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 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 #include <linux/unistd.h>
  43 _syscall0(pid_t,gettid)
  44 #endif /* G_THREAD_USE_PID_SURROGATE */
  45
  46 #ifdef HAVE_UNISTD_H
  47 #include <unistd.h>
  48 #endif
  49
  50 #include <string.h>
  51
  52 #include "glib.h"
  53 #include "gthreadinit.h"
  54
  55 #if GLIB_SIZEOF_SYSTEM_THREAD == SIZEOF_VOID_P
  56 # define g_system_thread_equal_simple(thread1, thread2)                 \
  57    ((thread1).dummy_pointer == (thread2).dummy_pointer)
  58 # define g_system_thread_assign(dest, src)                              \
  59    ((dest).dummy_pointer = (src).dummy_pointer)
  60 #else /* GLIB_SIZEOF_SYSTEM_THREAD != SIZEOF_VOID_P */
  61 # define g_system_thread_equal_simple(thread1, thread2)                 \
  62    (memcmp (&(thread1), &(thread2), GLIB_SIZEOF_SYSTEM_THREAD) == 0)
  63 # define g_system_thread_assign(dest, src)                              \
  64    (memcpy (&(dest), &(src), GLIB_SIZEOF_SYSTEM_THREAD))
  65 #endif /* GLIB_SIZEOF_SYSTEM_THREAD == SIZEOF_VOID_P */
  66
  67 #define g_system_thread_equal(thread1, thread2)                         \
  68   (g_thread_functions_for_glib_use.thread_equal ?                       \
  69    g_thread_functions_for_glib_use.thread_equal (&(thread1), &(thread2)) :\
  70    g_system_thread_equal_simple((thread1), (thread2)))
  71
  72 GQuark
  73 g_thread_error_quark (void)
  74 {
  75   static GQuark quark;
  76   if (!quark)
  77     quark = g_quark_from_static_string ("g_thread_error");
  78   return quark;
  79 }
  80
  81 /* Keep this in sync with GRealThread in gmain.c! */
  82 typedef struct _GRealThread GRealThread;
  83 struct  _GRealThread
  84 {
  85   GThread thread;
  86   gpointer private_data;
  87   gpointer retval;
  88   GSystemThread system_thread;
  89 #ifdef G_THREAD_USE_PID_SURROGATE
  90   pid_t tid;
  91 #endif /* G_THREAD_USE_PID_SURROGATE */
  92 };
  93
  94 #ifdef G_THREAD_USE_PID_SURROGATE
  95 static gint priority_map[4];
  96 static gboolean prio_warned = FALSE;
  97 # define SET_PRIO(tid, prio) G_STMT_START{                              \
  98   gint error = setpriority (PRIO_PROCESS, (tid), priority_map[prio]);   \
  99   if (error == -1 && errno == EACCES && !prio_warned)                   \
 100     {                                                                   \
 101       prio_warned = TRUE;                                               \
 102       g_warning ("Priorities can only be increased by root.");          \
 103     }                                                                   \
 104   }G_STMT_END
 105 #endif /* G_THREAD_USE_PID_SURROGATE */
 106
 107 typedef struct _GStaticPrivateNode GStaticPrivateNode;
 108 struct _GStaticPrivateNode
 109 {
 110   gpointer       data;
 111   GDestroyNotify destroy;
 112 };
 113
 114 static void g_thread_cleanup (gpointer data);
 115 static void g_thread_fail (void);
 116
 117 /* Global variables */
 118
 119 static GSystemThread zero_thread; /* This is initialized to all zero */
 120 gboolean g_thread_use_default_impl = TRUE;
 121 gboolean g_threads_got_initialized = FALSE;
 122
 123 #if defined(G_PLATFORM_WIN32) && defined(__GNUC__)
 124 __declspec(dllexport)
 125 #endif
 126 GThreadFunctions g_thread_functions_for_glib_use = {
 127   (GMutex*(*)())g_thread_fail,                 /* mutex_new */
 128   NULL,                                        /* mutex_lock */
 129   NULL,                                        /* mutex_trylock */
 130   NULL,                                        /* mutex_unlock */
