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
  37 #ifdef G_THREAD_USE_PID_SURROGATE
  38 #include <sys/types.h>
  39 #include <sys/time.h>
  40 #include <sys/resource.h>
  41 #include <errno.h>
  42 #endif /* G_THREAD_USE_PID_SURROGATE */
  43
  44 #ifdef HAVE_UNISTD_H
  45 #include <unistd.h>
  46 #endif
  47
  48 #include <string.h>
  49
  50 #include "glib.h"
  51 #include "gthreadinit.h"
  52
  53 #if GLIB_SIZEOF_SYSTEM_THREAD == SIZEOF_VOID_P
  54 # define g_system_thread_equal_simple(thread1, thread2)                 \
  55    ((thread1).dummy_pointer == (thread2).dummy_pointer)
  56 # define g_system_thread_assign(dest, src)                              \
  57    ((dest).dummy_pointer = (src).dummy_pointer)
  58 #else /* GLIB_SIZEOF_SYSTEM_THREAD != SIZEOF_VOID_P */
  59 # define g_system_thread_equal_simple(thread1, thread2)                 \
  60    (memcmp (&(thread1), &(thread2), GLIB_SIZEOF_SYSTEM_THREAD) == 0)
  61 # define g_system_thread_assign(dest, src)                              \
  62    (memcpy (&(dest), &(src), GLIB_SIZEOF_SYSTEM_THREAD))
  63 #endif /* GLIB_SIZEOF_SYSTEM_THREAD == SIZEOF_VOID_P */
  64
  65 #define g_system_thread_equal(thread1, thread2)                         \
  66   (g_thread_functions_for_glib_use.thread_equal ?                       \
  67    g_thread_functions_for_glib_use.thread_equal (&(thread1), &(thread2)) :\
  68    g_system_thread_equal_simple((thread1), (thread2)))
  69
  70 GQuark
  71 g_thread_error_quark (void)
  72 {
  73   static GQuark quark;
  74   if (!quark)
  75     quark = g_quark_from_static_string ("g_thread_error");
  76   return quark;
  77 }
  78
  79 /* Keep this in sync with GRealThread in gmain.c! */
  80 typedef struct _GRealThread GRealThread;
  81 struct  _GRealThread
  82 {
  83   GThread thread;
  84   gpointer private_data;
  85   gpointer retval;
  86   GSystemThread system_thread;
  87 #ifdef G_THREAD_USE_PID_SURROGATE
  88   pid_t pid;
  89 #endif /* G_THREAD_USE_PID_SURROGATE */
  90 };
  91
  92 #ifdef G_THREAD_USE_PID_SURROGATE
  93 static gint priority_map[4];
  94 static gboolean prio_warned = FALSE;
  95 # define SET_PRIO(pid, prio) G_STMT_START{                              \
  96   gint error = setpriority (PRIO_PROCESS, (pid), priority_map[prio]);   \
  97   if (error == -1 && errno == EACCES && !prio_warned)                   \
  98     {                                                                   \
  99       prio_warned = TRUE;                                               \
 100       g_warning ("Priorities can only be increased by root.");          \
 101     }                                                                   \
 102   }G_STMT_END
 103 #endif /* G_THREAD_USE_PID_SURROGATE */
 104
 105 typedef struct _GStaticPrivateNode GStaticPrivateNode;
 106 struct _GStaticPrivateNode
 107 {
 108   gpointer       data;
 109   GDestroyNotify destroy;
 110 };
 111
 112 static void g_thread_cleanup (gpointer data);
 113 static void g_thread_fail (void);
 114
 115 /* Global variables */
 116
 117 static GSystemThread zero_thread; /* This is initialized to all zero */
 118 gboolean g_thread_use_default_impl = TRUE;
 119 gboolean g_threads_got_initialized = FALSE;
 120
 121 #if defined(G_PLATFORM_WIN32) && defined(__GNUC__)
 122 __declspec(dllexport)
 123 #endif
 124 GThreadFunctions g_thread_functions_for_glib_use = {
 125   (GMutex*(*)())g_thread_fail,                 /* mutex_new */
 126   NULL,                                        /* mutex_lock */
 127   NULL,                                        /* mutex_trylock */
 128   NULL,                                        /* mutex_unlock */
 129   NULL,                                        /* mutex_free */
 130   (GCond*(*)())g_thread_fail,                  /* cond_new */
 131   NULL,                                        /* cond_signal */
 132   NULL,                                        /* cond_broadcast */
 133   NULL,                                        /* cond_wait */
 134   NULL,                                        /* cond_timed_wait  */
 135   NULL,                                        /* cond_free */
 136   (GPrivate*(*)(GDestroyNotify))g_thread_fail, /* private_new */
 137   NULL,                                        /* private_get */
 138   NULL,                                        /* private_set */
 139   (void(*)(GThreadFunc, gpointer, gulong,
 140            gboolean, gboolean, GThreadPriority,
 141            gpointer, GError**))g_thread_fail,  /* thread_create */
 142   NULL,                                        /* thread_yield */
 143   NULL,                                        /* thread_join */
 144   NULL,                                        /* thread_exit */
 145   NULL,                                        /* thread_set_priority */
 146   NULL                                         /* thread_self */
 147 };
 148
 149 /* Local data */
 150
 151 static GMutex   *g_mutex_protect_static_mutex_allocation = NULL;
 152 static GPrivate *g_thread_specific_private = NULL;
 153 static GSList   *g_thread_all_threads = NULL;
 154 static GSList   *g_thread_free_indeces = NULL;
 155
 156 G_LOCK_DEFINE_STATIC (g_thread);
 157
 158 #ifdef G_THREADS_ENABLED
 159 /* This must be called only once, before any threads are created.
