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  * gthread.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 HAVE_UNISTD_H
  38 #include <unistd.h>
  39 #endif
  40
  41 #include <string.h>
  42
  43 #include "glib.h"
  44 #include "gthreadprivate.h"
  45 #include "galias.h"
  46
  47 GQuark
  48 g_thread_error_quark (void)
  49 {
  50   return g_quark_from_static_string ("g_thread_error");
  51 }
  52
  53 /* Keep this in sync with GRealThread in gmain.c! */
  54 typedef struct _GRealThread GRealThread;
  55 struct  _GRealThread
  56 {
  57   GThread thread;
  58   gpointer private_data;
  59   GRealThread *next;
  60   gpointer retval;
  61   GSystemThread system_thread;
  62 };
  63
  64 typedef struct _GStaticPrivateNode GStaticPrivateNode;
  65 struct _GStaticPrivateNode
  66 {
  67   gpointer       data;
  68   GDestroyNotify destroy;
  69 };
  70
  71 static void g_thread_cleanup (gpointer data);
  72 static void g_thread_fail (void);
  73
  74 /* Global variables */
  75
  76 static GSystemThread zero_thread; /* This is initialized to all zero */
  77 gboolean g_thread_use_default_impl = TRUE;
  78 gboolean g_threads_got_initialized = FALSE;
  79
  80 GThreadFunctions g_thread_functions_for_glib_use = {
  81   (GMutex*(*)())g_thread_fail,                 /* mutex_new */
  82   NULL,                                        /* mutex_lock */
  83   NULL,                                        /* mutex_trylock */
  84   NULL,                                        /* mutex_unlock */
  85   NULL,                                        /* mutex_free */
  86   (GCond*(*)())g_thread_fail,                  /* cond_new */
  87   NULL,                                        /* cond_signal */
  88   NULL,                                        /* cond_broadcast */
  89   NULL,                                        /* cond_wait */
  90   NULL,                                        /* cond_timed_wait  */
  91   NULL,                                        /* cond_free */
  92   (GPrivate*(*)(GDestroyNotify))g_thread_fail, /* private_new */
  93   NULL,                                        /* private_get */
  94   NULL,                                        /* private_set */
  95   (void(*)(GThreadFunc, gpointer, gulong,
  96            gboolean, gboolean, GThreadPriority,
  97            gpointer, GError**))g_thread_fail,  /* thread_create */
  98   NULL,                                        /* thread_yield */
  99   NULL,                                        /* thread_join */
 100   NULL,                                        /* thread_exit */
 101   NULL,                                        /* thread_set_priority */
 102   NULL                                         /* thread_self */
 103 };
 104
 105 /* Local data */
 106
 107 static GMutex   *g_once_mutex = NULL;
 108 static GCond    *g_once_cond = NULL;
 109 static GPrivate *g_thread_specific_private = NULL;
 110 static GRealThread *g_thread_all_threads = NULL;
 111 static GSList   *g_thread_free_indeces = NULL;
 112
 113 G_LOCK_DEFINE_STATIC (g_thread);
 114
 115 #ifdef G_THREADS_ENABLED
 116 /* This must be called only once, before any threads are created.
 117  * It will only be called from g_thread_init() in -lgthread.
