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  * 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_simple(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_simple(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 #define g_system_thread_equal(thread1, thread2)                         \
  64   (g_thread_functions_for_glib_use.thread_equal ?                       \
  65    g_thread_functions_for_glib_use.thread_equal (&(thread1), &(thread2)) :\
  66    g_system_thread_equal_simple((thread1), (thread2)))
  67
  68 GQuark
  69 g_thread_error_quark (void)
  70 {
  71   static GQuark quark;
  72   if (!quark)
  73     quark = g_quark_from_static_string ("g_thread_error");
  74   return quark;
  75 }
  76
  77 /* Keep this in sync with GRealThread in gmain.c! */
  78 typedef struct _GRealThread GRealThread;
  79 struct  _GRealThread
  80 {
  81   GThread thread;
  82   gpointer private_data;
  83   gpointer retval;
  84   GSystemThread system_thread;
  85 #ifdef G_THREAD_USE_PID_SURROGATE
  86   pid_t pid;
  87 #endif /* G_THREAD_USE_PID_SURROGATE */
  88 };
  89
  90 #ifdef G_THREAD_USE_PID_SURROGATE
  91 static gint priority_map[] = { 15, 0, -15, -20 };
  92 static gboolean prio_warned = FALSE;
  93 # define SET_PRIO(pid, prio) G_STMT_START{                              \
  94   gint error = setpriority (PRIO_PROCESS, (pid), priority_map[prio]);   \
  95   if (error == -1 && errno == EACCES && !prio_warned)                   \
  96     {                                                                   \
  97       prio_warned = TRUE;                                               \
  98       g_warning ("Priorities can only be increased by root.");          \
  99     }                                                                   \
 100   }G_STMT_END
 101 #endif /* G_THREAD_USE_PID_SURROGATE */
 102
 103 typedef struct _GStaticPrivateNode GStaticPrivateNode;
 104 struct _GStaticPrivateNode
 105 {
 106   gpointer       data;
 107   GDestroyNotify destroy;
 108 };
 109
 110 static void g_thread_cleanup (gpointer data);
 111 static void g_thread_fail (void);
 112
 113 /* Global variables */
 114
 115 static GSystemThread zero_thread; /* This is initialized to all zero */
 116 gboolean g_thread_use_default_impl = TRUE;
 117 gboolean g_threads_got_initialized = FALSE;
 118
 119 #if defined(G_PLATFORM_WIN32) && defined(__GNUC__)
 120 __declspec(dllexport)
 121 #endif
 122 GThreadFunctions g_thread_functions_for_glib_use = {
 123   (GMutex*(*)())g_thread_fail,                 /* mutex_new */
 124   NULL,                                        /* mutex_lock */
 125   NULL,                                        /* mutex_trylock */
 126   NULL,                                        /* mutex_unlock */
 127   NULL,                                        /* mutex_free */
 128   (GCond*(*)())g_thread_fail,                  /* cond_new */
 129   NULL,                                        /* cond_signal */
 130   NULL,                                        /* cond_broadcast */
 131   NULL,                                        /* cond_wait */
 132   NULL,                                        /* cond_timed_wait  */
 133   NULL,                                        /* cond_free */
 134   (GPrivate*(*)(GDestroyNotify))g_thread_fail, /* private_new */
 135   NULL,                                        /* private_get */
 136   NULL,                                        /* private_set */
 137   (void(*)(GThreadFunc, gpointer, gulong,
 138            gboolean, gboolean, GThreadPriority,
 139            gpointer, GError**))g_thread_fail,  /* thread_create */
 140   NULL,                                        /* thread_yield */
 141   NULL,                                        /* thread_join */
 142   NULL,                                        /* thread_exit */
 143   NULL,                                        /* thread_set_priority */
 144   NULL                                         /* thread_self */
 145 };
 146
 147 /* Local data */
 148
 149 static GMutex   *g_mutex_protect_static_mutex_allocation = NULL;
 150 static GPrivate *g_thread_specific_private = NULL;
 151 static GSList   *g_thread_all_threads = NULL;
 152 static GSList   *g_thread_free_indeces = NULL;
 153
 154 G_LOCK_DEFINE_STATIC (g_thread);
 155
 156 /* This must be called only once, before any threads are created.
