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 HAVE_UNISTD_H
  39 #include <unistd.h>
  40 #endif
  41
  42 #if GLIB_SIZEOF_SYSTEM_THREAD == SIZEOF_VOID_P
  43 # define g_system_thread_equal(thread1, thread2)                        \
  44    (thread1.dummy_pointer == thread2.dummy_pointer)
  45 # define g_system_thread_assign(dest, src)                              \
  46    (dest.dummy_pointer = src.dummy_pointer)
  47 #else /* GLIB_SIZEOF_SYSTEM_THREAD != SIZEOF_VOID_P */
  48 # define g_system_thread_equal(thread1, thread2)                        \
  49    (memcmp (&thread1, &thread2, GLIB_SIZEOF_SYSTEM_THREAD) == 0)
  50 # define g_system_thread_assign(dest, src)                              \
  51    (memcpy (&dest, &src, GLIB_SIZEOF_SYSTEM_THREAD))
  52 #endif /* GLIB_SIZEOF_SYSTEM_THREAD == SIZEOF_VOID_P */
  53
  54 GQuark
  55 g_thread_error_quark()
  56 {
  57   static GQuark quark;
  58   if (!quark)
  59     quark = g_quark_from_static_string ("g_thread_error");
  60   return quark;
  61 }
  62
  63 typedef struct _GRealThread GRealThread;
  64 struct  _GRealThread
  65 {
  66   GThread thread;
  67   GThreadFunc func;
  68   gpointer arg;
  69   gpointer private_data;
  70   GSystemThread system_thread;
  71 };
  72
  73 typedef struct _GStaticPrivateNode GStaticPrivateNode;
  74 struct _GStaticPrivateNode
  75 {
  76   gpointer       data;
  77   GDestroyNotify destroy;
  78 };
  79
  80 static void g_thread_cleanup (gpointer data);
  81 static void g_thread_fail (void);
  82
  83 /* Global variables */
  84
  85 static GSystemThread zero_thread; /* This is initialized to all zero */
  86 gboolean g_thread_use_default_impl = TRUE;
  87 gboolean g_threads_got_initialized = FALSE;
  88
  89 #if defined(G_OS_WIN32) && defined(__GNUC__)
  90 __declspec(dllexport)
  91 #endif
  92 GThreadFunctions g_thread_functions_for_glib_use = {
  93   (GMutex*(*)())g_thread_fail,                 /* mutex_new */
  94   NULL,                                        /* mutex_lock */
  95   NULL,                                        /* mutex_trylock */
  96   NULL,                                        /* mutex_unlock */
  97   NULL,                                        /* mutex_free */
  98   (GCond*(*)())g_thread_fail,                  /* cond_new */
  99   NULL,                                        /* cond_signal */
 100   NULL,                                        /* cond_broadcast */
 101   NULL,                                        /* cond_wait */
 102   NULL,                                        /* cond_timed_wait  */
 103   NULL,                                        /* cond_free */
 104   (GPrivate*(*)(GDestroyNotify))g_thread_fail, /* private_new */
 105   NULL,                                        /* private_get */
 106   NULL,                                        /* private_set */
 107   (void(*)(GThreadFunc, gpointer, gulong,
 108            gboolean, gboolean, GThreadPriority,
 109            gpointer, GError**))g_thread_fail,  /* thread_create */
 110   NULL,                                        /* thread_yield */
 111   NULL,                                        /* thread_join */
 112   NULL,                                        /* thread_exit */
 113   NULL,                                        /* thread_set_priority */
 114   NULL                                         /* thread_self */
 115 };
 116
 117 /* Local data */
 118
 119 static GMutex   *g_mutex_protect_static_mutex_allocation = NULL;
 120 static GMutex   *g_thread_specific_mutex = NULL;
 121 static GPrivate *g_thread_specific_private = NULL;
 122
 123 /* This must be called only once, before any threads are created.
 124  * It will only be called from g_thread_init() in -lgthread.