 118  */
 119 void
 120 g_thread_init_glib (void)
 121 {
 122   /* We let the main thread (the one that calls g_thread_init) inherit
 123    * the static_private data set before calling g_thread_init
 124    */
 125   GRealThread* main_thread = (GRealThread*) g_thread_self ();
 126
 127   /* mutex and cond creation works without g_threads_got_initialized */
 128   g_once_mutex = g_mutex_new ();
 129   g_once_cond = g_cond_new ();
 130
 131   /* we may only create mutex and cond in here */
 132   _g_mem_thread_init_noprivate_nomessage ();
 133
 134   /* setup the basic threading system */
 135   g_threads_got_initialized = TRUE;
 136   g_thread_specific_private = g_private_new (g_thread_cleanup);
 137   g_private_set (g_thread_specific_private, main_thread);
 138   G_THREAD_UF (thread_self, (&main_thread->system_thread));
 139
 140   /* complete memory system initialization, g_private_*() works now */
 141   _g_slice_thread_init_nomessage ();
 142
 143   /* accomplish log system initialization to enable messaging */
 144   _g_messages_thread_init_nomessage ();
 145
 146   /* we may run full-fledged initializers from here */
 147   _g_convert_thread_init ();
 148   _g_rand_thread_init ();
 149   _g_main_thread_init ();
 150   _g_atomic_thread_init ();
 151   _g_utils_thread_init ();
 152 #ifdef G_OS_WIN32
 153   _g_win32_thread_init ();
 154 #endif
 155 }
 156 #endif /* G_THREADS_ENABLED */
 157
 158 gpointer
 159 g_once_impl (GOnce       *once,
 160              GThreadFunc  func,
 161              gpointer     arg)
 162 {
 163   g_mutex_lock (g_once_mutex);
 164
 165   while (once->status == G_ONCE_STATUS_PROGRESS)
 166     g_cond_wait (g_once_cond, g_once_mutex);
 167
 168   if (once->status != G_ONCE_STATUS_READY)
 169     {
 170       once->status = G_ONCE_STATUS_PROGRESS;
 171       g_mutex_unlock (g_once_mutex);
 172
 173       once->retval = func (arg);
 174
 175       g_mutex_lock (g_once_mutex);
 176       once->status = G_ONCE_STATUS_READY;
 177       g_cond_broadcast (g_once_cond);
 178     }
 179
 180   g_mutex_unlock (g_once_mutex);
 181
 182   return once->retval;
 183 }
 184
 185 void
 186 g_static_mutex_init (GStaticMutex *mutex)
 187 {
 188   static const GStaticMutex init_mutex = G_STATIC_MUTEX_INIT;
 189
 190   g_return_if_fail (mutex);
 191
 192   *mutex = init_mutex;
 193 }
 194
 195 GMutex *
 196 g_static_mutex_get_mutex_impl (GMutex** mutex)
 197 {
 198   if (!g_thread_supported ())
 199     return NULL;
 200
 201   g_assert (g_once_mutex);
 202
 203   g_mutex_lock (g_once_mutex);
 204
 205   if (!(*mutex))
 206     {
 207       GMutex *new_mutex = g_mutex_new ();
 208
 209       /* The following is a memory barrier to avoid the write
 210        * to *new_mutex being reordered to after writing *mutex */
 211       g_mutex_lock (new_mutex);
 212       g_mutex_unlock (new_mutex);
 213
 214       *mutex = new_mutex;
 215     }
 216
 217   g_mutex_unlock (g_once_mutex);
 218
 219   return *mutex;
 220 }
 221
 222 void
 223 g_static_mutex_free (GStaticMutex* mutex)
 224 {
 225   GMutex **runtime_mutex;
 226
 227   g_return_if_fail (mutex);
 228
 229   /* The runtime_mutex is the first (or only) member of GStaticMutex,
 230    * see both versions (of glibconfig.h) in configure.in */
 231   runtime_mutex = ((GMutex**)mutex);
 232
 233   if (*runtime_mutex)
 234     g_mutex_free (*runtime_mutex);
 235
 236   *runtime_mutex = NULL;
 237 }
 238
 239 void
 240 g_static_rec_mutex_init (GStaticRecMutex *mutex)
 241 {
 242   static const GStaticRecMutex init_mutex = G_STATIC_REC_MUTEX_INIT;
 243
 244   g_return_if_fail (mutex);
 245
 246   *mutex = init_mutex;
 247 }
 248
 249 void
 250 g_static_rec_mutex_lock (GStaticRecMutex* mutex)
 251 {
 252   GSystemThread self;
 253
 254   g_return_if_fail (mutex);
 255
 256   if (!g_thread_supported ())
 257     return;
 258
 259   G_THREAD_UF (thread_self, (&self));
 260
 261   if (g_system_thread_equal (self, mutex->owner))
 262     {
 263       mutex->depth++;
 264       return;
 265     }
 266   g_static_mutex_lock (&mutex->mutex);
 267   g_system_thread_assign (mutex->owner, self);
 268   mutex->depth = 1;
 269 }
 270
 271 gboolean
 272 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
 273 {
 274   GSystemThread self;
 275
 276   g_return_val_if_fail (mutex, FALSE);
 277
 278   if (!g_thread_supported ())
 279     return TRUE;