 157  * It will only be called from g_thread_init() in -lgthread.
 158  */
 159 void
 160 g_mutex_init (void)
 161 {
 162   GRealThread* main_thread;
 163
 164   /* We let the main thread (the one that calls g_thread_init) inherit
 165    * the data, that it set before calling g_thread_init
 166    */
 167   main_thread = (GRealThread*) g_thread_self ();
 168
 169   g_thread_specific_private = g_private_new (g_thread_cleanup);
 170   G_THREAD_UF (private_set, (g_thread_specific_private, main_thread));
 171   G_THREAD_UF (thread_self, (&main_thread->system_thread));
 172
 173   g_mutex_protect_static_mutex_allocation = g_mutex_new ();
 174 }
 175
 176 void
 177 g_static_mutex_init (GStaticMutex *mutex)
 178 {
 179   static GStaticMutex init_mutex = G_STATIC_MUTEX_INIT;
 180
 181   g_return_if_fail (mutex);
 182
 183   *mutex = init_mutex;
 184 }
 185
 186 GMutex *
 187 g_static_mutex_get_mutex_impl (GMutex** mutex)
 188 {
 189   if (!g_thread_supported ())
 190     return NULL;
 191
 192   g_assert (g_mutex_protect_static_mutex_allocation);
 193
 194   g_mutex_lock (g_mutex_protect_static_mutex_allocation);
 195
 196   if (!(*mutex))
 197     *mutex = g_mutex_new ();
 198
 199   g_mutex_unlock (g_mutex_protect_static_mutex_allocation);
 200
 201   return *mutex;
 202 }
 203
 204 void
 205 g_static_mutex_free (GStaticMutex* mutex)
 206 {
 207   GMutex **runtime_mutex;
 208
 209   g_return_if_fail (mutex);
 210
 211   /* The runtime_mutex is the first (or only) member of GStaticMutex,
 212    * see both versions (of glibconfig.h) in configure.in */
 213   runtime_mutex = ((GMutex**)mutex);
 214
 215   if (*runtime_mutex)
 216     g_mutex_free (*runtime_mutex);
 217
 218   *runtime_mutex = NULL;
 219 }
 220
 221 void
 222 g_static_rec_mutex_init (GStaticRecMutex *mutex)
 223 {
 224   static GStaticRecMutex init_mutex = G_STATIC_REC_MUTEX_INIT;
 225
 226   g_return_if_fail (mutex);
 227
 228   *mutex = init_mutex;
 229 }
 230
 231 void
 232 g_static_rec_mutex_lock (GStaticRecMutex* mutex)
 233 {
 234   GSystemThread self;
 235
 236   g_return_if_fail (mutex);
 237
 238   if (!g_thread_supported ())
 239     return;
 240
 241   G_THREAD_UF (thread_self, (&self));
 242
 243   if (g_system_thread_equal (self, mutex->owner))
 244     {
 245       mutex->depth++;
 246       return;
 247     }
 248   g_static_mutex_lock (&mutex->mutex);
 249   g_system_thread_assign (mutex->owner, self);
 250   mutex->depth = 1;
 251 }
 252
 253 gboolean
 254 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
 255 {
 256   GSystemThread self;
 257
 258   g_return_val_if_fail (mutex, FALSE);
 259
 260   if (!g_thread_supported ())
 261     return TRUE;
 262
 263   G_THREAD_UF (thread_self, (&self));
 264
 265   if (g_system_thread_equal (self, mutex->owner))
 266     {
 267       mutex->depth++;
 268       return TRUE;
 269     }
 270
 271   if (!g_static_mutex_trylock (&mutex->mutex))
 272     return FALSE;
 273
 274   g_system_thread_assign (mutex->owner, self);
 275   mutex->depth = 1;
 276   return TRUE;
 277 }
 278
 279 void
 280 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
 281 {
 282   g_return_if_fail (mutex);
 283
 284   if (!g_thread_supported ())
 285     return;
 286
 287   if (mutex->depth > 1)
 288     {
 289       mutex->depth--;
 290       return;
 291     }
 292   g_system_thread_assign (mutex->owner, zero_thread);
 293   g_static_mutex_unlock (&mutex->mutex);
 294 }
 295
 296 void
 297 g_static_rec_mutex_lock_full   (GStaticRecMutex *mutex,
 298                                 guint            depth)
 299 {
 300   GSystemThread self;
 301   g_return_if_fail (mutex);
 302
 303   if (!g_thread_supported ())
 304     return;
 305
 306   G_THREAD_UF (thread_self, (&self));
 307
