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[4];
  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 #ifdef G_THREAD_USE_PID_SURROGATE
 176   priority_map[G_THREAD_PRIORITY_NORMAL] =
 177     getpriority (PRIO_PROCESS, (getpid ()));
 178   priority_map[G_THREAD_PRIORITY_LOW] =
 179     MIN (20, priority_map[G_THREAD_PRIORITY_NORMAL] + 10);
 180   priority_map[G_THREAD_PRIORITY_HIGH] =
 181     MAX (-20, priority_map[G_THREAD_PRIORITY_NORMAL] - 10);
 182   priority_map[G_THREAD_PRIORITY_URGENT] =
 183     MAX (-20, priority_map[G_THREAD_PRIORITY_NORMAL] - 15);
 184 #endif /* G_THREAD_USE_PID_SURROGATE */
 185 }
 186
 187 void
 188 g_static_mutex_init (GStaticMutex *mutex)
 189 {
 190   static GStaticMutex init_mutex = G_STATIC_MUTEX_INIT;
 191
 192   g_return_if_fail (mutex);
 193
 194   *mutex = init_mutex;
 195 }
 196
 197 GMutex *
 198 g_static_mutex_get_mutex_impl (GMutex** mutex)
 199 {
 200   if (!g_thread_supported ())
 201     return NULL;
 202
 203   g_assert (g_mutex_protect_static_mutex_allocation);
 204
 205   g_mutex_lock (g_mutex_protect_static_mutex_allocation);
 206
 207   if (!(*mutex))
 208     *mutex = g_mutex_new ();
 209
 210   g_mutex_unlock (g_mutex_protect_static_mutex_allocation);
 211
 212   return *mutex;
 213 }
 214
 215 void
 216 g_static_mutex_free (GStaticMutex* mutex)
 217 {
 218   GMutex **runtime_mutex;
 219
 220   g_return_if_fail (mutex);
 221
 222   /* The runtime_mutex is the first (or only) member of GStaticMutex,
 223    * see both versions (of glibconfig.h) in configure.in */
 224   runtime_mutex = ((GMutex**)mutex);
 225
 226   if (*runtime_mutex)
 227     g_mutex_free (*runtime_mutex);
 228
 229   *runtime_mutex = NULL;
 230 }
 231
 232 void
 233 g_static_rec_mutex_init (GStaticRecMutex *mutex)
 234 {
 235   static GStaticRecMutex init_mutex = G_STATIC_REC_MUTEX_INIT;
 236
 237   g_return_if_fail (mutex);
 238
 239   *mutex = init_mutex;
 240 }
 241
 242 void
 243 g_static_rec_mutex_lock (GStaticRecMutex* mutex)
 244 {
 245   GSystemThread self;
 246
 247   g_return_if_fail (mutex);
 248
 249   if (!g_thread_supported ())
 250     return;
 251
 252   G_THREAD_UF (thread_self, (&self));
 253
 254   if (g_system_thread_equal (self, mutex->owner))
 255     {
 256       mutex->depth++;
 257       return;
 258     }
 259   g_static_mutex_lock (&mutex->mutex);
 260   g_system_thread_assign (mutex->owner, self);
 261   mutex->depth = 1;
 262 }
 263
 264 gboolean
 265 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
 266 {
 267   GSystemThread self;
 268
 269   g_return_val_if_fail (mutex, FALSE);
 270
 271   if (!g_thread_supported ())
 272     return TRUE;
 273
 274   G_THREAD_UF (thread_self, (&self));
 275
 276   if (g_system_thread_equal (self, mutex->owner))
 277     {
 278       mutex->depth++;
 279       return TRUE;
 280     }
 281
 282   if (!g_static_mutex_trylock (&mutex->mutex))
 283     return FALSE;
 284
 285   g_system_thread_assign (mutex->owner, self);
 286   mutex->depth = 1;
 287   return TRUE;
 288 }
 289
 290 void
 291 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
 292 {
 293   g_return_if_fail (mutex);
 294
 295   if (!g_thread_supported ())
 296     return;
 297
 298   if (mutex->depth > 1)
 299     {
 300       mutex->depth--;
 301       return;
 302     }
 303   g_system_thread_assign (mutex->owner, zero_thread);
 304   g_static_mutex_unlock (&mutex->mutex);
 305 }
 306
 307 void
 308 g_static_rec_mutex_lock_full   (GStaticRecMutex *mutex,
 309                                 guint            depth)
 310 {
 311   GSystemThread self;
 312   g_return_if_fail (mutex);
 313
 314   if (!g_thread_supported ())
 315     return;
 316
 317   G_THREAD_UF (thread_self, (&self));
 318
