intl/lock.h

   1 /* Locking in multithreaded situations.
   2    Copyright (C) 2005-2008 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify it
   5    under the terms of the GNU Library General Public License as published
   6    by the Free Software Foundation; either version 2, 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 GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with this program; if not, write to the Free Software
  16    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  17    USA.  */
  18
  19 /* Written by Bruno Haible <bruno@clisp.org>, 2005.
  20    Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-solaris.h,
  21    gthr-win32.h.  */
  22
  23 /* This file contains locking primitives for use with a given thread library.
  24    It does not contain primitives for creating threads or for other
  25    synchronization primitives.
  26
  27    Normal (non-recursive) locks:
  28      Type:                gl_lock_t
  29      Declaration:         gl_lock_define(extern, name)
  30      Initializer:         gl_lock_define_initialized(, name)
  31      Initialization:      gl_lock_init (name);
  32      Taking the lock:     gl_lock_lock (name);
  33      Releasing the lock:  gl_lock_unlock (name);
  34      De-initialization:   gl_lock_destroy (name);
  35    Equivalent functions with control of error handling:
  36      Initialization:      err = glthread_lock_init (&name);
  37      Taking the lock:     err = glthread_lock_lock (&name);
  38      Releasing the lock:  err = glthread_lock_unlock (&name);
  39      De-initialization:   err = glthread_lock_destroy (&name);
  40
  41    Read-Write (non-recursive) locks:
  42      Type:                gl_rwlock_t
  43      Declaration:         gl_rwlock_define(extern, name)
  44      Initializer:         gl_rwlock_define_initialized(, name)
  45      Initialization:      gl_rwlock_init (name);
  46      Taking the lock:     gl_rwlock_rdlock (name);
  47                           gl_rwlock_wrlock (name);
  48      Releasing the lock:  gl_rwlock_unlock (name);
  49      De-initialization:   gl_rwlock_destroy (name);
  50    Equivalent functions with control of error handling:
  51      Initialization:      err = glthread_rwlock_init (&name);
  52      Taking the lock:     err = glthread_rwlock_rdlock (&name);
  53                           err = glthread_rwlock_wrlock (&name);
  54      Releasing the lock:  err = glthread_rwlock_unlock (&name);
  55      De-initialization:   err = glthread_rwlock_destroy (&name);
  56
  57    Recursive locks:
  58      Type:                gl_recursive_lock_t
  59      Declaration:         gl_recursive_lock_define(extern, name)
  60      Initializer:         gl_recursive_lock_define_initialized(, name)
  61      Initialization:      gl_recursive_lock_init (name);
  62      Taking the lock:     gl_recursive_lock_lock (name);
  63      Releasing the lock:  gl_recursive_lock_unlock (name);
  64      De-initialization:   gl_recursive_lock_destroy (name);
  65    Equivalent functions with control of error handling:
  66      Initialization:      err = glthread_recursive_lock_init (&name);
  67      Taking the lock:     err = glthread_recursive_lock_lock (&name);
  68      Releasing the lock:  err = glthread_recursive_lock_unlock (&name);
  69      De-initialization:   err = glthread_recursive_lock_destroy (&name);
  70
  71   Once-only execution:
  72      Type:                gl_once_t
  73      Initializer:         gl_once_define(extern, name)
  74      Execution:           gl_once (name, initfunction);
  75    Equivalent functions with control of error handling:
  76      Execution:           err = glthread_once (&name, initfunction);
  77 */
  78
  79
  80 #ifndef _LOCK_H
  81 #define _LOCK_H
  82
  83 #include <errno.h>
  84 #include <stdlib.h>
  85
  86 /* ========================================================================= */
  87
  88 #if USE_POSIX_THREADS
  89
  90 /* Use the POSIX threads library.  */
  91
  92 # include <pthread.h>
  93
  94 # ifdef __cplusplus
  95 extern "C" {
  96 # endif
  97
  98 # if PTHREAD_IN_USE_DETECTION_HARD
  99
 100 /* The pthread_in_use() detection needs to be done at runtime.  */
 101 #  define pthread_in_use() \
 102      glthread_in_use ()
 103 extern int glthread_in_use (void);
 104
 105 # endif
 106
 107 # if USE_POSIX_THREADS_WEAK
 108
 109 /* Use weak references to the POSIX threads library.  */
 110
 111 /* Weak references avoid dragging in external libraries if the other parts
 112    of the program don't use them.  Here we use them, because we don't want
 113    every program that uses libintl to depend on libpthread.  This assumes
 114    that libpthread would not be loaded after libintl; i.e. if libintl is
 115    loaded first, by an executable that does not depend on libpthread, and
 116    then a module is dynamically loaded that depends on libpthread, libintl
 117    will not be multithread-safe.  */
 118
