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  * gmutex.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 #include "glib.h"
  37
  38 #ifdef G_THREAD_USE_PID_SURROGATE
  39 #include <sys/types.h>
  40 #include <sys/time.h>
  41 #include <sys/resource.h>
  42 #include <errno.h>
  43 #endif /* G_THREAD_USE_PID_SURROGATE */
  44
  45 #ifdef HAVE_UNISTD_H
  46 #include <unistd.h>
  47 #endif
  48
  49 #include <string.h>
  50
  51 #if GLIB_SIZEOF_SYSTEM_THREAD == SIZEOF_VOID_P
  52 # define g_system_thread_equal(thread1, thread2)                        \
  53    (thread1.dummy_pointer == thread2.dummy_pointer)
  54 # define g_system_thread_assign(dest, src)                              \
  55    (dest.dummy_pointer = src.dummy_pointer)
  56 #else /* GLIB_SIZEOF_SYSTEM_THREAD != SIZEOF_VOID_P */
  57 # define g_system_thread_equal(thread1, thread2)                        \
  58    (memcmp (&thread1, &thread2, GLIB_SIZEOF_SYSTEM_THREAD) == 0)
  59 # define g_system_thread_assign(dest, src)                              \
  60    (memcpy (&dest, &src, GLIB_SIZEOF_SYSTEM_THREAD))
  61 #endif /* GLIB_SIZEOF_SYSTEM_THREAD == SIZEOF_VOID_P */
  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 typedef struct _GRealThread GRealThread;
  73 struct  _GRealThread
  74 {
  75   GThread thread;
  76   GThreadFunc func;
  77   gpointer arg;
  78   gpointer private_data;
  79   GSystemThread system_thread;
  80 #ifdef G_THREAD_USE_PID_SURROGATE
  81   pid_t pid;
  82 #endif /* G_THREAD_USE_PID_SURROGATE */
  83 };
  84
  85 #ifdef G_THREAD_USE_PID_SURROGATE
  86 static gint priority_map[] = { 15, 0, -15, -20 };
  87 static gboolean prio_warned = FALSE;
  88 # define SET_PRIO(pid, prio) G_STMT_START{                              \
  89   gint error = setpriority (PRIO_PROCESS, (pid), priority_map[prio]);   \
  90   if (error == -1 && errno == EACCES && !prio_warned)                   \
  91     {                                                                   \
  92       prio_warned = TRUE;                                               \
  93       g_warning ("Priorities can only be increased by root.");          \
  94     }                                                                   \
  95   }G_STMT_END
  96 #endif /* G_THREAD_USE_PID_SURROGATE */
  97
  98 typedef struct _GStaticPrivateNode GStaticPrivateNode;
  99 struct _GStaticPrivateNode
 100 {
 101   gpointer       data;
 102   GDestroyNotify destroy;
 103 };
 104
 105 static void g_thread_cleanup (gpointer data);
 106 static void g_thread_fail (void);
 107
 108 /* Global variables */
 109
 110 static GSystemThread zero_thread; /* This is initialized to all zero */
 111 gboolean g_thread_use_default_impl = TRUE;
 112 gboolean g_threads_got_initialized = FALSE;
 113
 114 #if defined(G_OS_WIN32) && defined(__GNUC__)
 115 __declspec(dllexport)
 116 #endif
 117 GThreadFunctions g_thread_functions_for_glib_use = {
 118   (GMutex*(*)())g_thread_fail,                 /* mutex_new */
 119   NULL,                                        /* mutex_lock */
 120   NULL,                                        /* mutex_trylock */
 121   NULL,                                        /* mutex_unlock */
 122   NULL,                                        /* mutex_free */
 123   (GCond*(*)())g_thread_fail,                  /* cond_new */
 124   NULL,                                        /* cond_signal */
 125   NULL,                                        /* cond_broadcast */
 126   NULL,                                        /* cond_wait */
 127   NULL,                                        /* cond_timed_wait  */
 128   NULL,                                        /* cond_free */
 129   (GPrivate*(*)(GDestroyNotify))g_thread_fail, /* private_new */
 130   NULL,                                        /* private_get */
 131   NULL,                                        /* private_set */
 132   (void(*)(GThreadFunc, gpointer, gulong,
 133            gboolean, gboolean, GThreadPriority,
 134            gpointer, GError**))g_thread_fail,  /* thread_create */
 135   NULL,                                        /* thread_yield */
 136   NULL,                                        /* thread_join */
 137   NULL,                                        /* thread_exit */
 138   NULL,                                        /* thread_set_priority */
 139   NULL                                         /* thread_self */
 140 };
 141
 142 /* Local data */
 143
 144 static GMutex   *g_mutex_protect_static_mutex_allocation = NULL;
 145 static GPrivate *g_thread_specific_private = NULL;
 146 static GSList   *g_thread_all_threads = NULL;
 147 static GSList   *g_thread_free_indeces = NULL;
 148
 149 G_LOCK_DEFINE_STATIC (g_thread);
 150
 151 /* This must be called only once, before any threads are created.
