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 #ifdef G_OS_WIN32
 156   _g_win32_thread_init ();
 157 #endif
 158
 159   g_threads_got_initialized = TRUE;
 160
 161   g_thread_specific_private = g_private_new (g_thread_cleanup);
 162   g_private_set (g_thread_specific_private, main_thread);
 163   G_THREAD_UF (thread_self, (&main_thread->system_thread));
 164
 165   _g_mem_thread_private_init ();
 166   _g_messages_thread_private_init ();
 167
 168 }
 169 #endif /* G_THREADS_ENABLED */
 170
 171 gpointer
 172 g_once_impl (GOnce       *once,
 173              GThreadFunc  func,
 174              gpointer     arg)
 175 {
 176   g_mutex_lock (g_once_mutex);
 177
 178   while (once->status == G_ONCE_STATUS_PROGRESS)
 179     g_cond_wait (g_once_cond, g_once_mutex);
 180
 181   if (once->status != G_ONCE_STATUS_READY)
 182     {
 183       once->status = G_ONCE_STATUS_PROGRESS;
 184       g_mutex_unlock (g_once_mutex);
 185
 186       once->retval = func (arg);
 187
 188       g_mutex_lock (g_once_mutex);
 189       once->status = G_ONCE_STATUS_READY;
 190       g_cond_broadcast (g_once_cond);
 191     }
 192
 193   g_mutex_unlock (g_once_mutex);
 194
 195   return once->retval;
 196 }
 197
 198 void
 199 g_static_mutex_init (GStaticMutex *mutex)
 200 {
 201   static GStaticMutex init_mutex = G_STATIC_MUTEX_INIT;
 202
 203   g_return_if_fail (mutex);
 204
 205   *mutex = init_mutex;
 206 }
 207
 208 GMutex *
 209 g_static_mutex_get_mutex_impl (GMutex** mutex)
 210 {
 211   if (!g_thread_supported ())
 212     return NULL;
 213
 214   g_assert (g_once_mutex);
 215
 216   g_mutex_lock (g_once_mutex);
 217
 218   if (!(*mutex))
 219     {
 220       GMutex *new_mutex = g_mutex_new ();
 221
 222       /* The following is a memory barrier to avoid the write
 223        * to *new_mutex being reordered to after writing *mutex */
 224       g_mutex_lock (new_mutex);
 225       g_mutex_unlock (new_mutex);
 226
 227       *mutex = new_mutex;
 228     }
 229
 230   g_mutex_unlock (g_once_mutex);
 231
 232   return *mutex;
 233 }
 234
 235 void
 236 g_static_mutex_free (GStaticMutex* mutex)
 237 {
 238   GMutex **runtime_mutex;
 239
 240   g_return_if_fail (mutex);
 241
 242   /* The runtime_mutex is the first (or only) member of GStaticMutex,
 243    * see both versions (of glibconfig.h) in configure.in */
 244   runtime_mutex = ((GMutex**)mutex);
 245
 246   if (*runtime_mutex)
 247     g_mutex_free (*runtime_mutex);
 248
 249   *runtime_mutex = NULL;
 250 }
 251
 252 void
 253 g_static_rec_mutex_init (GStaticRecMutex *mutex)
 254 {
 255   static GStaticRecMutex init_mutex = G_STATIC_REC_MUTEX_INIT;
 256
 257   g_return_if_fail (mutex);
 258
 259   *mutex = init_mutex;
 260 }
 261
 262 void
 263 g_static_rec_mutex_lock (GStaticRecMutex* mutex)
 264 {
 265   GSystemThread self;
 266
 267   g_return_if_fail (mutex);
 268
 269   if (!g_thread_supported ())
 270     return;
 271
 272   G_THREAD_UF (thread_self, (&self));
 273
 274   if (g_system_thread_equal (self, mutex->owner))
 275     {
 276       mutex->depth++;
 277       return;
 278     }
 279   g_static_mutex_lock (&mutex->mutex);
 280   g_system_thread_assign (mutex->owner, self);
 281   mutex->depth = 1;
 282 }
 283
 284 gboolean
 285 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
 286 {
 287   GSystemThread self;
 288
 289   g_return_val_if_fail (mutex, FALSE);
 290
 291   if (!g_thread_supported ())
 292     return TRUE;
 293
 294   G_THREAD_UF (thread_self, (&self));
 295
 296   if (g_system_thread_equal (self, mutex->owner))
 297     {
 298       mutex->depth++;
 299       return TRUE;
 300     }
 301
 302   if (!g_static_mutex_trylock (&mutex->mutex))
 303     return FALSE;
 304
 305   g_system_thread_assign (mutex->owner, self);
 306   mutex->depth = 1;
