glib/gthread.c

   1 /* GLIB - Library of useful routines for C programming
   2  * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
   3  *
   4  * gthread.c: MT safety related functions
   5  * Copyright 1998 Sebastian Wilhelmi; University of Karlsruhe
   6  *                Owen Taylor
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2 of the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the
  20  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  21  * Boston, MA 02111-1307, USA.
  22  */
  23
  24 /*
  25  * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
  26  * file for a list of people on the GLib Team.  See the ChangeLog
  27  * files for a list of changes.  These files are distributed with
  28  * GLib at ftp://ftp.gtk.org/pub/gtk/.
  29  */
  30
  31 /*
  32  * MT safe
  33  */
  34
  35 #include "config.h"
  36
  37 #ifdef HAVE_UNISTD_H
  38 #include <unistd.h>
  39 #endif
  40
  41 #include <string.h>
  42
  43 #include "galias.h"
  44 #include "glib.h"
  45 #include "gthreadinit.h"
  46
  47 #if GLIB_SIZEOF_SYSTEM_THREAD == SIZEOF_VOID_P
  48 # define g_system_thread_equal_simple(thread1, thread2)                 \
  49    ((thread1).dummy_pointer == (thread2).dummy_pointer)
  50 # define g_system_thread_assign(dest, src)                              \
  51    ((dest).dummy_pointer = (src).dummy_pointer)
  52 #else /* GLIB_SIZEOF_SYSTEM_THREAD != SIZEOF_VOID_P */
  53 # define g_system_thread_equal_simple(thread1, thread2)                 \
  54    (memcmp (&(thread1), &(thread2), GLIB_SIZEOF_SYSTEM_THREAD) == 0)
  55 # define g_system_thread_assign(dest, src)                              \
  56    (memcpy (&(dest), &(src), GLIB_SIZEOF_SYSTEM_THREAD))
  57 #endif /* GLIB_SIZEOF_SYSTEM_THREAD == SIZEOF_VOID_P */
  58
  59 #define g_system_thread_equal(thread1, thread2)                         \
  60   (g_thread_functions_for_glib_use.thread_equal ?                       \
  61    g_thread_functions_for_glib_use.thread_equal (&(thread1), &(thread2)) :\
  62    g_system_thread_equal_simple((thread1), (thread2)))
  63
  64 GQuark
  65 g_thread_error_quark (void)
  66 {
  67   static GQuark quark;
  68   if (!quark)
  69     quark = g_quark_from_static_string ("g_thread_error");
  70   return quark;
  71 }
  72
  73 /* Keep this in sync with GRealThread in gmain.c! */
  74 typedef struct _GRealThread GRealThread;
  75 struct  _GRealThread
  76 {
  77   GThread thread;
  78   gpointer private_data;
  79   gpointer retval;
  80   GSystemThread system_thread;
  81 };
  82
  83 typedef struct _GStaticPrivateNode GStaticPrivateNode;
  84 struct _GStaticPrivateNode
  85 {
  86   gpointer       data;
  87   GDestroyNotify destroy;
  88 };
  89
  90 static void g_thread_cleanup (gpointer data);
  91 static void g_thread_fail (void);
  92
  93 /* Global variables */
  94
  95 static GSystemThread zero_thread; /* This is initialized to all zero */
  96 gboolean g_thread_use_default_impl = TRUE;
  97 gboolean g_threads_got_initialized = FALSE;
  98
  99 GThreadFunctions g_thread_functions_for_glib_use = {
 100   (GMutex*(*)())g_thread_fail,                 /* mutex_new */
 101   NULL,                                        /* mutex_lock */
 102   NULL,                                        /* mutex_trylock */
 103   NULL,                                        /* mutex_unlock */
 104   NULL,                                        /* mutex_free */
 105   (GCond*(*)())g_thread_fail,                  /* cond_new */
 106   NULL,                                        /* cond_signal */
 107   NULL,                                        /* cond_broadcast */
 108   NULL,                                        /* cond_wait */
 109   NULL,                                        /* cond_timed_wait  */
 110   NULL,                                        /* cond_free */
 111   (GPrivate*(*)(GDestroyNotify))g_thread_fail, /* private_new */
 112   NULL,                                        /* private_get */
 113   NULL,                                        /* private_set */
 114   (void(*)(GThreadFunc, gpointer, gulong,
 115            gboolean, gboolean, GThreadPriority,
 116            gpointer, GError**))g_thread_fail,  /* thread_create */
 117   NULL,                                        /* thread_yield */
 118   NULL,                                        /* thread_join */
 119   NULL,                                        /* thread_exit */
 120   NULL,                                        /* thread_set_priority */
 121   NULL                                         /* thread_self */
 122 };
 123
 124 /* Local data */
 125
 126 static GMutex   *g_once_mutex = NULL;
 127 static GCond    *g_once_cond = NULL;
 128 static GPrivate *g_thread_specific_private = NULL;
 129 static GSList   *g_thread_all_threads = NULL;
 130 static GSList   *g_thread_free_indeces = NULL;
 131
 132 G_LOCK_DEFINE_STATIC (g_thread);
 133
 134 #ifdef G_THREADS_ENABLED
 135 /* This must be called only once, before any threads are created.