 160  * It will only be called from g_thread_init() in -lgthread.
 161  */
 162 void
 163 g_thread_init_glib (void)
 164 {
 165   /* We let the main thread (the one that calls g_thread_init) inherit
 166    * the static_private data set before calling g_thread_init
 167    */
 168   GRealThread* main_thread = (GRealThread*) g_thread_self ();
 169
 170   g_mutex_protect_static_mutex_allocation = g_mutex_new ();
 171
 172   _g_convert_thread_init ();
 173   _g_rand_thread_init ();
 174   _g_main_thread_init ();
 175   _g_mem_thread_init ();
 176   _g_messages_thread_init ();
 177
 178 #ifdef G_THREAD_USE_PID_SURROGATE
 179   priority_map[G_THREAD_PRIORITY_NORMAL] =
 180     getpriority (PRIO_PROCESS, (getpid ()));
 181   priority_map[G_THREAD_PRIORITY_LOW] =
 182     MIN (20, priority_map[G_THREAD_PRIORITY_NORMAL] + 10);
 183   priority_map[G_THREAD_PRIORITY_HIGH] =
 184     MAX (-20, priority_map[G_THREAD_PRIORITY_NORMAL] - 10);
 185   priority_map[G_THREAD_PRIORITY_URGENT] =
 186     MAX (-20, priority_map[G_THREAD_PRIORITY_NORMAL] - 15);
 187 #endif /* G_THREAD_USE_PID_SURROGATE */
 188
 189   g_threads_got_initialized = TRUE;
 190
 191   g_thread_specific_private = g_private_new (g_thread_cleanup);
 192   g_private_set (g_thread_specific_private, main_thread);
 193   G_THREAD_UF (thread_self, (&main_thread->system_thread));
 194
 195   _g_mem_thread_private_init ();
 196   _g_messages_thread_private_init ();
 197
 198 }
 199 #endif /* G_THREADS_ENABLED */
 200
 201 void
 202 g_static_mutex_init (GStaticMutex *mutex)
 203 {
 204   static GStaticMutex init_mutex = G_STATIC_MUTEX_INIT;
 205
 206   g_return_if_fail (mutex);
 207
 208   *mutex = init_mutex;
 209 }
 210
 211 GMutex *
 212 g_static_mutex_get_mutex_impl (GMutex** mutex)
 213 {
 214   if (!g_thread_supported ())
 215     return NULL;
 216
 217   g_assert (g_mutex_protect_static_mutex_allocation);
 218
 219   g_mutex_lock (g_mutex_protect_static_mutex_allocation);
 220
 221   if (!(*mutex))
 222     *mutex = g_mutex_new ();
 223
 224   g_mutex_unlock (g_mutex_protect_static_mutex_allocation);
 225
 226   return *mutex;
 227 }
 228
 229 void
 230 g_static_mutex_free (GStaticMutex* mutex)
 231 {
 232   GMutex **runtime_mutex;
 233
 234   g_return_if_fail (mutex);
 235
 236   /* The runtime_mutex is the first (or only) member of GStaticMutex,
 237    * see both versions (of glibconfig.h) in configure.in */
 238   runtime_mutex = ((GMutex**)mutex);
 239
 240   if (*runtime_mutex)
 241     g_mutex_free (*runtime_mutex);
 242
 243   *runtime_mutex = NULL;
 244 }
 245
 246 void
 247 g_static_rec_mutex_init (GStaticRecMutex *mutex)
 248 {
 249   static GStaticRecMutex init_mutex = G_STATIC_REC_MUTEX_INIT;
 250
 251   g_return_if_fail (mutex);
 252
 253   *mutex = init_mutex;
 254 }
 255
 256 void
 257 g_static_rec_mutex_lock (GStaticRecMutex* mutex)
 258 {
 259   GSystemThread self;
 260
 261   g_return_if_fail (mutex);
 262
 263   if (!g_thread_supported ())
 264     return;
 265
 266   G_THREAD_UF (thread_self, (&self));
 267
 268   if (g_system_thread_equal (self, mutex->owner))
 269     {
 270       mutex->depth++;
 271       return;
 272     }
 273   g_static_mutex_lock (&mutex->mutex);
 274   g_system_thread_assign (mutex->owner, self);
 275   mutex->depth = 1;
 276 }
 277
 278 gboolean
 279 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
 280 {
 281   GSystemThread self;
 282
 283   g_return_val_if_fail (mutex, FALSE);
 284
 285   if (!g_thread_supported ())
 286     return TRUE;
 287
 288   G_THREAD_UF (thread_self, (&self));
 289
 290   if (g_system_thread_equal (self, mutex->owner))
 291     {
 292       mutex->depth++;
 293       return TRUE;
 294     }
 295
 296   if (!g_static_mutex_trylock (&mutex->mutex))
 297     return FALSE;
 298
 299   g_system_thread_assign (mutex->owner, self);
