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1 /* Locking in multithreaded situations.
2    Copyright (C) 2005-2012 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 <http://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-solaris.h,
19    gthr-win32.h.  */
20 
21 /* This file contains locking primitives for use with a given thread library.
22    It does not contain primitives for creating threads or for other
23    synchronization primitives.
24 
25    Normal (non-recursive) locks:
26      Type:                gl_lock_t
27      Declaration:         gl_lock_define(extern, name)
28      Initializer:         gl_lock_define_initialized(, name)
29      Initialization:      gl_lock_init (name);
30      Taking the lock:     gl_lock_lock (name);
31      Releasing the lock:  gl_lock_unlock (name);
32      De-initialization:   gl_lock_destroy (name);
33    Equivalent functions with control of error handling:
34      Initialization:      err = glthread_lock_init (&name);
35      Taking the lock:     err = glthread_lock_lock (&name);
36      Releasing the lock:  err = glthread_lock_unlock (&name);
37      De-initialization:   err = glthread_lock_destroy (&name);
38 
39    Read-Write (non-recursive) locks:
40      Type:                gl_rwlock_t
41      Declaration:         gl_rwlock_define(extern, name)
42      Initializer:         gl_rwlock_define_initialized(, name)
43      Initialization:      gl_rwlock_init (name);
44      Taking the lock:     gl_rwlock_rdlock (name);
45                           gl_rwlock_wrlock (name);
46      Releasing the lock:  gl_rwlock_unlock (name);
47      De-initialization:   gl_rwlock_destroy (name);
48    Equivalent functions with control of error handling:
49      Initialization:      err = glthread_rwlock_init (&name);
50      Taking the lock:     err = glthread_rwlock_rdlock (&name);
51                           err = glthread_rwlock_wrlock (&name);
52      Releasing the lock:  err = glthread_rwlock_unlock (&name);
53      De-initialization:   err = glthread_rwlock_destroy (&name);
54 
55    Recursive locks:
56      Type:                gl_recursive_lock_t
57      Declaration:         gl_recursive_lock_define(extern, name)
58      Initializer:         gl_recursive_lock_define_initialized(, name)
59      Initialization:      gl_recursive_lock_init (name);
60      Taking the lock:     gl_recursive_lock_lock (name);
61      Releasing the lock:  gl_recursive_lock_unlock (name);
62      De-initialization:   gl_recursive_lock_destroy (name);
63    Equivalent functions with control of error handling:
64      Initialization:      err = glthread_recursive_lock_init (&name);
65      Taking the lock:     err = glthread_recursive_lock_lock (&name);
66      Releasing the lock:  err = glthread_recursive_lock_unlock (&name);
67      De-initialization:   err = glthread_recursive_lock_destroy (&name);
68 
69   Once-only execution:
70      Type:                gl_once_t
71      Initializer:         gl_once_define(extern, name)
72      Execution:           gl_once (name, initfunction);
73    Equivalent functions with control of error handling:
74      Execution:           err = glthread_once (&name, initfunction);
75 */
76 
77 
78 #ifndef _LOCK_H
79 #define _LOCK_H
80 
81 #include <errno.h>
82 #include <stdlib.h>
83 
84 /* ========================================================================= */
85 
86 #if USE_POSIX_THREADS
87 
88 /* Use the POSIX threads library.  */
89 
90 # include <pthread.h>
91 
92 # ifdef __cplusplus
93 extern "C" {
94 # endif
95 
96 # if PTHREAD_IN_USE_DETECTION_HARD
97 
98 /* The pthread_in_use() detection needs to be done at runtime.  */
99 #  define pthread_in_use() \
100      glthread_in_use ()
101 extern int glthread_in_use (void);
102 
103 # endif
104 
105 # if USE_POSIX_THREADS_WEAK
106 
107 /* Use weak references to the POSIX threads library.  */
108 
109 /* Weak references avoid dragging in external libraries if the other parts
110    of the program don't use them.  Here we use them, because we don't want
111    every program that uses libintl to depend on libpthread.  This assumes
112    that libpthread would not be loaded after libintl; i.e. if libintl is
113    loaded first, by an executable that does not depend on libpthread, and
114    then a module is dynamically loaded that depends on libpthread, libintl
115    will not be multithread-safe.  */
116 
117 /* The way to test at runtime whether libpthread is present is to test
118    whether a function pointer's value, such as &pthread_mutex_init, is
119    non-NULL.  However, some versions of GCC have a bug through which, in
120    PIC mode, &foo != NULL always evaluates to true if there is a direct
