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   1 /* Locking in multithreaded situations.
   2    Copyright (C) 2005-2010 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, write to the Free Software Foundation,
  16    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  17
  18 /* Written by Bruno Haible <bruno@clisp.org>, 2005.
  19    Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-solaris.h,
  20    gthr-win32.h.  */
  21
  22 /* This file contains locking primitives for use with a given thread library.
  23    It does not contain primitives for creating threads or for other
  24    synchronization primitives.
  25
  26    Normal (non-recursive) locks:
  27      Type:                gl_lock_t
  28      Declaration:         gl_lock_define(extern, name)
  29      Initializer:         gl_lock_define_initialized(, name)
  30      Initialization:      gl_lock_init (name);
  31      Taking the lock:     gl_lock_lock (name);
  32      Releasing the lock:  gl_lock_unlock (name);
  33      De-initialization:   gl_lock_destroy (name);
  34    Equivalent functions with control of error handling:
  35      Initialization:      err = glthread_lock_init (&name);
  36      Taking the lock:     err = glthread_lock_lock (&name);
  37      Releasing the lock:  err = glthread_lock_unlock (&name);
  38      De-initialization:   err = glthread_lock_destroy (&name);
  39
  40    Read-Write (non-recursive) locks:
  41      Type:                gl_rwlock_t
  42      Declaration:         gl_rwlock_define(extern, name)
  43      Initializer:         gl_rwlock_define_initialized(, name)
  44      Initialization:      gl_rwlock_init (name);
  45      Taking the lock:     gl_rwlock_rdlock (name);
  46                           gl_rwlock_wrlock (name);
  47      Releasing the lock:  gl_rwlock_unlock (name);
  48      De-initialization:   gl_rwlock_destroy (name);
  49    Equivalent functions with control of error handling:
  50      Initialization:      err = glthread_rwlock_init (&name);
  51      Taking the lock:     err = glthread_rwlock_rdlock (&name);
  52                           err = glthread_rwlock_wrlock (&name);
  53      Releasing the lock:  err = glthread_rwlock_unlock (&name);
  54      De-initialization:   err = glthread_rwlock_destroy (&name);
  55
  56    Recursive locks:
  57      Type:                gl_recursive_lock_t
  58      Declaration:         gl_recursive_lock_define(extern, name)
  59      Initializer:         gl_recursive_lock_define_initialized(, name)
  60      Initialization:      gl_recursive_lock_init (name);
  61      Taking the lock:     gl_recursive_lock_lock (name);
  62      Releasing the lock:  gl_recursive_lock_unlock (name);
  63      De-initialization:   gl_recursive_lock_destroy (name);
  64    Equivalent functions with control of error handling:
  65      Initialization:      err = glthread_recursive_lock_init (&name);
  66      Taking the lock:     err = glthread_recursive_lock_lock (&name);
  67      Releasing the lock:  err = glthread_recursive_lock_unlock (&name);
  68      De-initialization:   err = glthread_recursive_lock_destroy (&name);
  69
  70   Once-only execution:
  71      Type:                gl_once_t
  72      Initializer:         gl_once_define(extern, name)
  73      Execution:           gl_once (name, initfunction);
  74    Equivalent functions with control of error handling:
  75      Execution:           err = glthread_once (&name, initfunction);
  76 */
  77
  78
  79 #ifndef _LOCK_H
  80 #define _LOCK_H
  81
  82 #include <errno.h>
  83 #include <stdlib.h>
  84
  85 /* ========================================================================= */
  86
