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 #if GLIB_SIZEOF_SYSTEM_THREAD == SIZEOF_VOID_P
  50 # define g_system_thread_equal(thread1, thread2)                        \
  51    (thread1.dummy_pointer == thread2.dummy_pointer)
  52 # define g_system_thread_assign(dest, src)                              \
  53    (dest.dummy_pointer = src.dummy_pointer)
  54 #else /* GLIB_SIZEOF_SYSTEM_THREAD != SIZEOF_VOID_P */
  55 # define g_system_thread_equal(thread1, thread2)                        \
  56    (memcmp (&thread1, &thread2, GLIB_SIZEOF_SYSTEM_THREAD) == 0)
  57 # define g_system_thread_assign(dest, src)                              \
  58    (memcpy (&dest, &src, GLIB_SIZEOF_SYSTEM_THREAD))
  59 #endif /* GLIB_SIZEOF_SYSTEM_THREAD == SIZEOF_VOID_P */
  60
  61 GQuark
  62 g_thread_error_quark (void)
  63 {
  64   static GQuark quark;
  65   if (!quark)
  66     quark = g_quark_from_static_string ("g_thread_error");
  67   return quark;
  68 }
  69
  70 typedef struct _GRealThread GRealThread;
  71 struct  _GRealThread
  72 {
  73   GThread thread;
  74   GThreadFunc func;
  75   gpointer arg;
  76   gpointer private_data;
  77   GSystemThread system_thread;
  78 #ifdef G_THREAD_USE_PID_SURROGATE
  79   pid_t pid;
  80 #endif /* G_THREAD_USE_PID_SURROGATE */
  81 };
  82
  83 #ifdef G_THREAD_USE_PID_SURROGATE
  84 static gint priority_map[] = { 15, 0, -15, -20 };
  85 static gboolean prio_warned = FALSE;
  86 # define SET_PRIO(pid, prio) G_STMT_START{                              \
  87   gint error = setpriority (PRIO_PROCESS, (pid), priority_map[prio]);   \
  88   if (error == -1 && errno == EACCES && !prio_warned)                   \
  89     {                                                                   \
  90       prio_warned = TRUE;                                               \
  91       g_warning ("Priorities can only be increased by root.");          \
  92     }                                                                   \
  93   }G_STMT_END
  94 #endif /* G_THREAD_USE_PID_SURROGATE */
  95
  96 typedef struct _GStaticPrivateNode GStaticPrivateNode;
  97 struct _GStaticPrivateNode
  98 {
  99   gpointer       data;
 100   GDestroyNotify destroy;
 101 };
 102
 103 static void g_thread_cleanup (gpointer data);
 104 static void g_thread_fail (void);
 105
 106 /* Global variables */
 107
 108 static GSystemThread zero_thread; /* This is initialized to all zero */
 109 gboolean g_thread_use_default_impl = TRUE;
 110 gboolean g_threads_got_initialized = FALSE;
 111
 112 #if defined(G_OS_WIN32) && defined(__GNUC__)
 113 __declspec(dllexport)
 114 #endif
 115 GThreadFunctions g_thread_functions_for_glib_use = {
 116   (GMutex*(*)())g_thread_fail,                 /* mutex_new */
 117   NULL,                                        /* mutex_lock */
 118   NULL,                                        /* mutex_trylock */
 119   NULL,                                        /* mutex_unlock */
 120   NULL,                                        /* mutex_free */
 121   (GCond*(*)())g_thread_fail,                  /* cond_new */
 122   NULL,                                        /* cond_signal */
 123   NULL,                                        /* cond_broadcast */
 124   NULL,                                        /* cond_wait */
 125   NULL,                                        /* cond_timed_wait  */
 126   NULL,                                        /* cond_free */
 127   (GPrivate*(*)(GDestroyNotify))g_thread_fail, /* private_new */
 128   NULL,                                        /* private_get */
 129   NULL,                                        /* private_set */
 130   (void(*)(GThreadFunc, gpointer, gulong,
 131            gboolean, gboolean, GThreadPriority,
 132            gpointer, GError**))g_thread_fail,  /* thread_create */
 133   NULL,                                        /* thread_yield */
 134   NULL,                                        /* thread_join */
 135   NULL,                                        /* thread_exit */
 136   NULL,                                        /* thread_set_priority */
 137   NULL                                         /* thread_self */
 138 };
 139
 140 /* Local data */
 141
 142 static GMutex   *g_mutex_protect_static_mutex_allocation = NULL;
 143 static GPrivate *g_thread_specific_private = NULL;
 144 static GSList   *g_thread_all_threads = NULL;
 145 static GSList   *g_thread_free_indeces = NULL;
 146
 147 G_LOCK_DEFINE_STATIC (g_thread);
 148
 149 /* This must be called only once, before any threads are created.