 131   NULL,                                        /* mutex_free */
 132   (GCond*(*)())g_thread_fail,                  /* cond_new */
 133   NULL,                                        /* cond_signal */
 134   NULL,                                        /* cond_broadcast */
 135   NULL,                                        /* cond_wait */
 136   NULL,                                        /* cond_timed_wait  */
 137   NULL,                                        /* cond_free */
 138   (GPrivate*(*)(GDestroyNotify))g_thread_fail, /* private_new */
 139   NULL,                                        /* private_get */
 140   NULL,                                        /* private_set */
 141   (void(*)(GThreadFunc, gpointer, gulong,
 142            gboolean, gboolean, GThreadPriority,
 143            gpointer, GError**))g_thread_fail,  /* thread_create */
 144   NULL,                                        /* thread_yield */
 145   NULL,                                        /* thread_join */
 146   NULL,                                        /* thread_exit */
 147   NULL,                                        /* thread_set_priority */
 148   NULL                                         /* thread_self */
 149 };
 150
 151 /* Local data */
 152
 153 static GMutex   *g_once_mutex = NULL;
 154 static GCond    *g_once_cond = NULL;
 155 static GPrivate *g_thread_specific_private = NULL;
 156 static GSList   *g_thread_all_threads = NULL;
 157 static GSList   *g_thread_free_indeces = NULL;
 158
 159 G_LOCK_DEFINE_STATIC (g_thread);
 160
 161 #ifdef G_THREADS_ENABLED
 162 /* This must be called only once, before any threads are created.
 163  * It will only be called from g_thread_init() in -lgthread.
 164  */
 165 void
 166 g_thread_init_glib (void)
 167 {
 168   /* We let the main thread (the one that calls g_thread_init) inherit
 169    * the static_private data set before calling g_thread_init
 170    */
 171   GRealThread* main_thread = (GRealThread*) g_thread_self ();
 172
 173   g_once_mutex = g_mutex_new ();
 174   g_once_cond = g_cond_new ();
 175
 176   _g_convert_thread_init ();
 177   _g_rand_thread_init ();
 178   _g_main_thread_init ();
 179   _g_mem_thread_init ();
 180   _g_messages_thread_init ();
 181
 182 #ifdef G_THREAD_USE_PID_SURROGATE
 183   priority_map[G_THREAD_PRIORITY_NORMAL] =
 184     getpriority (PRIO_PROCESS, (gettid ()));
 185   priority_map[G_THREAD_PRIORITY_LOW] =
 186     MIN (20, priority_map[G_THREAD_PRIORITY_NORMAL] + 10);
 187   priority_map[G_THREAD_PRIORITY_HIGH] =
 188     MAX (-20, priority_map[G_THREAD_PRIORITY_NORMAL] - 10);
 189   priority_map[G_THREAD_PRIORITY_URGENT] =
 190     MAX (-20, priority_map[G_THREAD_PRIORITY_NORMAL] - 15);
 191 #endif /* G_THREAD_USE_PID_SURROGATE */
 192
 193   g_threads_got_initialized = TRUE;
 194
 195   g_thread_specific_private = g_private_new (g_thread_cleanup);
 196   g_private_set (g_thread_specific_private, main_thread);
 197   G_THREAD_UF (thread_self, (&main_thread->system_thread));
 198
 199   _g_mem_thread_private_init ();
 200   _g_messages_thread_private_init ();
 201
 202 }
 203 #endif /* G_THREADS_ENABLED */
 204
 205 gpointer
 206 g_once_impl (GOnce       *once,
 207              GThreadFunc  func,
 208              gpointer     arg)
 209 {
 210   g_mutex_lock (g_once_mutex);
 211
 212   while (once->status == G_ONCE_STATUS_PROGRESS)
 213     g_cond_wait (g_once_cond, g_once_mutex);
 214
 215   if (once->status != G_ONCE_STATUS_READY)
 216     {
 217       once->status = G_ONCE_STATUS_PROGRESS;
 218       g_mutex_unlock (g_once_mutex);
 219
 220       once->retval = func (arg);
 221