 119 /* The way to test at runtime whether libpthread is present is to test
 120    whether a function pointer's value, such as &pthread_mutex_init, is
 121    non-NULL.  However, some versions of GCC have a bug through which, in
 122    PIC mode, &foo != NULL always evaluates to true if there is a direct
 123    call to foo(...) in the same function.  To avoid this, we test the
 124    address of a function in libpthread that we don't use.  */
 125
 126 #  pragma weak pthread_mutex_init
 127 #  pragma weak pthread_mutex_lock
 128 #  pragma weak pthread_mutex_unlock
 129 #  pragma weak pthread_mutex_destroy
 130 #  pragma weak pthread_rwlock_init
 131 #  pragma weak pthread_rwlock_rdlock
 132 #  pragma weak pthread_rwlock_wrlock
 133 #  pragma weak pthread_rwlock_unlock
 134 #  pragma weak pthread_rwlock_destroy
 135 #  pragma weak pthread_once
 136 #  pragma weak pthread_cond_init
 137 #  pragma weak pthread_cond_wait
 138 #  pragma weak pthread_cond_signal
 139 #  pragma weak pthread_cond_broadcast
 140 #  pragma weak pthread_cond_destroy
 141 #  pragma weak pthread_mutexattr_init
 142 #  pragma weak pthread_mutexattr_settype
 143 #  pragma weak pthread_mutexattr_destroy
 144 #  ifndef pthread_self
 145 #   pragma weak pthread_self
 146 #  endif
 147
 148 #  if !PTHREAD_IN_USE_DETECTION_HARD
 149 #   pragma weak pthread_cancel
 150 #   define pthread_in_use() (pthread_cancel != NULL)
 151 #  endif
 152
 153 # else
 154
 155 #  if !PTHREAD_IN_USE_DETECTION_HARD
 156 #   define pthread_in_use() 1
 157 #  endif
 158
 159 # endif
 160
 161 /* -------------------------- gl_lock_t datatype -------------------------- */
 162
 163 typedef pthread_mutex_t gl_lock_t;
 164 # define gl_lock_define(STORAGECLASS, NAME) \
 165     STORAGECLASS pthread_mutex_t NAME;
 166 # define gl_lock_define_initialized(STORAGECLASS, NAME) \
 167     STORAGECLASS pthread_mutex_t NAME = gl_lock_initializer;
 168 # define gl_lock_initializer \
 169     PTHREAD_MUTEX_INITIALIZER
 170 # define glthread_lock_init(LOCK) \
 171     (pthread_in_use () ? pthread_mutex_init (LOCK, NULL) : 0)
 172 # define glthread_lock_lock(LOCK) \
 173     (pthread_in_use () ? pthread_mutex_lock (LOCK) : 0)
 174 # define glthread_lock_unlock(LOCK) \
 175     (pthread_in_use () ? pthread_mutex_unlock (LOCK) : 0)
 176 # define glthread_lock_destroy(LOCK) \
 177     (pthread_in_use () ? pthread_mutex_destroy (LOCK) : 0)
 178
 179 /* ------------------------- gl_rwlock_t datatype ------------------------- */
 180
 181 # if HAVE_PTHREAD_RWLOCK
 182
 183 #  ifdef PTHREAD_RWLOCK_INITIALIZER
 184
 185 typedef pthread_rwlock_t gl_rwlock_t;
 186 #   define gl_rwlock_define(STORAGECLASS, NAME) \
 187       STORAGECLASS pthread_rwlock_t NAME;
 188 #   define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
 189       STORAGECLASS pthread_rwlock_t NAME = gl_rwlock_initializer;
 190 #   define gl_rwlock_initializer \
 191       PTHREAD_RWLOCK_INITIALIZER
 192 #   define glthread_rwlock_init(LOCK) \
 193       (pthread_in_use () ? pthread_rwlock_init (LOCK, NULL) : 0)
 194 #   define glthread_rwlock_rdlock(LOCK) \
 195       (pthread_in_use () ? pthread_rwlock_rdlock (LOCK) : 0)
 196 #   define glthread_rwlock_wrlock(LOCK) \
 197       (pthread_in_use () ? pthread_rwlock_wrlock (LOCK) : 0)
 198 #   define glthread_rwlock_unlock(LOCK) \
 199       (pthread_in_use () ? pthread_rwlock_unlock (LOCK) : 0)
 200 #   define glthread_rwlock_destroy(LOCK) \
 201       (pthread_in_use () ? pthread_rwlock_destroy (LOCK) : 0)
 202
 203 #  else
 204
 205 typedef struct
 206         {
 207           int initialized;
 208           pthread_mutex_t guard;   /* protects the initialization */
 209           pthread_rwlock_t rwlock; /* read-write lock */
 210         }
 211         gl_rwlock_t;
 212 #   define gl_rwlock_define(STORAGECLASS, NAME) \
 213       STORAGECLASS gl_rwlock_t NAME;
 214 #   define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
 215       STORAGECLASS gl_rwlock_t NAME = gl_rwlock_initializer;
 216 #   define gl_rwlock_initializer \
 217       { 0, PTHREAD_MUTEX_INITIALIZER }
 218 #   define glthread_rwlock_init(LOCK) \
 219       (pthread_in_use () ? glthread_rwlock_init_multithreaded (LOCK) : 0)
 220 #   define glthread_rwlock_rdlock(LOCK) \
 221       (pthread_in_use () ? glthread_rwlock_rdlock_multithreaded (LOCK) : 0)
 222 #   define glthread_rwlock_wrlock(LOCK) \
 223       (pthread_in_use () ? glthread_rwlock_wrlock_multithreaded (LOCK) : 0)
 224 #   define glthread_rwlock_unlock(LOCK) \
 225       (pthread_in_use () ? glthread_rwlock_unlock_multithreaded (LOCK) : 0)
 226 #   define glthread_rwlock_destroy(LOCK) \
 227       (pthread_in_use () ? glthread_rwlock_destroy_multithreaded (LOCK) : 0)
 228 extern int glthread_rwlock_init_multithreaded (gl_rwlock_t *lock);
 229 extern int glthread_rwlock_rdlock_multithreaded (gl_rwlock_t *lock);
 230 extern int glthread_rwlock_wrlock_multithreaded (gl_rwlock_t *lock);
 231 extern int glthread_rwlock_unlock_multithreaded (gl_rwlock_t *lock);