 319   if (g_system_thread_equal (self, mutex->owner))
 320     {
 321       mutex->depth += depth;
 322       return;
 323     }
 324   g_static_mutex_lock (&mutex->mutex);
 325   g_system_thread_assign (mutex->owner, self);
 326   mutex->depth = depth;
 327 }
 328
 329 guint
 330 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
 331 {
 332   guint depth;
 333
 334   g_return_val_if_fail (mutex, 0);
 335
 336   if (!g_thread_supported ())
 337     return 1;
 338
 339   depth = mutex->depth;
 340
 341   g_system_thread_assign (mutex->owner, zero_thread);
 342   mutex->depth = 0;
 343   g_static_mutex_unlock (&mutex->mutex);
 344
 345   return depth;
 346 }
 347
 348 void
 349 g_static_rec_mutex_free (GStaticRecMutex *mutex)
 350 {
 351   g_return_if_fail (mutex);
 352
 353   g_static_mutex_free (&mutex->mutex);
 354 }
 355
 356 void
 357 g_static_private_init (GStaticPrivate *private_key)
 358 {
 359   private_key->index = 0;
 360 }
 361
 362 gpointer
 363 g_static_private_get (GStaticPrivate *private_key)
 364 {
 365   GRealThread *self = (GRealThread*) g_thread_self ();
 366   GArray *array;
 367
 368   array = self->private_data;
 369   if (!array)
 370     return NULL;
 371
 372   if (!private_key->index)
 373     return NULL;
 374   else if (private_key->index <= array->len)
 375     return g_array_index (array, GStaticPrivateNode,
 376                           private_key->index - 1).data;
 377   else
 378     return NULL;
 379 }
 380
 381 void
 382 g_static_private_set (GStaticPrivate *private_key,
 383                       gpointer        data,
 384                       GDestroyNotify  notify)
 385 {
 386   GRealThread *self = (GRealThread*) g_thread_self ();
 387   GArray *array;
 388   static guint next_index = 0;
 389   GStaticPrivateNode *node;
 390
 391   array = self->private_data;
 392   if (!array)
 393     {
 394       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 395       self->private_data = array;
 396     }
 397
 398   if (!private_key->index)
 399     {
 400       G_LOCK (g_thread);
 401
 402       if (!private_key->index)
 403         {
 404           if (g_thread_free_indeces)
 405             {
 406               private_key->index =
 407                 GPOINTER_TO_UINT (g_thread_free_indeces->data);
 408               g_thread_free_indeces =
 409                 g_slist_delete_link (g_thread_free_indeces,
 410                                      g_thread_free_indeces);
 411             }
 412           else
 413             private_key->index = ++next_index;
 414         }
 415
 416       G_UNLOCK (g_thread);
 417     }
 418
 419   if (private_key->index > array->len)
 420     g_array_set_size (array, private_key->index);
 421
 422   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 423   if (node->destroy)
 424     {
 425       gpointer ddata = node->data;
 426       GDestroyNotify ddestroy = node->destroy;
 427
 428       node->data = data;
 429       node->destroy = notify;
 430
 431       ddestroy (ddata);
 432     }
 433   else
 434     {
 435       node->data = data;
 436       node->destroy = notify;
 437     }
 438 }
 439
 440 void
 441 g_static_private_free (GStaticPrivate *private_key)
 442 {
 443   guint index = private_key->index;
 444   GSList *list;
 445
 446   if (!index)
 447     return;
 448
 449   private_key->index = 0;
 450
 451   G_LOCK (g_thread);
 452   list =  g_thread_all_threads;
 453   while (list)
 454     {
 455       GRealThread *thread = list->data;
 456       GArray *array = thread->private_data;
 457       list = list->next;
 458
 459       if (array && index <= array->len)
 460         {
 461           GStaticPrivateNode *node = &g_array_index (array,
 462                                                      GStaticPrivateNode,