 222       g_mutex_lock (g_once_mutex);
 223       once->status = G_ONCE_STATUS_READY;
 224       g_cond_broadcast (g_once_cond);
 225     }
 226
 227   g_mutex_unlock (g_once_mutex);
 228
 229   return once->retval;
 230 }
 231
 232 void
 233 g_static_mutex_init (GStaticMutex *mutex)
 234 {
 235   static GStaticMutex init_mutex = G_STATIC_MUTEX_INIT;
 236
 237   g_return_if_fail (mutex);
 238
 239   *mutex = init_mutex;
 240 }
 241
 242 GMutex *
 243 g_static_mutex_get_mutex_impl (GMutex** mutex)
 244 {
 245   if (!g_thread_supported ())
 246     return NULL;
 247
 248   g_assert (g_once_mutex);
 249
 250   g_mutex_lock (g_once_mutex);
 251
 252   if (!(*mutex))
 253     {
 254       GMutex *new_mutex = g_mutex_new ();
 255
 256       /* The following is a memory barrier to avoid the write
 257        * to *new_mutex being reordered to after writing *mutex */
 258       g_mutex_lock (new_mutex);
 259       g_mutex_unlock (new_mutex);
 260
 261       *mutex = new_mutex;
 262     }
 263
 264   g_mutex_unlock (g_once_mutex);
 265
 266   return *mutex;
 267 }
 268
 269 void
 270 g_static_mutex_free (GStaticMutex* mutex)
 271 {
 272   GMutex **runtime_mutex;
 273
 274   g_return_if_fail (mutex);
 275
 276   /* The runtime_mutex is the first (or only) member of GStaticMutex,
 277    * see both versions (of glibconfig.h) in configure.in */
 278   runtime_mutex = ((GMutex**)mutex);
 279
 280   if (*runtime_mutex)
 281     g_mutex_free (*runtime_mutex);
 282
 283   *runtime_mutex = NULL;
 284 }
 285
 286 void
 287 g_static_rec_mutex_init (GStaticRecMutex *mutex)
 288 {
 289   static GStaticRecMutex init_mutex = G_STATIC_REC_MUTEX_INIT;
 290
 291   g_return_if_fail (mutex);
 292
 293   *mutex = init_mutex;
 294 }
 295
 296 void
 297 g_static_rec_mutex_lock (GStaticRecMutex* mutex)
 298 {
 299   GSystemThread self;
 300
 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++;
 311       return;
 312     }
 313   g_static_mutex_lock (&mutex->mutex);
 314   g_system_thread_assign (mutex->owner, self);
 315   mutex->depth = 1;
 316 }
 317
 318 gboolean
 319 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
 320 {
 321   GSystemThread self;
 322
 323   g_return_val_if_fail (mutex, FALSE);
 324
 325   if (!g_thread_supported ())
 326     return TRUE;
 327
 328   G_THREAD_UF (thread_self, (&self));
 329
 330   if (g_system_thread_equal (self, mutex->owner))
 331     {
 332       mutex->depth++;
 333       return TRUE;
 334     }
 335
 336   if (!g_static_mutex_trylock (&mutex->mutex))
 337     return FALSE;
 338
 339   g_system_thread_assign (mutex->owner, self);
 340   mutex->depth = 1;
 341   return TRUE;
 342 }
 343
 344 void
 345 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
 346 {
 347   g_return_if_fail (mutex);
 348
 349   if (!g_thread_supported ())
 350     return;
 351
 352   if (mutex->depth > 1)
 353     {
 354       mutex->depth--;
 355       return;
 356     }
 357   g_system_thread_assign (mutex->owner, zero_thread);
 358   g_static_mutex_unlock (&mutex->mutex);
 359 }
 360
 361 void
 362 g_static_rec_mutex_lock_full   (GStaticRecMutex *mutex,
 363                                 guint            depth)
 364 {
 365   GSystemThread self;
 366   g_return_if_fail (mutex);
 367
 368   if (!g_thread_supported ())
 369     return;
 370
 371   G_THREAD_UF (thread_self, (&self));
 372
 373   if (g_system_thread_equal (self, mutex->owner))
 374     {
 375       mutex->depth += depth;
 376       return;
 377     }
 378   g_static_mutex_lock (&mutex->mutex);
 379   g_system_thread_assign (mutex->owner, self);
 380   mutex->depth = depth;
 381 }
 382
 383 guint