121    call to foo(...) in the same function.  To avoid this, we test the
122    address of a function in libpthread that we don't use.  */
123 
124 #  pragma weak pthread_mutex_init
125 #  pragma weak pthread_mutex_lock
126 #  pragma weak pthread_mutex_unlock
127 #  pragma weak pthread_mutex_destroy
128 #  pragma weak pthread_rwlock_init
129 #  pragma weak pthread_rwlock_rdlock
130 #  pragma weak pthread_rwlock_wrlock
131 #  pragma weak pthread_rwlock_unlock
132 #  pragma weak pthread_rwlock_destroy
133 #  pragma weak pthread_once
134 #  pragma weak pthread_cond_init
135 #  pragma weak pthread_cond_wait
136 #  pragma weak pthread_cond_signal
137 #  pragma weak pthread_cond_broadcast
138 #  pragma weak pthread_cond_destroy
139 #  pragma weak pthread_mutexattr_init
140 #  pragma weak pthread_mutexattr_settype
141 #  pragma weak pthread_mutexattr_destroy
142 #  ifndef pthread_self
143 #   pragma weak pthread_self
144 #  endif
145 
146 #  if !PTHREAD_IN_USE_DETECTION_HARD
147 #   pragma weak pthread_cancel
148 #   define pthread_in_use() (pthread_cancel != NULL)
149 #  endif
150 
151 # else
152 
153 #  if !PTHREAD_IN_USE_DETECTION_HARD
154 #   define pthread_in_use() 1
155 #  endif
156 
157 # endif
158 
159 /* -------------------------- gl_lock_t datatype -------------------------- */
160 
161 typedef pthread_mutex_t gl_lock_t;
162 # define gl_lock_define(STORAGECLASS, NAME) \
163     STORAGECLASS pthread_mutex_t NAME;
164 # define gl_lock_define_initialized(STORAGECLASS, NAME) \
165     STORAGECLASS pthread_mutex_t NAME = gl_lock_initializer;
166 # define gl_lock_initializer \
167     PTHREAD_MUTEX_INITIALIZER
168 # define glthread_lock_init(LOCK) \
169     (pthread_in_use () ? pthread_mutex_init (LOCK, NULL) : 0)
170 # define glthread_lock_lock(LOCK) \
171     (pthread_in_use () ? pthread_mutex_lock (LOCK) : 0)
172 # define glthread_lock_unlock(LOCK) \
173     (pthread_in_use () ? pthread_mutex_unlock (LOCK) : 0)
174 # define glthread_lock_destroy(LOCK) \
175     (pthread_in_use () ? pthread_mutex_destroy (LOCK) : 0)
176 
177 /* ------------------------- gl_rwlock_t datatype ------------------------- */
178 
179 # if HAVE_PTHREAD_RWLOCK
180 
181 #  ifdef PTHREAD_RWLOCK_INITIALIZER
182 
183 typedef pthread_rwlock_t gl_rwlock_t;
184 #   define gl_rwlock_define(STORAGECLASS, NAME) \
185       STORAGECLASS pthread_rwlock_t NAME;
186 #   define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
187       STORAGECLASS pthread_rwlock_t NAME = gl_rwlock_initializer;
188 #   define gl_rwlock_initializer \
189       PTHREAD_RWLOCK_INITIALIZER
190 #   define glthread_rwlock_init(LOCK) \
191       (pthread_in_use () ? pthread_rwlock_init (LOCK, NULL) : 0)
192 #   define glthread_rwlock_rdlock(LOCK) \
193       (pthread_in_use () ? pthread_rwlock_rdlock (LOCK) : 0)
194 #   define glthread_rwlock_wrlock(LOCK) \
195       (pthread_in_use () ? pthread_rwlock_wrlock (LOCK) : 0)
196 #   define glthread_rwlock_unlock(LOCK) \
197       (pthread_in_use () ? pthread_rwlock_unlock (LOCK) : 0)
198 #   define glthread_rwlock_destroy(LOCK) \
199       (pthread_in_use () ? pthread_rwlock_destroy (LOCK) : 0)
200 
201 #  else
202 
203 typedef struct
204         {
205           int initialized;
206           pthread_mutex_t guard;   /* protects the initialization */
207           pthread_rwlock_t rwlock; /* read-write lock */
208         }
209         gl_rwlock_t;
210 #   define gl_rwlock_define(STORAGECLASS, NAME) \
211       STORAGECLASS gl_rwlock_t NAME;
212 #   define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
213       STORAGECLASS gl_rwlock_t NAME = gl_rwlock_initializer;
214 #   define gl_rwlock_initializer \
215       { 0, PTHREAD_MUTEX_INITIALIZER }
216 #   define glthread_rwlock_init(LOCK) \
217       (pthread_in_use () ? glthread_rwlock_init_multithreaded (LOCK) : 0)
218 #   define glthread_rwlock_rdlock(LOCK) \
219       (pthread_in_use () ? glthread_rwlock_rdlock_multithreaded (LOCK) : 0)
220 #   define glthread_rwlock_wrlock(LOCK) \
221       (pthread_in_use () ? glthread_rwlock_wrlock_multithreaded (LOCK) : 0)
222 #   define glthread_rwlock_unlock(LOCK) \
223       (pthread_in_use () ? glthread_rwlock_unlock_multithreaded (LOCK) : 0)
224 #   define glthread_rwlock_destroy(LOCK) \
225       (pthread_in_use () ? glthread_rwlock_destroy_multithreaded (LOCK) : 0)
226 extern int glthread_rwlock_init_multithreaded (gl_rwlock_t *lock);
227 extern int glthread_rwlock_rdlock_multithreaded (gl_rwlock_t *lock);
228 extern int glthread_rwlock_wrlock_multithreaded (gl_rwlock_t *lock);
229 extern int glthread_rwlock_unlock_multithreaded (gl_rwlock_t *lock);
230 extern int glthread_rwlock_destroy_multithreaded (gl_rwlock_t *lock);
231 
232 #  endif
233 
234 # else
235 
236 typedef struct
237         {