 300   mutex->depth = 1;
 301   return TRUE;
 302 }
 303
 304 void
 305 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
 306 {
 307   g_return_if_fail (mutex);
 308
 309   if (!g_thread_supported ())
 310     return;
 311
 312   if (mutex->depth > 1)
 313     {
 314       mutex->depth--;
 315       return;
 316     }
 317   g_system_thread_assign (mutex->owner, zero_thread);
 318   g_static_mutex_unlock (&mutex->mutex);
 319 }
 320
 321 void
 322 g_static_rec_mutex_lock_full   (GStaticRecMutex *mutex,
 323                                 guint            depth)
 324 {
 325   GSystemThread self;
 326   g_return_if_fail (mutex);
 327
 328   if (!g_thread_supported ())
 329     return;
 330
 331   G_THREAD_UF (thread_self, (&self));
 332
 333   if (g_system_thread_equal (self, mutex->owner))
 334     {
 335       mutex->depth += depth;
 336       return;
 337     }
 338   g_static_mutex_lock (&mutex->mutex);
 339   g_system_thread_assign (mutex->owner, self);
 340   mutex->depth = depth;
 341 }
 342
 343 guint
 344 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
 345 {
 346   guint depth;
 347
 348   g_return_val_if_fail (mutex, 0);
 349
 350   if (!g_thread_supported ())
 351     return 1;
 352
 353   depth = mutex->depth;
 354
 355   g_system_thread_assign (mutex->owner, zero_thread);
 356   mutex->depth = 0;
 357   g_static_mutex_unlock (&mutex->mutex);
 358
 359   return depth;
 360 }
 361
 362 void
 363 g_static_rec_mutex_free (GStaticRecMutex *mutex)
 364 {
 365   g_return_if_fail (mutex);
 366
 367   g_static_mutex_free (&mutex->mutex);
 368 }
 369
 370 void
 371 g_static_private_init (GStaticPrivate *private_key)
 372 {
 373   private_key->index = 0;
 374 }
 375
 376 gpointer
 377 g_static_private_get (GStaticPrivate *private_key)
 378 {
 379   GRealThread *self = (GRealThread*) g_thread_self ();
 380   GArray *array;
 381
 382   array = self->private_data;
 383   if (!array)
 384     return NULL;
 385
 386   if (!private_key->index)
 387     return NULL;
 388   else if (private_key->index <= array->len)
 389     return g_array_index (array, GStaticPrivateNode,
 390                           private_key->index - 1).data;
 391   else
 392     return NULL;
 393 }
 394
 395 void
 396 g_static_private_set (GStaticPrivate *private_key,
 397                       gpointer        data,
 398                       GDestroyNotify  notify)
 399 {
 400   GRealThread *self = (GRealThread*) g_thread_self ();
 401   GArray *array;
 402   static guint next_index = 0;
 403   GStaticPrivateNode *node;
 404
 405   array = self->private_data;
 406   if (!array)
 407     {
 408       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 409       self->private_data = array;
 410     }
 411
 412   if (!private_key->index)
 413     {
 414       G_LOCK (g_thread);
 415
 416       if (!private_key->index)
 417         {
 418           if (g_thread_free_indeces)
 419             {
 420               private_key->index =
 421                 GPOINTER_TO_UINT (g_thread_free_indeces->data);
 422               g_thread_free_indeces =
 423                 g_slist_delete_link (g_thread_free_indeces,
 424                                      g_thread_free_indeces);
 425             }
 426           else
 427             private_key->index = ++next_index;
 428         }
 429
 430       G_UNLOCK (g_thread);
 431     }
 432
 433   if (private_key->index > array->len)
 434     g_array_set_size (array, private_key->index);
 435
 436   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 437   if (node->destroy)
 438     {
 439       gpointer ddata = node->data;
 440       GDestroyNotify ddestroy = node->destroy;
 441
 442       node->data = data;
 443       node->destroy = notify;
 444
 445       ddestroy (ddata);
 446     }
 447   else
 448     {
