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