 308   if (g_system_thread_equal (self, mutex->owner))
 309     {
 310       mutex->depth += depth;
 311       return;
 312     }
 313   g_static_mutex_lock (&mutex->mutex);
 314   g_system_thread_assign (mutex->owner, self);
 315   mutex->depth = depth;
 316 }
 317
 318 guint
 319 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
 320 {
 321   guint depth;
 322
 323   g_return_val_if_fail (mutex, 0);
 324
 325   if (!g_thread_supported ())
 326     return 1;
 327
 328   depth = mutex->depth;
 329
 330   g_system_thread_assign (mutex->owner, zero_thread);
 331   mutex->depth = 0;
 332   g_static_mutex_unlock (&mutex->mutex);
 333
 334   return depth;
 335 }
 336
 337 void
 338 g_static_rec_mutex_free (GStaticRecMutex *mutex)
 339 {
 340   g_return_if_fail (mutex);
 341
 342   g_static_mutex_free (&mutex->mutex);
 343 }
 344
 345 void
 346 g_static_private_init (GStaticPrivate *private_key)
 347 {
 348   private_key->index = 0;
 349 }
 350
 351 gpointer
 352 g_static_private_get (GStaticPrivate *private_key)
 353 {
 354   GRealThread *self = (GRealThread*) g_thread_self ();
 355   GArray *array;
 356
 357   array = self->private_data;
 358   if (!array)
 359     return NULL;
 360
 361   if (!private_key->index)
 362     return NULL;
 363   else if (private_key->index <= array->len)
 364     return g_array_index (array, GStaticPrivateNode,
 365                           private_key->index - 1).data;
 366   else
 367     return NULL;
 368 }
 369
 370 void
 371 g_static_private_set (GStaticPrivate *private_key,
 372                       gpointer        data,
 373                       GDestroyNotify  notify)
 374 {
 375   GRealThread *self = (GRealThread*) g_thread_self ();
 376   GArray *array;
 377   static guint next_index = 0;
 378   GStaticPrivateNode *node;
 379
 380   array = self->private_data;
 381   if (!array)
 382     {
 383       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 384       self->private_data = array;
 385     }
 386
 387   if (!private_key->index)
 388     {
 389       G_LOCK (g_thread);
 390
 391       if (!private_key->index)
 392         {
 393           if (g_thread_free_indeces)
 394             {
 395               private_key->index =
 396                 GPOINTER_TO_UINT (g_thread_free_indeces->data);
 397               g_thread_free_indeces =
 398                 g_slist_delete_link (g_thread_free_indeces,
 399                                      g_thread_free_indeces);
 400             }
 401           else
 402             private_key->index = ++next_index;
 403         }
 404
 405       G_UNLOCK (g_thread);
 406     }
 407
 408   if (private_key->index > array->len)
 409     g_array_set_size (array, private_key->index);
 410
 411   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 412   if (node->destroy)
 413     {
 414       gpointer ddata = node->data;
 415       GDestroyNotify ddestroy = node->destroy;
 416
 417       node->data = data;
 418       node->destroy = notify;
 419
 420       ddestroy (ddata);
 421     }
 422   else
 423     {
 424       node->data = data;
 425       node->destroy = notify;
 426     }
 427 }
 428
 429 void
 430 g_static_private_free (GStaticPrivate *private_key)
 431 {
 432   guint index = private_key->index;
 433   GSList *list;
 434
 435   if (!index)
 436     return;
 437
 438   private_key->index = 0;
 439
 440   G_LOCK (g_thread);
 441   list =  g_thread_all_threads;
 442   while (list)
 443     {
 444       GRealThread *thread = list->data;
 445       GArray *array = thread->private_data;
 446       list = list->next;
 447
 448       if (array && index <= array->len)
 449         {
 450           GStaticPrivateNode *node = &g_array_index (array,
 451                                                      GStaticPrivateNode,