 449       node->data = data;
 450       node->destroy = notify;
 451     }
 452 }
 453
 454 void
 455 g_static_private_free (GStaticPrivate *private_key)
 456 {
 457   guint index = private_key->index;
 458   GSList *list;
 459
 460   if (!index)
 461     return;
 462
 463   private_key->index = 0;
 464
 465   G_LOCK (g_thread);
 466   list =  g_thread_all_threads;
 467   while (list)
 468     {
 469       GRealThread *thread = list->data;
 470       GArray *array = thread->private_data;
 471       list = list->next;
 472
 473       if (array && index <= array->len)
 474         {
 475           GStaticPrivateNode *node = &g_array_index (array,
 476                                                      GStaticPrivateNode,
 477                                                      index - 1);
 478           gpointer ddata = node->data;
 479           GDestroyNotify ddestroy = node->destroy;
 480
 481           node->data = NULL;
 482           node->destroy = NULL;
 483
 484           if (ddestroy)
 485             {
 486               G_UNLOCK (g_thread);
 487               ddestroy (ddata);
 488               G_LOCK (g_thread);
 489               }
 490         }
 491     }
 492   g_thread_free_indeces = g_slist_prepend (g_thread_free_indeces,
 493                                            GUINT_TO_POINTER (index));
 494   G_UNLOCK (g_thread);
 495 }
 496
 497 static void
 498 g_thread_cleanup (gpointer data)
 499 {
 500   if (data)
 501     {
 502       GRealThread* thread = data;
 503       if (thread->private_data)
 504         {
 505           GArray* array = thread->private_data;
 506           guint i;
 507
 508           for (i = 0; i < array->len; i++ )
 509             {
 510               GStaticPrivateNode *node =
 511                 &g_array_index (array, GStaticPrivateNode, i);
 512               if (node->destroy)
 513                 node->destroy (node->data);
 514             }
 515           g_array_free (array, TRUE);
 516         }
 517
 518       /* We only free the thread structure, if it isn't joinable. If
 519          it is, the structure is freed in g_thread_join */
 520       if (!thread->thread.joinable)
 521         {
 522           G_LOCK (g_thread);
 523           g_thread_all_threads = g_slist_remove (g_thread_all_threads, data);
 524           G_UNLOCK (g_thread);
 525
 526           /* Just to make sure, this isn't used any more */
 527           g_system_thread_assign (thread->system_thread, zero_thread);
 528           g_free (thread);
 529         }
 530     }
 531 }
 532
 533 static void
 534 g_thread_fail (void)
 535 {
 536   g_error ("The thread system is not yet initialized.");
 537 }
 538
 539 static gpointer
 540 g_thread_create_proxy (gpointer data)
 541 {
 542   GRealThread* thread = data;
 543
 544   g_assert (data);
 545
 546 #ifdef G_THREAD_USE_PID_SURROGATE
 547   thread->pid = getpid ();
 548 #endif /* G_THREAD_USE_PID_SURROGATE */
 549
 550   /* This has to happen before G_LOCK, as that might call g_thread_self */
 551   g_private_set (g_thread_specific_private, data);
 552
 553   /* the lock makes sure, that thread->system_thread is written,
 554      before thread->thread.func is called. See g_thread_create. */
 555   G_LOCK (g_thread);
 556   G_UNLOCK (g_thread);
 557
 558 #ifdef G_THREAD_USE_PID_SURROGATE
 559   if (g_thread_use_default_impl)
 560     SET_PRIO (thread->pid, thread->thread.priority);
 561 #endif /* G_THREAD_USE_PID_SURROGATE */
 562
 563   thread->retval = thread->thread.func (thread->thread.data);
 564
 565   return NULL;
 566 }
 567
 568 GThread*
 569 g_thread_create_full (GThreadFunc                func,
 570                       gpointer           data,
 571                       gulong             stack_size,
 572                       gboolean           joinable,