 232 extern int glthread_rwlock_destroy_multithreaded (gl_rwlock_t *lock);
 233
 234 #  endif
 235
 236 # else
 237
 238 typedef struct
 239         {
 240           pthread_mutex_t lock; /* protects the remaining fields */
 241           pthread_cond_t waiting_readers; /* waiting readers */
 242           pthread_cond_t waiting_writers; /* waiting writers */
 243           unsigned int waiting_writers_count; /* number of waiting writers */
 244           int runcount; /* number of readers running, or -1 when a writer runs */
 245         }
 246         gl_rwlock_t;
 247 # define gl_rwlock_define(STORAGECLASS, NAME) \
 248     STORAGECLASS gl_rwlock_t NAME;
 249 # define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
 250     STORAGECLASS gl_rwlock_t NAME = gl_rwlock_initializer;
 251 # define gl_rwlock_initializer \
 252     { PTHREAD_MUTEX_INITIALIZER, PTHREAD_COND_INITIALIZER, PTHREAD_COND_INITIALIZER, 0, 0 }
 253 # define glthread_rwlock_init(LOCK) \
 254     (pthread_in_use () ? glthread_rwlock_init_multithreaded (LOCK) : 0)
 255 # define glthread_rwlock_rdlock(LOCK) \
 256     (pthread_in_use () ? glthread_rwlock_rdlock_multithreaded (LOCK) : 0)
 257 # define glthread_rwlock_wrlock(LOCK) \
 258     (pthread_in_use () ? glthread_rwlock_wrlock_multithreaded (LOCK) : 0)
 259 # define glthread_rwlock_unlock(LOCK) \
 260     (pthread_in_use () ? glthread_rwlock_unlock_multithreaded (LOCK) : 0)
 261 # define glthread_rwlock_destroy(LOCK) \
 262     (pthread_in_use () ? glthread_rwlock_destroy_multithreaded (LOCK) : 0)
 263 extern int glthread_rwlock_init_multithreaded (gl_rwlock_t *lock);
 264 extern int glthread_rwlock_rdlock_multithreaded (gl_rwlock_t *lock);
 265 extern int glthread_rwlock_wrlock_multithreaded (gl_rwlock_t *lock);
 266 extern int glthread_rwlock_unlock_multithreaded (gl_rwlock_t *lock);
 267 extern int glthread_rwlock_destroy_multithreaded (gl_rwlock_t *lock);
 268
 269 # endif
 270
 271 /* --------------------- gl_recursive_lock_t datatype --------------------- */
 272
 273 # if HAVE_PTHREAD_MUTEX_RECURSIVE
 274
 275 #  if defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER || defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
 276
 277 typedef pthread_mutex_t gl_recursive_lock_t;
 278 #   define gl_recursive_lock_define(STORAGECLASS, NAME) \
 279       STORAGECLASS pthread_mutex_t NAME;
 280 #   define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
 281       STORAGECLASS pthread_mutex_t NAME = gl_recursive_lock_initializer;
 282 #   ifdef PTHREAD_RECURSIVE_MUTEX_INITIALIZER
 283 #    define gl_recursive_lock_initializer \
 284        PTHREAD_RECURSIVE_MUTEX_INITIALIZER
 285 #   else
 286 #    define gl_recursive_lock_initializer \
 287        PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
 288 #   endif
 289 #   define glthread_recursive_lock_init(LOCK) \
 290       (pthread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
 291 #   define glthread_recursive_lock_lock(LOCK) \
 292       (pthread_in_use () ? pthread_mutex_lock (LOCK) : 0)
 293 #   define glthread_recursive_lock_unlock(LOCK) \
 294       (pthread_in_use () ? pthread_mutex_unlock (LOCK) : 0)
 295 #   define glthread_recursive_lock_destroy(LOCK) \
 296       (pthread_in_use () ? pthread_mutex_destroy (LOCK) : 0)
 297 extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
 298
 299 #  else
 300
 301 typedef struct
 302         {
 303           pthread_mutex_t recmutex; /* recursive mutex */
 304           pthread_mutex_t guard;    /* protects the initialization */
 305           int initialized;
 306         }
 307         gl_recursive_lock_t;
 308 #   define gl_recursive_lock_define(STORAGECLASS, NAME) \
 309       STORAGECLASS gl_recursive_lock_t NAME;
 310 #   define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
 311       STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
 312 #   define gl_recursive_lock_initializer \
 313       { PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, 0 }
 314 #   define glthread_recursive_lock_init(LOCK) \
 315       (pthread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
 316 #   define glthread_recursive_lock_lock(LOCK) \
 317       (pthread_in_use () ? glthread_recursive_lock_lock_multithreaded (LOCK) : 0)
 318 #   define glthread_recursive_lock_unlock(LOCK) \
 319       (pthread_in_use () ? glthread_recursive_lock_unlock_multithreaded (LOCK) : 0)
 320 #   define glthread_recursive_lock_destroy(LOCK) \
 321       (pthread_in_use () ? glthread_recursive_lock_destroy_multithreaded (LOCK) : 0)
 322 extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
 323 extern int glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock);
 324 extern int glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock);
 325 extern int glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock);
 326
 327 #  endif
 328
 329 # else
 330
 331 /* Old versions of POSIX threads on Solaris did not have recursive locks.