 307   return TRUE;
 308 }
 309
 310 void
 311 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
 312 {
 313   g_return_if_fail (mutex);
 314
 315   if (!g_thread_supported ())
 316     return;
 317
 318   if (mutex->depth > 1)
 319     {
 320       mutex->depth--;
 321       return;
 322     }
 323   g_system_thread_assign (mutex->owner, zero_thread);
 324   g_static_mutex_unlock (&mutex->mutex);
 325 }
 326
 327 void
 328 g_static_rec_mutex_lock_full   (GStaticRecMutex *mutex,
 329                                 guint            depth)
 330 {
 331   GSystemThread self;
 332   g_return_if_fail (mutex);
 333
 334   if (!g_thread_supported ())
 335     return;
 336
 337   G_THREAD_UF (thread_self, (&self));
 338
 339   if (g_system_thread_equal (self, mutex->owner))
 340     {
 341       mutex->depth += depth;
 342       return;
 343     }
 344   g_static_mutex_lock (&mutex->mutex);
 345   g_system_thread_assign (mutex->owner, self);
 346   mutex->depth = depth;
 347 }
 348
 349 guint
 350 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
 351 {
 352   guint depth;
 353
 354   g_return_val_if_fail (mutex, 0);
 355
 356   if (!g_thread_supported ())
 357     return 1;
 358
 359   depth = mutex->depth;
 360
 361   g_system_thread_assign (mutex->owner, zero_thread);
 362   mutex->depth = 0;
 363   g_static_mutex_unlock (&mutex->mutex);
 364
 365   return depth;
 366 }
 367
 368 void
 369 g_static_rec_mutex_free (GStaticRecMutex *mutex)
 370 {
 371   g_return_if_fail (mutex);
 372
 373   g_static_mutex_free (&mutex->mutex);
 374 }
 375
 376 void
 377 g_static_private_init (GStaticPrivate *private_key)
 378 {
 379   private_key->index = 0;
 380 }
 381
 382 gpointer
 383 g_static_private_get (GStaticPrivate *private_key)
 384 {
 385   GRealThread *self = (GRealThread*) g_thread_self ();
 386   GArray *array;
 387
 388   array = self->private_data;
 389   if (!array)
 390     return NULL;
 391
 392   if (!private_key->index)
 393     return NULL;
 394   else if (private_key->index <= array->len)
 395     return g_array_index (array, GStaticPrivateNode,
 396                           private_key->index - 1).data;
 397   else
 398     return NULL;
 399 }
 400
 401 void
 402 g_static_private_set (GStaticPrivate *private_key,
 403                       gpointer        data,
 404                       GDestroyNotify  notify)
 405 {
 406   GRealThread *self = (GRealThread*) g_thread_self ();
 407   GArray *array;
 408   static guint next_index = 0;
 409   GStaticPrivateNode *node;
 410
 411   array = self->private_data;
 412   if (!array)
 413     {
 414       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 415       self->private_data = array;
 416     }
 417
 418   if (!private_key->index)
 419     {
 420       G_LOCK (g_thread);
 421
 422       if (!private_key->index)
 423         {
 424           if (g_thread_free_indeces)
 425             {
 426               private_key->index =
 427                 GPOINTER_TO_UINT (g_thread_free_indeces->data);
 428               g_thread_free_indeces =
 429                 g_slist_delete_link (g_thread_free_indeces,
 430                                      g_thread_free_indeces);
 431             }
 432           else
 433             private_key->index = ++next_index;
 434         }
 435
 436       G_UNLOCK (g_thread);
 437     }
 438
 439   if (private_key->index > array->len)
 440     g_array_set_size (array, private_key->index);
 441
 442   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 443   if (node->destroy)
 444     {
 445       gpointer ddata = node->data;
 446       GDestroyNotify ddestroy = node->destroy;
 447
 448       node->data = data;
 449       node->destroy = notify;
 450
 451       ddestroy (ddata);
 452     }
 453   else
 454     {
 455       node->data = data;