 125  */
 126 void
 127 g_mutex_init (void)
 128 {
 129   GRealThread* main_thread;
 130
 131   /* We let the main thread (the one that calls g_thread_init) inherit
 132    * the data, that it set before calling g_thread_init
 133    */
 134   main_thread = (GRealThread*) g_thread_self ();
 135
 136   g_thread_specific_private = g_private_new (g_thread_cleanup);
 137   G_THREAD_UF (private_set, (g_thread_specific_private, main_thread));
 138   G_THREAD_UF (thread_self, (&main_thread->system_thread));
 139
 140   g_mutex_protect_static_mutex_allocation = g_mutex_new();
 141   g_thread_specific_mutex = g_mutex_new();
 142 }
 143
 144 GMutex *
 145 g_static_mutex_get_mutex_impl (GMutex** mutex)
 146 {
 147   if (!g_thread_supported ())
 148     return NULL;
 149
 150   g_assert (g_mutex_protect_static_mutex_allocation);
 151
 152   g_mutex_lock (g_mutex_protect_static_mutex_allocation);
 153
 154   if (!(*mutex))
 155     *mutex = g_mutex_new();
 156
 157   g_mutex_unlock (g_mutex_protect_static_mutex_allocation);
 158
 159   return *mutex;
 160 }
 161
 162 void
 163 g_static_mutex_init (GStaticMutex *mutex)
 164 {
 165   static GStaticMutex init_mutex = G_STATIC_MUTEX_INIT;
 166
 167   g_return_if_fail (mutex);
 168
 169   memcpy (mutex, &init_mutex, sizeof (GStaticMutex));
 170 }
 171
 172 void
 173 g_static_mutex_free (GStaticMutex* mutex)
 174 {
 175   GMutex **runtime_mutex;
 176
 177   g_return_if_fail (mutex);
 178
 179   /* The runtime_mutex is the first (or only) member of GStaticMutex,
 180    * see both versions (of glibconfig.h) in configure.in */
 181   runtime_mutex = ((GMutex**)mutex);
 182
 183   if (*runtime_mutex)
 184     g_mutex_free (*runtime_mutex);
 185
 186   *runtime_mutex = NULL;
 187 }
 188
 189 void
 190 g_static_rec_mutex_lock (GStaticRecMutex* mutex)
 191 {
 192   GSystemThread self;
 193
 194   g_return_if_fail (mutex);
 195
 196   if (!g_thread_supported ())
 197     return;
 198
 199   G_THREAD_UF (thread_self, (&self));
 200
 201   if (g_system_thread_equal (self, mutex->owner))
 202     {
 203       mutex->depth++;
 204       return;
 205     }
 206   g_static_mutex_lock (&mutex->mutex);
 207   g_system_thread_assign (mutex->owner, self);
 208   mutex->depth = 1;
 209 }
 210
 211 gboolean
 212 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
 213 {
 214   GSystemThread self;
 215
 216   g_return_val_if_fail (mutex, FALSE);
 217
 218   if (!g_thread_supported ())
 219     return TRUE;
 220
 221   G_THREAD_UF (thread_self, (&self));
 222
 223   if (g_system_thread_equal (self, mutex->owner))
 224     {
 225       mutex->depth++;
 226       return TRUE;
 227     }
 228
 229   if (!g_static_mutex_trylock (&mutex->mutex))
 230     return FALSE;
 231
 232   g_system_thread_assign (mutex->owner, self);
 233   mutex->depth = 1;
 234   return TRUE;
 235 }
 236
 237 void
 238 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
 239 {
 240   g_return_if_fail (mutex);
 241
 242   if (!g_thread_supported ())
 243     return;
 244
 245   if (mutex->depth > 1)
 246     {
 247       mutex->depth--;
 248       return;
 249     }
 250   g_system_thread_assign (mutex->owner, zero_thread);
 251   g_static_mutex_unlock (&mutex->mutex);
 252 }
 253
 254 void
 255 g_static_rec_mutex_lock_full   (GStaticRecMutex *mutex,
 256                                 guint            depth)
 257 {
 258   g_return_if_fail (mutex);
 259
 260   if (!g_thread_supported ())
 261     return;
 262
 263   g_static_mutex_lock (&mutex->mutex);
 264   G_THREAD_UF (thread_self, (&mutex->owner));
 265   mutex->depth = depth;
 266 }
 267
 268 guint
 269 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
 270 {
 271   gint depth;
 272
 273   g_return_val_if_fail (mutex, 0);
 274
 275   if (!g_thread_supported ())
 276     return 1;
 277
 278   depth = mutex->depth;
 279
 280   g_system_thread_assign (mutex->owner, zero_thread);
 281   mutex->depth = 0;
 282   g_static_mutex_unlock (&mutex->mutex);
 283
 284   return depth;
 285 }
 286
 287
 288 gpointer
 289 g_static_private_get (GStaticPrivate *private_key)
 290 {
 291   return g_static_private_get_for_thread (private_key, g_thread_self ());
 292 }
 293
 294 gpointer
 295 g_static_private_get_for_thread (GStaticPrivate *private_key,
 296                                  GThread        *thread)
 297 {
 298   GArray *array;
 299   GRealThread *self = (GRealThread*) thread;
 300
 301   g_return_val_if_fail (thread, NULL);
 302
 303   array = self->private_data;
 304   if (!array)
 305     return NULL;
 306
 307   if (!private_key->index)
 308     return NULL;
 309   else if (private_key->index <= array->len)
 310     return g_array_index (array, GStaticPrivateNode, private_key->index - 1).data;
 311   else
 312     return NULL;
 313 }
 314
 315 void
 316 g_static_private_set (GStaticPrivate *private_key,
 317                       gpointer        data,
 318                       GDestroyNotify  notify)
 319 {
 320   g_static_private_set_for_thread (private_key, g_thread_self (),
 321                                    data, notify);