 150  * It will only be called from g_thread_init() in -lgthread.
 151  */
 152 void
 153 g_mutex_init (void)
 154 {
 155   GRealThread* main_thread;
 156
 157   /* We let the main thread (the one that calls g_thread_init) inherit
 158    * the data, that it set before calling g_thread_init
 159    */
 160   main_thread = (GRealThread*) g_thread_self ();
 161
 162   g_thread_specific_private = g_private_new (g_thread_cleanup);
 163   G_THREAD_UF (private_set, (g_thread_specific_private, main_thread));
 164   G_THREAD_UF (thread_self, (&main_thread->system_thread));
 165
 166   g_mutex_protect_static_mutex_allocation = g_mutex_new ();
 167 }
 168
 169 void
 170 g_static_mutex_init (GStaticMutex *mutex)
 171 {
 172   static GStaticMutex init_mutex = G_STATIC_MUTEX_INIT;
 173
 174   g_return_if_fail (mutex);
 175
 176   memcpy (mutex, &init_mutex, sizeof (GStaticMutex));
 177 }
 178
 179 GMutex *
 180 g_static_mutex_get_mutex_impl (GMutex** mutex)
 181 {
 182   if (!g_thread_supported ())
 183     return NULL;
 184
 185   g_assert (g_mutex_protect_static_mutex_allocation);
 186
 187   g_mutex_lock (g_mutex_protect_static_mutex_allocation);
 188
 189   if (!(*mutex))
 190     *mutex = g_mutex_new ();
 191
 192   g_mutex_unlock (g_mutex_protect_static_mutex_allocation);
 193
 194   return *mutex;
 195 }
 196
 197 void
 198 g_static_mutex_free (GStaticMutex* mutex)
 199 {
 200   GMutex **runtime_mutex;
 201
 202   g_return_if_fail (mutex);
 203
 204   /* The runtime_mutex is the first (or only) member of GStaticMutex,
 205    * see both versions (of glibconfig.h) in configure.in */
 206   runtime_mutex = ((GMutex**)mutex);
 207
 208   if (*runtime_mutex)
 209     g_mutex_free (*runtime_mutex);
 210
 211   *runtime_mutex = NULL;
 212 }
 213
 214 void
 215 g_static_rec_mutex_init (GStaticRecMutex *mutex)
 216 {
 217   static GStaticRecMutex init_mutex = G_STATIC_REC_MUTEX_INIT;
 218
 219   g_return_if_fail (mutex);
 220
 221   memcpy (mutex, &init_mutex, sizeof (GStaticRecMutex));
 222 }
 223
 224 void
 225 g_static_rec_mutex_lock (GStaticRecMutex* mutex)
 226 {
 227   GSystemThread self;
 228
 229   g_return_if_fail (mutex);
 230
 231   if (!g_thread_supported ())
 232     return;
 233
 234   G_THREAD_UF (thread_self, (&self));
 235
 236   if (g_system_thread_equal (self, mutex->owner))
 237     {
 238       mutex->depth++;
 239       return;
 240     }
 241   g_static_mutex_lock (&mutex->mutex);
 242   g_system_thread_assign (mutex->owner, self);
 243   mutex->depth = 1;
 244 }
 245
 246 gboolean
 247 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
 248 {
 249   GSystemThread self;
 250
 251   g_return_val_if_fail (mutex, FALSE);
 252
 253   if (!g_thread_supported ())
 254     return TRUE;
 255
 256   G_THREAD_UF (thread_self, (&self));
 257
 258   if (g_system_thread_equal (self, mutex->owner))
 259     {
 260       mutex->depth++;
 261       return TRUE;
 262     }
 263
 264   if (!g_static_mutex_trylock (&mutex->mutex))
 265     return FALSE;
 266
 267   g_system_thread_assign (mutex->owner, self);
 268   mutex->depth = 1;
 269   return TRUE;
 270 }
 271
 272 void
 273 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
 274 {
 275   g_return_if_fail (mutex);
 276
 277   if (!g_thread_supported ())
 278     return;
 279
 280   if (mutex->depth > 1)
 281     {
 282       mutex->depth--;
 283       return;
 284     }
 285   g_system_thread_assign (mutex->owner, zero_thread);
 286   g_static_mutex_unlock (&mutex->mutex);
 287 }
 288
 289 void
 290 g_static_rec_mutex_lock_full   (GStaticRecMutex *mutex,
 291                                 guint            depth)
 292 {