 136  * It will only be called from g_thread_init() in -lgthread.
 137  */
 138 void
 139 g_thread_init_glib (void)
 140 {
 141   /* We let the main thread (the one that calls g_thread_init) inherit
 142    * the static_private data set before calling g_thread_init
 143    */
 144   GRealThread* main_thread = (GRealThread*) g_thread_self ();
 145
 146   g_once_mutex = g_mutex_new ();
 147   g_once_cond = g_cond_new ();
 148
 149   _g_convert_thread_init ();
 150   _g_rand_thread_init ();
 151   _g_main_thread_init ();
 152   _g_mem_thread_init ();
 153   _g_messages_thread_init ();
 154   _g_atomic_thread_init ();
 155   _g_utils_thread_init ();
 156 #ifdef G_OS_WIN32
 157   _g_win32_thread_init ();
 158 #endif
 159
 160   g_threads_got_initialized = TRUE;
 161
 162   g_thread_specific_private = g_private_new (g_thread_cleanup);
 163   g_private_set (g_thread_specific_private, main_thread);
 164   G_THREAD_UF (thread_self, (&main_thread->system_thread));
 165
 166   _g_mem_thread_private_init ();
 167   _g_messages_thread_private_init ();
 168
 169 }
 170 #endif /* G_THREADS_ENABLED */
 171
 172 gpointer
 173 g_once_impl (GOnce       *once,
 174              GThreadFunc  func,
 175              gpointer     arg)
 176 {
 177   g_mutex_lock (g_once_mutex);
 178
 179   while (once->status == G_ONCE_STATUS_PROGRESS)
 180     g_cond_wait (g_once_cond, g_once_mutex);
 181
 182   if (once->status != G_ONCE_STATUS_READY)
 183     {
 184       once->status = G_ONCE_STATUS_PROGRESS;
 185       g_mutex_unlock (g_once_mutex);
 186
 187       once->retval = func (arg);
 188
 189       g_mutex_lock (g_once_mutex);
 190       once->status = G_ONCE_STATUS_READY;
 191       g_cond_broadcast (g_once_cond);
 192     }
 193
 194   g_mutex_unlock (g_once_mutex);
 195
 196   return once->retval;
 197 }
 198
 199 void
 200 g_static_mutex_init (GStaticMutex *mutex)
 201 {
 202   static GStaticMutex init_mutex = G_STATIC_MUTEX_INIT;
 203
 204   g_return_if_fail (mutex);
 205
 206   *mutex = init_mutex;
 207 }
 208
 209 GMutex *
 210 g_static_mutex_get_mutex_impl (GMutex** mutex)
 211 {
 212   if (!g_thread_supported ())
 213     return NULL;
 214
 215   g_assert (g_once_mutex);
 216
 217   g_mutex_lock (g_once_mutex);
 218
 219   if (!(*mutex))
 220     {
 221       GMutex *new_mutex = g_mutex_new ();
 222
 223       /* The following is a memory barrier to avoid the write
 224        * to *new_mutex being reordered to after writing *mutex */
 225       g_mutex_lock (new_mutex);
 226       g_mutex_unlock (new_mutex);
 227
 228       *mutex = new_mutex;
 229     }
 230
 231   g_mutex_unlock (g_once_mutex);
 232
 233   return *mutex;
 234 }
 235
 236 void
 237 g_static_mutex_free (GStaticMutex* mutex)
 238 {
 239   GMutex **runtime_mutex;
 240
 241   g_return_if_fail (mutex);
 242
 243   /* The runtime_mutex is the first (or only) member of GStaticMutex,
 244    * see both versions (of glibconfig.h) in configure.in */
 245   runtime_mutex = ((GMutex**)mutex);
 246
 247   if (*runtime_mutex)
 248     g_mutex_free (*runtime_mutex);
 249
 250   *runtime_mutex = NULL;
 251 }
 252
 253 void
 254 g_static_rec_mutex_init (GStaticRecMutex *mutex)
 255 {
 256   static GStaticRecMutex init_mutex = G_STATIC_REC_MUTEX_INIT;
 257
 258   g_return_if_fail (mutex);
 259
 260   *mutex = init_mutex;
 261 }
 262
 263 void
 264 g_static_rec_mutex_lock (GStaticRecMutex* mutex)
 265 {
 266   GSystemThread self;
 267
 268   g_return_if_fail (mutex);
 269
 270   if (!g_thread_supported ())
 271     return;
 272
 273   G_THREAD_UF (thread_self, (&self));
 274
 275   if (g_system_thread_equal (self, mutex->owner))
 276     {
 277       mutex->depth++;
 278       return;
 279     }
 280   g_static_mutex_lock (&mutex->mutex);
 281   g_system_thread_assign (mutex->owner, self);
 282   mutex->depth = 1;
 283 }
 284
 285 gboolean
 286 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
 287 {