 332    We have to implement them ourselves.  */
 333
 334 typedef struct
 335         {
 336           pthread_mutex_t mutex;
 337           pthread_t owner;
 338           unsigned long depth;
 339         }
 340         gl_recursive_lock_t;
 341 #  define gl_recursive_lock_define(STORAGECLASS, NAME) \
 342      STORAGECLASS gl_recursive_lock_t NAME;
 343 #  define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
 344      STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
 345 #  define gl_recursive_lock_initializer \
 346      { PTHREAD_MUTEX_INITIALIZER, (pthread_t) 0, 0 }
 347 #  define glthread_recursive_lock_init(LOCK) \
 348      (pthread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
 349 #  define glthread_recursive_lock_lock(LOCK) \
 350      (pthread_in_use () ? glthread_recursive_lock_lock_multithreaded (LOCK) : 0)
 351 #  define glthread_recursive_lock_unlock(LOCK) \
 352      (pthread_in_use () ? glthread_recursive_lock_unlock_multithreaded (LOCK) : 0)
 353 #  define glthread_recursive_lock_destroy(LOCK) \
 354      (pthread_in_use () ? glthread_recursive_lock_destroy_multithreaded (LOCK) : 0)
 355 extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
 356 extern int glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock);
 357 extern int glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock);
 358 extern int glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock);
 359
 360 # endif
 361
 362 /* -------------------------- gl_once_t datatype -------------------------- */
 363
 364 typedef pthread_once_t gl_once_t;
 365 # define gl_once_define(STORAGECLASS, NAME) \
 366     STORAGECLASS pthread_once_t NAME = PTHREAD_ONCE_INIT;
 367 # define glthread_once(ONCE_CONTROL, INITFUNCTION) \
 368     (pthread_in_use ()                                                         \
 369      ? pthread_once (ONCE_CONTROL, INITFUNCTION)                               \
 370      : (glthread_once_singlethreaded (ONCE_CONTROL) ? (INITFUNCTION (), 0) : 0))
 371 extern int glthread_once_singlethreaded (pthread_once_t *once_control);
 372
 373 # ifdef __cplusplus
 374 }
 375 # endif
 376
 377 #endif
 378
 379 /* ========================================================================= */
 380
 381 #if USE_PTH_THREADS
 382
 383 /* Use the GNU Pth threads library.  */
 384
 385 # include <pth.h>
 386
 387 # ifdef __cplusplus
 388 extern "C" {
 389 # endif
 390
 391 # if USE_PTH_THREADS_WEAK
 392
 393 /* Use weak references to the GNU Pth threads library.  */
 394
 395 #  pragma weak pth_mutex_init
 396 #  pragma weak pth_mutex_acquire
 397 #  pragma weak pth_mutex_release
 398 #  pragma weak pth_rwlock_init
 399 #  pragma weak pth_rwlock_acquire
 400 #  pragma weak pth_rwlock_release
 401 #  pragma weak pth_once
 402
 403 #  pragma weak pth_cancel
 404 #  define pth_in_use() (pth_cancel != NULL)
 405
 406 # else
 407
 408 #  define pth_in_use() 1
 409
 410 # endif
 411
 412 /* -------------------------- gl_lock_t datatype -------------------------- */
 413
 414 typedef pth_mutex_t gl_lock_t;
 415 # define gl_lock_define(STORAGECLASS, NAME) \
 416     STORAGECLASS pth_mutex_t NAME;
 417 # define gl_lock_define_initialized(STORAGECLASS, NAME) \
 418     STORAGECLASS pth_mutex_t NAME = gl_lock_initializer;
 419 # define gl_lock_initializer \
 420     PTH_MUTEX_INIT
 421 # define glthread_lock_init(LOCK) \
 422     (pth_in_use () && !pth_mutex_init (LOCK) ? errno : 0)
 423 # define glthread_lock_lock(LOCK) \
 424     (pth_in_use () && !pth_mutex_acquire (LOCK, 0, NULL) ? errno : 0)
 425 # define glthread_lock_unlock(LOCK) \
 426     (pth_in_use () && !pth_mutex_release (LOCK) ? errno : 0)
 427 # define glthread_lock_destroy(LOCK) \
 428     ((void)(LOCK), 0)
 429
 430 /* ------------------------- gl_rwlock_t datatype ------------------------- */
 431
 432 typedef pth_rwlock_t gl_rwlock_t;
 433 #  define gl_rwlock_define(STORAGECLASS, NAME) \
 434      STORAGECLASS pth_rwlock_t NAME;
 435 #  define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
 436      STORAGECLASS pth_rwlock_t NAME = gl_rwlock_initializer;
 437 #  define gl_rwlock_initializer \
 438      PTH_RWLOCK_INIT
 439 #  define glthread_rwlock_init(LOCK) \
 440      (pth_in_use () && !pth_rwlock_init (LOCK) ? errno : 0)
 441 #  define glthread_rwlock_rdlock(LOCK) \
 442      (pth_in_use () && !pth_rwlock_acquire (LOCK, PTH_RWLOCK_RD, 0, NULL) ? errno : 0)
 443 #  define glthread_rwlock_wrlock(LOCK) \
 444      (pth_in_use () && !pth_rwlock_acquire (LOCK, PTH_RWLOCK_RW, 0, NULL) ? errno : 0)
 445 #  define glthread_rwlock_unlock(LOCK) \