238           pthread_mutex_t lock; /* protects the remaining fields */
239           pthread_cond_t waiting_readers; /* waiting readers */
240           pthread_cond_t waiting_writers; /* waiting writers */
241           unsigned int waiting_writers_count; /* number of waiting writers */
242           int runcount; /* number of readers running, or -1 when a writer runs */
243         }
244         gl_rwlock_t;
245 # define gl_rwlock_define(STORAGECLASS, NAME) \
246     STORAGECLASS gl_rwlock_t NAME;
247 # define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
248     STORAGECLASS gl_rwlock_t NAME = gl_rwlock_initializer;
249 # define gl_rwlock_initializer \
250     { PTHREAD_MUTEX_INITIALIZER, PTHREAD_COND_INITIALIZER, PTHREAD_COND_INITIALIZER, 0, 0 }
251 # define glthread_rwlock_init(LOCK) \
252     (pthread_in_use () ? glthread_rwlock_init_multithreaded (LOCK) : 0)
253 # define glthread_rwlock_rdlock(LOCK) \
254     (pthread_in_use () ? glthread_rwlock_rdlock_multithreaded (LOCK) : 0)
255 # define glthread_rwlock_wrlock(LOCK) \
256     (pthread_in_use () ? glthread_rwlock_wrlock_multithreaded (LOCK) : 0)
257 # define glthread_rwlock_unlock(LOCK) \
258     (pthread_in_use () ? glthread_rwlock_unlock_multithreaded (LOCK) : 0)
259 # define glthread_rwlock_destroy(LOCK) \
260     (pthread_in_use () ? glthread_rwlock_destroy_multithreaded (LOCK) : 0)
261 extern int glthread_rwlock_init_multithreaded (gl_rwlock_t *lock);
262 extern int glthread_rwlock_rdlock_multithreaded (gl_rwlock_t *lock);
263 extern int glthread_rwlock_wrlock_multithreaded (gl_rwlock_t *lock);
264 extern int glthread_rwlock_unlock_multithreaded (gl_rwlock_t *lock);
265 extern int glthread_rwlock_destroy_multithreaded (gl_rwlock_t *lock);
266 
267 # endif
268 
269 /* --------------------- gl_recursive_lock_t datatype --------------------- */
270 
271 # if HAVE_PTHREAD_MUTEX_RECURSIVE
272 
273 #  if defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER || defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
274 
275 typedef pthread_mutex_t gl_recursive_lock_t;
276 #   define gl_recursive_lock_define(STORAGECLASS, NAME) \
277       STORAGECLASS pthread_mutex_t NAME;
278 #   define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
279       STORAGECLASS pthread_mutex_t NAME = gl_recursive_lock_initializer;
280 #   ifdef PTHREAD_RECURSIVE_MUTEX_INITIALIZER
281 #    define gl_recursive_lock_initializer \
282        PTHREAD_RECURSIVE_MUTEX_INITIALIZER
283 #   else
284 #    define gl_recursive_lock_initializer \
285        PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
286 #   endif
287 #   define glthread_recursive_lock_init(LOCK) \
288       (pthread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
289 #   define glthread_recursive_lock_lock(LOCK) \
290       (pthread_in_use () ? pthread_mutex_lock (LOCK) : 0)
291 #   define glthread_recursive_lock_unlock(LOCK) \
292       (pthread_in_use () ? pthread_mutex_unlock (LOCK) : 0)
293 #   define glthread_recursive_lock_destroy(LOCK) \
294       (pthread_in_use () ? pthread_mutex_destroy (LOCK) : 0)
295 extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
296 
297 #  else
298 
299 typedef struct
300         {
301           pthread_mutex_t recmutex; /* recursive mutex */
302           pthread_mutex_t guard;    /* protects the initialization */
303           int initialized;
304         }
305         gl_recursive_lock_t;
306 #   define gl_recursive_lock_define(STORAGECLASS, NAME) \
307       STORAGECLASS gl_recursive_lock_t NAME;
308 #   define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
309       STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
310 #   define gl_recursive_lock_initializer \
311       { PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, 0 }
312 #   define glthread_recursive_lock_init(LOCK) \
313       (pthread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
314 #   define glthread_recursive_lock_lock(LOCK) \
315       (pthread_in_use () ? glthread_recursive_lock_lock_multithreaded (LOCK) : 0)
316 #   define glthread_recursive_lock_unlock(LOCK) \
317       (pthread_in_use () ? glthread_recursive_lock_unlock_multithreaded (LOCK) : 0)
318 #   define glthread_recursive_lock_destroy(LOCK) \
319       (pthread_in_use () ? glthread_recursive_lock_destroy_multithreaded (LOCK) : 0)
320 extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
321 extern int glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock);
322 extern int glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock);
323 extern int glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock);
324 
325 #  endif
326 
327 # else
328 
329 /* Old versions of POSIX threads on Solaris did not have recursive locks.