 463                                                      index - 1);
 464           gpointer ddata = node->data;
 465           GDestroyNotify ddestroy = node->destroy;
 466
 467           node->data = NULL;
 468           node->destroy = NULL;
 469
 470           if (ddestroy)
 471             {
 472               G_UNLOCK (g_thread);
 473               ddestroy (ddata);
 474               G_LOCK (g_thread);
 475               }
 476         }
 477     }
 478   g_thread_free_indeces = g_slist_prepend (g_thread_free_indeces,
 479                                            GUINT_TO_POINTER (index));
 480   G_UNLOCK (g_thread);
 481 }
 482
 483 static void
 484 g_thread_cleanup (gpointer data)
 485 {
 486   if (data)
 487     {
 488       GRealThread* thread = data;
 489       if (thread->private_data)
 490         {
 491           GArray* array = thread->private_data;
 492           guint i;
 493
 494           for (i = 0; i < array->len; i++ )
 495             {
 496               GStaticPrivateNode *node =
 497                 &g_array_index (array, GStaticPrivateNode, i);
 498               if (node->destroy)
 499                 node->destroy (node->data);
 500             }
 501           g_array_free (array, TRUE);
 502         }
 503
 504       /* We only free the thread structure, if it isn't joinable. If
 505          it is, the structure is freed in g_thread_join */
 506       if (!thread->thread.joinable)
 507         {
 508           G_LOCK (g_thread);
 509           g_thread_all_threads = g_slist_remove (g_thread_all_threads, data);
 510           G_UNLOCK (g_thread);
 511
 512           /* Just to make sure, this isn't used any more */
 513           g_system_thread_assign (thread->system_thread, zero_thread);
 514           g_free (thread);
 515         }
 516     }
 517 }
 518
 519 static void
 520 g_thread_fail (void)
 521 {
 522   g_error ("The thread system is not yet initialized.");
 523 }
 524
 525 static gpointer
 526 g_thread_create_proxy (gpointer data)
 527 {
 528   GRealThread* thread = data;
 529
 530   g_assert (data);
 531
 532 #ifdef G_THREAD_USE_PID_SURROGATE
 533   thread->pid = getpid ();
 534 #endif /* G_THREAD_USE_PID_SURROGATE */
 535
 536   /* This has to happen before G_LOCK, as that might call g_thread_self */
 537   g_private_set (g_thread_specific_private, data);
 538
 539   /* the lock makes sure, that thread->system_thread is written,
 540      before thread->thread.func is called. See g_thread_create. */
 541   G_LOCK (g_thread);
 542   G_UNLOCK (g_thread);
 543
 544 #ifdef G_THREAD_USE_PID_SURROGATE
 545   if (g_thread_use_default_impl)
 546     SET_PRIO (thread->pid, thread->thread.priority);
 547 #endif /* G_THREAD_USE_PID_SURROGATE */
 548
 549   thread->retval = thread->thread.func (thread->thread.data);
 550
 551   return NULL;
 552 }
 553
 554 GThread*
 555 g_thread_create_full (GThreadFunc                func,
 556                       gpointer           data,
 557                       gulong             stack_size,
 558                       gboolean           joinable,
 559                       gboolean           bound,
 560                       GThreadPriority    priority,
 561                       GError                **error)
 562 {
 563   GRealThread* result;
 564   GError *local_error = NULL;
 565   g_return_val_if_fail (func, NULL);
 566   g_return_val_if_fail (priority >= G_THREAD_PRIORITY_LOW, NULL);
 567   g_return_val_if_fail (priority <= G_THREAD_PRIORITY_URGENT, NULL);
 568
 569   result = g_new (GRealThread, 1);
 570
 571   result->thread.joinable = joinable;
 572   result->thread.priority = priority;
 573   result->thread.func = func;
 574   result->thread.data = data;
 575   result->private_data = NULL;
