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 #if defined(G_PLATFORM_WIN32) && defined(__GNUC__)
  99 __declspec(dllexport)
 100 #endif
 101 GThreadFunctions g_thread_functions_for_glib_use = {
 102   (GMutex*(*)())g_thread_fail,                 /* mutex_new */
 103   NULL,                                        /* mutex_lock */
 104   NULL,                                        /* mutex_trylock */
 105   NULL,                                        /* mutex_unlock */
 106   NULL,                                        /* mutex_free */
 107   (GCond*(*)())g_thread_fail,                  /* cond_new */
 108   NULL,                                        /* cond_signal */
 109   NULL,                                        /* cond_broadcast */
 110   NULL,                                        /* cond_wait */
 111   NULL,                                        /* cond_timed_wait  */
 112   NULL,                                        /* cond_free */
 113   (GPrivate*(*)(GDestroyNotify))g_thread_fail, /* private_new */
 114   NULL,                                        /* private_get */
 115   NULL,                                        /* private_set */
 116   (void(*)(GThreadFunc, gpointer, gulong,
 117            gboolean, gboolean, GThreadPriority,
 118            gpointer, GError**))g_thread_fail,  /* thread_create */
 119   NULL,                                        /* thread_yield */
 120   NULL,                                        /* thread_join */
 121   NULL,                                        /* thread_exit */
 122   NULL,                                        /* thread_set_priority */
 123   NULL                                         /* thread_self */
 124 };
 125
 126 /* Local data */
 127
 128 static GMutex   *g_once_mutex = NULL;
 129 static GCond    *g_once_cond = NULL;
 130 static GPrivate *g_thread_specific_private = NULL;
 131 static GSList   *g_thread_all_threads = NULL;
 132 static GSList   *g_thread_free_indeces = NULL;
 133
 134 G_LOCK_DEFINE_STATIC (g_thread);
 135
 136 #ifdef G_THREADS_ENABLED
 137 /* This must be called only once, before any threads are created.
 138  * It will only be called from g_thread_init() in -lgthread.
 139  */
 140 void
 141 g_thread_init_glib (void)
 142 {
 143   /* We let the main thread (the one that calls g_thread_init) inherit
 144    * the static_private data set before calling g_thread_init
 145    */
 146   GRealThread* main_thread = (GRealThread*) g_thread_self ();
 147
 148   g_once_mutex = g_mutex_new ();
 149   g_once_cond = g_cond_new ();
 150
 151   _g_convert_thread_init ();
 152   _g_rand_thread_init ();
 153   _g_main_thread_init ();
 154   _g_mem_thread_init ();
 155   _g_messages_thread_init ();
 156   _g_atomic_thread_init ();
 157
 158   g_threads_got_initialized = TRUE;
 159
 160   g_thread_specific_private = g_private_new (g_thread_cleanup);
 161   g_private_set (g_thread_specific_private, main_thread);
 162   G_THREAD_UF (thread_self, (&main_thread->system_thread));
 163
 164   _g_mem_thread_private_init ();
 165   _g_messages_thread_private_init ();
 166
 167 }
 168 #endif /* G_THREADS_ENABLED */
 169
 170 gpointer
 171 g_once_impl (GOnce       *once,
 172              GThreadFunc  func,
 173              gpointer     arg)
 174 {
 175   g_mutex_lock (g_once_mutex);
 176
 177   while (once->status == G_ONCE_STATUS_PROGRESS)
 178     g_cond_wait (g_once_cond, g_once_mutex);
 179
 180   if (once->status != G_ONCE_STATUS_READY)
 181     {
 182       once->status = G_ONCE_STATUS_PROGRESS;
 183       g_mutex_unlock (g_once_mutex);
 184