 293   g_return_if_fail (mutex);
 294
 295   if (!g_thread_supported ())
 296     return;
 297
 298   g_static_mutex_lock (&mutex->mutex);
 299   G_THREAD_UF (thread_self, (&mutex->owner));
 300   mutex->depth = depth;
 301 }
 302
 303 guint
 304 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
 305 {
 306   gint depth;
 307
 308   g_return_val_if_fail (mutex, 0);
 309
 310   if (!g_thread_supported ())
 311     return 1;
 312
 313   depth = mutex->depth;
 314
 315   g_system_thread_assign (mutex->owner, zero_thread);
 316   mutex->depth = 0;
 317   g_static_mutex_unlock (&mutex->mutex);
 318
 319   return depth;
 320 }
 321
 322 void
 323 g_static_rec_mutex_free (GStaticRecMutex *mutex)
 324 {
 325   g_return_if_fail (mutex);
 326
 327   g_static_mutex_free (&mutex->mutex);
 328 }
 329
 330 void
 331 g_static_private_init (GStaticPrivate *private_key)
 332 {
 333   private_key->index = 0;
 334 }
 335
 336 gpointer
 337 g_static_private_get (GStaticPrivate *private_key)
 338 {
 339   return g_static_private_get_for_thread (private_key, g_thread_self ());
 340 }
 341
 342 gpointer
 343 g_static_private_get_for_thread (GStaticPrivate *private_key,
 344                                  GThread        *thread)
 345 {
 346   GArray *array;
 347   GRealThread *self = (GRealThread*) thread;
 348
 349   g_return_val_if_fail (thread, NULL);
 350
 351   array = self->private_data;
 352   if (!array)
 353     return NULL;
 354
 355   if (!private_key->index)
 356     return NULL;
 357   else if (private_key->index <= array->len)
 358     return g_array_index (array, GStaticPrivateNode, private_key->index - 1).data;
 359   else
 360     return NULL;
 361 }
 362
 363 void
 364 g_static_private_set (GStaticPrivate *private_key,
 365                       gpointer        data,
 366                       GDestroyNotify  notify)
 367 {
 368   g_static_private_set_for_thread (private_key, g_thread_self (),
 369                                    data, notify);
 370 }
 371
 372 void
 373 g_static_private_set_for_thread (GStaticPrivate *private_key,
 374                                  GThread        *thread,
 375                                  gpointer        data,
 376                                  GDestroyNotify  notify)
 377 {
 378   GArray *array;
 379   GRealThread *self =(GRealThread*) thread;
 380   static guint next_index = 0;
 381   GStaticPrivateNode *node;
 382
 383   g_return_if_fail (thread);
 384
 385   array = self->private_data;
 386   if (!array)
 387     {
 388       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 389       self->private_data = array;
 390     }
 391
 392   if (!private_key->index)
 393     {
 394       G_LOCK (g_thread);
 395
 396       if (!private_key->index)
 397         {
 398           if (g_thread_free_indeces)
 399             {
 400               private_key->index =
 401                 GPOINTER_TO_UINT (g_thread_free_indeces->data);
 402               g_thread_free_indeces =
 403                 g_slist_delete_link (g_thread_free_indeces,
 404                                      g_thread_free_indeces);
 405             }
 406           else
 407             private_key->index = ++next_index;
 408         }
 409
 410       G_UNLOCK (g_thread);
 411     }
 412
 413   if (private_key->index > array->len)
 414     g_array_set_size (array, private_key->index);
 415
 416   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 417   if (node->destroy)
 418     {
 419       gpointer ddata = node->data;
 420       GDestroyNotify ddestroy = node->destroy;
 421
 422       node->data = data;
 423       node->destroy = notify;
 424
 425       ddestroy (ddata);
 426     }