 152  * It will only be called from g_thread_init() in -lgthread.
 153  */
 154 void
 155 g_mutex_init (void)
 156 {
 157   GRealThread* main_thread;
 158
 159   /* We let the main thread (the one that calls g_thread_init) inherit
 160    * the data, that it set before calling g_thread_init
 161    */
 162   main_thread = (GRealThread*) g_thread_self ();
 163
 164   g_thread_specific_private = g_private_new (g_thread_cleanup);
 165   G_THREAD_UF (private_set, (g_thread_specific_private, main_thread));
 166   G_THREAD_UF (thread_self, (&main_thread->system_thread));
 167
 168   g_mutex_protect_static_mutex_allocation = g_mutex_new ();
 169 }
 170
 171 void
 172 g_static_mutex_init (GStaticMutex *mutex)
 173 {
 174   static GStaticMutex init_mutex = G_STATIC_MUTEX_INIT;
 175
 176   g_return_if_fail (mutex);
 177
 178   memcpy (mutex, &init_mutex, sizeof (GStaticMutex));
 179 }
 180
 181 GMutex *
 182 g_static_mutex_get_mutex_impl (GMutex** mutex)
 183 {
 184   if (!g_thread_supported ())
 185     return NULL;
 186
 187   g_assert (g_mutex_protect_static_mutex_allocation);
 188
 189   g_mutex_lock (g_mutex_protect_static_mutex_allocation);
 190
 191   if (!(*mutex))
 192     *mutex = g_mutex_new ();
 193
 194   g_mutex_unlock (g_mutex_protect_static_mutex_allocation);
 195
 196   return *mutex;
 197 }
 198
 199 void
 200 g_static_mutex_free (GStaticMutex* mutex)
 201 {
 202   GMutex **runtime_mutex;
 203
 204   g_return_if_fail (mutex);
 205
 206   /* The runtime_mutex is the first (or only) member of GStaticMutex,
 207    * see both versions (of glibconfig.h) in configure.in */
 208   runtime_mutex = ((GMutex**)mutex);
 209
 210   if (*runtime_mutex)
 211     g_mutex_free (*runtime_mutex);
 212
 213   *runtime_mutex = NULL;
 214 }
 215
 216 void
 217 g_static_rec_mutex_init (GStaticRecMutex *mutex)
 218 {
 219   static GStaticRecMutex init_mutex = G_STATIC_REC_MUTEX_INIT;
 220
 221   g_return_if_fail (mutex);
 222
 223   memcpy (mutex, &init_mutex, sizeof (GStaticRecMutex));
 224 }
 225
 226 void
 227 g_static_rec_mutex_lock (GStaticRecMutex* mutex)
 228 {
 229   GSystemThread self;
 230
 231   g_return_if_fail (mutex);
 232
 233   if (!g_thread_supported ())
 234     return;
 235
 236   G_THREAD_UF (thread_self, (&self));
 237
 238   if (g_system_thread_equal (self, mutex->owner))
 239     {
 240       mutex->depth++;
 241       return;
 242     }
 243   g_static_mutex_lock (&mutex->mutex);
 244   g_system_thread_assign (mutex->owner, self);
 245   mutex->depth = 1;
 246 }
 247
 248 gboolean
 249 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
 250 {
 251   GSystemThread self;
 252
 253   g_return_val_if_fail (mutex, FALSE);
 254
 255   if (!g_thread_supported ())
 256     return TRUE;
 257
 258   G_THREAD_UF (thread_self, (&self));
 259
 260   if (g_system_thread_equal (self, mutex->owner))
 261     {
 262       mutex->depth++;
 263       return TRUE;
 264     }
 265
 266   if (!g_static_mutex_trylock (&mutex->mutex))
 267     return FALSE;
 268
 269   g_system_thread_assign (mutex->owner, self);
 270   mutex->depth = 1;
 271   return TRUE;
 272 }
 273
 274 void
 275 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
 276 {
 277   g_return_if_fail (mutex);
 278
 279   if (!g_thread_supported ())
 280     return;
 281
 282   if (mutex->depth > 1)
 283     {
 284       mutex->depth--;
 285       return;
 286     }
 287   g_system_thread_assign (mutex->owner, zero_thread);
 288   g_static_mutex_unlock (&mutex->mutex);
 289 }
 290
 291 void
 292 g_static_rec_mutex_lock_full   (GStaticRecMutex *mutex,