330    We have to implement them ourselves.  */
331 
332 typedef struct
333         {
334           pthread_mutex_t mutex;
335           pthread_t owner;
336           unsigned long depth;
337         }
338         gl_recursive_lock_t;
339 #  define gl_recursive_lock_define(STORAGECLASS, NAME) \
340      STORAGECLASS gl_recursive_lock_t NAME;
341 #  define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
342      STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
343 #  define gl_recursive_lock_initializer \
344      { PTHREAD_MUTEX_INITIALIZER, (pthread_t) 0, 0 }
345 #  define glthread_recursive_lock_init(LOCK) \
346      (pthread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
347 #  define glthread_recursive_lock_lock(LOCK) \
348      (pthread_in_use () ? glthread_recursive_lock_lock_multithreaded (LOCK) : 0)
349 #  define glthread_recursive_lock_unlock(LOCK) \
350      (pthread_in_use () ? glthread_recursive_lock_unlock_multithreaded (LOCK) : 0)
351 #  define glthread_recursive_lock_destroy(LOCK) \
352      (pthread_in_use () ? glthread_recursive_lock_destroy_multithreaded (LOCK) : 0)
353 extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
354 extern int glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock);
355 extern int glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock);
356 extern int glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock);
357 
358 # endif
359 
360 /* -------------------------- gl_once_t datatype -------------------------- */
361 
362 typedef pthread_once_t gl_once_t;
363 # define gl_once_define(STORAGECLASS, NAME) \
364     STORAGECLASS pthread_once_t NAME = PTHREAD_ONCE_INIT;
365 # define glthread_once(ONCE_CONTROL, INITFUNCTION) \
366     (pthread_in_use ()                                                         \
367      ? pthread_once (ONCE_CONTROL, INITFUNCTION)                               \
368      : (glthread_once_singlethreaded (ONCE_CONTROL) ? (INITFUNCTION (), 0) : 0))
369 extern int glthread_once_singlethreaded (pthread_once_t *once_control);
370 
371 # ifdef __cplusplus
372 }
373 # endif
374 
375 #endif
376 
377 /* ========================================================================= */
378 
379 #if USE_PTH_THREADS
380 
381 /* Use the GNU Pth threads library.  */
382 
383 # include <pth.h>
384 
385 # ifdef __cplusplus
386 extern "C" {
387 # endif
388 
389 # if USE_PTH_THREADS_WEAK
390 
391 /* Use weak references to the GNU Pth threads library.  */
392 
393 #  pragma weak pth_mutex_init
394 #  pragma weak pth_mutex_acquire
395 #  pragma weak pth_mutex_release
396 #  pragma weak pth_rwlock_init
397 #  pragma weak pth_rwlock_acquire
398 #  pragma weak pth_rwlock_release
399 #  pragma weak pth_once
400 
401 #  pragma weak pth_cancel
402 #  define pth_in_use() (pth_cancel != NULL)
403 
404 # else
405 
406 #  define pth_in_use() 1
407 
408 # endif
409 
410 /* -------------------------- gl_lock_t datatype -------------------------- */
411 
412 typedef pth_mutex_t gl_lock_t;
413 # define gl_lock_define(STORAGECLASS, NAME) \
414     STORAGECLASS pth_mutex_t NAME;
415 # define gl_lock_define_initialized(STORAGECLASS, NAME) \
416     STORAGECLASS pth_mutex_t NAME = gl_lock_initializer;
417 # define gl_lock_initializer \
418     PTH_MUTEX_INIT
419 # define glthread_lock_init(LOCK) \
420     (pth_in_use () && !pth_mutex_init (LOCK) ? errno : 0)
421 # define glthread_lock_lock(LOCK) \
422     (pth_in_use () && !pth_mutex_acquire (LOCK, 0, NULL) ? errno : 0)
423 # define glthread_lock_unlock(LOCK) \
424     (pth_in_use () && !pth_mutex_release (LOCK) ? errno : 0)
425 # define glthread_lock_destroy(LOCK) \
426     ((void)(LOCK), 0)
427 
428 /* ------------------------- gl_rwlock_t datatype ------------------------- */
429 
430 typedef pth_rwlock_t gl_rwlock_t;
431 #  define gl_rwlock_define(STORAGECLASS, NAME) \
432      STORAGECLASS pth_rwlock_t NAME;
433 #  define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
434      STORAGECLASS pth_rwlock_t NAME = gl_rwlock_initializer;
435 #  define gl_rwlock_initializer \
436      PTH_RWLOCK_INIT
437 #  define glthread_rwlock_init(LOCK) \
438      (pth_in_use () && !pth_rwlock_init (LOCK) ? errno : 0)
439 #  define glthread_rwlock_rdlock(LOCK) \
440      (pth_in_use () && !pth_rwlock_acquire (LOCK, PTH_RWLOCK_RD, 0, NULL) ? errno : 0)
441 #  define glthread_rwlock_wrlock(LOCK) \
442      (pth_in_use () && !pth_rwlock_acquire (LOCK, PTH_RWLOCK_RW, 0, NULL) ? errno : 0)
443 #  define glthread_rwlock_unlock(LOCK) \