 446      (pth_in_use () && !pth_rwlock_release (LOCK) ? errno : 0)
 447 #  define glthread_rwlock_destroy(LOCK) \
 448      ((void)(LOCK), 0)
 449
 450 /* --------------------- gl_recursive_lock_t datatype --------------------- */
 451
 452 /* In Pth, mutexes are recursive by default.  */
 453 typedef pth_mutex_t gl_recursive_lock_t;
 454 #  define gl_recursive_lock_define(STORAGECLASS, NAME) \
 455      STORAGECLASS pth_mutex_t NAME;
 456 #  define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
 457      STORAGECLASS pth_mutex_t NAME = gl_recursive_lock_initializer;
 458 #  define gl_recursive_lock_initializer \
 459      PTH_MUTEX_INIT
 460 #  define glthread_recursive_lock_init(LOCK) \
 461      (pth_in_use () && !pth_mutex_init (LOCK) ? errno : 0)
 462 #  define glthread_recursive_lock_lock(LOCK) \
 463      (pth_in_use () && !pth_mutex_acquire (LOCK, 0, NULL) ? errno : 0)
 464 #  define glthread_recursive_lock_unlock(LOCK) \
 465      (pth_in_use () && !pth_mutex_release (LOCK) ? errno : 0)
 466 #  define glthread_recursive_lock_destroy(LOCK) \
 467      ((void)(LOCK), 0)
 468
 469 /* -------------------------- gl_once_t datatype -------------------------- */
 470
 471 typedef pth_once_t gl_once_t;
 472 # define gl_once_define(STORAGECLASS, NAME) \
 473     STORAGECLASS pth_once_t NAME = PTH_ONCE_INIT;
 474 # define glthread_once(ONCE_CONTROL, INITFUNCTION) \
 475     (pth_in_use ()                                                             \
 476      ? glthread_once_multithreaded (ONCE_CONTROL, INITFUNCTION)                \
 477      : (glthread_once_singlethreaded (ONCE_CONTROL) ? (INITFUNCTION (), 0) : 0))
 478 extern int glthread_once_multithreaded (pth_once_t *once_control, void (*initfunction) (void));
 479 extern int glthread_once_singlethreaded (pth_once_t *once_control);
 480
 481 # ifdef __cplusplus
 482 }
 483 # endif
 484
 485 #endif
 486
 487 /* ========================================================================= */
 488
 489 #if USE_SOLARIS_THREADS
 490
 491 /* Use the old Solaris threads library.  */
 492
 493 # include <thread.h>
 494 # include <synch.h>
 495
 496 # ifdef __cplusplus
 497 extern "C" {
 498 # endif
 499
 500 # if USE_SOLARIS_THREADS_WEAK
 501
 502 /* Use weak references to the old Solaris threads library.  */
 503
 504 #  pragma weak mutex_init
 505 #  pragma weak mutex_lock
 506 #  pragma weak mutex_unlock
 507 #  pragma weak mutex_destroy
 508 #  pragma weak rwlock_init
 509 #  pragma weak rw_rdlock
 510 #  pragma weak rw_wrlock
 511 #  pragma weak rw_unlock
 512 #  pragma weak rwlock_destroy
 513 #  pragma weak thr_self
 514
 515 #  pragma weak thr_suspend
 516 #  define thread_in_use() (thr_suspend != NULL)
 517
 518 # else
 519
 520 #  define thread_in_use() 1
 521
 522 # endif
 523
 524 /* -------------------------- gl_lock_t datatype -------------------------- */
 525
 526 typedef mutex_t gl_lock_t;
 527 # define gl_lock_define(STORAGECLASS, NAME) \
 528     STORAGECLASS mutex_t NAME;
 529 # define gl_lock_define_initialized(STORAGECLASS, NAME) \
 530     STORAGECLASS mutex_t NAME = gl_lock_initializer;
 531 # define gl_lock_initializer \
 532     DEFAULTMUTEX
 533 # define glthread_lock_init(LOCK) \
 534     (thread_in_use () ? mutex_init (LOCK, USYNC_THREAD, NULL) : 0)
 535 # define glthread_lock_lock(LOCK) \
 536     (thread_in_use () ? mutex_lock (LOCK) : 0)
 537 # define glthread_lock_unlock(LOCK) \
 538     (thread_in_use () ? mutex_unlock (LOCK) : 0)
 539 # define glthread_lock_destroy(LOCK) \
 540     (thread_in_use () ? mutex_destroy (LOCK) : 0)
 541
 542 /* ------------------------- gl_rwlock_t datatype ------------------------- */
 543
 544 typedef rwlock_t gl_rwlock_t;
 545 # define gl_rwlock_define(STORAGECLASS, NAME) \
 546     STORAGECLASS rwlock_t NAME;
 547 # define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
 548     STORAGECLASS rwlock_t NAME = gl_rwlock_initializer;
 549 # define gl_rwlock_initializer \
 550     DEFAULTRWLOCK
 551 # define glthread_rwlock_init(LOCK) \
 552     (thread_in_use () ? rwlock_init (LOCK, USYNC_THREAD, NULL) : 0)
 553 # define glthread_rwlock_rdlock(LOCK) \
 554     (thread_in_use () ? rw_rdlock (LOCK) : 0)
 555 # define glthread_rwlock_wrlock(LOCK) \
 556     (thread_in_use () ? rw_wrlock (LOCK) : 0)
 557 # define glthread_rwlock_unlock(LOCK) \
 558     (thread_in_use () ? rw_unlock (LOCK) : 0)
 559 # define glthread_rwlock_destroy(LOCK) \
 560     (thread_in_use () ? rwlock_destroy (LOCK) : 0)
 561
 562 /* --------------------- gl_recursive_lock_t datatype --------------------- */
 563
 564 /* Old Solaris threads did not have recursive locks.