 280
 281   G_THREAD_UF (thread_self, (&self));
 282
 283   if (g_system_thread_equal (self, mutex->owner))
 284     {
 285       mutex->depth++;
 286       return TRUE;
 287     }
 288
 289   if (!g_static_mutex_trylock (&mutex->mutex))
 290     return FALSE;
 291
 292   g_system_thread_assign (mutex->owner, self);
 293   mutex->depth = 1;
 294   return TRUE;
 295 }
 296
 297 void
 298 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
 299 {
 300   g_return_if_fail (mutex);
 301
 302   if (!g_thread_supported ())
 303     return;
 304
 305   if (mutex->depth > 1)
 306     {
 307       mutex->depth--;
 308       return;
 309     }
 310   g_system_thread_assign (mutex->owner, zero_thread);
 311   g_static_mutex_unlock (&mutex->mutex);
 312 }
 313
 314 void
 315 g_static_rec_mutex_lock_full   (GStaticRecMutex *mutex,
 316                                 guint            depth)
 317 {
 318   GSystemThread self;
 319   g_return_if_fail (mutex);
 320
 321   if (!g_thread_supported ())
 322     return;
 323
 324   if (depth == 0)
 325     return;
 326
 327   G_THREAD_UF (thread_self, (&self));
 328
 329   if (g_system_thread_equal (self, mutex->owner))
 330     {
 331       mutex->depth += depth;
 332       return;
 333     }
 334   g_static_mutex_lock (&mutex->mutex);
 335   g_system_thread_assign (mutex->owner, self);
 336   mutex->depth = depth;
 337 }
 338
 339 guint
 340 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
 341 {
 342   guint depth;
 343
 344   g_return_val_if_fail (mutex, 0);
 345
 346   if (!g_thread_supported ())
 347     return 1;
 348
 349   depth = mutex->depth;
 350
 351   g_system_thread_assign (mutex->owner, zero_thread);
 352   mutex->depth = 0;
 353   g_static_mutex_unlock (&mutex->mutex);
 354
 355   return depth;
 356 }
 357
 358 void
 359 g_static_rec_mutex_free (GStaticRecMutex *mutex)
 360 {
 361   g_return_if_fail (mutex);
 362
 363   g_static_mutex_free (&mutex->mutex);
 364 }
 365
 366 void
 367 g_static_private_init (GStaticPrivate *private_key)
 368 {
 369   private_key->index = 0;
 370 }
 371
 372 gpointer
 373 g_static_private_get (GStaticPrivate *private_key)
 374 {
 375   GRealThread *self = (GRealThread*) g_thread_self ();
 376   GArray *array;
 377
 378   array = self->private_data;
 379   if (!array)
 380     return NULL;
 381
 382   if (!private_key->index)
 383     return NULL;
 384   else if (private_key->index <= array->len)
 385     return g_array_index (array, GStaticPrivateNode,
 386                           private_key->index - 1).data;
 387   else
 388     return NULL;
 389 }
 390
 391 void
 392 g_static_private_set (GStaticPrivate *private_key,
 393                       gpointer        data,
 394                       GDestroyNotify  notify)
 395 {
 396   GRealThread *self = (GRealThread*) g_thread_self ();
 397   GArray *array;
 398   static guint next_index = 0;
 399   GStaticPrivateNode *node;
 400
 401   array = self->private_data;
 402   if (!array)
 403     {
 404       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 405       self->private_data = array;
 406     }
 407
 408   if (!private_key->index)
 409     {
 410       G_LOCK (g_thread);
 411
 412       if (!private_key->index)
 413         {
 414           if (g_thread_free_indeces)
 415             {
 416               private_key->index =
 417                 GPOINTER_TO_UINT (g_thread_free_indeces->data);
 418               g_thread_free_indeces =
 419                 g_slist_delete_link (g_thread_free_indeces,
 420                                      g_thread_free_indeces);
 421             }
 422           else
 423             private_key->index = ++next_index;
 424         }
 425
 426       G_UNLOCK (g_thread);
 427     }
 428
 429   if (private_key->index > array->len)
 430     g_array_set_size (array, private_key->index);
 431
 432   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 433   if (node->destroy)
 434     {
 435       gpointer ddata = node->data;
 436       GDestroyNotify ddestroy = node->destroy;
 437
 438       node->data = data;
 439       node->destroy = notify;
 440
 441       ddestroy (ddata);
 442     }
 443   else
 444     {
 445       node->data = data;
 446       node->destroy = notify;
 447     }
 448 }
 449
 450 void
 451 g_static_private_free (GStaticPrivate *private_key)
 452 {
 453   guint index = private_key->index;