 293                                 guint            depth)
 294 {
 295   g_return_if_fail (mutex);
 296
 297   if (!g_thread_supported ())
 298     return;
 299
 300   g_static_mutex_lock (&mutex->mutex);
 301   G_THREAD_UF (thread_self, (&mutex->owner));
 302   mutex->depth = depth;
 303 }
 304
 305 guint
 306 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
 307 {
 308   gint depth;
 309
 310   g_return_val_if_fail (mutex, 0);
 311
 312   if (!g_thread_supported ())
 313     return 1;
 314
 315   depth = mutex->depth;
 316
 317   g_system_thread_assign (mutex->owner, zero_thread);
 318   mutex->depth = 0;
 319   g_static_mutex_unlock (&mutex->mutex);
 320
 321   return depth;
 322 }
 323
 324 void
 325 g_static_rec_mutex_free (GStaticRecMutex *mutex)
 326 {
 327   g_return_if_fail (mutex);
 328
 329   g_static_mutex_free (&mutex->mutex);
 330 }
 331
 332 void
 333 g_static_private_init (GStaticPrivate *private_key)
 334 {
 335   private_key->index = 0;
 336 }
 337
 338 gpointer
 339 g_static_private_get (GStaticPrivate *private_key)
 340 {
 341   return g_static_private_get_for_thread (private_key, g_thread_self ());
 342 }
 343
 344 gpointer
 345 g_static_private_get_for_thread (GStaticPrivate *private_key,
 346                                  GThread        *thread)
 347 {
 348   GArray *array;
 349   GRealThread *self = (GRealThread*) thread;
 350
 351   g_return_val_if_fail (thread, NULL);
 352
 353   array = self->private_data;
 354   if (!array)
 355     return NULL;
 356
 357   if (!private_key->index)
 358     return NULL;
 359   else if (private_key->index <= array->len)
 360     return g_array_index (array, GStaticPrivateNode, private_key->index - 1).data;
 361   else
 362     return NULL;
 363 }
 364
 365 void
 366 g_static_private_set (GStaticPrivate *private_key,
 367                       gpointer        data,
 368                       GDestroyNotify  notify)
 369 {
 370   g_static_private_set_for_thread (private_key, g_thread_self (),
 371                                    data, notify);
 372 }
 373
 374 void
 375 g_static_private_set_for_thread (GStaticPrivate *private_key,
 376                                  GThread        *thread,
 377                                  gpointer        data,
 378                                  GDestroyNotify  notify)
 379 {
 380   GArray *array;
 381   GRealThread *self =(GRealThread*) thread;
 382   static guint next_index = 0;
 383   GStaticPrivateNode *node;
 384
 385   g_return_if_fail (thread);
 386
 387   array = self->private_data;
 388   if (!array)
 389     {
 390       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 391       self->private_data = array;
 392     }
 393
 394   if (!private_key->index)
 395     {
 396       G_LOCK (g_thread);
 397
 398       if (!private_key->index)
 399         {
 400           if (g_thread_free_indeces)
 401             {
 402               private_key->index =
 403                 GPOINTER_TO_UINT (g_thread_free_indeces->data);
 404               g_thread_free_indeces =
 405                 g_slist_delete_link (g_thread_free_indeces,
 406                                      g_thread_free_indeces);
 407             }
 408           else
 409             private_key->index = ++next_index;
 410         }
 411
 412       G_UNLOCK (g_thread);
 413     }
 414
 415   if (private_key->index > array->len)
 416     g_array_set_size (array, private_key->index);
 417
 418   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 419   if (node->destroy)
 420     {
 421       gpointer ddata = node->data;
 422       GDestroyNotify ddestroy = node->destroy;
 423