 456       node->destroy = notify;
 457     }
 458 }
 459
 460 void
 461 g_static_private_free (GStaticPrivate *private_key)
 462 {
 463   guint index = private_key->index;
 464   GSList *list;
 465
 466   if (!index)
 467     return;
 468
 469   private_key->index = 0;
 470
 471   G_LOCK (g_thread);
 472   list =  g_thread_all_threads;
 473   while (list)
 474     {
 475       GRealThread *thread = list->data;
 476       GArray *array = thread->private_data;
 477       list = list->next;
 478
 479       if (array && index <= array->len)
 480         {
 481           GStaticPrivateNode *node = &g_array_index (array,
 482                                                      GStaticPrivateNode,
 483                                                      index - 1);
 484           gpointer ddata = node->data;
 485           GDestroyNotify ddestroy = node->destroy;
 486
 487           node->data = NULL;
 488           node->destroy = NULL;
 489
 490           if (ddestroy)
 491             {
 492               G_UNLOCK (g_thread);
 493               ddestroy (ddata);
 494               G_LOCK (g_thread);
 495               }
 496         }
 497     }
 498   g_thread_free_indeces = g_slist_prepend (g_thread_free_indeces,
 499                                            GUINT_TO_POINTER (index));
 500   G_UNLOCK (g_thread);
 501 }
 502
 503 static void
 504 g_thread_cleanup (gpointer data)
 505 {
 506   if (data)
 507     {
 508       GRealThread* thread = data;
 509       if (thread->private_data)
 510         {
 511           GArray* array = thread->private_data;
 512           guint i;
 513
 514           for (i = 0; i < array->len; i++ )
 515             {
 516               GStaticPrivateNode *node =
 517                 &g_array_index (array, GStaticPrivateNode, i);
 518               if (node->destroy)
 519                 node->destroy (node->data);
 520             }
 521           g_array_free (array, TRUE);
 522         }
 523
 524       /* We only free the thread structure, if it isn't joinable. If
 525          it is, the structure is freed in g_thread_join */
 526       if (!thread->thread.joinable)
 527         {
 528           G_LOCK (g_thread);
 529           g_thread_all_threads = g_slist_remove (g_thread_all_threads, data);
 530           G_UNLOCK (g_thread);
 531
 532           /* Just to make sure, this isn't used any more */
 533           g_system_thread_assign (thread->system_thread, zero_thread);
 534           g_free (thread);
 535         }
 536     }
 537 }
 538
 539 static void
 540 g_thread_fail (void)
 541 {
 542   g_error ("The thread system is not yet initialized.");
 543 }
 544
 545 static gpointer
 546 g_thread_create_proxy (gpointer data)
 547 {
 548   GRealThread* thread = data;
 549
 550   g_assert (data);
 551
 552   /* This has to happen before G_LOCK, as that might call g_thread_self */
 553   g_private_set (g_thread_specific_private, data);
 554
 555   /* the lock makes sure, that thread->system_thread is written,
 556      before thread->thread.func is called. See g_thread_create. */
 557   G_LOCK (g_thread);
 558   G_UNLOCK (g_thread);
 559
 560   thread->retval = thread->thread.func (thread->thread.data);
 561
 562   return NULL;
 563 }
 564
 565 GThread*
 566 g_thread_create_full (GThreadFunc                func,
 567                       gpointer           data,
 568                       gulong             stack_size,
 569                       gboolean           joinable,
 570                       gboolean           bound,
 571                       GThreadPriority    priority,
 572                       GError                **error)
 573 {
 574   GRealThread* result;
 575   GError *local_error = NULL;
 576   g_return_val_if_fail (func, NULL);
 577   g_return_val_if_fail (priority >= G_THREAD_PRIORITY_LOW, NULL);