 185       once->retval = func (arg);
 186
 187       g_mutex_lock (g_once_mutex);
 188       once->status = G_ONCE_STATUS_READY;
 189       g_cond_broadcast (g_once_cond);
 190     }
 191
 192   g_mutex_unlock (g_once_mutex);
 193
 194   return once->retval;
 195 }
 196
 197 void
 198 g_static_mutex_init (GStaticMutex *mutex)
 199 {
 200   static GStaticMutex init_mutex = G_STATIC_MUTEX_INIT;
 201
 202   g_return_if_fail (mutex);
 203
 204   *mutex = init_mutex;
 205 }
 206
 207 GMutex *
 208 g_static_mutex_get_mutex_impl (GMutex** mutex)
 209 {
 210   if (!g_thread_supported ())
 211     return NULL;
 212
 213   g_assert (g_once_mutex);
 214
 215   g_mutex_lock (g_once_mutex);
 216
 217   if (!(*mutex))
 218     {
 219       GMutex *new_mutex = g_mutex_new ();
 220
 221       /* The following is a memory barrier to avoid the write
 222        * to *new_mutex being reordered to after writing *mutex */
 223       g_mutex_lock (new_mutex);
 224       g_mutex_unlock (new_mutex);
 225
 226       *mutex = new_mutex;
 227     }
 228
 229   g_mutex_unlock (g_once_mutex);
 230
 231   return *mutex;
 232 }
 233
 234 void
 235 g_static_mutex_free (GStaticMutex* mutex)
 236 {
 237   GMutex **runtime_mutex;
 238
 239   g_return_if_fail (mutex);
 240
 241   /* The runtime_mutex is the first (or only) member of GStaticMutex,
 242    * see both versions (of glibconfig.h) in configure.in */
 243   runtime_mutex = ((GMutex**)mutex);
 244
 245   if (*runtime_mutex)
 246     g_mutex_free (*runtime_mutex);
 247
 248   *runtime_mutex = NULL;
 249 }
 250
 251 void
 252 g_static_rec_mutex_init (GStaticRecMutex *mutex)
 253 {
 254   static GStaticRecMutex init_mutex = G_STATIC_REC_MUTEX_INIT;
 255
 256   g_return_if_fail (mutex);
 257
 258   *mutex = init_mutex;
 259 }
 260
 261 void
 262 g_static_rec_mutex_lock (GStaticRecMutex* mutex)
 263 {
 264   GSystemThread self;
 265
 266   g_return_if_fail (mutex);
 267
 268   if (!g_thread_supported ())
 269     return;
 270
 271   G_THREAD_UF (thread_self, (&self));
 272
 273   if (g_system_thread_equal (self, mutex->owner))
 274     {
 275       mutex->depth++;
 276       return;
 277     }
 278   g_static_mutex_lock (&mutex->mutex);
 279   g_system_thread_assign (mutex->owner, self);
 280   mutex->depth = 1;
 281 }
 282
 283 gboolean
 284 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
 285 {
 286   GSystemThread self;
 287
 288   g_return_val_if_fail (mutex, FALSE);
 289
 290   if (!g_thread_supported ())
 291     return TRUE;
 292
 293   G_THREAD_UF (thread_self, (&self));
 294
 295   if (g_system_thread_equal (self, mutex->owner))
 296     {
 297       mutex->depth++;
 298       return TRUE;
 299     }
 300
 301   if (!g_static_mutex_trylock (&mutex->mutex))
 302     return FALSE;
 303
 304   g_system_thread_assign (mutex->owner, self);
 305   mutex->depth = 1;
 306   return TRUE;
 307 }
 308
 309 void
 310 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
 311 {
 312   g_return_if_fail (mutex);
 313
 314   if (!g_thread_supported ())
 315     return;
 316
 317   if (mutex->depth > 1)
 318     {
 319       mutex->depth--;
 320       return;
 321     }
 322   g_system_thread_assign (mutex->owner, zero_thread);
 323   g_static_mutex_unlock (&mutex->mutex);
 324 }
 325
 326 void
 327 g_static_rec_mutex_lock_full   (GStaticRecMutex *mutex,
 328                                 guint            depth)
 329 {
 330   GSystemThread self;
 331   g_return_if_fail (mutex);
 332
 333   if (!g_thread_supported ())
 334     return;
 335
 336   G_THREAD_UF (thread_self, (&self));
 337
 338   if (g_system_thread_equal (self, mutex->owner))