 452                                                      index - 1);
 453           gpointer ddata = node->data;
 454           GDestroyNotify ddestroy = node->destroy;
 455
 456           node->data = NULL;
 457           node->destroy = NULL;
 458
 459           if (ddestroy)
 460             {
 461               G_UNLOCK (g_thread);
 462               ddestroy (ddata);
 463               G_LOCK (g_thread);
 464               }
 465         }
 466     }
 467   g_thread_free_indeces = g_slist_prepend (g_thread_free_indeces,
 468                                            GUINT_TO_POINTER (index));
 469   G_UNLOCK (g_thread);
 470 }
 471
 472 static void
 473 g_thread_cleanup (gpointer data)
 474 {
 475   if (data)
 476     {
 477       GRealThread* thread = data;
 478       if (thread->private_data)
 479         {
 480           GArray* array = thread->private_data;
 481           guint i;
 482
 483           for (i = 0; i < array->len; i++ )
 484             {
 485               GStaticPrivateNode *node =
 486                 &g_array_index (array, GStaticPrivateNode, i);
 487               if (node->destroy)
 488                 node->destroy (node->data);
 489             }
 490           g_array_free (array, TRUE);
 491         }
 492
 493       /* We only free the thread structure, if it isn't joinable. If
 494          it is, the structure is freed in g_thread_join */
 495       if (!thread->thread.joinable)
 496         {
 497           G_LOCK (g_thread);
 498           g_thread_all_threads = g_slist_remove (g_thread_all_threads, data);
 499           G_UNLOCK (g_thread);
 500
 501           /* Just to make sure, this isn't used any more */
 502           g_system_thread_assign (thread->system_thread, zero_thread);
 503           g_free (thread);
 504         }
 505     }
 506 }
 507
 508 static void
 509 g_thread_fail (void)
 510 {
 511   g_error ("The thread system is not yet initialized.");
 512 }
 513
 514 static gpointer
 515 g_thread_create_proxy (gpointer data)
 516 {
 517   GRealThread* thread = data;
 518
 519   g_assert (data);
 520
 521 #ifdef G_THREAD_USE_PID_SURROGATE
 522   thread->pid = getpid ();
 523 #endif /* G_THREAD_USE_PID_SURROGATE */
 524
 525   /* This has to happen before G_LOCK, as that might call g_thread_self */
 526   g_private_set (g_thread_specific_private, data);
 527
 528   /* the lock makes sure, that thread->system_thread is written,
 529      before thread->thread.func is called. See g_thread_create. */
 530   G_LOCK (g_thread);
 531   G_UNLOCK (g_thread);
 532
 533 #ifdef G_THREAD_USE_PID_SURROGATE
 534   if (g_thread_use_default_impl)
 535     SET_PRIO (thread->pid, thread->thread.priority);
 536 #endif /* G_THREAD_USE_PID_SURROGATE */
 537
 538   thread->retval = thread->thread.func (thread->thread.data);
 539
 540   return NULL;
 541 }
 542
 543 GThread*
 544 g_thread_create_full (GThreadFunc                func,
 545                       gpointer           data,
 546                       gulong             stack_size,
 547                       gboolean           joinable,
 548                       gboolean           bound,
 549                       GThreadPriority    priority,
 550                       GError                **error)
 551 {
 552   GRealThread* result;
 553   GError *local_error = NULL;
 554   g_return_val_if_fail (func, NULL);
 555   g_return_val_if_fail (priority >= G_THREAD_PRIORITY_LOW, NULL);
 556   g_return_val_if_fail (priority <= G_THREAD_PRIORITY_URGENT, NULL);
 557
 558   result = g_new (GRealThread, 1);
 559
 560   result->thread.joinable = joinable;
 561   result->thread.priority = priority;
 562   result->thread.func = func;
 563   result->thread.data = data;
 564   result->private_data = NULL;