  87 #if USE_POSIX_THREADS
  88
  89 /* Use the POSIX threads library.  */
  90
  91 # include <pthread.h>
  92
  93 # ifdef __cplusplus
  94 extern "C" {
  95 # endif
  96
  97 # if PTHREAD_IN_USE_DETECTION_HARD
  98
  99 /* The pthread_in_use() detection needs to be done at runtime.  */
 100 #  define pthread_in_use() \
 101      glthread_in_use ()
 102 extern int glthread_in_use (void);
 103
 104 # endif
 105
 106 # if USE_POSIX_THREADS_WEAK
 107
 108 /* Use weak references to the POSIX threads library.  */
 109
 110 /* Weak references avoid dragging in external libraries if the other parts
 111    of the program don't use them.  Here we use them, because we don't want
 112    every program that uses libintl to depend on libpthread.  This assumes
 113    that libpthread would not be loaded after libintl; i.e. if libintl is
 114    loaded first, by an executable that does not depend on libpthread, and
 115    then a module is dynamically loaded that depends on libpthread, libintl
 116    will not be multithread-safe.  */
 117
 118 /* The way to test at runtime whether libpthread is present is to test
 119    whether a function pointer's value, such as &pthread_mutex_init, is
 120    non-NULL.  However, some versions of GCC have a bug through which, in
 121    PIC mode, &foo != NULL always evaluates to true if there is a direct
 122    call to foo(...) in the same function.  To avoid this, we test the
 123    address of a function in libpthread that we don't use.  */
 124
 125 #  pragma weak pthread_mutex_init
 126 #  pragma weak pthread_mutex_lock
 127 #  pragma weak pthread_mutex_unlock
 128 #  pragma weak pthread_mutex_destroy
 129 #  pragma weak pthread_rwlock_init
 130 #  pragma weak pthread_rwlock_rdlock
 131 #  pragma weak pthread_rwlock_wrlock
 132 #  pragma weak pthread_rwlock_unlock
 133 #  pragma weak pthread_rwlock_destroy
 134 #  pragma weak pthread_once
 135 #  pragma weak pthread_cond_init
 136 #  pragma weak pthread_cond_wait
 137 #  pragma weak pthread_cond_signal
 138 #  pragma weak pthread_cond_broadcast
 139 #  pragma weak pthread_cond_destroy
 140 #  pragma weak pthread_mutexattr_init
 141 #  pragma weak pthread_mutexattr_settype
 142 #  pragma weak pthread_mutexattr_destroy
 143 #  ifndef pthread_self
 144 #   pragma weak pthread_self
 145 #  endif
 146
 147 #  if !PTHREAD_IN_USE_DETECTION_HARD
 148 #   pragma weak pthread_cancel
 149 #   define pthread_in_use() (pthread_cancel != NULL)
 150 #  endif
 151
 152 # else
 153
 154 #  if !PTHREAD_IN_USE_DETECTION_HARD
 155 #   define pthread_in_use() 1
 156 #  endif
 157
 158 # endif
 159
 160 /* -------------------------- gl_lock_t datatype -------------------------- */
 161
 162 typedef pthread_mutex_t gl_lock_t;
 163 # define gl_lock_define(STORAGECLASS, NAME) \
 164     STORAGECLASS pthread_mutex_t NAME;
 165 # define gl_lock_define_initialized(STORAGECLASS, NAME) \
 166     STORAGECLASS pthread_mutex_t NAME = gl_lock_initializer;
 167 # define gl_lock_initializer \
 168     PTHREAD_MUTEX_INITIALIZER
 169 # define glthread_lock_init(LOCK) \
 170     (pthread_in_use () ? pthread_mutex_init (LOCK, NULL) : 0)
 171 # define glthread_lock_lock(LOCK) \
 172     (pthread_in_use () ? pthread_mutex_lock (LOCK) : 0)
 173 # define glthread_lock_unlock(LOCK) \
 174     (pthread_in_use () ? pthread_mutex_unlock (LOCK) : 0)
 175 # define glthread_lock_destroy(LOCK) \
 176     (pthread_in_use () ? pthread_mutex_destroy (LOCK) : 0)
 177
 178 /* ------------------------- gl_rwlock_t datatype ------------------------- */
 179
 180 # if HAVE_PTHREAD_RWLOCK
 181
 182 #  ifdef PTHREAD_RWLOCK_INITIALIZER
 183
 184 typedef pthread_rwlock_t gl_rwlock_t;
