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