 288   GSystemThread self;
 289
 290   g_return_val_if_fail (mutex, FALSE);
 291
 292   if (!g_thread_supported ())
 293     return TRUE;
 294
 295   G_THREAD_UF (thread_self, (&self));
 296
 297   if (g_system_thread_equal (self, mutex->owner))
 298     {
 299       mutex->depth++;
 300       return TRUE;
 301     }
 302
 303   if (!g_static_mutex_trylock (&mutex->mutex))
 304     return FALSE;
 305
 306   g_system_thread_assign (mutex->owner, self);
 307   mutex->depth = 1;
 308   return TRUE;
 309 }
 310
 311 void
 312 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
 313 {
 314   g_return_if_fail (mutex);
 315
 316   if (!g_thread_supported ())
 317     return;
 318
 319   if (mutex->depth > 1)
 320     {
 321       mutex->depth--;
 322       return;
 323     }
 324   g_system_thread_assign (mutex->owner, zero_thread);
 325   g_static_mutex_unlock (&mutex->mutex);
 326 }
 327
 328 void
 329 g_static_rec_mutex_lock_full   (GStaticRecMutex *mutex,
 330                                 guint            depth)
 331 {
 332   GSystemThread self;
 333   g_return_if_fail (mutex);
 334
 335   if (!g_thread_supported ())
 336     return;
 337
 338   G_THREAD_UF (thread_self, (&self));
 339
 340   if (g_system_thread_equal (self, mutex->owner))
 341     {
 342       mutex->depth += depth;
 343       return;
 344     }
 345   g_static_mutex_lock (&mutex->mutex);
 346   g_system_thread_assign (mutex->owner, self);
 347   mutex->depth = depth;
 348 }
 349
 350 guint
 351 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
 352 {
 353   guint depth;
 354
 355   g_return_val_if_fail (mutex, 0);
 356
 357   if (!g_thread_supported ())
 358     return 1;
 359
 360   depth = mutex->depth;
 361
 362   g_system_thread_assign (mutex->owner, zero_thread);
 363   mutex->depth = 0;
 364   g_static_mutex_unlock (&mutex->mutex);
 365
 366   return depth;
 367 }
 368
 369 void
 370 g_static_rec_mutex_free (GStaticRecMutex *mutex)
 371 {
 372   g_return_if_fail (mutex);
 373
 374   g_static_mutex_free (&mutex->mutex);
 375 }
 376
 377 void
 378 g_static_private_init (GStaticPrivate *private_key)
 379 {
 380   private_key->index = 0;
 381 }
 382
 383 gpointer
 384 g_static_private_get (GStaticPrivate *private_key)
 385 {
 386   GRealThread *self = (GRealThread*) g_thread_self ();
 387   GArray *array;
 388
 389   array = self->private_data;
 390   if (!array)
 391     return NULL;
 392
 393   if (!private_key->index)
 394     return NULL;
 395   else if (private_key->index <= array->len)
 396     return g_array_index (array, GStaticPrivateNode,
 397                           private_key->index - 1).data;
 398   else
 399     return NULL;
 400 }
 401
 402 void
 403 g_static_private_set (GStaticPrivate *private_key,
 404                       gpointer        data,
 405                       GDestroyNotify  notify)
 406 {
 407   GRealThread *self = (GRealThread*) g_thread_self ();
 408   GArray *array;
 409   static guint next_index = 0;
 410   GStaticPrivateNode *node;
 411
 412   array = self->private_data;
 413   if (!array)
 414     {
 415       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 416       self->private_data = array;
 417     }
 418
 419   if (!private_key->index)
 420     {
 421       G_LOCK (g_thread);
 422
 423       if (!private_key->index)
 424         {
 425           if (g_thread_free_indeces)
 426             {
 427               private_key->index =
 428                 GPOINTER_TO_UINT (g_thread_free_indeces->data);
 429               g_thread_free_indeces =
 430                 g_slist_delete_link (g_thread_free_indeces,
 431                                      g_thread_free_indeces);
 432             }
 433           else
 434             private_key->index = ++next_index;
 435         }
 436
 437       G_UNLOCK (g_thread);
 438     }
 439
 440   if (private_key->index > array->len)
 441     g_array_set_size (array, private_key->index);
