lib/glthread/lock.h

   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 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
  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_WINDOWS_THREADS
 618
 619 # define WIN32_LEAN_AND_MEAN  /* avoid including junk */
 620 # include <windows.h>
 621
 622 # ifdef __cplusplus
 623 extern "C" {
 624 # endif
 625
 626 /* We can use CRITICAL_SECTION directly, rather than the native Windows Event,
 627    Mutex, 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 native Windows documentation says that CRITICAL_SECTION already
 714    implements a recursive lock.  But we need not rely on it: It's easy to
 715    implement a 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_WINDOWS_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 */