 565    We have to implement them ourselves.  */
 566
 567 typedef struct
 568         {
 569           mutex_t mutex;
 570           thread_t owner;
 571           unsigned long depth;
 572         }
 573         gl_recursive_lock_t;
 574 # define gl_recursive_lock_define(STORAGECLASS, NAME) \
 575     STORAGECLASS gl_recursive_lock_t NAME;
 576 # define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
 577     STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
 578 # define gl_recursive_lock_initializer \
 579     { DEFAULTMUTEX, (thread_t) 0, 0 }
 580 # define glthread_recursive_lock_init(LOCK) \
 581     (thread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
 582 # define glthread_recursive_lock_lock(LOCK) \
 583     (thread_in_use () ? glthread_recursive_lock_lock_multithreaded (LOCK) : 0)
 584 # define glthread_recursive_lock_unlock(LOCK) \
 585     (thread_in_use () ? glthread_recursive_lock_unlock_multithreaded (LOCK) : 0)
 586 # define glthread_recursive_lock_destroy(LOCK) \
 587     (thread_in_use () ? glthread_recursive_lock_destroy_multithreaded (LOCK) : 0)
 588 extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
 589 extern int glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock);
 590 extern int glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock);
 591 extern int glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock);
 592
 593 /* -------------------------- gl_once_t datatype -------------------------- */
 594
 595 typedef struct
 596         {
 597           volatile int inited;
 598           mutex_t mutex;
 599         }
 600         gl_once_t;
 601 # define gl_once_define(STORAGECLASS, NAME) \
 602     STORAGECLASS gl_once_t NAME = { 0, DEFAULTMUTEX };
 603 # define glthread_once(ONCE_CONTROL, INITFUNCTION) \
 604     (thread_in_use ()                                                          \
 605      ? glthread_once_multithreaded (ONCE_CONTROL, INITFUNCTION)                \
 606      : (glthread_once_singlethreaded (ONCE_CONTROL) ? (INITFUNCTION (), 0) : 0))
 607 extern int glthread_once_multithreaded (gl_once_t *once_control, void (*initfunction) (void));
 608 extern int glthread_once_singlethreaded (gl_once_t *once_control);
 609
 610 # ifdef __cplusplus
 611 }
 612 # endif
 613
 614 #endif
 615
 616 /* ========================================================================= */
 617
 618 #if USE_WIN32_THREADS
 619
 620 # include <windows.h>
 621
 622 # ifdef __cplusplus
 623 extern "C" {
 624 # endif
 625
 626 /* We can use CRITICAL_SECTION directly, rather than the Win32 Event, Mutex,
 627    Semaphore types, because
 628      - we need only to synchronize inside a single process (address space),
 629        not inter-process locking,
 630      - we don't need to support trylock operations.  (TryEnterCriticalSection
 631        does not work on Windows 95/98/ME.  Packages that need trylock usually
 632        define their own mutex type.)  */
 633
 634 /* There is no way to statically initialize a CRITICAL_SECTION.  It needs
 635    to be done lazily, once only.  For this we need spinlocks.  */
 636
 637 typedef struct { volatile int done; volatile long started; } gl_spinlock_t;
 638
 639 /* -------------------------- gl_lock_t datatype -------------------------- */
 640
 641 typedef struct
 642         {
 643           gl_spinlock_t guard; /* protects the initialization */
 644           CRITICAL_SECTION lock;
 645         }
 646         gl_lock_t;
 647 # define gl_lock_define(STORAGECLASS, NAME) \
 648     STORAGECLASS gl_lock_t NAME;
 649 # define gl_lock_define_initialized(STORAGECLASS, NAME) \
 650     STORAGECLASS gl_lock_t NAME = gl_lock_initializer;
 651 # define gl_lock_initializer \
 652     { { 0, -1 } }
 653 # define glthread_lock_init(LOCK) \
 654     (glthread_lock_init_func (LOCK), 0)
 655 # define glthread_lock_lock(LOCK) \
 656     glthread_lock_lock_func (LOCK)
 657 # define glthread_lock_unlock(LOCK) \
 658     glthread_lock_unlock_func (LOCK)
 659 # define glthread_lock_destroy(LOCK) \
 660     glthread_lock_destroy_func (LOCK)
 661 extern void glthread_lock_init_func (gl_lock_t *lock);
 662 extern int glthread_lock_lock_func (gl_lock_t *lock);
 663 extern int glthread_lock_unlock_func (gl_lock_t *lock);
 664 extern int glthread_lock_destroy_func (gl_lock_t *lock);
 665
 666 /* ------------------------- gl_rwlock_t datatype ------------------------- */
 667
 668 /* It is impossible to implement read-write locks using plain locks, without
 669    introducing an extra thread dedicated to managing read-write locks.