 384 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
 385 {
 386   guint depth;
 387
 388   g_return_val_if_fail (mutex, 0);
 389
 390   if (!g_thread_supported ())
 391     return 1;
 392
 393   depth = mutex->depth;
 394
 395   g_system_thread_assign (mutex->owner, zero_thread);
 396   mutex->depth = 0;
 397   g_static_mutex_unlock (&mutex->mutex);
 398
 399   return depth;
 400 }
 401
 402 void
 403 g_static_rec_mutex_free (GStaticRecMutex *mutex)
 404 {
 405   g_return_if_fail (mutex);
 406
 407   g_static_mutex_free (&mutex->mutex);
 408 }
 409
 410 void
 411 g_static_private_init (GStaticPrivate *private_key)
 412 {
 413   private_key->index = 0;
 414 }
 415
 416 gpointer
 417 g_static_private_get (GStaticPrivate *private_key)
 418 {
 419   GRealThread *self = (GRealThread*) g_thread_self ();
 420   GArray *array;
 421
 422   array = self->private_data;
 423   if (!array)
 424     return NULL;
 425
 426   if (!private_key->index)
 427     return NULL;
 428   else if (private_key->index <= array->len)
 429     return g_array_index (array, GStaticPrivateNode,
 430                           private_key->index - 1).data;
 431   else
 432     return NULL;
 433 }
 434
 435 void
 436 g_static_private_set (GStaticPrivate *private_key,
 437                       gpointer        data,
 438                       GDestroyNotify  notify)
 439 {
 440   GRealThread *self = (GRealThread*) g_thread_self ();
 441   GArray *array;
 442   static guint next_index = 0;
 443   GStaticPrivateNode *node;
 444
 445   array = self->private_data;
 446   if (!array)
 447     {
 448       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 449       self->private_data = array;
 450     }
 451
 452   if (!private_key->index)
 453     {
 454       G_LOCK (g_thread);
 455
 456       if (!private_key->index)
 457         {
 458           if (g_thread_free_indeces)
 459             {
 460               private_key->index =
 461                 GPOINTER_TO_UINT (g_thread_free_indeces->data);
 462               g_thread_free_indeces =
 463                 g_slist_delete_link (g_thread_free_indeces,
 464                                      g_thread_free_indeces);
 465             }
 466           else
 467             private_key->index = ++next_index;
 468         }
 469
 470       G_UNLOCK (g_thread);
 471     }
 472
 473   if (private_key->index > array->len)
 474     g_array_set_size (array, private_key->index);
 475
 476   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 477   if (node->destroy)
 478     {
 479       gpointer ddata = node->data;
 480       GDestroyNotify ddestroy = node->destroy;
 481
 482       node->data = data;
 483       node->destroy = notify;
 484
 485       ddestroy (ddata);
 486     }
 487   else
 488     {
 489       node->data = data;
 490       node->destroy = notify;
 491     }
 492 }
 493
 494 void
 495 g_static_private_free (GStaticPrivate *private_key)
 496 {
 497   guint index = private_key->index;
 498   GSList *list;
 499
 500   if (!index)
 501     return;
 502
 503   private_key->index = 0;
 504
 505   G_LOCK (g_thread);
 506   list =  g_thread_all_threads;
 507   while (list)
 508     {
 509       GRealThread *thread = list->data;
 510       GArray *array = thread->private_data;
 511       list = list->next;
 512
 513       if (array && index <= array->len)
 514         {
 515           GStaticPrivateNode *node = &g_array_index (array,
 516                                                      GStaticPrivateNode,
 517                                                      index - 1);
 518           gpointer ddata = node->data;