 565   G_LOCK (g_thread);
 566   G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
 567                                stack_size, joinable, bound, priority,
 568                                &result->system_thread, &local_error));
 569   g_thread_all_threads = g_slist_prepend (g_thread_all_threads, result);
 570   G_UNLOCK (g_thread);
 571
 572   if (local_error)
 573     {
 574       g_propagate_error (error, local_error);
 575       g_free (result);
 576       return NULL;
 577     }
 578
 579   return (GThread*) result;
 580 }
 581
 582 void
 583 g_thread_exit (gpointer retval)
 584 {
 585   GRealThread* real = (GRealThread*) g_thread_self ();
 586   real->retval = retval;
 587   G_THREAD_CF (thread_exit, (void)0, ());
 588 }
 589
 590 gpointer
 591 g_thread_join (GThread* thread)
 592 {
 593   GRealThread* real = (GRealThread*) thread;
 594   gpointer retval;
 595
 596   g_return_val_if_fail (thread, NULL);
 597   g_return_val_if_fail (thread->joinable, NULL);
 598   g_return_val_if_fail (!g_system_thread_equal (real->system_thread,
 599                                                 zero_thread), NULL);
 600
 601   G_THREAD_UF (thread_join, (&real->system_thread));
 602
 603   retval = real->retval;
 604
 605   G_LOCK (g_thread);
 606   g_thread_all_threads = g_slist_remove (g_thread_all_threads, thread);
 607   G_UNLOCK (g_thread);
 608
 609   /* Just to make sure, this isn't used any more */
 610   thread->joinable = 0;
 611   g_system_thread_assign (real->system_thread, zero_thread);
 612
 613   /* the thread structure for non-joinable threads is freed upon
 614      thread end. We free the memory here. This will leave a loose end,
 615      if a joinable thread is not joined. */
 616
 617   g_free (thread);
 618
 619   return retval;
 620 }
 621
 622 void
 623 g_thread_set_priority (GThread* thread,
 624                        GThreadPriority priority)
 625 {
 626   GRealThread* real = (GRealThread*) thread;
 627
 628   g_return_if_fail (thread);
 629   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 630   g_return_if_fail (priority >= G_THREAD_PRIORITY_LOW);
 631   g_return_if_fail (priority <= G_THREAD_PRIORITY_URGENT);
 632
 633   thread->priority = priority;
 634
 635 #ifdef G_THREAD_USE_PID_SURROGATE
 636   if (g_thread_use_default_impl)
 637     SET_PRIO (real->pid, priority);
 638   else
 639 #endif /* G_THREAD_USE_PID_SURROGATE */
 640     G_THREAD_CF (thread_set_priority, (void)0,
 641                  (&real->system_thread, priority));
 642 }
 643
 644 GThread*
 645 g_thread_self (void)
 646 {
 647   GRealThread* thread = g_private_get (g_thread_specific_private);
 648
 649   if (!thread)
 650     {
 651       /* If no thread data is available, provide and set one.  This
 652          can happen for the main thread and for threads, that are not
 653          created by GLib. */
 654       thread = g_new (GRealThread, 1);
 655       thread->thread.joinable = FALSE; /* This is a save guess */
 656       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 657                                                              just a guess */
 658       thread->thread.func = NULL;
 659       thread->thread.data = NULL;
 660       thread->private_data = NULL;
 661
 662       if (g_thread_supported ())
 663         G_THREAD_UF (thread_self, (&thread->system_thread));
 664
 665 #ifdef G_THREAD_USE_PID_SURROGATE
 666       thread->pid = getpid ();
 667 #endif /* G_THREAD_USE_PID_SURROGATE */
 668
 669       g_private_set (g_thread_specific_private, thread);
 670
 671       G_LOCK (g_thread);
 672       g_thread_all_threads = g_slist_prepend (g_thread_all_threads, thread);
 673       G_UNLOCK (g_thread);
 674     }
 675
 676   return (GThread*)thread;
 677 }
 678