 424       node->data = data;
 425       node->destroy = notify;
 426
 427       ddestroy (ddata);
 428     }
 429   else
 430     {
 431       node->data = data;
 432       node->destroy = notify;
 433     }
 434 }
 435
 436 void
 437 g_static_private_free (GStaticPrivate *private_key)
 438 {
 439   GStaticPrivate copied_key;
 440   GSList *list;
 441
 442   copied_key.index = private_key->index;
 443   private_key->index = 0;
 444
 445   if (!copied_key.index)
 446     return;
 447
 448   G_LOCK (g_thread);
 449   list =  g_thread_all_threads;
 450   while (list)
 451     {
 452       GThread *thread = list->data;
 453       list = list->next;
 454
 455       G_UNLOCK (g_thread);
 456       g_static_private_set_for_thread (&copied_key, thread, NULL, NULL);
 457       G_LOCK (g_thread);
 458     }
 459   g_thread_free_indeces =
 460     g_slist_prepend (g_thread_free_indeces,
 461                      GUINT_TO_POINTER (copied_key.index));
 462   G_UNLOCK (g_thread);
 463 }
 464
 465 static void
 466 g_thread_cleanup (gpointer data)
 467 {
 468   if (data)
 469     {
 470       GRealThread* thread = data;
 471       if (thread->private_data)
 472         {
 473           GArray* array = thread->private_data;
 474           guint i;
 475
 476           for (i = 0; i < array->len; i++ )
 477             {
 478               GStaticPrivateNode *node =
 479                 &g_array_index (array, GStaticPrivateNode, i);
 480               if (node->destroy)
 481                 node->destroy (node->data);
 482             }
 483           g_array_free (array, TRUE);
 484         }
 485       /* We only free the thread structure, if it isn't joinable. If
 486          it is, the structure is freed in g_thread_join */
 487       if (!thread->thread.joinable)
 488         {
 489           G_LOCK (g_thread);
 490           g_thread_all_threads = g_slist_remove (g_thread_all_threads, data);
 491           G_UNLOCK (g_thread);
 492
 493           /* Just to make sure, this isn't used any more */
 494           g_system_thread_assign (thread->system_thread, zero_thread);
 495           g_free (thread);
 496         }
 497     }
 498 }
 499
 500 static void
 501 g_thread_fail (void)
 502 {
 503   g_error ("The thread system is not yet initialized.");
 504 }
 505
 506 static void
 507 g_thread_create_proxy (gpointer data)
 508 {
 509   GRealThread* thread = data;
 510
 511   g_assert (data);
 512
 513 #ifdef G_THREAD_USE_PID_SURROGATE
 514   thread->pid = getpid ();
 515 #endif /* G_THREAD_USE_PID_SURROGATE */
 516
 517   /* This has to happen before G_LOCK, as that might call g_thread_self */
 518   g_private_set (g_thread_specific_private, data);
 519
 520   /* the lock makes sure, that thread->system_thread is written,
 521      before thread->func is called. See g_thread_create. */
 522   G_LOCK (g_thread);
 523   G_UNLOCK (g_thread);
 524
 525   if (g_thread_use_default_impl)
 526     SET_PRIO (thread->pid, thread->thread.priority);
 527
 528   thread->func (thread->arg);
 529 }
 530
 531 GThread*
 532 g_thread_create (GThreadFunc             thread_func,
 533                  gpointer                arg,
 534                  gulong                  stack_size,
 535                  gboolean                joinable,
 536                  gboolean                bound,
 537                  GThreadPriority         priority,
 538                  GError                **error)
 539 {
 540   GRealThread* result = g_new (GRealThread, 1);
 541   GError *local_error = NULL;
 542   g_return_val_if_fail (thread_func, NULL);