 454   GRealThread *thread;
 455
 456   if (!index)
 457     return;
 458
 459   private_key->index = 0;
 460
 461   G_LOCK (g_thread);
 462
 463   thread = g_thread_all_threads;
 464   while (thread)
 465     {
 466       GArray *array = thread->private_data;
 467       thread = thread->next;
 468
 469       if (array && index <= array->len)
 470         {
 471           GStaticPrivateNode *node = &g_array_index (array,
 472                                                      GStaticPrivateNode,
 473                                                      index - 1);
 474           gpointer ddata = node->data;
 475           GDestroyNotify ddestroy = node->destroy;
 476
 477           node->data = NULL;
 478           node->destroy = NULL;
 479
 480           if (ddestroy)
 481             {
 482               G_UNLOCK (g_thread);
 483               ddestroy (ddata);
 484               G_LOCK (g_thread);
 485               }
 486         }
 487     }
 488   g_thread_free_indeces = g_slist_prepend (g_thread_free_indeces,
 489                                            GUINT_TO_POINTER (index));
 490   G_UNLOCK (g_thread);
 491 }
 492
 493 static void
 494 g_thread_cleanup (gpointer data)
 495 {
 496   if (data)
 497     {
 498       GRealThread* thread = data;
 499       if (thread->private_data)
 500         {
 501           GArray* array = thread->private_data;
 502           guint i;
 503
 504           for (i = 0; i < array->len; i++ )
 505             {
 506               GStaticPrivateNode *node =
 507                 &g_array_index (array, GStaticPrivateNode, i);
 508               if (node->destroy)
 509                 node->destroy (node->data);
 510             }
 511           g_array_free (array, TRUE);
 512         }
 513
 514       /* We only free the thread structure, if it isn't joinable. If
 515          it is, the structure is freed in g_thread_join */
 516       if (!thread->thread.joinable)
 517         {
 518           GRealThread *t, *p;
 519
 520           G_LOCK (g_thread);
 521           for (t = g_thread_all_threads, p = NULL; t; p = t, t = t->next)
 522             {
 523               if (t == thread)
 524                 {
 525                   if (p)
 526                     p->next = t->next;
 527                   else
 528                     g_thread_all_threads = t->next;
 529                   break;
 530                 }
 531             }
 532           G_UNLOCK (g_thread);
 533
 534           /* Just to make sure, this isn't used any more */
 535           g_system_thread_assign (thread->system_thread, zero_thread);
 536           g_free (thread);
 537         }
 538     }
 539 }
 540
 541 static void
 542 g_thread_fail (void)
 543 {
 544   g_error ("The thread system is not yet initialized.");
 545 }
 546
 547 static gpointer
 548 g_thread_create_proxy (gpointer data)
 549 {
 550   GRealThread* thread = data;
 551
 552   g_assert (data);
 553
 554   /* This has to happen before G_LOCK, as that might call g_thread_self */
 555   g_private_set (g_thread_specific_private, data);
 556
 557   /* the lock makes sure, that thread->system_thread is written,
 558      before thread->thread.func is called. See g_thread_create. */
 559   G_LOCK (g_thread);
 560   G_UNLOCK (g_thread);
 561
 562   thread->retval = thread->thread.func (thread->thread.data);
 563
 564   return NULL;
 565 }
 566
 567 GThread*
 568 g_thread_create_full (GThreadFunc                func,
 569                       gpointer           data,
 570                       gulong             stack_size,
 571                       gboolean           joinable,
 572                       gboolean           bound,
 573                       GThreadPriority    priority,
 574                       GError                **error)
 575 {
 576   GRealThread* result;
 577   GError *local_error = NULL;
 578   g_return_val_if_fail (func, NULL);
 579   g_return_val_if_fail (priority >= G_THREAD_PRIORITY_LOW, NULL);
 580   g_return_val_if_fail (priority <= G_THREAD_PRIORITY_URGENT, NULL);
 581
 582   result = g_new0 (GRealThread, 1);
 583
 584   result->thread.joinable = joinable;
 585   result->thread.priority = priority;
 586   result->thread.func = func;
 587   result->thread.data = data;
 588   result->private_data = NULL;
 589   G_LOCK (g_thread);
 590   G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