 339     {
 340       mutex->depth += depth;
 341       return;
 342     }
 343   g_static_mutex_lock (&mutex->mutex);
 344   g_system_thread_assign (mutex->owner, self);
 345   mutex->depth = depth;
 346 }
 347
 348 guint
 349 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
 350 {
 351   guint depth;
 352
 353   g_return_val_if_fail (mutex, 0);
 354
 355   if (!g_thread_supported ())
 356     return 1;
 357
 358   depth = mutex->depth;
 359
 360   g_system_thread_assign (mutex->owner, zero_thread);
 361   mutex->depth = 0;
 362   g_static_mutex_unlock (&mutex->mutex);
 363
 364   return depth;
 365 }
 366
 367 void
 368 g_static_rec_mutex_free (GStaticRecMutex *mutex)
 369 {
 370   g_return_if_fail (mutex);
 371
 372   g_static_mutex_free (&mutex->mutex);
 373 }
 374
 375 void
 376 g_static_private_init (GStaticPrivate *private_key)
 377 {
 378   private_key->index = 0;
 379 }
 380
 381 gpointer
 382 g_static_private_get (GStaticPrivate *private_key)
 383 {
 384   GRealThread *self = (GRealThread*) g_thread_self ();
 385   GArray *array;
 386
 387   array = self->private_data;
 388   if (!array)
 389     return NULL;
 390
 391   if (!private_key->index)
 392     return NULL;
 393   else if (private_key->index <= array->len)
 394     return g_array_index (array, GStaticPrivateNode,
 395                           private_key->index - 1).data;
 396   else
 397     return NULL;
 398 }
 399
 400 void
 401 g_static_private_set (GStaticPrivate *private_key,
 402                       gpointer        data,
 403                       GDestroyNotify  notify)
 404 {
 405   GRealThread *self = (GRealThread*) g_thread_self ();
 406   GArray *array;
 407   static guint next_index = 0;
 408   GStaticPrivateNode *node;
 409
 410   array = self->private_data;
 411   if (!array)
 412     {
 413       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 414       self->private_data = array;
 415     }
 416
 417   if (!private_key->index)
 418     {
 419       G_LOCK (g_thread);
 420
 421       if (!private_key->index)
 422         {
 423           if (g_thread_free_indeces)
 424             {
 425               private_key->index =
 426                 GPOINTER_TO_UINT (g_thread_free_indeces->data);
 427               g_thread_free_indeces =
 428                 g_slist_delete_link (g_thread_free_indeces,
 429                                      g_thread_free_indeces);
 430             }
 431           else
 432             private_key->index = ++next_index;
 433         }
 434
 435       G_UNLOCK (g_thread);
 436     }
 437
 438   if (private_key->index > array->len)
 439     g_array_set_size (array, private_key->index);
 440
 441   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 442   if (node->destroy)
 443     {
 444       gpointer ddata = node->data;
 445       GDestroyNotify ddestroy = node->destroy;
 446
 447       node->data = data;
 448       node->destroy = notify;
 449
 450       ddestroy (ddata);
 451     }
 452   else
 453     {
 454       node->data = data;
 455       node->destroy = notify;
 456     }
 457 }
 458
 459 void
 460 g_static_private_free (GStaticPrivate *private_key)
 461 {
 462   guint index = private_key->index;
 463   GSList *list;
 464
 465   if (!index)
 466     return;
 467
 468   private_key->index = 0;
 469
 470   G_LOCK (g_thread);
 471   list =  g_thread_all_threads;
 472   while (list)
 473     {
 474       GRealThread *thread = list->data;
 475       GArray *array = thread->private_data;
 476       list = list->next;
 477
 478       if (array && index <= array->len)
 479         {