 519           GDestroyNotify ddestroy = node->destroy;
 520
 521           node->data = NULL;
 522           node->destroy = NULL;
 523
 524           if (ddestroy)
 525             {
 526               G_UNLOCK (g_thread);
 527               ddestroy (ddata);
 528               G_LOCK (g_thread);
 529               }
 530         }
 531     }
 532   g_thread_free_indeces = g_slist_prepend (g_thread_free_indeces,
 533                                            GUINT_TO_POINTER (index));
 534   G_UNLOCK (g_thread);
 535 }
 536
 537 static void
 538 g_thread_cleanup (gpointer data)
 539 {
 540   if (data)
 541     {
 542       GRealThread* thread = data;
 543       if (thread->private_data)
 544         {
 545           GArray* array = thread->private_data;
 546           guint i;
 547
 548           for (i = 0; i < array->len; i++ )
 549             {
 550               GStaticPrivateNode *node =
 551                 &g_array_index (array, GStaticPrivateNode, i);
 552               if (node->destroy)
 553                 node->destroy (node->data);
 554             }
 555           g_array_free (array, TRUE);
 556         }
 557
 558       /* We only free the thread structure, if it isn't joinable. If
 559          it is, the structure is freed in g_thread_join */
 560       if (!thread->thread.joinable)
 561         {
 562           G_LOCK (g_thread);
 563           g_thread_all_threads = g_slist_remove (g_thread_all_threads, data);
 564           G_UNLOCK (g_thread);
 565
 566           /* Just to make sure, this isn't used any more */
 567           g_system_thread_assign (thread->system_thread, zero_thread);
 568           g_free (thread);
 569         }
 570     }
 571 }
 572
 573 static void
 574 g_thread_fail (void)
 575 {
 576   g_error ("The thread system is not yet initialized.");
 577 }
 578
 579 static gpointer
 580 g_thread_create_proxy (gpointer data)
 581 {
 582   GRealThread* thread = data;
 583
 584   g_assert (data);
 585
 586 #ifdef G_THREAD_USE_PID_SURROGATE
 587   thread->tid = gettid ();
 588 #endif /* G_THREAD_USE_PID_SURROGATE */
 589
 590   /* This has to happen before G_LOCK, as that might call g_thread_self */
 591   g_private_set (g_thread_specific_private, data);
 592
 593   /* the lock makes sure, that thread->system_thread is written,
 594      before thread->thread.func is called. See g_thread_create. */
 595   G_LOCK (g_thread);
 596   G_UNLOCK (g_thread);
 597
 598 #ifdef G_THREAD_USE_PID_SURROGATE
 599   if (g_thread_use_default_impl)
 600     SET_PRIO (thread->tid, thread->thread.priority);
 601 #endif /* G_THREAD_USE_PID_SURROGATE */
 602
 603   thread->retval = thread->thread.func (thread->thread.data);
 604
 605   return NULL;
 606 }
 607
 608 GThread*
 609 g_thread_create_full (GThreadFunc                func,
 610                       gpointer           data,
 611                       gulong             stack_size,
 612                       gboolean           joinable,
 613                       gboolean           bound,
 614                       GThreadPriority    priority,
 615                       GError                **error)
 616 {
 617   GRealThread* result;
 618   GError *local_error = NULL;
 619   g_return_val_if_fail (func, NULL);
 620   g_return_val_if_fail (priority >= G_THREAD_PRIORITY_LOW, NULL);
 621   g_return_val_if_fail (priority <= G_THREAD_PRIORITY_URGENT, NULL);
 622
 623   result = g_new (GRealThread, 1);
 624
 625   result->thread.joinable = joinable;
 626   result->thread.priority = priority;
 627   result->thread.func = func;
 628   result->thread.data = data;
 629   result->private_data = NULL;
 630   G_LOCK (g_thread);