 573                       gboolean           bound,
 574                       GThreadPriority    priority,
 575                       GError                **error)
 576 {
 577   GRealThread* result;
 578   GError *local_error = NULL;
 579   g_return_val_if_fail (func, NULL);
 580   g_return_val_if_fail (priority >= G_THREAD_PRIORITY_LOW, NULL);
 581   g_return_val_if_fail (priority <= G_THREAD_PRIORITY_URGENT, NULL);
 582
 583   result = g_new (GRealThread, 1);
 584
 585   result->thread.joinable = joinable;
 586   result->thread.priority = priority;
 587   result->thread.func = func;
 588   result->thread.data = data;
 589   result->private_data = NULL;
 590   G_LOCK (g_thread);
 591   G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
 592                                stack_size, joinable, bound, priority,
 593                                &result->system_thread, &local_error));
 594   g_thread_all_threads = g_slist_prepend (g_thread_all_threads, result);
 595   G_UNLOCK (g_thread);
 596
 597   if (local_error)
 598     {
 599       g_propagate_error (error, local_error);
 600       g_free (result);
 601       return NULL;
 602     }
 603
 604   return (GThread*) result;
 605 }
 606
 607 void
 608 g_thread_exit (gpointer retval)
 609 {
 610   GRealThread* real = (GRealThread*) g_thread_self ();
 611   real->retval = retval;
 612   G_THREAD_CF (thread_exit, (void)0, ());
 613 }
 614
 615 gpointer
 616 g_thread_join (GThread* thread)
 617 {
 618   GRealThread* real = (GRealThread*) thread;
 619   gpointer retval;
 620
 621   g_return_val_if_fail (thread, NULL);
 622   g_return_val_if_fail (thread->joinable, NULL);
 623   g_return_val_if_fail (!g_system_thread_equal (real->system_thread,
 624                                                 zero_thread), NULL);
 625
 626   G_THREAD_UF (thread_join, (&real->system_thread));
 627
 628   retval = real->retval;
 629
 630   G_LOCK (g_thread);
 631   g_thread_all_threads = g_slist_remove (g_thread_all_threads, thread);
 632   G_UNLOCK (g_thread);
 633
 634   /* Just to make sure, this isn't used any more */
 635   thread->joinable = 0;
 636   g_system_thread_assign (real->system_thread, zero_thread);
 637
 638   /* the thread structure for non-joinable threads is freed upon
 639      thread end. We free the memory here. This will leave a loose end,
 640      if a joinable thread is not joined. */
 641
 642   g_free (thread);
 643
 644   return retval;
 645 }
 646
 647 void
 648 g_thread_set_priority (GThread* thread,
 649                        GThreadPriority priority)
 650 {
 651   GRealThread* real = (GRealThread*) thread;
 652
 653   g_return_if_fail (thread);
 654   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 655   g_return_if_fail (priority >= G_THREAD_PRIORITY_LOW);
 656   g_return_if_fail (priority <= G_THREAD_PRIORITY_URGENT);
 657
 658   thread->priority = priority;
 659
 660 #ifdef G_THREAD_USE_PID_SURROGATE
 661   if (g_thread_use_default_impl)
 662     SET_PRIO (real->pid, priority);
 663   else
 664 #endif /* G_THREAD_USE_PID_SURROGATE */
 665     G_THREAD_CF (thread_set_priority, (void)0,
 666                  (&real->system_thread, priority));
 667 }
 668
 669 GThread*
 670 g_thread_self (void)
 671 {
 672   GRealThread* thread = g_private_get (g_thread_specific_private);
 673
 674   if (!thread)
 675     {
 676       /* If no thread data is available, provide and set one.  This
 677          can happen for the main thread and for threads, that are not
 678          created by GLib. */
 679       thread = g_new (GRealThread, 1);
 680       thread->thread.joinable = FALSE; /* This is a save guess */
 681       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 682                                                              just a guess */
 683       thread->thread.func = NULL;