 480           GStaticPrivateNode *node = &g_array_index (array,
 481                                                      GStaticPrivateNode,
 482                                                      index - 1);
 483           gpointer ddata = node->data;
 484           GDestroyNotify ddestroy = node->destroy;
 485
 486           node->data = NULL;
 487           node->destroy = NULL;
 488
 489           if (ddestroy)
 490             {
 491               G_UNLOCK (g_thread);
 492               ddestroy (ddata);
 493               G_LOCK (g_thread);
 494               }
 495         }
 496     }
 497   g_thread_free_indeces = g_slist_prepend (g_thread_free_indeces,
 498                                            GUINT_TO_POINTER (index));
 499   G_UNLOCK (g_thread);
 500 }
 501
 502 static void
 503 g_thread_cleanup (gpointer data)
 504 {
 505   if (data)
 506     {
 507       GRealThread* thread = data;
 508       if (thread->private_data)
 509         {
 510           GArray* array = thread->private_data;
 511           guint i;
 512
 513           for (i = 0; i < array->len; i++ )
 514             {
 515               GStaticPrivateNode *node =
 516                 &g_array_index (array, GStaticPrivateNode, i);
 517               if (node->destroy)
 518                 node->destroy (node->data);
 519             }
 520           g_array_free (array, TRUE);
 521         }
 522
 523       /* We only free the thread structure, if it isn't joinable. If
 524          it is, the structure is freed in g_thread_join */
 525       if (!thread->thread.joinable)
 526         {
 527           G_LOCK (g_thread);
 528           g_thread_all_threads = g_slist_remove (g_thread_all_threads, data);
 529           G_UNLOCK (g_thread);
 530
 531           /* Just to make sure, this isn't used any more */
 532           g_system_thread_assign (thread->system_thread, zero_thread);
 533           g_free (thread);
 534         }
 535     }
 536 }
 537
 538 static void
 539 g_thread_fail (void)
 540 {
 541   g_error ("The thread system is not yet initialized.");
 542 }
 543
 544 static gpointer
 545 g_thread_create_proxy (gpointer data)
 546 {
 547   GRealThread* thread = data;
 548
 549   g_assert (data);
 550
 551   /* This has to happen before G_LOCK, as that might call g_thread_self */
 552   g_private_set (g_thread_specific_private, data);
 553
 554   /* the lock makes sure, that thread->system_thread is written,
 555      before thread->thread.func is called. See g_thread_create. */
 556   G_LOCK (g_thread);
 557   G_UNLOCK (g_thread);
 558
 559   thread->retval = thread->thread.func (thread->thread.data);
 560
 561   return NULL;
 562 }
 563
 564 GThread*
 565 g_thread_create_full (GThreadFunc                func,
 566                       gpointer           data,
 567                       gulong             stack_size,
 568                       gboolean           joinable,
 569                       gboolean           bound,
 570                       GThreadPriority    priority,
 571                       GError                **error)
 572 {
 573   GRealThread* result;
 574   GError *local_error = NULL;
 575   g_return_val_if_fail (func, NULL);
 576   g_return_val_if_fail (priority >= G_THREAD_PRIORITY_LOW, NULL);
 577   g_return_val_if_fail (priority <= G_THREAD_PRIORITY_URGENT, NULL);
 578
 579   result = g_new (GRealThread, 1);
 580
 581   result->thread.joinable = joinable;
 582   result->thread.priority = priority;
 583   result->thread.func = func;
 584   result->thread.data = data;
 585   result->private_data = NULL;
 586   G_LOCK (g_thread);