 442
 443   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 444   if (node->destroy)
 445     {
 446       gpointer ddata = node->data;
 447       GDestroyNotify ddestroy = node->destroy;
 448
 449       node->data = data;
 450       node->destroy = notify;
 451
 452       ddestroy (ddata);
 453     }
 454   else
 455     {
 456       node->data = data;
 457       node->destroy = notify;
 458     }
 459 }
 460
 461 void
 462 g_static_private_free (GStaticPrivate *private_key)
 463 {
 464   guint index = private_key->index;
 465   GSList *list;
 466
 467   if (!index)
 468     return;
 469
 470   private_key->index = 0;
 471
 472   G_LOCK (g_thread);
 473   list =  g_thread_all_threads;
 474   while (list)
 475     {
 476       GRealThread *thread = list->data;
 477       GArray *array = thread->private_data;
 478       list = list->next;
 479
 480       if (array && index <= array->len)
 481         {
 482           GStaticPrivateNode *node = &g_array_index (array,
 483                                                      GStaticPrivateNode,
 484                                                      index - 1);
 485           gpointer ddata = node->data;
 486           GDestroyNotify ddestroy = node->destroy;
 487
 488           node->data = NULL;
 489           node->destroy = NULL;
 490
 491           if (ddestroy)
 492             {
 493               G_UNLOCK (g_thread);
 494               ddestroy (ddata);
 495               G_LOCK (g_thread);
 496               }
 497         }
 498     }
 499   g_thread_free_indeces = g_slist_prepend (g_thread_free_indeces,
 500                                            GUINT_TO_POINTER (index));
 501   G_UNLOCK (g_thread);
 502 }
 503
 504 static void
 505 g_thread_cleanup (gpointer data)
 506 {
 507   if (data)
 508     {
 509       GRealThread* thread = data;
 510       if (thread->private_data)
 511         {
 512           GArray* array = thread->private_data;
 513           guint i;
 514
 515           for (i = 0; i < array->len; i++ )
 516             {
 517               GStaticPrivateNode *node =
 518                 &g_array_index (array, GStaticPrivateNode, i);
 519               if (node->destroy)
 520                 node->destroy (node->data);
 521             }
 522           g_array_free (array, TRUE);
 523         }
 524
 525       /* We only free the thread structure, if it isn't joinable. If
 526          it is, the structure is freed in g_thread_join */
 527       if (!thread->thread.joinable)
 528         {
 529           G_LOCK (g_thread);
 530           g_thread_all_threads = g_slist_remove (g_thread_all_threads, data);
 531           G_UNLOCK (g_thread);
 532
 533           /* Just to make sure, this isn't used any more */
 534           g_system_thread_assign (thread->system_thread, zero_thread);
 535           g_free (thread);
 536         }
 537     }
 538 }
 539
 540 static void
 541 g_thread_fail (void)
 542 {
 543   g_error ("The thread system is not yet initialized.");
 544 }
 545
 546 static gpointer
 547 g_thread_create_proxy (gpointer data)
 548 {
 549   GRealThread* thread = data;
 550
 551   g_assert (data);
 552
 553   /* This has to happen before G_LOCK, as that might call g_thread_self */
 554   g_private_set (g_thread_specific_private, data);
 555
 556   /* the lock makes sure, that thread->system_thread is written,
 557      before thread->thread.func is called. See g_thread_create. */
 558   G_LOCK (g_thread);
 559   G_UNLOCK (g_thread);
 560
 561   thread->retval = thread->thread.func (thread->thread.data);
 562
 563   return NULL;
 564 }
 565
 566 GThread*
 567 g_thread_create_full (GThreadFunc                func,
 568                       gpointer           data,
 569                       gulong             stack_size,
 570                       gboolean           joinable,
 571                       gboolean           bound,