 185 #   define gl_rwlock_define(STORAGECLASS, NAME) \
 186       STORAGECLASS pthread_rwlock_t NAME;
 187 #   define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
 188       STORAGECLASS pthread_rwlock_t NAME = gl_rwlock_initializer;
 189 #   define gl_rwlock_initializer \
 190       PTHREAD_RWLOCK_INITIALIZER
 191 #   define glthread_rwlock_init(LOCK) \
 192       (pthread_in_use () ? pthread_rwlock_init (LOCK, NULL) : 0)
 193 #   define glthread_rwlock_rdlock(LOCK) \
 194       (pthread_in_use () ? pthread_rwlock_rdlock (LOCK) : 0)
 195 #   define glthread_rwlock_wrlock(LOCK) \
 196       (pthread_in_use () ? pthread_rwlock_wrlock (LOCK) : 0)
 197 #   define glthread_rwlock_unlock(LOCK) \
 198       (pthread_in_use () ? pthread_rwlock_unlock (LOCK) : 0)
 199 #   define glthread_rwlock_destroy(LOCK) \
 200       (pthread_in_use () ? pthread_rwlock_destroy (LOCK) : 0)
 201
 202 #  else
 203
 204 typedef struct
 205         {
 206           int initialized;
 207           pthread_mutex_t guard;   /* protects the initialization */
 208           pthread_rwlock_t rwlock; /* read-write lock */
 209         }
 210         gl_rwlock_t;
 211 #   define gl_rwlock_define(STORAGECLASS, NAME) \
 212       STORAGECLASS gl_rwlock_t NAME;
 213 #   define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
 214       STORAGECLASS gl_rwlock_t NAME = gl_rwlock_initializer;
 215 #   define gl_rwlock_initializer \
 216       { 0, PTHREAD_MUTEX_INITIALIZER }
 217 #   define glthread_rwlock_init(LOCK) \
 218       (pthread_in_use () ? glthread_rwlock_init_multithreaded (LOCK) : 0)
 219 #   define glthread_rwlock_rdlock(LOCK) \
 220       (pthread_in_use () ? glthread_rwlock_rdlock_multithreaded (LOCK) : 0)
 221 #   define glthread_rwlock_wrlock(LOCK) \
 222       (pthread_in_use () ? glthread_rwlock_wrlock_multithreaded (LOCK) : 0)
 223 #   define glthread_rwlock_unlock(LOCK) \
 224       (pthread_in_use () ? glthread_rwlock_unlock_multithreaded (LOCK) : 0)
 225 #   define glthread_rwlock_destroy(LOCK) \
 226       (pthread_in_use () ? glthread_rwlock_destroy_multithreaded (LOCK) : 0)
 227 extern int glthread_rwlock_init_multithreaded (gl_rwlock_t *lock);
 228 extern int glthread_rwlock_rdlock_multithreaded (gl_rwlock_t *lock);
 229 extern int glthread_rwlock_wrlock_multithreaded (gl_rwlock_t *lock);
 230 extern int glthread_rwlock_unlock_multithreaded (gl_rwlock_t *lock);
 231 extern int glthread_rwlock_destroy_multithreaded (gl_rwlock_t *lock);
 232
 233 #  endif
 234
 235 # else
 236
 237 typedef struct
 238         {
 239           pthread_mutex_t lock; /* protects the remaining fields */
 240           pthread_cond_t waiting_readers; /* waiting readers */
 241           pthread_cond_t waiting_writers; /* waiting writers */
 242           unsigned int waiting_writers_count; /* number of waiting writers */
 243           int runcount; /* number of readers running, or -1 when a writer runs */
 244         }
 245         gl_rwlock_t;
 246 # define gl_rwlock_define(STORAGECLASS, NAME) \
 247     STORAGECLASS gl_rwlock_t NAME;
 248 # define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
 249     STORAGECLASS gl_rwlock_t NAME = gl_rwlock_initializer;
 250 # define gl_rwlock_initializer \
 251     { PTHREAD_MUTEX_INITIALIZER, PTHREAD_COND_INITIALIZER, PTHREAD_COND_INITIALIZER, 0, 0 }
 252 # define glthread_rwlock_init(LOCK) \
 253     (pthread_in_use () ? glthread_rwlock_init_multithreaded (LOCK) : 0)
 254 # define glthread_rwlock_rdlock(LOCK) \
 255     (pthread_in_use () ? glthread_rwlock_rdlock_multithreaded (LOCK) : 0)
 256 # define glthread_rwlock_wrlock(LOCK) \
 257     (pthread_in_use () ? glthread_rwlock_wrlock_multithreaded (LOCK) : 0)