 631   G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
 632                                stack_size, joinable, bound, priority,
 633                                &result->system_thread, &local_error));
 634   g_thread_all_threads = g_slist_prepend (g_thread_all_threads, result);
 635   G_UNLOCK (g_thread);
 636
 637   if (local_error)
 638     {
 639       g_propagate_error (error, local_error);
 640       g_free (result);
 641       return NULL;
 642     }
 643
 644   return (GThread*) result;
 645 }
 646
 647 void
 648 g_thread_exit (gpointer retval)
 649 {
 650   GRealThread* real = (GRealThread*) g_thread_self ();
 651   real->retval = retval;
 652   G_THREAD_CF (thread_exit, (void)0, ());
 653 }
 654
 655 gpointer
 656 g_thread_join (GThread* thread)
 657 {
 658   GRealThread* real = (GRealThread*) thread;
 659   gpointer retval;
 660
 661   g_return_val_if_fail (thread, NULL);
 662   g_return_val_if_fail (thread->joinable, NULL);
 663   g_return_val_if_fail (!g_system_thread_equal (real->system_thread,
 664                                                 zero_thread), NULL);
 665
 666   G_THREAD_UF (thread_join, (&real->system_thread));
 667
 668   retval = real->retval;
 669
 670   G_LOCK (g_thread);
 671   g_thread_all_threads = g_slist_remove (g_thread_all_threads, thread);
 672   G_UNLOCK (g_thread);
 673
 674   /* Just to make sure, this isn't used any more */
 675   thread->joinable = 0;
 676   g_system_thread_assign (real->system_thread, zero_thread);
 677
 678   /* the thread structure for non-joinable threads is freed upon
 679      thread end. We free the memory here. This will leave a loose end,
 680      if a joinable thread is not joined. */
 681
 682   g_free (thread);
 683
 684   return retval;
 685 }
 686
 687 void
 688 g_thread_set_priority (GThread* thread,
 689                        GThreadPriority priority)
 690 {
 691   GRealThread* real = (GRealThread*) thread;
 692
 693   g_return_if_fail (thread);
 694   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 695   g_return_if_fail (priority >= G_THREAD_PRIORITY_LOW);
 696   g_return_if_fail (priority <= G_THREAD_PRIORITY_URGENT);
 697
 698   thread->priority = priority;
 699
 700 #ifdef G_THREAD_USE_PID_SURROGATE
 701   if (g_thread_use_default_impl)
 702     SET_PRIO (real->tid, priority);
 703   else
 704 #endif /* G_THREAD_USE_PID_SURROGATE */
 705     G_THREAD_CF (thread_set_priority, (void)0,
 706                  (&real->system_thread, priority));
 707 }
 708
 709 GThread*
 710 g_thread_self (void)
 711 {
 712   GRealThread* thread = g_private_get (g_thread_specific_private);
 713
 714   if (!thread)
 715     {
 716       /* If no thread data is available, provide and set one.  This
 717          can happen for the main thread and for threads, that are not
 718          created by GLib. */
 719       thread = g_new (GRealThread, 1);
 720       thread->thread.joinable = FALSE; /* This is a save guess */
 721       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 722                                                              just a guess */
 723       thread->thread.func = NULL;
 724       thread->thread.data = NULL;
 725       thread->private_data = NULL;
 726
 727       if (g_thread_supported ())
 728         G_THREAD_UF (thread_self, (&thread->system_thread));
 729
 730 #ifdef G_THREAD_USE_PID_SURROGATE
 731       thread->tid = gettid ();
 732 #endif /* G_THREAD_USE_PID_SURROGATE */
 733
 734       g_private_set (g_thread_specific_private, thread);
 735
 736       G_LOCK (g_thread);
 737       g_thread_all_threads = g_slist_prepend (g_thread_all_threads, thread);