 543   g_return_val_if_fail (priority >= G_THREAD_PRIORITY_LOW, NULL);
 544   g_return_val_if_fail (priority <= G_THREAD_PRIORITY_URGENT, NULL);
 545
 546   result->thread.joinable = joinable;
 547   result->thread.bound = bound;
 548   result->thread.priority = priority;
 549   result->func = thread_func;
 550   result->arg = arg;
 551   result->private_data = NULL;
 552   G_LOCK (g_thread);
 553   G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
 554                                stack_size, joinable, bound, priority,
 555                                &result->system_thread, &local_error));
 556   g_thread_all_threads = g_slist_prepend (g_thread_all_threads, result);
 557   G_UNLOCK (g_thread);
 558
 559   if (local_error)
 560     {
 561       g_propagate_error (error, local_error);
 562       g_free (result);
 563       return NULL;
 564     }
 565
 566   return (GThread*) result;
 567 }
 568
 569 void
 570 g_thread_join (GThread* thread)
 571 {
 572   GRealThread* real = (GRealThread*) thread;
 573
 574
 575   g_return_if_fail (thread);
 576   g_return_if_fail (thread->joinable);
 577   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 578
 579   G_THREAD_UF (thread_join, (&real->system_thread));
 580
 581   G_LOCK (g_thread);
 582   g_thread_all_threads = g_slist_remove (g_thread_all_threads, thread);
 583   G_UNLOCK (g_thread);
 584
 585   /* Just to make sure, this isn't used any more */
 586   thread->joinable = 0;
 587   g_system_thread_assign (real->system_thread, zero_thread);
 588
 589   /* the thread structure for non-joinable threads is freed upon
 590      thread end. We free the memory here. This will leave loose end,
 591      if a joinable thread is not joined. */
 592
 593   g_free (thread);
 594 }
 595
 596 void
 597 g_thread_set_priority (GThread* thread,
 598                        GThreadPriority priority)
 599 {
 600   GRealThread* real = (GRealThread*) thread;
 601
 602   g_return_if_fail (thread);
 603   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 604   g_return_if_fail (priority >= G_THREAD_PRIORITY_LOW);
 605   g_return_if_fail (priority <= G_THREAD_PRIORITY_URGENT);
 606
 607   thread->priority = priority;
 608
 609 #ifdef G_THREAD_USE_PID_SURROGATE
 610   if (g_thread_use_default_impl)
 611     SET_PRIO (real->pid, priority);
 612   else
 613 #endif /* G_THREAD_USE_PID_SURROGATE */
 614     G_THREAD_CF (thread_set_priority, (void)0,
 615                  (&real->system_thread, priority));
 616 }
 617
 618 GThread*
 619 g_thread_self (void)
 620 {
 621   GRealThread* thread = g_private_get (g_thread_specific_private);
 622
 623   if (!thread)
 624     {
 625       /* If no thread data is available, provide and set one.  This
 626          can happen for the main thread and for threads, that are not
 627          created by GLib. */
 628       thread = g_new (GRealThread, 1);
 629       thread->thread.joinable = FALSE; /* This is a save guess */
 630       thread->thread.bound = TRUE; /* This isn't important at all */
 631       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 632                                                              just a guess */
 633       thread->func = NULL;
 634       thread->arg = NULL;
 635       thread->private_data = NULL;
 636
 637       if (g_thread_supported ())
 638         G_THREAD_UF (thread_self, (&thread->system_thread));
 639
 640 #ifdef G_THREAD_USE_PID_SURROGATE
 641       thread->pid = getpid ();
 642 #endif /* G_THREAD_USE_PID_SURROGATE */
 643
 644       g_private_set (g_thread_specific_private, thread);
 645
 646       G_LOCK (g_thread);