 670    Therefore here we need to use the low-level Event type.  */
 671
 672 typedef struct
 673         {
 674           HANDLE *array; /* array of waiting threads, each represented by an event */
 675           unsigned int count; /* number of waiting threads */
 676           unsigned int alloc; /* length of allocated array */
 677           unsigned int offset; /* index of first waiting thread in array */
 678         }
 679         gl_carray_waitqueue_t;
 680 typedef struct
 681         {
 682           gl_spinlock_t guard; /* protects the initialization */
 683           CRITICAL_SECTION lock; /* protects the remaining fields */
 684           gl_carray_waitqueue_t waiting_readers; /* waiting readers */
 685           gl_carray_waitqueue_t waiting_writers; /* waiting writers */
 686           int runcount; /* number of readers running, or -1 when a writer runs */
 687         }
 688         gl_rwlock_t;
 689 # define gl_rwlock_define(STORAGECLASS, NAME) \
 690     STORAGECLASS gl_rwlock_t NAME;
 691 # define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
 692     STORAGECLASS gl_rwlock_t NAME = gl_rwlock_initializer;
 693 # define gl_rwlock_initializer \
 694     { { 0, -1 } }
 695 # define glthread_rwlock_init(LOCK) \
 696     (glthread_rwlock_init_func (LOCK), 0)
 697 # define glthread_rwlock_rdlock(LOCK) \
 698     glthread_rwlock_rdlock_func (LOCK)
 699 # define glthread_rwlock_wrlock(LOCK) \
 700     glthread_rwlock_wrlock_func (LOCK)
 701 # define glthread_rwlock_unlock(LOCK) \
 702     glthread_rwlock_unlock_func (LOCK)
 703 # define glthread_rwlock_destroy(LOCK) \
 704     glthread_rwlock_destroy_func (LOCK)
 705 extern void glthread_rwlock_init_func (gl_rwlock_t *lock);
 706 extern int glthread_rwlock_rdlock_func (gl_rwlock_t *lock);
 707 extern int glthread_rwlock_wrlock_func (gl_rwlock_t *lock);
 708 extern int glthread_rwlock_unlock_func (gl_rwlock_t *lock);
 709 extern int glthread_rwlock_destroy_func (gl_rwlock_t *lock);
 710
 711 /* --------------------- gl_recursive_lock_t datatype --------------------- */
 712
 713 /* The Win32 documentation says that CRITICAL_SECTION already implements a
 714    recursive lock.  But we need not rely on it: It's easy to implement a
 715    recursive lock without this assumption.  */
 716
 717 typedef struct
 718         {
 719           gl_spinlock_t guard; /* protects the initialization */
 720           DWORD owner;
 721           unsigned long depth;
 722           CRITICAL_SECTION lock;
 723         }
 724         gl_recursive_lock_t;
 725 # define gl_recursive_lock_define(STORAGECLASS, NAME) \
 726     STORAGECLASS gl_recursive_lock_t NAME;
 727 # define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
 728     STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
 729 # define gl_recursive_lock_initializer \
 730     { { 0, -1 }, 0, 0 }
 731 # define glthread_recursive_lock_init(LOCK) \
 732     (glthread_recursive_lock_init_func (LOCK), 0)
 733 # define glthread_recursive_lock_lock(LOCK) \
 734     glthread_recursive_lock_lock_func (LOCK)
 735 # define glthread_recursive_lock_unlock(LOCK) \
 736     glthread_recursive_lock_unlock_func (LOCK)
 737 # define glthread_recursive_lock_destroy(LOCK) \
 738     glthread_recursive_lock_destroy_func (LOCK)
 739 extern void glthread_recursive_lock_init_func (gl_recursive_lock_t *lock);
 740 extern int glthread_recursive_lock_lock_func (gl_recursive_lock_t *lock);
 741 extern int glthread_recursive_lock_unlock_func (gl_recursive_lock_t *lock);
 742 extern int glthread_recursive_lock_destroy_func (gl_recursive_lock_t *lock);
 743
 744 /* -------------------------- gl_once_t datatype -------------------------- */
 745
 746 typedef struct
 747         {
 748           volatile int inited;
 749           volatile long started;
 750           CRITICAL_SECTION lock;
 751         }
 752         gl_once_t;
 753 # define gl_once_define(STORAGECLASS, NAME) \
 754     STORAGECLASS gl_once_t NAME = { -1, -1 };
 755 # define glthread_once(ONCE_CONTROL, INITFUNCTION) \
 756     (glthread_once_func (ONCE_CONTROL, INITFUNCTION), 0)
 757 extern void glthread_once_func (gl_once_t *once_control, void (*initfunction) (void));
 758
 759 # ifdef __cplusplus
 760 }
 761 # endif
 762
 763 #endif
 764
 765 /* ========================================================================= */
 766
 767 #if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_SOLARIS_THREADS || USE_WIN32_THREADS)
 768
 769 /* Provide dummy implementation if threads are not supported.  */
 770
 771 /* -------------------------- gl_lock_t datatype -------------------------- */
 772
 773 typedef int gl_lock_t;
 774 # define gl_lock_define(STORAGECLASS, NAME)
 775 # define gl_lock_define_initialized(STORAGECLASS, NAME)
 776 # define glthread_lock_init(NAME) 0
 777 # define glthread_lock_lock(NAME) 0
 778 # define glthread_lock_unlock(NAME) 0
 779 # define glthread_lock_destroy(NAME) 0
 780
 781 /* ------------------------- gl_rwlock_t datatype ------------------------- */
 782
 783 typedef int gl_rwlock_t;
 784 # define gl_rwlock_define(STORAGECLASS, NAME)
 785 # define gl_rwlock_define_initialized(STORAGECLASS, NAME)
 786 # define glthread_rwlock_init(NAME) 0
 787 # define glthread_rwlock_rdlock(NAME) 0
 788 # define glthread_rwlock_wrlock(NAME) 0
 789 # define glthread_rwlock_unlock(NAME) 0
 790 # define glthread_rwlock_destroy(NAME) 0
 791
 792 /* --------------------- gl_recursive_lock_t datatype --------------------- */
 793
 794 typedef int gl_recursive_lock_t;
 795 # define gl_recursive_lock_define(STORAGECLASS, NAME)
 796 # define gl_recursive_lock_define_initialized(STORAGECLASS, NAME)