 738       G_UNLOCK (g_thread);
 739     }
 740
 741   return (GThread*)thread;
 742 }
 743
 744 void
 745 g_static_rw_lock_init (GStaticRWLock* lock)
 746 {
 747   static GStaticRWLock init_lock = G_STATIC_RW_LOCK_INIT;
 748
 749   g_return_if_fail (lock);
 750
 751   *lock = init_lock;
 752 }
 753
 754 static void inline
 755 g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 756 {
 757   if (!*cond)
 758       *cond = g_cond_new ();
 759   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 760 }
 761
 762 static void inline
 763 g_static_rw_lock_signal (GStaticRWLock* lock)
 764 {
 765   if (lock->want_to_write && lock->write_cond)
 766     g_cond_signal (lock->write_cond);
 767   else if (lock->want_to_read && lock->read_cond)
 768     g_cond_broadcast (lock->read_cond);
 769 }
 770
 771 void
 772 g_static_rw_lock_reader_lock (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->want_to_read++;
 781   while (lock->have_writer || lock->want_to_write)
 782     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 783   lock->want_to_read--;
 784   lock->read_counter++;
 785   g_static_mutex_unlock (&lock->mutex);
 786 }
 787
 788 gboolean
 789 g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
 790 {
 791   gboolean ret_val = FALSE;
 792
 793   g_return_val_if_fail (lock, FALSE);
 794
 795   if (!g_threads_got_initialized)
 796     return TRUE;
 797
 798   g_static_mutex_lock (&lock->mutex);
 799   if (!lock->have_writer && !lock->want_to_write)
 800     {
 801       lock->read_counter++;
 802       ret_val = TRUE;
 803     }
 804   g_static_mutex_unlock (&lock->mutex);
 805   return ret_val;
 806 }
 807
 808 void
 809 g_static_rw_lock_reader_unlock  (GStaticRWLock* lock)
 810 {
 811   g_return_if_fail (lock);
 812
 813   if (!g_threads_got_initialized)
 814     return;
 815
 816   g_static_mutex_lock (&lock->mutex);
 817   lock->read_counter--;
 818   if (lock->read_counter == 0)
 819     g_static_rw_lock_signal (lock);
 820   g_static_mutex_unlock (&lock->mutex);
 821 }
 822
 823 void
 824 g_static_rw_lock_writer_lock (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->want_to_write++;
 833   while (lock->have_writer || lock->read_counter)
 834     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 835   lock->want_to_write--;
 836   lock->have_writer = TRUE;
 837   g_static_mutex_unlock (&lock->mutex);
 838 }
 839
 840 gboolean
 841 g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 842 {
 843   gboolean ret_val = FALSE;
 844
 845   g_return_val_if_fail (lock, FALSE);
 846
 847   if (!g_threads_got_initialized)
 848     return TRUE;
 849
 850   g_static_mutex_lock (&lock->mutex);
 851   if (!lock->have_writer && !lock->read_counter)
 852     {
 853       lock->have_writer = TRUE;
 854       ret_val = TRUE;
 855     }
 856   g_static_mutex_unlock (&lock->mutex);
 857   return ret_val;
 858 }
 859
 860 void
 861 g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
 862 {
 863   g_return_if_fail (lock);
 864
 865   if (!g_threads_got_initialized)
 866     return;
 867
 868   g_static_mutex_lock (&lock->mutex);
 869   lock->have_writer = FALSE;
 870   g_static_rw_lock_signal (lock);
 871   g_static_mutex_unlock (&lock->mutex);
 872 }
 873
 874 void
 875 g_static_rw_lock_free (GStaticRWLock* lock)
 876 {
 877   g_return_if_fail (lock);
 878
 879   if (lock->read_cond)
 880     {
 881       g_cond_free (lock->read_cond);
 882       lock->read_cond = NULL;
 883     }
 884   if (lock->write_cond)
 885     {
 886       g_cond_free (lock->write_cond);
 887       lock->write_cond = NULL;
 888     }
 889   g_static_mutex_free (&lock->mutex);
 890 }