 576   G_LOCK (g_thread);
 577   G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
 578                                stack_size, joinable, bound, priority,
 579                                &result->system_thread, &local_error));
 580   g_thread_all_threads = g_slist_prepend (g_thread_all_threads, result);
 581   G_UNLOCK (g_thread);
 582
 583   if (local_error)
 584     {
 585       g_propagate_error (error, local_error);
 586       g_free (result);
 587       return NULL;
 588     }
 589
 590   return (GThread*) result;
 591 }
 592
 593 void
 594 g_thread_exit (gpointer retval)
 595 {
 596   GRealThread* real = (GRealThread*) g_thread_self ();
 597   real->retval = retval;
 598   G_THREAD_CF (thread_exit, (void)0, ());
 599 }
 600
 601 gpointer
 602 g_thread_join (GThread* thread)
 603 {
 604   GRealThread* real = (GRealThread*) thread;
 605   gpointer retval;
 606
 607   g_return_val_if_fail (thread, NULL);
 608   g_return_val_if_fail (thread->joinable, NULL);
 609   g_return_val_if_fail (!g_system_thread_equal (real->system_thread,
 610                                                 zero_thread), NULL);
 611
 612   G_THREAD_UF (thread_join, (&real->system_thread));
 613
 614   retval = real->retval;
 615
 616   G_LOCK (g_thread);
 617   g_thread_all_threads = g_slist_remove (g_thread_all_threads, thread);
 618   G_UNLOCK (g_thread);
 619
 620   /* Just to make sure, this isn't used any more */
 621   thread->joinable = 0;
 622   g_system_thread_assign (real->system_thread, zero_thread);
 623
 624   /* the thread structure for non-joinable threads is freed upon
 625      thread end. We free the memory here. This will leave a loose end,
 626      if a joinable thread is not joined. */
 627
 628   g_free (thread);
 629
 630   return retval;
 631 }
 632
 633 void
 634 g_thread_set_priority (GThread* thread,
 635                        GThreadPriority priority)
 636 {
 637   GRealThread* real = (GRealThread*) thread;
 638
 639   g_return_if_fail (thread);
 640   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 641   g_return_if_fail (priority >= G_THREAD_PRIORITY_LOW);
 642   g_return_if_fail (priority <= G_THREAD_PRIORITY_URGENT);
 643
 644   thread->priority = priority;
 645
 646 #ifdef G_THREAD_USE_PID_SURROGATE
 647   if (g_thread_use_default_impl)
 648     SET_PRIO (real->pid, priority);
 649   else
 650 #endif /* G_THREAD_USE_PID_SURROGATE */
 651     G_THREAD_CF (thread_set_priority, (void)0,
 652                  (&real->system_thread, priority));
 653 }
 654
 655 GThread*
 656 g_thread_self (void)
 657 {
 658   GRealThread* thread = g_private_get (g_thread_specific_private);
 659
 660   if (!thread)
 661     {
 662       /* If no thread data is available, provide and set one.  This
 663          can happen for the main thread and for threads, that are not
 664          created by GLib. */
 665       thread = g_new (GRealThread, 1);
 666       thread->thread.joinable = FALSE; /* This is a save guess */
 667       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 668                                                              just a guess */
 669       thread->thread.func = NULL;
 670       thread->thread.data = NULL;
 671       thread->private_data = NULL;
 672
 673       if (g_thread_supported ())
 674         G_THREAD_UF (thread_self, (&thread->system_thread));
 675
 676 #ifdef G_THREAD_USE_PID_SURROGATE
 677       thread->pid = getpid ();
 678 #endif /* G_THREAD_USE_PID_SURROGATE */
 679
 680       g_private_set (g_thread_specific_private, thread);
 681
 682       G_LOCK (g_thread);
 683       g_thread_all_threads = g_slist_prepend (g_thread_all_threads, thread);
 684       G_UNLOCK (g_thread);
 685     }
 686
 687   return (GThread*)thread;
 688 }
 689