 258 # define glthread_rwlock_unlock(LOCK) \
 259     (pthread_in_use () ? glthread_rwlock_unlock_multithreaded (LOCK) : 0)
 260 # define glthread_rwlock_destroy(LOCK) \
 261     (pthread_in_use () ? glthread_rwlock_destroy_multithreaded (LOCK) : 0)
 262 extern int glthread_rwlock_init_multithreaded (gl_rwlock_t *lock);
 263 extern int glthread_rwlock_rdlock_multithreaded (gl_rwlock_t *lock);
 264 extern int glthread_rwlock_wrlock_multithreaded (gl_rwlock_t *lock);
 265 extern int glthread_rwlock_unlock_multithreaded (gl_rwlock_t *lock);
 266 extern int glthread_rwlock_destroy_multithreaded (gl_rwlock_t *lock);
 267
 268 # endif
 269
 270 /* --------------------- gl_recursive_lock_t datatype --------------------- */
 271
 272 # if HAVE_PTHREAD_MUTEX_RECURSIVE
 273
 274 #  if defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER || defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
 275
 276 typedef pthread_mutex_t gl_recursive_lock_t;
 277 #   define gl_recursive_lock_define(STORAGECLASS, NAME) \
 278       STORAGECLASS pthread_mutex_t NAME;
 279 #   define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
 280       STORAGECLASS pthread_mutex_t NAME = gl_recursive_lock_initializer;
 281 #   ifdef PTHREAD_RECURSIVE_MUTEX_INITIALIZER
 282 #    define gl_recursive_lock_initializer \
 283        PTHREAD_RECURSIVE_MUTEX_INITIALIZER
 284 #   else
 285 #    define gl_recursive_lock_initializer \
 286        PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
 287 #   endif
 288 #   define glthread_recursive_lock_init(LOCK) \
 289       (pthread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
 290 #   define glthread_recursive_lock_lock(LOCK) \
 291       (pthread_in_use () ? pthread_mutex_lock (LOCK) : 0)
 292 #   define glthread_recursive_lock_unlock(LOCK) \
 293       (pthread_in_use () ? pthread_mutex_unlock (LOCK) : 0)
 294 #   define glthread_recursive_lock_destroy(LOCK) \
 295       (pthread_in_use () ? pthread_mutex_destroy (LOCK) : 0)
 296 extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
 297
 298 #  else
 299
 300 typedef struct
 301         {
 302           pthread_mutex_t recmutex; /* recursive mutex */
 303           pthread_mutex_t guard;    /* protects the initialization */
 304           int initialized;
 305         }
 306         gl_recursive_lock_t;
 307 #   define gl_recursive_lock_define(STORAGECLASS, NAME) \
 308       STORAGECLASS gl_recursive_lock_t NAME;
 309 #   define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
 310       STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
 311 #   define gl_recursive_lock_initializer \
 312       { PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, 0 }
 313 #   define glthread_recursive_lock_init(LOCK) \
 314       (pthread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
 315 #   define glthread_recursive_lock_lock(LOCK) \
 316       (pthread_in_use () ? glthread_recursive_lock_lock_multithreaded (LOCK) : 0)
 317 #   define glthread_recursive_lock_unlock(LOCK) \
 318       (pthread_in_use () ? glthread_recursive_lock_unlock_multithreaded (LOCK) : 0)
 319 #   define glthread_recursive_lock_destroy(LOCK) \
 320       (pthread_in_use () ? glthread_recursive_lock_destroy_multithreaded (LOCK) : 0)
 321 extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
 322 extern int glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock);
 323 extern int glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock);
 324 extern int glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock);
 325
 326 #  endif
 327
 328 # else
 329
 330 /* Old versions of POSIX threads on Solaris did not have recursive locks.