 572                       GThreadPriority    priority,
 573                       GError                **error)
 574 {
 575   GRealThread* result;
 576   GError *local_error = NULL;
 577   g_return_val_if_fail (func, NULL);
 578   g_return_val_if_fail (priority >= G_THREAD_PRIORITY_LOW, NULL);
 579   g_return_val_if_fail (priority <= G_THREAD_PRIORITY_URGENT, NULL);
 580
 581   result = g_new (GRealThread, 1);
 582
 583   result->thread.joinable = joinable;
 584   result->thread.priority = priority;
 585   result->thread.func = func;
 586   result->thread.data = data;
 587   result->private_data = NULL;
 588   G_LOCK (g_thread);
 589   G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
 590                                stack_size, joinable, bound, priority,
 591                                &result->system_thread, &local_error));
 592   g_thread_all_threads = g_slist_prepend (g_thread_all_threads, result);
 593   G_UNLOCK (g_thread);
 594
 595   if (local_error)
 596     {
 597       g_propagate_error (error, local_error);
 598       g_free (result);
 599       return NULL;
 600     }
 601
 602   return (GThread*) result;
 603 }
 604
 605 void
 606 g_thread_exit (gpointer retval)
 607 {
 608   GRealThread* real = (GRealThread*) g_thread_self ();
 609   real->retval = retval;
 610   G_THREAD_CF (thread_exit, (void)0, ());
 611 }
 612
 613 gpointer
 614 g_thread_join (GThread* thread)
 615 {
 616   GRealThread* real = (GRealThread*) thread;
 617   gpointer retval;
 618
 619   g_return_val_if_fail (thread, NULL);
 620   g_return_val_if_fail (thread->joinable, NULL);
 621   g_return_val_if_fail (!g_system_thread_equal (real->system_thread,
 622                                                 zero_thread), NULL);
 623
 624   G_THREAD_UF (thread_join, (&real->system_thread));
 625
 626   retval = real->retval;
 627
 628   G_LOCK (g_thread);
 629   g_thread_all_threads = g_slist_remove (g_thread_all_threads, thread);
 630   G_UNLOCK (g_thread);
 631
 632   /* Just to make sure, this isn't used any more */
 633   thread->joinable = 0;
 634   g_system_thread_assign (real->system_thread, zero_thread);
 635
 636   /* the thread structure for non-joinable threads is freed upon
 637      thread end. We free the memory here. This will leave a loose end,
 638      if a joinable thread is not joined. */
 639
 640   g_free (thread);
 641
 642   return retval;
 643 }
 644
 645 void
 646 g_thread_set_priority (GThread* thread,
 647                        GThreadPriority priority)
 648 {
 649   GRealThread* real = (GRealThread*) thread;
 650
 651   g_return_if_fail (thread);
 652   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 653   g_return_if_fail (priority >= G_THREAD_PRIORITY_LOW);
 654   g_return_if_fail (priority <= G_THREAD_PRIORITY_URGENT);
 655
 656   thread->priority = priority;
 657
 658   G_THREAD_CF (thread_set_priority, (void)0,
 659                (&real->system_thread, priority));
 660 }
 661
 662 GThread*
 663 g_thread_self (void)
 664 {
 665   GRealThread* thread = g_private_get (g_thread_specific_private);
 666
 667   if (!thread)
 668     {
 669       /* If no thread data is available, provide and set one.  This
 670          can happen for the main thread and for threads, that are not
 671          created by GLib. */
 672       thread = g_new (GRealThread, 1);
 673       thread->thread.joinable = FALSE; /* This is a save guess */
 674       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 675                                                              just a guess */
 676       thread->thread.func = NULL;
 677       thread->thread.data = NULL;
 678       thread->private_data = NULL;
 679
 680       if (g_thread_supported ())
 681         G_THREAD_UF (thread_self, (&thread->system_thread));
 682
 683       g_private_set (g_thread_specific_private, thread);
 684
 685       G_LOCK (g_thread);
 686       g_thread_all_threads = g_slist_prepend (g_thread_all_threads, thread);