444      (pth_in_use () && !pth_rwlock_release (LOCK) ? errno : 0)
445 #  define glthread_rwlock_destroy(LOCK) \
446      ((void)(LOCK), 0)
447 
448 /* --------------------- gl_recursive_lock_t datatype --------------------- */
449 
450 /* In Pth, mutexes are recursive by default.  */
451 typedef pth_mutex_t gl_recursive_lock_t;
452 #  define gl_recursive_lock_define(STORAGECLASS, NAME) \
453      STORAGECLASS pth_mutex_t NAME;
454 #  define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
455      STORAGECLASS pth_mutex_t NAME = gl_recursive_lock_initializer;
456 #  define gl_recursive_lock_initializer \
457      PTH_MUTEX_INIT
458 #  define glthread_recursive_lock_init(LOCK) \
459      (pth_in_use () && !pth_mutex_init (LOCK) ? errno : 0)
460 #  define glthread_recursive_lock_lock(LOCK) \
461      (pth_in_use () && !pth_mutex_acquire (LOCK, 0, NULL) ? errno : 0)
462 #  define glthread_recursive_lock_unlock(LOCK) \
463      (pth_in_use () && !pth_mutex_release (LOCK) ? errno : 0)
464 #  define glthread_recursive_lock_destroy(LOCK) \
465      ((void)(LOCK), 0)
466 
467 /* -------------------------- gl_once_t datatype -------------------------- */
468 
469 typedef pth_once_t gl_once_t;
470 # define gl_once_define(STORAGECLASS, NAME) \
471     STORAGECLASS pth_once_t NAME = PTH_ONCE_INIT;
472 # define glthread_once(ONCE_CONTROL, INITFUNCTION) \
473     (pth_in_use ()                                                             \
474      ? glthread_once_multithreaded (ONCE_CONTROL, INITFUNCTION)                \
475      : (glthread_once_singlethreaded (ONCE_CONTROL) ? (INITFUNCTION (), 0) : 0))
476 extern int glthread_once_multithreaded (pth_once_t *once_control, void (*initfunction) (void));
477 extern int glthread_once_singlethreaded (pth_once_t *once_control);
478 
479 # ifdef __cplusplus
480 }
481 # endif
482 
483 #endif
484 
485 /* ========================================================================= */
486 
487 #if USE_SOLARIS_THREADS
488 
489 /* Use the old Solaris threads library.  */
490 
491 # include <thread.h>
492 # include <synch.h>
493 
494 # ifdef __cplusplus
495 extern "C" {
496 # endif
497 
498 # if USE_SOLARIS_THREADS_WEAK
499 
500 /* Use weak references to the old Solaris threads library.  */
501 
502 #  pragma weak mutex_init
503 #  pragma weak mutex_lock
504 #  pragma weak mutex_unlock
505 #  pragma weak mutex_destroy
506 #  pragma weak rwlock_init
507 #  pragma weak rw_rdlock
508 #  pragma weak rw_wrlock
509 #  pragma weak rw_unlock
510 #  pragma weak rwlock_destroy
511 #  pragma weak thr_self
512 
513 #  pragma weak thr_suspend
514 #  define thread_in_use() (thr_suspend != NULL)
515 
516 # else
517 
518 #  define thread_in_use() 1
519 
520 # endif
521 
522 /* -------------------------- gl_lock_t datatype -------------------------- */
523 
524 typedef mutex_t gl_lock_t;
525 # define gl_lock_define(STORAGECLASS, NAME) \
526     STORAGECLASS mutex_t NAME;
527 # define gl_lock_define_initialized(STORAGECLASS, NAME) \
528     STORAGECLASS mutex_t NAME = gl_lock_initializer;
529 # define gl_lock_initializer \
530     DEFAULTMUTEX
531 # define glthread_lock_init(LOCK) \
532     (thread_in_use () ? mutex_init (LOCK, USYNC_THREAD, NULL) : 0)
533 # define glthread_lock_lock(LOCK) \
534     (thread_in_use () ? mutex_lock (LOCK) : 0)
535 # define glthread_lock_unlock(LOCK) \
536     (thread_in_use () ? mutex_unlock (LOCK) : 0)
537 # define glthread_lock_destroy(LOCK) \
538     (thread_in_use () ? mutex_destroy (LOCK) : 0)
539 
540 /* ------------------------- gl_rwlock_t datatype ------------------------- */
541 
542 typedef rwlock_t gl_rwlock_t;
543 # define gl_rwlock_define(STORAGECLASS, NAME) \
544     STORAGECLASS rwlock_t NAME;
545 # define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
546     STORAGECLASS rwlock_t NAME = gl_rwlock_initializer;
547 # define gl_rwlock_initializer \
548     DEFAULTRWLOCK
549 # define glthread_rwlock_init(LOCK) \
550     (thread_in_use () ? rwlock_init (LOCK, USYNC_THREAD, NULL) : 0)
551 # define glthread_rwlock_rdlock(LOCK) \
552     (thread_in_use () ? rw_rdlock (LOCK) : 0)
553 # define glthread_rwlock_wrlock(LOCK) \
554     (thread_in_use () ? rw_wrlock (LOCK) : 0)
555 # define glthread_rwlock_unlock(LOCK) \
556     (thread_in_use () ? rw_unlock (LOCK) : 0)
557 # define glthread_rwlock_destroy(LOCK) \
558     (thread_in_use () ? rwlock_destroy (LOCK) : 0)
559 
560 /* --------------------- gl_recursive_lock_t datatype --------------------- */
561 
562 /* Old Solaris threads did not have recursive locks.