 679 void
 680 g_static_rw_lock_init (GStaticRWLock* lock)
 681 {
 682   static GStaticRWLock init_lock = G_STATIC_RW_LOCK_INIT;
 683
 684   g_return_if_fail (lock);
 685
 686   *lock = init_lock;
 687 }
 688
 689 static void inline
 690 g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 691 {
 692   if (!*cond)
 693       *cond = g_cond_new ();
 694   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 695 }
 696
 697 static void inline
 698 g_static_rw_lock_signal (GStaticRWLock* lock)
 699 {
 700   if (lock->want_to_write && lock->write_cond)
 701     g_cond_signal (lock->write_cond);
 702   else if (lock->want_to_read && lock->read_cond)
 703     g_cond_broadcast (lock->read_cond);
 704 }
 705
 706 void
 707 g_static_rw_lock_reader_lock (GStaticRWLock* lock)
 708 {
 709   g_return_if_fail (lock);
 710
 711   if (!g_threads_got_initialized)
 712     return;
 713
 714   g_static_mutex_lock (&lock->mutex);
 715   lock->want_to_read++;
 716   while (lock->write || lock->want_to_write)
 717     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 718   lock->want_to_read--;
 719   lock->read_counter++;
 720   g_static_mutex_unlock (&lock->mutex);
 721 }
 722
 723 gboolean
 724 g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
 725 {
 726   gboolean ret_val = FALSE;
 727
 728   g_return_val_if_fail (lock, FALSE);
 729
 730   if (!g_threads_got_initialized)
 731     return TRUE;
 732
 733   g_static_mutex_lock (&lock->mutex);
 734   if (!lock->write && !lock->want_to_write)
 735     {
 736       lock->read_counter++;
 737       ret_val = TRUE;
 738     }
 739   g_static_mutex_unlock (&lock->mutex);
 740   return ret_val;
 741 }
 742
 743 void
 744 g_static_rw_lock_reader_unlock  (GStaticRWLock* lock)
 745 {
 746   g_return_if_fail (lock);
 747
 748   if (!g_threads_got_initialized)
 749     return;
 750
 751   g_static_mutex_lock (&lock->mutex);
 752   lock->read_counter--;
 753   if (lock->read_counter == 0)
 754     g_static_rw_lock_signal (lock);
 755   g_static_mutex_unlock (&lock->mutex);
 756 }
 757
 758 void
 759 g_static_rw_lock_writer_lock (GStaticRWLock* lock)
 760 {
 761   g_return_if_fail (lock);
 762
 763   if (!g_threads_got_initialized)
 764     return;
 765
 766   g_static_mutex_lock (&lock->mutex);
 767   lock->want_to_write++;
 768   while (lock->write || lock->read_counter)
 769     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 770   lock->want_to_write--;
 771   lock->write = TRUE;
 772   g_static_mutex_unlock (&lock->mutex);
 773 }
 774
 775 gboolean
 776 g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 777 {
 778   gboolean ret_val = FALSE;
 779
 780   g_return_val_if_fail (lock, FALSE);
 781
 782   if (!g_threads_got_initialized)
 783     return TRUE;
 784
 785   g_static_mutex_lock (&lock->mutex);
 786   if (!lock->write && !lock->read_counter)
 787     {
 788       lock->write = TRUE;
 789       ret_val = TRUE;
 790     }
 791   g_static_mutex_unlock (&lock->mutex);
 792   return ret_val;
 793 }
 794
 795 void
 796 g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
 797 {
 798   g_return_if_fail (lock);
 799
 800   if (!g_threads_got_initialized)
 801     return;
 802
 803   g_static_mutex_lock (&lock->mutex);
 804   lock->write = FALSE;
 805   g_static_rw_lock_signal (lock);
 806   g_static_mutex_unlock (&lock->mutex);
 807 }
 808
 809 void
 810 g_static_rw_lock_free (GStaticRWLock* lock)
 811 {
 812   g_return_if_fail (lock);
 813
 814   if (lock->read_cond)
 815     {
 816       g_cond_free (lock->read_cond);
 817       lock->read_cond = NULL;
 818     }
 819   if (lock->write_cond)
 820     {
 821       g_cond_free (lock->write_cond);
 822       lock->write_cond = NULL;
 823     }
 824   g_static_mutex_free (&lock->mutex);
 825 }