 647       g_thread_all_threads = g_slist_prepend (g_thread_all_threads, thread);
 648       G_UNLOCK (g_thread);
 649     }
 650
 651   return (GThread*)thread;
 652 }
 653
 654 void
 655 g_static_rw_lock_init (GStaticRWLock* lock)
 656 {
 657   static GStaticRWLock init_lock = G_STATIC_RW_LOCK_INIT;
 658
 659   g_return_if_fail (lock);
 660
 661   memcpy (lock, &init_lock, sizeof (GStaticRWLock));
 662 }
 663
 664 static void inline
 665 g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 666 {
 667   if (!*cond)
 668       *cond = g_cond_new ();
 669   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 670 }
 671
 672 static void inline
 673 g_static_rw_lock_signal (GStaticRWLock* lock)
 674 {
 675   if (lock->want_to_write && lock->write_cond)
 676     g_cond_signal (lock->write_cond);
 677   else if (lock->read_cond)
 678     g_cond_broadcast (lock->read_cond);
 679 }
 680
 681 void
 682 g_static_rw_lock_reader_lock (GStaticRWLock* lock)
 683 {
 684   g_return_if_fail (lock);
 685
 686   if (!g_threads_got_initialized)
 687     return;
 688
 689   g_static_mutex_lock (&lock->mutex);
 690   while (lock->write || lock->want_to_write)
 691     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 692   lock->read_counter++;
 693   g_static_mutex_unlock (&lock->mutex);
 694 }
 695
 696 gboolean
 697 g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
 698 {
 699   gboolean ret_val = FALSE;
 700
 701   g_return_val_if_fail (lock, FALSE);
 702
 703   if (!g_threads_got_initialized)
 704     return TRUE;
 705
 706   g_static_mutex_lock (&lock->mutex);
 707   if (!lock->write && !lock->want_to_write)
 708     {
 709       lock->read_counter++;
 710       ret_val = TRUE;
 711     }
 712   g_static_mutex_unlock (&lock->mutex);
 713   return ret_val;
 714 }
 715
 716 void
 717 g_static_rw_lock_reader_unlock  (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->read_counter--;
 726   if (lock->read_counter == 0)
 727     g_static_rw_lock_signal (lock);
 728   g_static_mutex_unlock (&lock->mutex);
 729 }
 730
 731 void
 732 g_static_rw_lock_writer_lock (GStaticRWLock* lock)
 733 {
 734   g_return_if_fail (lock);
 735
 736   if (!g_threads_got_initialized)
 737     return;
 738
 739   g_static_mutex_lock (&lock->mutex);
 740   lock->want_to_write++;
 741   while (lock->write || lock->read_counter)
 742     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 743   lock->want_to_write--;
 744   lock->write = TRUE;
 745   g_static_mutex_unlock (&lock->mutex);
 746 }
 747
 748 gboolean
 749 g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 750 {
 751   gboolean ret_val = FALSE;
 752
 753   g_return_val_if_fail (lock, FALSE);
 754
 755   if (!g_threads_got_initialized)
 756     return TRUE;
 757
 758   g_static_mutex_lock (&lock->mutex);
 759   if (!lock->write && !lock->read_counter)
 760     {
 761       lock->write = TRUE;
 762       ret_val = TRUE;
 763     }
 764   g_static_mutex_unlock (&lock->mutex);
 765   return ret_val;
 766 }
 767
 768 void
 769 g_static_rw_lock_writer_unlock (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->write = FALSE;
 778   g_static_rw_lock_signal (lock);
 779   g_static_mutex_unlock (&lock->mutex);
 780 }
 781
 782 void
 783 g_static_rw_lock_free (GStaticRWLock* lock)
 784 {
 785   g_return_if_fail (lock);
 786
 787   if (lock->read_cond)
 788     {
 789       g_cond_free (lock->read_cond);
 790       lock->read_cond = NULL;
 791     }
 792   if (lock->write_cond)
 793     {
 794       g_cond_free (lock->write_cond);
 795       lock->write_cond = NULL;
 796     }
 797   g_static_mutex_free (&lock->mutex);
 798 }