 587   G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
 588                                stack_size, joinable, bound, priority,
 589                                &result->system_thread, &local_error));
 590   g_thread_all_threads = g_slist_prepend (g_thread_all_threads, result);
 591   G_UNLOCK (g_thread);
 592
 593   if (local_error)
 594     {
 595       g_propagate_error (error, local_error);
 596       g_free (result);
 597       return NULL;
 598     }
 599
 600   return (GThread*) result;
 601 }
 602
 603 void
 604 g_thread_exit (gpointer retval)
 605 {
 606   GRealThread* real = (GRealThread*) g_thread_self ();
 607   real->retval = retval;
 608   G_THREAD_CF (thread_exit, (void)0, ());
 609 }
 610
 611 gpointer
 612 g_thread_join (GThread* thread)
 613 {
 614   GRealThread* real = (GRealThread*) thread;
 615   gpointer retval;
 616
 617   g_return_val_if_fail (thread, NULL);
 618   g_return_val_if_fail (thread->joinable, NULL);
 619   g_return_val_if_fail (!g_system_thread_equal (real->system_thread,
 620                                                 zero_thread), NULL);
 621
 622   G_THREAD_UF (thread_join, (&real->system_thread));
 623
 624   retval = real->retval;
 625
 626   G_LOCK (g_thread);
 627   g_thread_all_threads = g_slist_remove (g_thread_all_threads, thread);
 628   G_UNLOCK (g_thread);
 629
 630   /* Just to make sure, this isn't used any more */
 631   thread->joinable = 0;
 632   g_system_thread_assign (real->system_thread, zero_thread);
 633
 634   /* the thread structure for non-joinable threads is freed upon
 635      thread end. We free the memory here. This will leave a loose end,
 636      if a joinable thread is not joined. */
 637
 638   g_free (thread);
 639
 640   return retval;
 641 }
 642
 643 void
 644 g_thread_set_priority (GThread* thread,
 645                        GThreadPriority priority)
 646 {
 647   GRealThread* real = (GRealThread*) thread;
 648
 649   g_return_if_fail (thread);
 650   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 651   g_return_if_fail (priority >= G_THREAD_PRIORITY_LOW);
 652   g_return_if_fail (priority <= G_THREAD_PRIORITY_URGENT);
 653
 654   thread->priority = priority;
 655
 656   G_THREAD_CF (thread_set_priority, (void)0,
 657                (&real->system_thread, priority));
 658 }
 659
 660 GThread*
 661 g_thread_self (void)
 662 {
 663   GRealThread* thread = g_private_get (g_thread_specific_private);
 664
 665   if (!thread)
 666     {
 667       /* If no thread data is available, provide and set one.  This
 668          can happen for the main thread and for threads, that are not
 669          created by GLib. */
 670       thread = g_new (GRealThread, 1);
 671       thread->thread.joinable = FALSE; /* This is a save guess */
 672       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 673                                                              just a guess */
 674       thread->thread.func = NULL;
 675       thread->thread.data = NULL;
 676       thread->private_data = NULL;
 677
 678       if (g_thread_supported ())
 679         G_THREAD_UF (thread_self, (&thread->system_thread));
 680
 681       g_private_set (g_thread_specific_private, thread);
 682
 683       G_LOCK (g_thread);
 684       g_thread_all_threads = g_slist_prepend (g_thread_all_threads, thread);
 685       G_UNLOCK (g_thread);
 686     }
 687
 688   return (GThread*)thread;
 689 }
 690
 691 void
 692 g_static_rw_lock_init (GStaticRWLock* lock)
 693 {
 694   static GStaticRWLock init_lock = G_STATIC_RW_LOCK_INIT;
 695
 696   g_return_if_fail (lock);
 697
 698   *lock = init_lock;