 591                                stack_size, joinable, bound, priority,
 592                                &result->system_thread, &local_error));
 593   result->next = g_thread_all_threads;
 594   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   GRealThread *p, *t;
 620   gpointer retval;
 621
 622   g_return_val_if_fail (thread, NULL);
 623   g_return_val_if_fail (thread->joinable, NULL);
 624   g_return_val_if_fail (!g_system_thread_equal (real->system_thread,
 625                                                 zero_thread), NULL);
 626
 627   G_THREAD_UF (thread_join, (&real->system_thread));
 628
 629   retval = real->retval;
 630
 631   G_LOCK (g_thread);
 632   for (t = g_thread_all_threads, p = NULL; t; p = t, t = t->next)
 633     {
 634       if (t == (GRealThread*) thread)
 635         {
 636           if (p)
 637             p->next = t->next;
 638           else
 639             g_thread_all_threads = t->next;
 640           break;
 641         }
 642     }
 643   G_UNLOCK (g_thread);
 644
 645   /* Just to make sure, this isn't used any more */
 646   thread->joinable = 0;
 647   g_system_thread_assign (real->system_thread, zero_thread);
 648
 649   /* the thread structure for non-joinable threads is freed upon
 650      thread end. We free the memory here. This will leave a loose end,
 651      if a joinable thread is not joined. */
 652
 653   g_free (thread);
 654
 655   return retval;
 656 }
 657
 658 void
 659 g_thread_set_priority (GThread* thread,
 660                        GThreadPriority priority)
 661 {
 662   GRealThread* real = (GRealThread*) thread;
 663
 664   g_return_if_fail (thread);
 665   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 666   g_return_if_fail (priority >= G_THREAD_PRIORITY_LOW);
 667   g_return_if_fail (priority <= G_THREAD_PRIORITY_URGENT);
 668
 669   thread->priority = priority;
 670
 671   G_THREAD_CF (thread_set_priority, (void)0,
 672                (&real->system_thread, priority));
 673 }
 674
 675 GThread*
 676 g_thread_self (void)
 677 {
 678   GRealThread* thread = g_private_get (g_thread_specific_private);
 679
 680   if (!thread)
 681     {
 682       /* If no thread data is available, provide and set one.  This
 683          can happen for the main thread and for threads, that are not
 684          created by GLib. */
 685       thread = g_new0 (GRealThread, 1);
 686       thread->thread.joinable = FALSE; /* This is a save guess */
 687       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 688                                                              just a guess */
 689       thread->thread.func = NULL;
 690       thread->thread.data = NULL;
 691       thread->private_data = NULL;
 692
 693       if (g_thread_supported ())
 694         G_THREAD_UF (thread_self, (&thread->system_thread));
 695
 696       g_private_set (g_thread_specific_private, thread);
 697
 698       G_LOCK (g_thread);
 699       thread->next = g_thread_all_threads;
 700       g_thread_all_threads = thread;
 701       G_UNLOCK (g_thread);
 702     }
 703
 704   return (GThread*)thread;
 705 }
 706
 707 void
 708 g_static_rw_lock_init (GStaticRWLock* lock)
 709 {
 710   static const GStaticRWLock init_lock = G_STATIC_RW_LOCK_INIT;
 711
 712   g_return_if_fail (lock);
 713
 714   *lock = init_lock;
 715 }
 716
 717 inline static void
 718 g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 719 {
 720   if (!*cond)
 721       *cond = g_cond_new ();
 722   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 723 }
 724
 725 inline static void
 726 g_static_rw_lock_signal (GStaticRWLock* lock)
 727 {
 728   if (lock->want_to_write && lock->write_cond)
 729     g_cond_signal (lock->write_cond);
 730   else if (lock->want_to_read && lock->read_cond)
 731     g_cond_broadcast (lock->read_cond);
 732 }
 733
 734 void
 735 g_static_rw_lock_reader_lock (GStaticRWLock* lock)
 736 {
 737   g_return_if_fail (lock);
 738
 739   if (!g_threads_got_initialized)
 740     return;
 741
 742   g_static_mutex_lock (&lock->mutex);
 743   lock->want_to_read++;
 744   while (lock->have_writer || lock->want_to_write)
 745     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 746   lock->want_to_read--;
 747   lock->read_counter++;
 748   g_static_mutex_unlock (&lock->mutex);
 749 }
 750
 751 gboolean
 752 g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