 684       thread->thread.data = NULL;
 685       thread->private_data = NULL;
 686
 687       if (g_thread_supported ())
 688         G_THREAD_UF (thread_self, (&thread->system_thread));
 689
 690 #ifdef G_THREAD_USE_PID_SURROGATE
 691       thread->pid = getpid ();
 692 #endif /* G_THREAD_USE_PID_SURROGATE */
 693
 694       g_private_set (g_thread_specific_private, thread);
 695
 696       G_LOCK (g_thread);
 697       g_thread_all_threads = g_slist_prepend (g_thread_all_threads, thread);
 698       G_UNLOCK (g_thread);
 699     }
 700
 701   return (GThread*)thread;
 702 }
 703
 704 void
 705 g_static_rw_lock_init (GStaticRWLock* lock)
 706 {
 707   static GStaticRWLock init_lock = G_STATIC_RW_LOCK_INIT;
 708
 709   g_return_if_fail (lock);
 710
 711   *lock = init_lock;
 712 }
 713
 714 static void inline
 715 g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 716 {
 717   if (!*cond)
 718       *cond = g_cond_new ();
 719   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 720 }
 721
 722 static void inline
 723 g_static_rw_lock_signal (GStaticRWLock* lock)
 724 {
 725   if (lock->want_to_write && lock->write_cond)
 726     g_cond_signal (lock->write_cond);
 727   else if (lock->want_to_read && lock->read_cond)
 728     g_cond_broadcast (lock->read_cond);
 729 }
 730
 731 void
 732 g_static_rw_lock_reader_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_read++;
 741   while (lock->have_writer || lock->want_to_write)
 742     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 743   lock->want_to_read--;
 744   lock->read_counter++;
 745   g_static_mutex_unlock (&lock->mutex);
 746 }
 747
 748 gboolean
 749 g_static_rw_lock_reader_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->have_writer && !lock->want_to_write)
 760     {
 761       lock->read_counter++;
 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_reader_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->read_counter--;
 778   if (lock->read_counter == 0)
 779     g_static_rw_lock_signal (lock);
 780   g_static_mutex_unlock (&lock->mutex);
 781 }
 782
 783 void
 784 g_static_rw_lock_writer_lock (GStaticRWLock* lock)
 785 {
 786   g_return_if_fail (lock);
 787
 788   if (!g_threads_got_initialized)
 789     return;
 790
 791   g_static_mutex_lock (&lock->mutex);
 792   lock->want_to_write++;
 793   while (lock->have_writer || lock->read_counter)
 794     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 795   lock->want_to_write--;
 796   lock->have_writer = TRUE;
 797   g_static_mutex_unlock (&lock->mutex);
 798 }
 799
 800 gboolean
 801 g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 802 {
 803   gboolean ret_val = FALSE;
 804
 805   g_return_val_if_fail (lock, FALSE);
 806
 807   if (!g_threads_got_initialized)
 808     return TRUE;
 809
 810   g_static_mutex_lock (&lock->mutex);
 811   if (!lock->have_writer && !lock->read_counter)
 812     {
 813       lock->have_writer = TRUE;
 814       ret_val = TRUE;
 815     }
 816   g_static_mutex_unlock (&lock->mutex);
 817   return ret_val;
 818 }
 819
 820 void
 821 g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
 822 {
 823   g_return_if_fail (lock);
 824
 825   if (!g_threads_got_initialized)
 826     return;
 827
 828   g_static_mutex_lock (&lock->mutex);
 829   lock->have_writer = FALSE;
 830   g_static_rw_lock_signal (lock);
 831   g_static_mutex_unlock (&lock->mutex);
 832 }
 833
 834 void
 835 g_static_rw_lock_free (GStaticRWLock* lock)
 836 {
 837   g_return_if_fail (lock);
 838
 839   if (lock->read_cond)
 840     {
 841       g_cond_free (lock->read_cond);
 842       lock->read_cond = NULL;
 843     }
 844   if (lock->write_cond)
 845     {
 846       g_cond_free (lock->write_cond);
 847       lock->write_cond = NULL;
 848     }
 849   g_static_mutex_free (&lock->mutex);
 850 }