563    We have to implement them ourselves.  */
564 
565 typedef struct
566         {
567           mutex_t mutex;
568           thread_t owner;
569           unsigned long depth;
570         }
571         gl_recursive_lock_t;
572 # define gl_recursive_lock_define(STORAGECLASS, NAME) \
573     STORAGECLASS gl_recursive_lock_t NAME;
574 # define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
575     STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
576 # define gl_recursive_lock_initializer \
577     { DEFAULTMUTEX, (thread_t) 0, 0 }
578 # define glthread_recursive_lock_init(LOCK) \
579     (thread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
580 # define glthread_recursive_lock_lock(LOCK) \
581     (thread_in_use () ? glthread_recursive_lock_lock_multithreaded (LOCK) : 0)
582 # define glthread_recursive_lock_unlock(LOCK) \
583     (thread_in_use () ? glthread_recursive_lock_unlock_multithreaded (LOCK) : 0)
584 # define glthread_recursive_lock_destroy(LOCK) \
585     (thread_in_use () ? glthread_recursive_lock_destroy_multithreaded (LOCK) : 0)
586 extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
587 extern int glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock);
588 extern int glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock);
589 extern int glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock);
590 
591 /* -------------------------- gl_once_t datatype -------------------------- */
592 
593 typedef struct
594         {
595           volatile int inited;
596           mutex_t mutex;
597         }
598         gl_once_t;
599 # define gl_once_define(STORAGECLASS, NAME) \
600     STORAGECLASS gl_once_t NAME = { 0, DEFAULTMUTEX };
601 # define glthread_once(ONCE_CONTROL, INITFUNCTION) \
602     (thread_in_use ()                                                          \
603      ? glthread_once_multithreaded (ONCE_CONTROL, INITFUNCTION)                \
604      : (glthread_once_singlethreaded (ONCE_CONTROL) ? (INITFUNCTION (), 0) : 0))
605 extern int glthread_once_multithreaded (gl_once_t *once_control, void (*initfunction) (void));
606 extern int glthread_once_singlethreaded (gl_once_t *once_control);
607 
608 # ifdef __cplusplus
609 }
610 # endif
611 
612 #endif
613 
614 /* ========================================================================= */
615 
616 #if USE_WINDOWS_THREADS
617 
618 # define WIN32_LEAN_AND_MEAN  /* avoid including junk */
619 # include <windows.h>
620 
621 # ifdef __cplusplus
622 extern "C" {
623 # endif
624 
625 /* We can use CRITICAL_SECTION directly, rather than the native Windows Event,
626    Mutex, Semaphore types, because
627      - we need only to synchronize inside a single process (address space),
628        not inter-process locking,
629      - we don't need to support trylock operations.  (TryEnterCriticalSection
630        does not work on Windows 95/98/ME.  Packages that need trylock usually
631        define their own mutex type.)  */
632 
633 /* There is no way to statically initialize a CRITICAL_SECTION.  It needs
634    to be done lazily, once only.  For this we need spinlocks.  */
635 
636 typedef struct { volatile int done; volatile long started; } gl_spinlock_t;
637 
638 /* -------------------------- gl_lock_t datatype -------------------------- */
639 
640 typedef struct
641         {
642           gl_spinlock_t guard; /* protects the initialization */
643           CRITICAL_SECTION lock;
644         }
645         gl_lock_t;
646 # define gl_lock_define(STORAGECLASS, NAME) \
647     STORAGECLASS gl_lock_t NAME;
648 # define gl_lock_define_initialized(STORAGECLASS, NAME) \
649     STORAGECLASS gl_lock_t NAME = gl_lock_initializer;
650 # define gl_lock_initializer \
651     { { 0, -1 } }
652 # define glthread_lock_init(LOCK) \
653     (glthread_lock_init_func (LOCK), 0)
654 # define glthread_lock_lock(LOCK) \
655     glthread_lock_lock_func (LOCK)
656 # define glthread_lock_unlock(LOCK) \
657     glthread_lock_unlock_func (LOCK)
658 # define glthread_lock_destroy(LOCK) \
659     glthread_lock_destroy_func (LOCK)
660 extern void glthread_lock_init_func (gl_lock_t *lock);
661 extern int glthread_lock_lock_func (gl_lock_t *lock);
662 extern int glthread_lock_unlock_func (gl_lock_t *lock);
663 extern int glthread_lock_destroy_func (gl_lock_t *lock);
664 
665 /* ------------------------- gl_rwlock_t datatype ------------------------- */
666 
667 /* It is impossible to implement read-write locks using plain locks, without
668    introducing an extra thread dedicated to managing read-write locks.