 578   g_return_val_if_fail (priority <= G_THREAD_PRIORITY_URGENT, NULL);
 579
 580   result = g_new (GRealThread, 1);
 581
 582   result->thread.joinable = joinable;
 583   result->thread.priority = priority;
 584   result->thread.func = func;
 585   result->thread.data = data;
 586   result->private_data = NULL;
 587   G_LOCK (g_thread);
 588   G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
 589                                stack_size, joinable, bound, priority,
 590                                &result->system_thread, &local_error));
 591   g_thread_all_threads = g_slist_prepend (g_thread_all_threads, result);
 592   G_UNLOCK (g_thread);
 593
 594   if (local_error)
 595     {
 596       g_propagate_error (error, local_error);
 597       g_free (result);
 598       return NULL;
 599     }
 600
 601   return (GThread*) result;
 602 }
 603
 604 void
 605 g_thread_exit (gpointer retval)
 606 {
 607   GRealThread* real = (GRealThread*) g_thread_self ();
 608   real->retval = retval;
 609   G_THREAD_CF (thread_exit, (void)0, ());
 610 }
 611
 612 gpointer
 613 g_thread_join (GThread* thread)
 614 {
 615   GRealThread* real = (GRealThread*) thread;
 616   gpointer retval;
 617
 618   g_return_val_if_fail (thread, NULL);
 619   g_return_val_if_fail (thread->joinable, NULL);
 620   g_return_val_if_fail (!g_system_thread_equal (real->system_thread,
 621                                                 zero_thread), NULL);
 622
 623   G_THREAD_UF (thread_join, (&real->system_thread));
 624
 625   retval = real->retval;
 626
 627   G_LOCK (g_thread);
 628   g_thread_all_threads = g_slist_remove (g_thread_all_threads, thread);
 629   G_UNLOCK (g_thread);
 630
 631   /* Just to make sure, this isn't used any more */
 632   thread->joinable = 0;
 633   g_system_thread_assign (real->system_thread, zero_thread);
 634
 635   /* the thread structure for non-joinable threads is freed upon
 636      thread end. We free the memory here. This will leave a loose end,
 637      if a joinable thread is not joined. */
 638
 639   g_free (thread);
 640
 641   return retval;
 642 }
 643
 644 void
 645 g_thread_set_priority (GThread* thread,
 646                        GThreadPriority priority)
 647 {
 648   GRealThread* real = (GRealThread*) thread;
 649
 650   g_return_if_fail (thread);
 651   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 652   g_return_if_fail (priority >= G_THREAD_PRIORITY_LOW);
 653   g_return_if_fail (priority <= G_THREAD_PRIORITY_URGENT);
 654
 655   thread->priority = priority;
 656
 657   G_THREAD_CF (thread_set_priority, (void)0,
 658                (&real->system_thread, priority));
 659 }
 660
 661 GThread*
 662 g_thread_self (void)
 663 {
 664   GRealThread* thread = g_private_get (g_thread_specific_private);
 665
 666   if (!thread)
 667     {
 668       /* If no thread data is available, provide and set one.  This
 669          can happen for the main thread and for threads, that are not
 670          created by GLib. */
 671       thread = g_new (GRealThread, 1);
 672       thread->thread.joinable = FALSE; /* This is a save guess */
 673       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 674                                                              just a guess */
 675       thread->thread.func = NULL;
 676       thread->thread.data = NULL;
 677       thread->private_data = NULL;
 678
 679       if (g_thread_supported ())
 680         G_THREAD_UF (thread_self, (&thread->system_thread));
 681
 682       g_private_set (g_thread_specific_private, thread);
 683
 684       G_LOCK (g_thread);
 685       g_thread_all_threads = g_slist_prepend (g_thread_all_threads, thread);
 686       G_UNLOCK (g_thread);
 687     }
 688
 689   return (GThread*)thread;
 690 }
 691