 331    We have to implement them ourselves.  */
 332
 333 typedef struct
 334         {
 335           pthread_mutex_t mutex;
 336           pthread_t owner;
 337           unsigned long depth;
 338         }
 339         gl_recursive_lock_t;
 340 #  define gl_recursive_lock_define(STORAGECLASS, NAME) \
 341      STORAGECLASS gl_recursive_lock_t NAME;
 342 #  define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
 343      STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
 344 #  define gl_recursive_lock_initializer \
 345      { PTHREAD_MUTEX_INITIALIZER, (pthread_t) 0, 0 }
 346 #  define glthread_recursive_lock_init(LOCK) \
 347      (pthread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
 348 #  define glthread_recursive_lock_lock(LOCK) \
 349      (pthread_in_use () ? glthread_recursive_lock_lock_multithreaded (LOCK) : 0)
 350 #  define glthread_recursive_lock_unlock(LOCK) \
 351      (pthread_in_use () ? glthread_recursive_lock_unlock_multithreaded (LOCK) : 0)
 352 #  define glthread_recursive_lock_destroy(LOCK) \
 353      (pthread_in_use () ? glthread_recursive_lock_destroy_multithreaded (LOCK) : 0)
 354 extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
 355 extern int glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock);
 356 extern int glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock);
 357 extern int glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock);
 358
 359 # endif
 360
 361 /* -------------------------- gl_once_t datatype -------------------------- */
 362
 363 typedef pthread_once_t gl_once_t;
 364 # define gl_once_define(STORAGECLASS, NAME) \
 365     STORAGECLASS pthread_once_t NAME = PTHREAD_ONCE_INIT;
 366 # define glthread_once(ONCE_CONTROL, INITFUNCTION) \
 367     (pthread_in_use ()                                                         \
 368      ? pthread_once (ONCE_CONTROL, INITFUNCTION)                               \
 369      : (glthread_once_singlethreaded (ONCE_CONTROL) ? (INITFUNCTION (), 0) : 0))
 370 extern int glthread_once_singlethreaded (pthread_once_t *once_control);
 371
 372 # ifdef __cplusplus
 373 }
 374 # endif
 375
 376 #endif
 377
 378 /* ========================================================================= */
 379
 380 #if USE_PTH_THREADS
 381
 382 /* Use the GNU Pth threads library.  */
 383
 384 # include <pth.h>
 385
 386 # ifdef __cplusplus
 387 extern "C" {
 388 # endif
 389
 390 # if USE_PTH_THREADS_WEAK
 391
 392 /* Use weak references to the GNU Pth threads library.  */
 393
 394 #  pragma weak pth_mutex_init
 395 #  pragma weak pth_mutex_acquire
 396 #  pragma weak pth_mutex_release
 397 #  pragma weak pth_rwlock_init
 398 #  pragma weak pth_rwlock_acquire
 399 #  pragma weak pth_rwlock_release
 400 #  pragma weak pth_once
 401
 402 #  pragma weak pth_cancel
 403 #  define pth_in_use() (pth_cancel != NULL)
 404
 405 # else
 406
 407 #  define pth_in_use() 1
 408
 409 # endif
 410
 411 /* -------------------------- gl_lock_t datatype -------------------------- */
 412
 413 typedef pth_mutex_t gl_lock_t;
 414 # define gl_lock_define(STORAGECLASS, NAME) \
 415     STORAGECLASS pth_mutex_t NAME;
 416 # define gl_lock_define_initialized(STORAGECLASS, NAME) \
 417     STORAGECLASS pth_mutex_t NAME = gl_lock_initializer;
 418 # define gl_lock_initializer \
 419     PTH_MUTEX_INIT
 420 # define glthread_lock_init(LOCK) \
 421     (pth_in_use () && !pth_mutex_init (LOCK) ? errno : 0)
 422 # define glthread_lock_lock(LOCK) \
 423     (pth_in_use () && !pth_mutex_acquire (LOCK, 0, NULL) ? errno : 0)
 424 # define glthread_lock_unlock(LOCK) \
 425     (pth_in_use () && !pth_mutex_release (LOCK) ? errno : 0)
 426 # define glthread_lock_destroy(LOCK) \
 427     ((void)(LOCK), 0)
 428
 429 /* ------------------------- gl_rwlock_t datatype ------------------------- */
 430
 431 typedef pth_rwlock_t gl_rwlock_t;
 432 #  define gl_rwlock_define(STORAGECLASS, NAME) \
 433      STORAGECLASS pth_rwlock_t NAME;
 434 #  define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