669    Therefore here we need to use the low-level Event type.  */
670 
671 typedef struct
672         {
673           HANDLE *array; /* array of waiting threads, each represented by an event */
674           unsigned int count; /* number of waiting threads */
675           unsigned int alloc; /* length of allocated array */
676           unsigned int offset; /* index of first waiting thread in array */
677         }
678         gl_carray_waitqueue_t;
679 typedef struct
680         {
681           gl_spinlock_t guard; /* protects the initialization */
682           CRITICAL_SECTION lock; /* protects the remaining fields */
683           gl_carray_waitqueue_t waiting_readers; /* waiting readers */
684           gl_carray_waitqueue_t waiting_writers; /* waiting writers */
685           int runcount; /* number of readers running, or -1 when a writer runs */
686         }
687         gl_rwlock_t;
688 # define gl_rwlock_define(STORAGECLASS, NAME) \
689     STORAGECLASS gl_rwlock_t NAME;
690 # define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
691     STORAGECLASS gl_rwlock_t NAME = gl_rwlock_initializer;
692 # define gl_rwlock_initializer \
693     { { 0, -1 } }
694 # define glthread_rwlock_init(LOCK) \
695     (glthread_rwlock_init_func (LOCK), 0)
696 # define glthread_rwlock_rdlock(LOCK) \
697     glthread_rwlock_rdlock_func (LOCK)
698 # define glthread_rwlock_wrlock(LOCK) \
699     glthread_rwlock_wrlock_func (LOCK)
700 # define glthread_rwlock_unlock(LOCK) \
701     glthread_rwlock_unlock_func (LOCK)
702 # define glthread_rwlock_destroy(LOCK) \
703     glthread_rwlock_destroy_func (LOCK)
704 extern void glthread_rwlock_init_func (gl_rwlock_t *lock);
705 extern int glthread_rwlock_rdlock_func (gl_rwlock_t *lock);
706 extern int glthread_rwlock_wrlock_func (gl_rwlock_t *lock);
707 extern int glthread_rwlock_unlock_func (gl_rwlock_t *lock);
708 extern int glthread_rwlock_destroy_func (gl_rwlock_t *lock);
709 
710 /* --------------------- gl_recursive_lock_t datatype --------------------- */
711 
712 /* The native Windows documentation says that CRITICAL_SECTION already
713    implements a recursive lock.  But we need not rely on it: It's easy to
714    implement a recursive lock without this assumption.  */
715 
716 typedef struct
717         {
718           gl_spinlock_t guard; /* protects the initialization */
719           DWORD owner;
720           unsigned long depth;
721           CRITICAL_SECTION lock;
722         }
723         gl_recursive_lock_t;
724 # define gl_recursive_lock_define(STORAGECLASS, NAME) \
725     STORAGECLASS gl_recursive_lock_t NAME;
726 # define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
727     STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
728 # define gl_recursive_lock_initializer \
729     { { 0, -1 }, 0, 0 }
730 # define glthread_recursive_lock_init(LOCK) \
731     (glthread_recursive_lock_init_func (LOCK), 0)
732 # define glthread_recursive_lock_lock(LOCK) \
733     glthread_recursive_lock_lock_func (LOCK)
734 # define glthread_recursive_lock_unlock(LOCK) \
735     glthread_recursive_lock_unlock_func (LOCK)
736 # define glthread_recursive_lock_destroy(LOCK) \
737     glthread_recursive_lock_destroy_func (LOCK)
738 extern void glthread_recursive_lock_init_func (gl_recursive_lock_t *lock);
739 extern int glthread_recursive_lock_lock_func (gl_recursive_lock_t *lock);
740 extern int glthread_recursive_lock_unlock_func (gl_recursive_lock_t *lock);
741 extern int glthread_recursive_lock_destroy_func (gl_recursive_lock_t *lock);
742 
743 /* -------------------------- gl_once_t datatype -------------------------- */
744 
745 typedef struct
746         {
747           volatile int inited;
748           volatile long started;
749           CRITICAL_SECTION lock;
750         }
751         gl_once_t;
752 # define gl_once_define(STORAGECLASS, NAME) \
753     STORAGECLASS gl_once_t NAME = { -1, -1 };
754 # define glthread_once(ONCE_CONTROL, INITFUNCTION) \
755     (glthread_once_func (ONCE_CONTROL, INITFUNCTION), 0)
756 extern void glthread_once_func (gl_once_t *once_control, void (*initfunction) (void));
757 
758 # ifdef __cplusplus
759 }
760 # endif
761 
762 #endif
763 
764 /* ========================================================================= */
765 
766 #if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_SOLARIS_THREADS || USE_WINDOWS_THREADS)
767 
768 /* Provide dummy implementation if threads are not supported.  */
769 
770 /* -------------------------- gl_lock_t datatype -------------------------- */
771 
772 typedef int gl_lock_t;
773 # define gl_lock_define(STORAGECLASS, NAME)
774 # define gl_lock_define_initialized(STORAGECLASS, NAME)
775 # define glthread_lock_init(NAME) 0
776 # define glthread_lock_lock(NAME) 0
777 # define glthread_lock_unlock(NAME) 0
778 # define glthread_lock_destroy(NAME) 0
779 
780 /* ------------------------- gl_rwlock_t datatype ------------------------- */
781 
782 typedef int gl_rwlock_t;
783 # define gl_rwlock_define(STORAGECLASS, NAME)
784 # define gl_rwlock_define_initialized(STORAGECLASS, NAME)
785 # define glthread_rwlock_init(NAME) 0
786 # define glthread_rwlock_rdlock(NAME) 0
787 # define glthread_rwlock_wrlock(NAME) 0
788 # define glthread_rwlock_unlock(NAME) 0
789 # define glthread_rwlock_destroy(NAME) 0
790 
791 /* --------------------- gl_recursive_lock_t datatype --------------------- */
792 
793 typedef int gl_recursive_lock_t;
794 # define gl_recursive_lock_define(STORAGECLASS, NAME)
795 # define gl_recursive_lock_define_initialized(STORAGECLASS, NAME)