 692 void
 693 g_static_rw_lock_init (GStaticRWLock* lock)
 694 {
 695   static GStaticRWLock init_lock = G_STATIC_RW_LOCK_INIT;
 696
 697   g_return_if_fail (lock);
 698
 699   *lock = init_lock;
 700 }
 701
 702 static void inline
 703 g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 704 {
 705   if (!*cond)
 706       *cond = g_cond_new ();
 707   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 708 }
 709
 710 static void inline
 711 g_static_rw_lock_signal (GStaticRWLock* lock)
 712 {
 713   if (lock->want_to_write && lock->write_cond)
 714     g_cond_signal (lock->write_cond);
 715   else if (lock->want_to_read && lock->read_cond)
 716     g_cond_broadcast (lock->read_cond);
 717 }
 718
 719 void
 720 g_static_rw_lock_reader_lock (GStaticRWLock* lock)
 721 {
 722   g_return_if_fail (lock);
 723
 724   if (!g_threads_got_initialized)
 725     return;
 726
 727   g_static_mutex_lock (&lock->mutex);
 728   lock->want_to_read++;
 729   while (lock->have_writer || lock->want_to_write)
 730     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 731   lock->want_to_read--;
 732   lock->read_counter++;
 733   g_static_mutex_unlock (&lock->mutex);
 734 }
 735
 736 gboolean
 737 g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
 738 {
 739   gboolean ret_val = FALSE;
 740
 741   g_return_val_if_fail (lock, FALSE);
 742
 743   if (!g_threads_got_initialized)
 744     return TRUE;
 745
 746   g_static_mutex_lock (&lock->mutex);
 747   if (!lock->have_writer && !lock->want_to_write)
 748     {
 749       lock->read_counter++;
 750       ret_val = TRUE;
 751     }
 752   g_static_mutex_unlock (&lock->mutex);
 753   return ret_val;
 754 }
 755
 756 void
 757 g_static_rw_lock_reader_unlock  (GStaticRWLock* lock)
 758 {
 759   g_return_if_fail (lock);
 760
 761   if (!g_threads_got_initialized)
 762     return;
 763
 764   g_static_mutex_lock (&lock->mutex);
 765   lock->read_counter--;
 766   if (lock->read_counter == 0)
 767     g_static_rw_lock_signal (lock);
 768   g_static_mutex_unlock (&lock->mutex);
 769 }
 770
 771 void
 772 g_static_rw_lock_writer_lock (GStaticRWLock* lock)
 773 {
 774   g_return_if_fail (lock);
 775
 776   if (!g_threads_got_initialized)
 777     return;
 778
 779   g_static_mutex_lock (&lock->mutex);
 780   lock->want_to_write++;
 781   while (lock->have_writer || lock->read_counter)
 782     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 783   lock->want_to_write--;
 784   lock->have_writer = TRUE;
 785   g_static_mutex_unlock (&lock->mutex);
 786 }
 787
 788 gboolean
 789 g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 790 {
 791   gboolean ret_val = FALSE;
 792
 793   g_return_val_if_fail (lock, FALSE);
 794
 795   if (!g_threads_got_initialized)
 796     return TRUE;
 797
 798   g_static_mutex_lock (&lock->mutex);
 799   if (!lock->have_writer && !lock->read_counter)
 800     {
 801       lock->have_writer = TRUE;
 802       ret_val = TRUE;
 803     }
 804   g_static_mutex_unlock (&lock->mutex);
 805   return ret_val;
 806 }
 807
 808 void
 809 g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
 810 {
 811   g_return_if_fail (lock);
 812
 813   if (!g_threads_got_initialized)
 814     return;
 815
 816   g_static_mutex_lock (&lock->mutex);
 817   lock->have_writer = FALSE;
 818   g_static_rw_lock_signal (lock);
 819   g_static_mutex_unlock (&lock->mutex);
 820 }
 821
 822 void
 823 g_static_rw_lock_free (GStaticRWLock* lock)
 824 {
 825   g_return_if_fail (lock);
 826
 827   if (lock->read_cond)
 828     {
 829       g_cond_free (lock->read_cond);
 830       lock->read_cond = NULL;
 831     }
 832   if (lock->write_cond)
 833     {
 834       g_cond_free (lock->write_cond);
 835       lock->write_cond = NULL;
 836     }
 837   g_static_mutex_free (&lock->mutex);
 838 }