 753 {
 754   gboolean ret_val = FALSE;
 755
 756   g_return_val_if_fail (lock, FALSE);
 757
 758   if (!g_threads_got_initialized)
 759     return TRUE;
 760
 761   g_static_mutex_lock (&lock->mutex);
 762   if (!lock->have_writer && !lock->want_to_write)
 763     {
 764       lock->read_counter++;
 765       ret_val = TRUE;
 766     }
 767   g_static_mutex_unlock (&lock->mutex);
 768   return ret_val;
 769 }
 770
 771 void
 772 g_static_rw_lock_reader_unlock  (GStaticRWLock* lock)
 773 {
 774   g_return_if_fail (lock);
 775
 776   if (!g_threads_got_initialized)
 777     return;
 778
 779   g_static_mutex_lock (&lock->mutex);
 780   lock->read_counter--;
 781   if (lock->read_counter == 0)
 782     g_static_rw_lock_signal (lock);
 783   g_static_mutex_unlock (&lock->mutex);
 784 }
 785
 786 void
 787 g_static_rw_lock_writer_lock (GStaticRWLock* lock)
 788 {
 789   g_return_if_fail (lock);
 790
 791   if (!g_threads_got_initialized)
 792     return;
 793
 794   g_static_mutex_lock (&lock->mutex);
 795   lock->want_to_write++;
 796   while (lock->have_writer || lock->read_counter)
 797     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 798   lock->want_to_write--;
 799   lock->have_writer = TRUE;
 800   g_static_mutex_unlock (&lock->mutex);
 801 }
 802
 803 gboolean
 804 g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 805 {
 806   gboolean ret_val = FALSE;
 807
 808   g_return_val_if_fail (lock, FALSE);
 809
 810   if (!g_threads_got_initialized)
 811     return TRUE;
 812
 813   g_static_mutex_lock (&lock->mutex);
 814   if (!lock->have_writer && !lock->read_counter)
 815     {
 816       lock->have_writer = TRUE;
 817       ret_val = TRUE;
 818     }
 819   g_static_mutex_unlock (&lock->mutex);
 820   return ret_val;
 821 }
 822
 823 void
 824 g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
 825 {
 826   g_return_if_fail (lock);
 827
 828   if (!g_threads_got_initialized)
 829     return;
 830
 831   g_static_mutex_lock (&lock->mutex);
 832   lock->have_writer = FALSE;
 833   g_static_rw_lock_signal (lock);
 834   g_static_mutex_unlock (&lock->mutex);
 835 }
 836
 837 void
 838 g_static_rw_lock_free (GStaticRWLock* lock)
 839 {
 840   g_return_if_fail (lock);
 841
 842   if (lock->read_cond)
 843     {
 844       g_cond_free (lock->read_cond);
 845       lock->read_cond = NULL;
 846     }
 847   if (lock->write_cond)
 848     {
 849       g_cond_free (lock->write_cond);
 850       lock->write_cond = NULL;
 851     }
 852   g_static_mutex_free (&lock->mutex);
 853 }
 854
 855 /**
 856  * g_thread_foreach
 857  * @thread_func: function to call for all GThread structures
 858  * @user_data:   second argument to @thread_func
 859  *
 860  * Call @thread_func on all existing #GThread structures. Note that
 861  * threads may decide to exit while @thread_func is running, so
 862  * without intimate knowledge about the lifetime of foreign threads,
 863  * @thread_func shouldn't access the GThread* pointer passed in as
 864  * first argument. However, @thread_func will not be called for threads
 865  * which are known to have exited already.
 866  *
 867  * Due to thread lifetime checks, this function has an execution complexity
 868  * which is quadratic in the number of existing threads.
 869  *
 870  * Since: 2.10
 871  */
 872 void
 873 g_thread_foreach (GFunc    thread_func,
 874                   gpointer user_data)
 875 {
 876   GSList *slist = NULL;
 877   GRealThread *thread;
 878   g_return_if_fail (thread_func != NULL);
 879   /* snapshot the list of threads for iteration */
 880   G_LOCK (g_thread);
 881   for (thread = g_thread_all_threads; thread; thread = thread->next)
 882     slist = g_slist_prepend (slist, thread);
 883   G_UNLOCK (g_thread);
 884   /* walk the list, skipping non-existant threads */
 885   while (slist)
 886     {
 887       GSList *node = slist;
 888       slist = node->next;
 889       /* check whether the current thread still exists */
 890       G_LOCK (g_thread);
 891       for (thread = g_thread_all_threads; thread; thread = thread->next)
 892         if (thread == node->data)
 893           break;
 894       G_UNLOCK (g_thread);
 895       if (thread)
 896         thread_func (thread, user_data);
 897       g_slist_free_1 (node);
 898     }
 899 }
 900
 901 #define __G_THREAD_C__
 902 #include "galiasdef.c"