796 # define glthread_recursive_lock_init(NAME) 0
797 # define glthread_recursive_lock_lock(NAME) 0
798 # define glthread_recursive_lock_unlock(NAME) 0
799 # define glthread_recursive_lock_destroy(NAME) 0
800 
801 /* -------------------------- gl_once_t datatype -------------------------- */
802 
803 typedef int gl_once_t;
804 # define gl_once_define(STORAGECLASS, NAME) \
805     STORAGECLASS gl_once_t NAME = 0;
806 # define glthread_once(ONCE_CONTROL, INITFUNCTION) \
807     (*(ONCE_CONTROL) == 0 ? (*(ONCE_CONTROL) = ~ 0, INITFUNCTION (), 0) : 0)
808 
809 #endif
810 
811 /* ========================================================================= */
812 
813 /* Macros with built-in error handling.  */
814 
815 /* -------------------------- gl_lock_t datatype -------------------------- */
816 
817 #define gl_lock_init(NAME) \
818    do                                  \
819      {                                 \
820        if (glthread_lock_init (&NAME)) \
821          abort ();                     \
822      }                                 \
823    while (0)
824 #define gl_lock_lock(NAME) \
825    do                                  \
826      {                                 \
827        if (glthread_lock_lock (&NAME)) \
828          abort ();                     \
829      }                                 \
830    while (0)
831 #define gl_lock_unlock(NAME) \
832    do                                    \
833      {                                   \
834        if (glthread_lock_unlock (&NAME)) \
835          abort ();                       \
836      }                                   \
837    while (0)
838 #define gl_lock_destroy(NAME) \
839    do                                     \
840      {                                    \
841        if (glthread_lock_destroy (&NAME)) \
842          abort ();                        \
843      }                                    \
844    while (0)
845 
846 /* ------------------------- gl_rwlock_t datatype ------------------------- */
847 
848 #define gl_rwlock_init(NAME) \
849    do                                    \
850      {                                   \
851        if (glthread_rwlock_init (&NAME)) \
852          abort ();                       \
853      }                                   \
854    while (0)
855 #define gl_rwlock_rdlock(NAME) \
856    do                                      \
857      {                                     \
858        if (glthread_rwlock_rdlock (&NAME)) \
859          abort ();                         \
860      }                                     \
861    while (0)
862 #define gl_rwlock_wrlock(NAME) \
863    do                                      \
864      {                                     \
865        if (glthread_rwlock_wrlock (&NAME)) \
866          abort ();                         \
867      }                                     \
868    while (0)
869 #define gl_rwlock_unlock(NAME) \
870    do                                      \
871      {                                     \
872        if (glthread_rwlock_unlock (&NAME)) \
873          abort ();                         \
874      }                                     \
875    while (0)
876 #define gl_rwlock_destroy(NAME) \
877    do                                       \
878      {                                      \
879        if (glthread_rwlock_destroy (&NAME)) \
880          abort ();                          \
881      }                                      \
882    while (0)
883 
884 /* --------------------- gl_recursive_lock_t datatype --------------------- */
885 
886 #define gl_recursive_lock_init(NAME) \
887    do                                            \
888      {                                           \
889        if (glthread_recursive_lock_init (&NAME)) \
890          abort ();                               \
891      }                                           \
892    while (0)
893 #define gl_recursive_lock_lock(NAME) \
894    do                                            \
895      {                                           \
896        if (glthread_recursive_lock_lock (&NAME)) \
897          abort ();                               \
898      }                                           \
899    while (0)
900 #define gl_recursive_lock_unlock(NAME) \
901    do                                              \
902      {                                             \
903        if (glthread_recursive_lock_unlock (&NAME)) \
904          abort ();                                 \
905      }                                             \
906    while (0)
907 #define gl_recursive_lock_destroy(NAME) \
908    do                                               \
909      {                                              \
910        if (glthread_recursive_lock_destroy (&NAME)) \
911          abort ();                                  \
912      }                                              \
913    while (0)
914 
915 /* -------------------------- gl_once_t datatype -------------------------- */
916 
917 #define gl_once(NAME, INITFUNCTION) \
918    do                                           \
919      {                                          \
920        if (glthread_once (&NAME, INITFUNCTION)) \
921          abort ();                              \
922      }                                          \
923    while (0)
924 
925 /* ========================================================================= */
926 
927 #endif /* _LOCK_H */
928