 427   else
 428     {
 429       node->data = data;
 430       node->destroy = notify;
 431     }
 432 }
 433
 434 void
 435 g_static_private_free (GStaticPrivate *private_key)
 436 {
 437   GStaticPrivate copied_key;
 438   GSList *list;
 439
 440   copied_key.index = private_key->index;
 441   private_key->index = 0;
 442
 443   if (!copied_key.index)
 444     return;
 445
 446   G_LOCK (g_thread);
 447   list =  g_thread_all_threads;
 448   while (list)
 449     {
 450       GThread *thread = list->data;
 451       list = list->next;
 452
 453       G_UNLOCK (g_thread);
 454       g_static_private_set_for_thread (&copied_key, thread, NULL, NULL);
 455       G_LOCK (g_thread);
 456     }
 457   g_thread_free_indeces =
 458     g_slist_prepend (g_thread_free_indeces,
 459                      GUINT_TO_POINTER (copied_key.index));
 460   G_UNLOCK (g_thread);
 461 }
 462
 463 static void
 464 g_thread_cleanup (gpointer data)
 465 {
 466   if (data)
 467     {
 468       GRealThread* thread = data;
 469       if (thread->private_data)
 470         {
 471           GArray* array = thread->private_data;
 472           guint i;
 473
 474           for (i = 0; i < array->len; i++ )
 475             {
 476               GStaticPrivateNode *node =
 477                 &g_array_index (array, GStaticPrivateNode, i);
 478               if (node->destroy)
 479                 node->destroy (node->data);
 480             }
 481           g_array_free (array, TRUE);
 482         }
 483       /* We only free the thread structure, if it isn't joinable. If
 484          it is, the structure is freed in g_thread_join */
 485       if (!thread->thread.joinable)
 486         {
 487           G_LOCK (g_thread);
 488           g_thread_all_threads = g_slist_remove (g_thread_all_threads, data);
 489           G_UNLOCK (g_thread);
 490
 491           /* Just to make sure, this isn't used any more */
 492           g_system_thread_assign (thread->system_thread, zero_thread);
 493           g_free (thread);
 494         }
 495     }
 496 }
 497
 498 static void
 499 g_thread_fail (void)
 500 {
 501   g_error ("The thread system is not yet initialized.");
 502 }
 503
 504 static void
 505 g_thread_create_proxy (gpointer data)
 506 {
 507   GRealThread* thread = data;
 508
 509   g_assert (data);
 510
 511 #ifdef G_THREAD_USE_PID_SURROGATE
 512   thread->pid = getpid ();
 513 #endif /* G_THREAD_USE_PID_SURROGATE */
 514
 515   /* This has to happen before G_LOCK, as that might call g_thread_self */
 516   g_private_set (g_thread_specific_private, data);
 517
 518   /* the lock makes sure, that thread->system_thread is written,
 519      before thread->func is called. See g_thread_create. */
 520   G_LOCK (g_thread);
 521   G_UNLOCK (g_thread);
 522
 523   if (g_thread_use_default_impl)
 524     SET_PRIO (thread->pid, thread->thread.priority);
 525
 526   thread->func (thread->arg);
 527 }
 528
 529 GThread*
 530 g_thread_create (GThreadFunc             thread_func,
 531                  gpointer                arg,
 532                  gulong                  stack_size,
 533                  gboolean                joinable,
 534                  gboolean                bound,
 535                  GThreadPriority         priority,
 536                  GError                **error)
 537 {
 538   GRealThread* result = g_new (GRealThread, 1);
 539   GError *local_error = NULL;
 540   g_return_val_if_fail (thread_func, NULL);
 541   g_return_val_if_fail (priority >= G_THREAD_PRIORITY_LOW, NULL);
 542   g_return_val_if_fail (priority <= G_THREAD_PRIORITY_URGENT, NULL);
 543
 544   result->thread.joinable = joinable;