 435      STORAGECLASS pth_rwlock_t NAME = gl_rwlock_initializer;
 436 #  define gl_rwlock_initializer \
 437      PTH_RWLOCK_INIT
 438 #  define glthread_rwlock_init(LOCK) \
 439      (pth_in_use () && !pth_rwlock_init (LOCK) ? errno : 0)
 440 #  define glthread_rwlock_rdlock(LOCK) \
 441      (pth_in_use () && !pth_rwlock_acquire (LOCK, PTH_RWLOCK_RD, 0, NULL) ? errno : 0)
 442 #  define glthread_rwlock_wrlock(LOCK) \
 443      (pth_in_use () && !pth_rwlock_acquire (LOCK, PTH_RWLOCK_RW, 0, NULL) ? errno : 0)
 444 #  define glthread_rwlock_unlock(LOCK) \
 445      (pth_in_use () && !pth_rwlock_release (LOCK) ? errno : 0)
 446 #  define glthread_rwlock_destroy(LOCK) \
 447      ((void)(LOCK), 0)
 448
 449 /* --------------------- gl_recursive_lock_t datatype --------------------- */
 450
 451 /* In Pth, mutexes are recursive by default.  */
 452 typedef pth_mutex_t gl_recursive_lock_t;
 453 #  define gl_recursive_lock_define(STORAGECLASS, NAME) \
 454      STORAGECLASS pth_mutex_t NAME;
 455 #  define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
 456      STORAGECLASS pth_mutex_t NAME = gl_recursive_lock_initializer;
 457 #  define gl_recursive_lock_initializer \
 458      PTH_MUTEX_INIT
 459 #  define glthread_recursive_lock_init(LOCK) \
 460      (pth_in_use () && !pth_mutex_init (LOCK) ? errno : 0)
 461 #  define glthread_recursive_lock_lock(LOCK) \
 462      (pth_in_use () && !pth_mutex_acquire (LOCK, 0, NULL) ? errno : 0)
 463 #  define glthread_recursive_lock_unlock(LOCK) \
 464      (pth_in_use () && !pth_mutex_release (LOCK) ? errno : 0)
 465 #  define glthread_recursive_lock_destroy(LOCK) \
 466      ((void)(LOCK), 0)
 467
 468 /* -------------------------- gl_once_t datatype -------------------------- */
 469
 470 typedef pth_once_t gl_once_t;
 471 # define gl_once_define(STORAGECLASS, NAME) \
 472     STORAGECLASS pth_once_t NAME = PTH_ONCE_INIT;
 473 # define glthread_once(ONCE_CONTROL, INITFUNCTION) \
 474     (pth_in_use ()                                                             \
 475      ? glthread_once_multithreaded (ONCE_CONTROL, INITFUNCTION)                \
 476      : (glthread_once_singlethreaded (ONCE_CONTROL) ? (INITFUNCTION (), 0) : 0))
 477 extern int glthread_once_multithreaded (pth_once_t *once_control, void (*initfunction) (void));
 478 extern int glthread_once_singlethreaded (pth_once_t *once_control);
 479
 480 # ifdef __cplusplus
 481 }
 482 # endif
 483
 484 #endif
 485
 486 /* ========================================================================= */
 487
 488 #if USE_SOLARIS_THREADS
 489
 490 /* Use the old Solaris threads library.  */
 491
 492 # include <thread.h>
 493 # include <synch.h>
 494
 495 # ifdef __cplusplus
 496 extern "C" {
 497 # endif
 498
 499 # if USE_SOLARIS_THREADS_WEAK
 500
 501 /* Use weak references to the old Solaris threads library.  */
 502
 503 #  pragma weak mutex_init
 504 #  pragma weak mutex_lock
 505 #  pragma weak mutex_unlock
 506 #  pragma weak mutex_destroy
 507 #  pragma weak rwlock_init
 508 #  pragma weak rw_rdlock
 509 #  pragma weak rw_wrlock
 510 #  pragma weak rw_unlock
 511 #  pragma weak rwlock_destroy
 512 #  pragma weak thr_self
 513
 514 #  pragma weak thr_suspend
 515 #  define thread_in_use() (thr_suspend != NULL)
 516
 517 # else
 518
 519 #  define thread_in_use() 1
 520
 521 # endif
 522
 523 /* -------------------------- gl_lock_t datatype -------------------------- */
 524
 525 typedef mutex_t gl_lock_t;
 526 # define gl_lock_define(STORAGECLASS, NAME) \
 527     STORAGECLASS mutex_t NAME;
 528 # define gl_lock_define_initialized(STORAGECLASS, NAME) \
 529     STORAGECLASS mutex_t NAME = gl_lock_initializer;
 530 # define gl_lock_initializer \
 531     DEFAULTMUTEX
 532 # define glthread_lock_init(LOCK) \
 533     (thread_in_use () ? mutex_init (LOCK, USYNC_THREAD, NULL) : 0)
 534 # define glthread_lock_lock(LOCK) \
 535     (thread_in_use () ? mutex_lock (LOCK) : 0)
 536 # define glthread_lock_unlock(LOCK) \
 537     (thread_in_use () ? mutex_unlock (LOCK) : 0)
 538 # define glthread_lock_destroy(LOCK) \