 690 void
 691 g_static_rw_lock_init (GStaticRWLock* lock)
 692 {
 693   static GStaticRWLock init_lock = G_STATIC_RW_LOCK_INIT;
 694
 695   g_return_if_fail (lock);
 696
 697   *lock = init_lock;
 698 }
 699
 700 static void inline
 701 g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 702 {
 703   if (!*cond)
 704       *cond = g_cond_new ();
 705   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 706 }
 707
 708 static void inline
 709 g_static_rw_lock_signal (GStaticRWLock* lock)
 710 {
 711   if (lock->want_to_write && lock->write_cond)
 712     g_cond_signal (lock->write_cond);
 713   else if (lock->want_to_read && lock->read_cond)
 714     g_cond_broadcast (lock->read_cond);
 715 }
 716
 717 void
 718 g_static_rw_lock_reader_lock (GStaticRWLock* lock)
 719 {
 720   g_return_if_fail (lock);
 721
 722   if (!g_threads_got_initialized)
 723     return;
 724
 725   g_static_mutex_lock (&lock->mutex);
 726   lock->want_to_read++;
 727   while (lock->write || lock->want_to_write)
 728     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 729   lock->want_to_read--;
 730   lock->read_counter++;
 731   g_static_mutex_unlock (&lock->mutex);
 732 }
 733
 734 gboolean
 735 g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
 736 {
 737   gboolean ret_val = FALSE;
 738
 739   g_return_val_if_fail (lock, FALSE);
 740
 741   if (!g_threads_got_initialized)
 742     return TRUE;
 743
 744   g_static_mutex_lock (&lock->mutex);
 745   if (!lock->write && !lock->want_to_write)
 746     {
 747       lock->read_counter++;
 748       ret_val = TRUE;
 749     }
 750   g_static_mutex_unlock (&lock->mutex);
 751   return ret_val;
 752 }
 753
 754 void
 755 g_static_rw_lock_reader_unlock  (GStaticRWLock* lock)
 756 {
 757   g_return_if_fail (lock);
 758
 759   if (!g_threads_got_initialized)
 760     return;
 761
 762   g_static_mutex_lock (&lock->mutex);
 763   lock->read_counter--;
 764   if (lock->read_counter == 0)
 765     g_static_rw_lock_signal (lock);
 766   g_static_mutex_unlock (&lock->mutex);
 767 }
 768
 769 void
 770 g_static_rw_lock_writer_lock (GStaticRWLock* lock)
 771 {
 772   g_return_if_fail (lock);
 773
 774   if (!g_threads_got_initialized)
 775     return;
 776
 777   g_static_mutex_lock (&lock->mutex);
 778   lock->want_to_write++;
 779   while (lock->write || lock->read_counter)
 780     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 781   lock->want_to_write--;
 782   lock->write = TRUE;
 783   g_static_mutex_unlock (&lock->mutex);
 784 }
 785
 786 gboolean
 787 g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 788 {
 789   gboolean ret_val = FALSE;
 790
 791   g_return_val_if_fail (lock, FALSE);
 792
 793   if (!g_threads_got_initialized)
 794     return TRUE;
 795
 796   g_static_mutex_lock (&lock->mutex);
 797   if (!lock->write && !lock->read_counter)
 798     {
 799       lock->write = TRUE;
 800       ret_val = TRUE;
 801     }
 802   g_static_mutex_unlock (&lock->mutex);
 803   return ret_val;
 804 }
 805
 806 void
 807 g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
 808 {
 809   g_return_if_fail (lock);
 810
 811   if (!g_threads_got_initialized)
 812     return;
 813
 814   g_static_mutex_lock (&lock->mutex);
 815   lock->write = FALSE;
 816   g_static_rw_lock_signal (lock);
 817   g_static_mutex_unlock (&lock->mutex);
 818 }
 819
 820 void
 821 g_static_rw_lock_free (GStaticRWLock* lock)
 822 {
 823   g_return_if_fail (lock);
 824
 825   if (lock->read_cond)
 826     {
 827       g_cond_free (lock->read_cond);
 828       lock->read_cond = NULL;
 829     }
 830   if (lock->write_cond)
 831     {
 832       g_cond_free (lock->write_cond);
 833       lock->write_cond = NULL;
 834     }
 835   g_static_mutex_free (&lock->mutex);
 836 }