 797 # define glthread_recursive_lock_init(NAME) 0
 798 # define glthread_recursive_lock_lock(NAME) 0
 799 # define glthread_recursive_lock_unlock(NAME) 0
 800 # define glthread_recursive_lock_destroy(NAME) 0
 801
 802 /* -------------------------- gl_once_t datatype -------------------------- */
 803
 804 typedef int gl_once_t;
 805 # define gl_once_define(STORAGECLASS, NAME) \
 806     STORAGECLASS gl_once_t NAME = 0;
 807 # define glthread_once(ONCE_CONTROL, INITFUNCTION) \
 808     (*(ONCE_CONTROL) == 0 ? (*(ONCE_CONTROL) = ~ 0, INITFUNCTION (), 0) : 0)
 809
 810 #endif
 811
 812 /* ========================================================================= */
 813
 814 /* Macros with built-in error handling.  */
 815
 816 /* -------------------------- gl_lock_t datatype -------------------------- */
 817
 818 #define gl_lock_init(NAME) \
 819    do                                  \
 820      {                                 \
 821        if (glthread_lock_init (&NAME)) \
 822          abort ();                     \
 823      }                                 \
 824    while (0)
 825 #define gl_lock_lock(NAME) \
 826    do                                  \
 827      {                                 \
 828        if (glthread_lock_lock (&NAME)) \
 829          abort ();                     \
 830      }                                 \
 831    while (0)
 832 #define gl_lock_unlock(NAME) \
 833    do                                    \
 834      {                                   \
 835        if (glthread_lock_unlock (&NAME)) \
 836          abort ();                       \
 837      }                                   \
 838    while (0)
 839 #define gl_lock_destroy(NAME) \
 840    do                                     \
 841      {                                    \
 842        if (glthread_lock_destroy (&NAME)) \
 843          abort ();                        \
 844      }                                    \
 845    while (0)
 846
 847 /* ------------------------- gl_rwlock_t datatype ------------------------- */
 848
 849 #define gl_rwlock_init(NAME) \
 850    do                                    \
 851      {                                   \
 852        if (glthread_rwlock_init (&NAME)) \
 853          abort ();                       \
 854      }                                   \
 855    while (0)
 856 #define gl_rwlock_rdlock(NAME) \
 857    do                                      \
 858      {                                     \
 859        if (glthread_rwlock_rdlock (&NAME)) \
 860          abort ();                         \
 861      }                                     \
 862    while (0)
 863 #define gl_rwlock_wrlock(NAME) \
 864    do                                      \
 865      {                                     \
 866        if (glthread_rwlock_wrlock (&NAME)) \
 867          abort ();                         \
 868      }                                     \
 869    while (0)
 870 #define gl_rwlock_unlock(NAME) \
 871    do                                      \
 872      {                                     \
 873        if (glthread_rwlock_unlock (&NAME)) \
 874          abort ();                         \
 875      }                                     \
 876    while (0)
 877 #define gl_rwlock_destroy(NAME) \
 878    do                                       \
 879      {                                      \
 880        if (glthread_rwlock_destroy (&NAME)) \
 881          abort ();                          \
 882      }                                      \
 883    while (0)
 884
 885 /* --------------------- gl_recursive_lock_t datatype --------------------- */
 886
 887 #define gl_recursive_lock_init(NAME) \
 888    do                                            \
 889      {                                           \
 890        if (glthread_recursive_lock_init (&NAME)) \
 891          abort ();                               \
 892      }                                           \
 893    while (0)
 894 #define gl_recursive_lock_lock(NAME) \
 895    do                                            \
 896      {                                           \
 897        if (glthread_recursive_lock_lock (&NAME)) \
 898          abort ();                               \
 899      }                                           \
 900    while (0)
 901 #define gl_recursive_lock_unlock(NAME) \
 902    do                                              \
 903      {                                             \
 904        if (glthread_recursive_lock_unlock (&NAME)) \
 905          abort ();                                 \
 906      }                                             \
 907    while (0)
 908 #define gl_recursive_lock_destroy(NAME) \
 909    do                                               \
 910      {                                              \
 911        if (glthread_recursive_lock_destroy (&NAME)) \
 912          abort ();                                  \
 913      }                                              \
 914    while (0)
 915
 916 /* -------------------------- gl_once_t datatype -------------------------- */
 917
 918 #define gl_once(NAME, INITFUNCTION) \
 919    do                                           \
 920      {                                          \
 921        if (glthread_once (&NAME, INITFUNCTION)) \
 922          abort ();                              \
 923      }                                          \
 924    while (0)
 925
 926 /* ========================================================================= */
 927
 928 #endif /* _LOCK_H */