 545   result->thread.bound = bound;
 546   result->thread.priority = priority;
 547   result->func = thread_func;
 548   result->arg = arg;
 549   result->private_data = NULL;
 550   G_LOCK (g_thread);
 551   G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
 552                                stack_size, joinable, bound, priority,
 553                                &result->system_thread, &local_error));
 554   g_thread_all_threads = g_slist_prepend (g_thread_all_threads, result);
 555   G_UNLOCK (g_thread);
 556
 557   if (local_error)
 558     {
 559       g_propagate_error (error, local_error);
 560       g_free (result);
 561       return NULL;
 562     }
 563
 564   return (GThread*) result;
 565 }
 566
 567 void
 568 g_thread_join (GThread* thread)
 569 {
 570   GRealThread* real = (GRealThread*) thread;
 571
 572
 573   g_return_if_fail (thread);
 574   g_return_if_fail (thread->joinable);
 575   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 576
 577   G_THREAD_UF (thread_join, (&real->system_thread));
 578
 579   G_LOCK (g_thread);
 580   g_thread_all_threads = g_slist_remove (g_thread_all_threads, thread);
 581   G_UNLOCK (g_thread);
 582
 583   /* Just to make sure, this isn't used any more */
 584   thread->joinable = 0;
 585   g_system_thread_assign (real->system_thread, zero_thread);
 586
 587   /* the thread structure for non-joinable threads is freed upon
 588      thread end. We free the memory here. This will leave loose end,
 589      if a joinable thread is not joined. */
 590
 591   g_free (thread);
 592 }
 593
 594 void
 595 g_thread_set_priority (GThread* thread,
 596                        GThreadPriority priority)
 597 {
 598   GRealThread* real = (GRealThread*) thread;
 599
 600   g_return_if_fail (thread);
 601   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 602   g_return_if_fail (priority >= G_THREAD_PRIORITY_LOW);
 603   g_return_if_fail (priority <= G_THREAD_PRIORITY_URGENT);
 604
 605   thread->priority = priority;
 606
 607 #ifdef G_THREAD_USE_PID_SURROGATE
 608   if (g_thread_use_default_impl)
 609     SET_PRIO (real->pid, priority);
 610   else
 611 #endif /* G_THREAD_USE_PID_SURROGATE */
 612     G_THREAD_CF (thread_set_priority, (void)0,
 613                  (&real->system_thread, priority));
 614 }
 615
 616 GThread*
 617 g_thread_self (void)
 618 {
 619   GRealThread* thread = g_private_get (g_thread_specific_private);
 620
 621   if (!thread)
 622     {
 623       /* If no thread data is available, provide and set one.  This
 624          can happen for the main thread and for threads, that are not
 625          created by GLib. */
 626       thread = g_new (GRealThread, 1);
 627       thread->thread.joinable = FALSE; /* This is a save guess */
 628       thread->thread.bound = TRUE; /* This isn't important at all */
 629       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 630                                                              just a guess */
 631       thread->func = NULL;
 632       thread->arg = NULL;
 633       thread->private_data = NULL;
 634
 635       if (g_thread_supported ())
 636         G_THREAD_UF (thread_self, (&thread->system_thread));
 637
 638 #ifdef G_THREAD_USE_PID_SURROGATE
 639       thread->pid = getpid ();
 640 #endif /* G_THREAD_USE_PID_SURROGATE */
 641
 642       g_private_set (g_thread_specific_private, thread);
 643
 644       G_LOCK (g_thread);
 645       g_thread_all_threads = g_slist_prepend (g_thread_all_threads, thread);
 646       G_UNLOCK (g_thread);
 647     }
 648
 649   return (GThread*)thread;
 650 }
 651
 652 void
 653 g_static_rw_lock_init (GStaticRWLock* lock)