 699 }
 700
 701 static void inline
 702 g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 703 {
 704   if (!*cond)
 705       *cond = g_cond_new ();
 706   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 707 }
 708
 709 static void inline
 710 g_static_rw_lock_signal (GStaticRWLock* lock)
 711 {
 712   if (lock->want_to_write && lock->write_cond)
 713     g_cond_signal (lock->write_cond);
 714   else if (lock->want_to_read && lock->read_cond)
 715     g_cond_broadcast (lock->read_cond);
 716 }
 717
 718 void
 719 g_static_rw_lock_reader_lock (GStaticRWLock* lock)
 720 {
 721   g_return_if_fail (lock);
 722
 723   if (!g_threads_got_initialized)
 724     return;
 725
 726   g_static_mutex_lock (&lock->mutex);
 727   lock->want_to_read++;
 728   while (lock->have_writer || lock->want_to_write)
 729     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 730   lock->want_to_read--;
 731   lock->read_counter++;
 732   g_static_mutex_unlock (&lock->mutex);
 733 }
 734
 735 gboolean
 736 g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
 737 {
 738   gboolean ret_val = FALSE;
 739
 740   g_return_val_if_fail (lock, FALSE);
 741
 742   if (!g_threads_got_initialized)
 743     return TRUE;
 744
 745   g_static_mutex_lock (&lock->mutex);
 746   if (!lock->have_writer && !lock->want_to_write)
 747     {
 748       lock->read_counter++;
 749       ret_val = TRUE;
 750     }
 751   g_static_mutex_unlock (&lock->mutex);
 752   return ret_val;
 753 }
 754
 755 void
 756 g_static_rw_lock_reader_unlock  (GStaticRWLock* lock)
 757 {
 758   g_return_if_fail (lock);
 759
 760   if (!g_threads_got_initialized)
 761     return;
 762
 763   g_static_mutex_lock (&lock->mutex);
 764   lock->read_counter--;
 765   if (lock->read_counter == 0)
 766     g_static_rw_lock_signal (lock);
 767   g_static_mutex_unlock (&lock->mutex);
 768 }
 769
 770 void
 771 g_static_rw_lock_writer_lock (GStaticRWLock* lock)
 772 {
 773   g_return_if_fail (lock);
 774
 775   if (!g_threads_got_initialized)
 776     return;
 777
 778   g_static_mutex_lock (&lock->mutex);
 779   lock->want_to_write++;
 780   while (lock->have_writer || lock->read_counter)
 781     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 782   lock->want_to_write--;
 783   lock->have_writer = TRUE;
 784   g_static_mutex_unlock (&lock->mutex);
 785 }
 786
 787 gboolean
 788 g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 789 {
 790   gboolean ret_val = FALSE;
 791
 792   g_return_val_if_fail (lock, FALSE);
 793
 794   if (!g_threads_got_initialized)
 795     return TRUE;
 796
 797   g_static_mutex_lock (&lock->mutex);
 798   if (!lock->have_writer && !lock->read_counter)
 799     {
 800       lock->have_writer = TRUE;
 801       ret_val = TRUE;
 802     }
 803   g_static_mutex_unlock (&lock->mutex);
 804   return ret_val;
 805 }
 806
 807 void
 808 g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
 809 {
 810   g_return_if_fail (lock);
 811
 812   if (!g_threads_got_initialized)
 813     return;
 814
 815   g_static_mutex_lock (&lock->mutex);
 816   lock->have_writer = FALSE;
 817   g_static_rw_lock_signal (lock);
 818   g_static_mutex_unlock (&lock->mutex);
 819 }
 820
 821 void
 822 g_static_rw_lock_free (GStaticRWLock* lock)
 823 {
 824   g_return_if_fail (lock);
 825
 826   if (lock->read_cond)
 827     {
 828       g_cond_free (lock->read_cond);
 829       lock->read_cond = NULL;
 830     }
 831   if (lock->write_cond)
 832     {
 833       g_cond_free (lock->write_cond);
 834       lock->write_cond = NULL;
 835     }
 836   g_static_mutex_free (&lock->mutex);
 837 }