
147 # define gl_thread_self() \
148 (pthread_in_use () ? (void *) pthread_self () : NULL)
149 # define gl_thread_exit(RETVAL) \
150 (pthread_in_use () ? pthread_exit (RETVAL) : 0)
152 # if HAVE_PTHREAD_ATFORK
153 # define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) \
154 (pthread_in_use () ? pthread_atfork (PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) : 0)
156 # define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
165 /* ========================================================================= */
169 /* Use the GNU Pth threads library. */
177 # if USE_PTH_THREADS_WEAK
179 /* Use weak references to the GNU Pth threads library. */
181 # pragma weak pth_spawn
182 # pragma weak pth_sigmask
183 # pragma weak pth_join
184 # pragma weak pth_self
185 # pragma weak pth_exit
187 # pragma weak pth_cancel
188 # define pth_in_use() (pth_cancel != NULL)
192 # define pth_in_use() 1
195 /* -------------------------- gl_thread_t datatype -------------------------- */
197 typedef pth_t gl_thread_t;
198 # define glthread_create(THREADP, FUNC, ARG) \
199 (pth_in_use () ? ((*(THREADP) = pth_spawn (NULL, FUNC, ARG)) ? 0 : errno) : 0)
200 # define glthread_sigmask(HOW, SET, OSET) \
201 (pth_in_use () && !pth_sigmask (HOW, SET, OSET) ? errno : 0)
202 # define glthread_join(THREAD, RETVALP) \
203 (pth_in_use () && !pth_join (THREAD, RETVALP) ? errno : 0)
204 # define gl_thread_self() \
205 (pth_in_use () ? (void *) pth_self () : 0)
206 # define gl_thread_exit(RETVAL) \
207 (pth_in_use () ? pth_exit (RETVAL) : 0)
208 # define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
216 /* ========================================================================= */
218 #if USE_SOLARIS_THREADS
220 /* Use the old Solaris threads library. */
229 # if USE_SOLARIS_THREADS_WEAK
231 /* Use weak references to the old Solaris threads library. */
233 # pragma weak thr_create
234 # pragma weak thr_join
235 # pragma weak thr_self
236 # pragma weak thr_exit
238 # pragma weak thr_suspend
239 # define thread_in_use() (thr_suspend != NULL)
243 # define thread_in_use() 1
247 /* -------------------------- gl_thread_t datatype -------------------------- */
249 typedef thread_t gl_thread_t;
250 # define glthread_create(THREADP, FUNC, ARG) \
251 (thread_in_use () ? thr_create (NULL, 0, FUNC, ARG, 0, THREADP) : 0)
252 # define glthread_sigmask(HOW, SET, OSET) \
253 (thread_in_use () ? sigprocmask (HOW, SET, OSET) : 0)
254 # define glthread_join(THREAD, RETVALP) \
255 (thread_in_use () ? thr_join (THREAD, NULL, RETVALP) : 0)
256 # define gl_thread_self() \
257 (thread_in_use () ? (void *) thr_self () : 0)
258 # define gl_thread_exit(RETVAL) \
259 (thread_in_use () ? thr_exit (RETVAL) : 0)
260 # define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
268 /* ========================================================================= */
270 #if USE_WIN32_THREADS
272 # include <windows.h>
278 /* -------------------------- gl_thread_t datatype -------------------------- */
280 /* The gl_thread_t is a pointer to a structure in memory.
281 Why not the thread handle? If it were the thread handle, it would be hard
282 to implement gl_thread_self() (since GetCurrentThread () returns a pseudo-
283 handle, DuplicateHandle (GetCurrentThread ()) returns a handle that must be
284 closed afterwards, and there is no function for quickly retrieving a thread
286 Why not the thread id? I tried it. It did not work: Sometimes ids appeared
287 that did not belong to running threads, and glthread_join failed with ESRCH.
289 typedef struct gl_thread_struct *gl_thread_t;
290 # define glthread_create(THREADP, FUNC, ARG) \
291 glthread_create_func (THREADP, FUNC, ARG)
292 # define glthread_sigmask(HOW, SET, OSET) \
294 # define glthread_join(THREAD, RETVALP) \
295 glthread_join_func (THREAD, RETVALP)
296 # define gl_thread_self() \
297 gl_thread_self_func ()
298 # define gl_thread_exit(RETVAL) \
299 gl_thread_exit_func (RETVAL)
300 # define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
301 extern int glthread_create_func (gl_thread_t *threadp, void * (*func) (void *), void *arg);
302 extern int glthread_join_func (gl_thread_t thread, void **retvalp);
303 extern gl_thread_t gl_thread_self_func (void);
304 extern int gl_thread_exit_func (void *retval);
312 /* ========================================================================= */
314 #if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_SOLARIS_THREADS || USE_WIN32_THREADS)
316 /* Provide dummy implementation if threads are not supported. */
318 typedef int gl_thread_t;
319 # define glthread_create(THREADP, FUNC, ARG) ENOSYS
320 # define glthread_sigmask(HOW, SET, OSET) 0
321 # define glthread_join(THREAD, RETVALP) 0
322 # define gl_thread_self() NULL
323 # define gl_thread_exit(RETVAL) 0
324 # define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
328 /* ========================================================================= */
330 /* Macros with built-in error handling. */
336 static inline gl_thread_t
337 gl_thread_create (void *(*func) (void *arg), void *arg)
342 ret = glthread_create (&thread, func, arg);
347 #define gl_thread_sigmask(HOW, SET, OSET) \
350 if (glthread_sigmask (HOW, SET, OSET)) \
354 #define gl_thread_join(THREAD, RETVAL) \
357 if (glthread_join (THREAD, RETVAL)) \
361 #define gl_thread_atfork(PREPARE, PARENT, CHILD) \
364 if (glthread_atfork (PREPARE, PARENT, CHILD)) \
373 #endif /* _GLTHREAD_THREAD_H */