 539     (thread_in_use () ? mutex_destroy (LOCK) : 0)
 540
 541 /* ------------------------- gl_rwlock_t datatype ------------------------- */
 542
 543 typedef rwlock_t gl_rwlock_t;
 544 # define gl_rwlock_define(STORAGECLASS, NAME) \
 545     STORAGECLASS rwlock_t NAME;
 546 # define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
 547     STORAGECLASS rwlock_t NAME = gl_rwlock_initializer;
 548 # define gl_rwlock_initializer \
 549     DEFAULTRWLOCK
 550 # define glthread_rwlock_init(LOCK) \
 551     (thread_in_use () ? rwlock_init (LOCK, USYNC_THREAD, NULL) : 0)
 552 # define glthread_rwlock_rdlock(LOCK) \
 553     (thread_in_use () ? rw_rdlock (LOCK) : 0)
 554 # define glthread_rwlock_wrlock(LOCK) \
 555     (thread_in_use () ? rw_wrlock (LOCK) : 0)
 556 # define glthread_rwlock_unlock(LOCK) \
 557     (thread_in_use () ? rw_unlock (LOCK) : 0)
 558 # define glthread_rwlock_destroy(LOCK) \
 559     (thread_in_use () ? rwlock_destroy (LOCK) : 0)
 560
 561 /* --------------------- gl_recursive_lock_t datatype --------------------- */
 562
 563 /* Old Solaris threads did not have recursive locks.
 564    We have to implement them ourselves.  */
 565
 566 typedef struct
 567         {
 568           mutex_t mutex;
 569           thread_t owner;
 570           unsigned long depth;
 571         }
 572         gl_recursive_lock_t;
 573 # define gl_recursive_lock_define(STORAGECLASS, NAME) \
 574     STORAGECLASS gl_recursive_lock_t NAME;
 575 # define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
 576     STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
 577 # define gl_recursive_lock_initializer \
 578     { DEFAULTMUTEX, (thread_t) 0, 0 }
 579 # define glthread_recursive_lock_init(LOCK) \
 580     (thread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
 581 # define glthread_recursive_lock_lock(LOCK) \
 582     (thread_in_use () ? glthread_recursive_lock_lock_multithreaded (LOCK) : 0)
 583 # define glthread_recursive_lock_unlock(LOCK) \
 584     (thread_in_use () ? glthread_recursive_lock_unlock_multithreaded (LOCK) : 0)
 585 # define glthread_recursive_lock_destroy(LOCK) \
 586     (thread_in_use () ? glthread_recursive_lock_destroy_multithreaded (LOCK) : 0)
 587 extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
 588 extern int glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock);
 589 extern int glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock);
 590 extern int glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock);
 591
 592 /* -------------------------- gl_once_t datatype -------------------------- */
 593
 594 typedef struct
 595         {
 596           volatile int inited;
 597           mutex_t mutex;
 598         }
 599         gl_once_t;
 600 # define gl_once_define(STORAGECLASS, NAME) \
 601     STORAGECLASS gl_once_t NAME = { 0, DEFAULTMUTEX };
 602 # define glthread_once(ONCE_CONTROL, INITFUNCTION) \
 603     (thread_in_use ()                                                          \
 604      ? glthread_once_multithreaded (ONCE_CONTROL, INITFUNCTION)                \
 605      : (glthread_once_singlethreaded (ONCE_CONTROL) ? (INITFUNCTION (), 0) : 0))
 606 extern int glthread_once_multithreaded (gl_once_t *once_control, void (*initfunction) (void));
 607 extern int glthread_once_singlethreaded (gl_once_t *once_control);
 608
 609 # ifdef __cplusplus
 610 }
 611 # endif
 612
 613 #endif
 614
 615 /* ========================================================================= */
 616
 617 #if USE_WIN32_THREADS
 618
 619 # include <windows.h>
 620
 621 # ifdef __cplusplus
 622 extern "C" {
 623 # endif
 624
 625 /* We can use CRITICAL_SECTION directly, rather than the Win32 Event, Mutex,
 626    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 Win32 documentation says that CRITICAL_SECTION already implements a
 713    recursive lock.  But we need not rely on it: It's easy to implement a
 714    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_WIN32_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 */