 654 {
 655   static GStaticRWLock init_lock = G_STATIC_RW_LOCK_INIT;
 656
 657   g_return_if_fail (lock);
 658
 659   memcpy (lock, &init_lock, sizeof (GStaticRWLock));
 660 }
 661
 662 static void inline
 663 g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 664 {
 665   if (!*cond)
 666       *cond = g_cond_new ();
 667   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 668 }
 669
 670 static void inline
 671 g_static_rw_lock_signal (GStaticRWLock* lock)
 672 {
 673   if (lock->want_to_write && lock->write_cond)
 674     g_cond_signal (lock->write_cond);
 675   else if (lock->read_cond)
 676     g_cond_broadcast (lock->read_cond);
 677 }
 678
 679 void
 680 g_static_rw_lock_reader_lock (GStaticRWLock* lock)
 681 {
 682   g_return_if_fail (lock);
 683
 684   if (!g_threads_got_initialized)
 685     return;
 686
 687   g_static_mutex_lock (&lock->mutex);
 688   while (lock->write || lock->want_to_write)
 689     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 690   lock->read_counter++;
 691   g_static_mutex_unlock (&lock->mutex);
 692 }
 693
 694 gboolean
 695 g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
 696 {
 697   gboolean ret_val = FALSE;
 698
 699   g_return_val_if_fail (lock, FALSE);
 700
 701   if (!g_threads_got_initialized)
 702     return TRUE;
 703
 704   g_static_mutex_lock (&lock->mutex);
 705   if (!lock->write && !lock->want_to_write)
 706     {
 707       lock->read_counter++;
 708       ret_val = TRUE;
 709     }
 710   g_static_mutex_unlock (&lock->mutex);
 711   return ret_val;
 712 }
 713
 714 void
 715 g_static_rw_lock_reader_unlock  (GStaticRWLock* lock)
 716 {
 717   g_return_if_fail (lock);
 718
 719   if (!g_threads_got_initialized)
 720     return;
 721
 722   g_static_mutex_lock (&lock->mutex);
 723   lock->read_counter--;
 724   if (lock->read_counter == 0)
 725     g_static_rw_lock_signal (lock);
 726   g_static_mutex_unlock (&lock->mutex);
 727 }
 728
 729 void
 730 g_static_rw_lock_writer_lock (GStaticRWLock* lock)
 731 {
 732   g_return_if_fail (lock);
 733
 734   if (!g_threads_got_initialized)
 735     return;
 736
 737   g_static_mutex_lock (&lock->mutex);
 738   lock->want_to_write++;
 739   while (lock->write || lock->read_counter)
 740     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 741   lock->want_to_write--;
 742   lock->write = TRUE;
 743   g_static_mutex_unlock (&lock->mutex);
 744 }
 745
 746 gboolean
 747 g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 748 {
 749   gboolean ret_val = FALSE;
 750
 751   g_return_val_if_fail (lock, FALSE);
 752
 753   if (!g_threads_got_initialized)
 754     return TRUE;
 755
 756   g_static_mutex_lock (&lock->mutex);
 757   if (!lock->write && !lock->read_counter)
 758     {
 759       lock->write = TRUE;
 760       ret_val = TRUE;
 761     }
 762   g_static_mutex_unlock (&lock->mutex);
 763   return ret_val;
 764 }
 765
 766 void
 767 g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
 768 {
 769   g_return_if_fail (lock);
 770
 771   if (!g_threads_got_initialized)
 772     return;
 773
 774   g_static_mutex_lock (&lock->mutex);
 775   lock->write = FALSE;
 776   g_static_rw_lock_signal (lock);
 777   g_static_mutex_unlock (&lock->mutex);
 778 }
 779
 780 void
 781 g_static_rw_lock_free (GStaticRWLock* lock)
 782 {
 783   g_return_if_fail (lock);
 784
 785   if (lock->read_cond)
 786     {
 787       g_cond_free (lock->read_cond);
 788       lock->read_cond = NULL;
 789     }
 790   if (lock->write_cond)
 791     {
 792       g_cond_free (lock->write_cond);
 793       lock->write_cond = NULL;
 794     }
 795   g_static_mutex_free (&lock->mutex);
 796 }