 687       G_UNLOCK (g_thread);
 688     }
 689
 690   return (GThread*)thread;
 691 }
 692
 693 void
 694 g_static_rw_lock_init (GStaticRWLock* lock)
 695 {
 696   static GStaticRWLock init_lock = G_STATIC_RW_LOCK_INIT;
 697
 698   g_return_if_fail (lock);
 699
 700   *lock = init_lock;
 701 }
 702
 703 static void inline
 704 g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 705 {
 706   if (!*cond)
 707       *cond = g_cond_new ();
 708   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 709 }
 710
 711 static void inline
 712 g_static_rw_lock_signal (GStaticRWLock* lock)
 713 {
 714   if (lock->want_to_write && lock->write_cond)
 715     g_cond_signal (lock->write_cond);
 716   else if (lock->want_to_read && lock->read_cond)
 717     g_cond_broadcast (lock->read_cond);
 718 }
 719
 720 void
 721 g_static_rw_lock_reader_lock (GStaticRWLock* lock)
 722 {
 723   g_return_if_fail (lock);
 724
 725   if (!g_threads_got_initialized)
 726     return;
 727
 728   g_static_mutex_lock (&lock->mutex);
 729   lock->want_to_read++;
 730   while (lock->have_writer || lock->want_to_write)
 731     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 732   lock->want_to_read--;
 733   lock->read_counter++;
 734   g_static_mutex_unlock (&lock->mutex);
 735 }
 736
 737 gboolean
 738 g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
 739 {
 740   gboolean ret_val = FALSE;
 741
 742   g_return_val_if_fail (lock, FALSE);
 743
 744   if (!g_threads_got_initialized)
 745     return TRUE;
 746
 747   g_static_mutex_lock (&lock->mutex);
 748   if (!lock->have_writer && !lock->want_to_write)
 749     {
 750       lock->read_counter++;
 751       ret_val = TRUE;
 752     }
 753   g_static_mutex_unlock (&lock->mutex);
 754   return ret_val;
 755 }
 756
 757 void
 758 g_static_rw_lock_reader_unlock  (GStaticRWLock* lock)
 759 {
 760   g_return_if_fail (lock);
 761
 762   if (!g_threads_got_initialized)
 763     return;
 764
 765   g_static_mutex_lock (&lock->mutex);
 766   lock->read_counter--;
 767   if (lock->read_counter == 0)
 768     g_static_rw_lock_signal (lock);
 769   g_static_mutex_unlock (&lock->mutex);
 770 }
 771
 772 void
 773 g_static_rw_lock_writer_lock (GStaticRWLock* lock)
 774 {
 775   g_return_if_fail (lock);
 776
 777   if (!g_threads_got_initialized)
 778     return;
 779
 780   g_static_mutex_lock (&lock->mutex);
 781   lock->want_to_write++;
 782   while (lock->have_writer || lock->read_counter)
 783     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 784   lock->want_to_write--;
 785   lock->have_writer = TRUE;
 786   g_static_mutex_unlock (&lock->mutex);
 787 }
 788
 789 gboolean
 790 g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 791 {
 792   gboolean ret_val = FALSE;
 793
 794   g_return_val_if_fail (lock, FALSE);
 795
 796   if (!g_threads_got_initialized)
 797     return TRUE;
 798
 799   g_static_mutex_lock (&lock->mutex);
 800   if (!lock->have_writer && !lock->read_counter)
 801     {
 802       lock->have_writer = TRUE;
 803       ret_val = TRUE;
 804     }
 805   g_static_mutex_unlock (&lock->mutex);
 806   return ret_val;
 807 }
 808
 809 void
 810 g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
 811 {
 812   g_return_if_fail (lock);
 813
 814   if (!g_threads_got_initialized)
 815     return;
 816
 817   g_static_mutex_lock (&lock->mutex);
 818   lock->have_writer = FALSE;
 819   g_static_rw_lock_signal (lock);
 820   g_static_mutex_unlock (&lock->mutex);
 821 }
 822
 823 void
 824 g_static_rw_lock_free (GStaticRWLock* lock)
 825 {
 826   g_return_if_fail (lock);
 827
 828   if (lock->read_cond)
 829     {
 830       g_cond_free (lock->read_cond);
 831       lock->read_cond = NULL;
 832     }
 833   if (lock->write_cond)
 834     {
 835       g_cond_free (lock->write_cond);
 836       lock->write_cond = NULL;
 837     }
 838   g_static_mutex_free (&lock->mutex);
 839 }