 322 }
 323
 324 void
 325 g_static_private_set_for_thread (GStaticPrivate *private_key,
 326                                  GThread        *thread,
 327                                  gpointer        data,
 328                                  GDestroyNotify  notify)
 329 {
 330   GArray *array;
 331   GRealThread *self =(GRealThread*) thread;
 332   static guint next_index = 0;
 333   GStaticPrivateNode *node;
 334
 335   g_return_if_fail (thread);
 336
 337   array = self->private_data;
 338   if (!array)
 339     {
 340       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 341       self->private_data = array;
 342     }
 343
 344   if (!private_key->index)
 345     {
 346       g_mutex_lock (g_thread_specific_mutex);
 347
 348       if (!private_key->index)
 349         private_key->index = ++next_index;
 350
 351       g_mutex_unlock (g_thread_specific_mutex);
 352     }
 353
 354   if (private_key->index > array->len)
 355     g_array_set_size (array, private_key->index);
 356
 357   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 358   if (node->destroy)
 359     {
 360       gpointer ddata = node->data;
 361       GDestroyNotify ddestroy = node->destroy;
 362
 363       node->data = data;
 364       node->destroy = notify;
 365
 366       ddestroy (ddata);
 367     }
 368   else
 369     {
 370       node->data = data;
 371       node->destroy = notify;
 372     }
 373 }
 374
 375 static void
 376 g_thread_cleanup (gpointer data)
 377 {
 378   if (data)
 379     {
 380       GRealThread* thread = data;
 381       if (thread->private_data)
 382         {
 383           GArray* array = thread->private_data;
 384           guint i;
 385
 386           for (i = 0; i < array->len; i++ )
 387             {
 388               GStaticPrivateNode *node =
 389                 &g_array_index (array, GStaticPrivateNode, i);
 390               if (node->destroy)
 391                 node->destroy (node->data);
 392             }
 393           g_array_free (array, TRUE);
 394         }
 395       /* We only free the thread structure, if it isn't joinable. If
 396          it is, the structure is freed in g_thread_join */
 397       if (!thread->thread.joinable)
 398         {
 399           /* Just to make sure, this isn't used any more */
 400           g_system_thread_assign (thread->system_thread, zero_thread);
 401           g_free (thread);
 402         }
 403     }
 404 }
 405
 406 static void
 407 g_thread_fail (void)
 408 {
 409   g_error ("The thread system is not yet initialized.");
 410 }
 411
 412 G_LOCK_DEFINE_STATIC (g_thread_create);
 413
 414 static void
 415 g_thread_create_proxy (gpointer data)
 416 {
 417   GRealThread* thread = data;
 418
 419   g_assert (data);
 420
 421   /* This has to happen before G_LOCK, as that might call g_thread_self */
 422   g_private_set (g_thread_specific_private, data);
 423
 424   /* the lock makes sure, that thread->system_thread is written,
 425      before thread->func is called. See g_thread_create. */
 426   G_LOCK (g_thread_create);
 427   G_UNLOCK (g_thread_create);
 428
 429   thread->func (thread->arg);
 430 }
 431
 432 GThread*
 433 g_thread_create (GThreadFunc             thread_func,
 434                  gpointer                arg,
 435                  gulong                  stack_size,
 436                  gboolean                joinable,
 437                  gboolean                bound,
 438                  GThreadPriority         priority,
 439                  GError                **error)
 440 {
 441   GRealThread* result = g_new (GRealThread, 1);
 442   GError *local_error = NULL;
 443   g_return_val_if_fail (thread_func, NULL);
 444   g_return_val_if_fail (priority >= G_THREAD_PRIORITY_LOW, NULL);
 445   g_return_val_if_fail (priority <= G_THREAD_PRIORITY_URGENT, NULL);
 446
 447   result->thread.joinable = joinable;
 448   result->thread.bound = bound;
 449   result->thread.priority = priority;
 450   result->func = thread_func;
 451   result->arg = arg;
 452   result->private_data = NULL;
 453   G_LOCK (g_thread_create);
 454   G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
 455                                stack_size, joinable, bound, priority,
 456                                &result->system_thread, &local_error));
 457   G_UNLOCK (g_thread_create);
 458
 459   if (local_error)
 460     {
 461       g_propagate_error (error, local_error);
 462       g_free (result);
 463       return NULL;
 464     }
 465
 466   return (GThread*) result;
 467 }
 468
 469 void
 470 g_thread_join (GThread* thread)
 471 {
 472   GRealThread* real = (GRealThread*) thread;
 473
 474
 475   g_return_if_fail (thread);
 476   g_return_if_fail (thread->joinable);
 477   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 478
 479   G_THREAD_UF (thread_join, (&real->system_thread));
 480
 481   /* Just to make sure, this isn't used any more */
 482   thread->joinable = 0;
 483   g_system_thread_assign (real->system_thread, zero_thread);
 484
 485   /* the thread structure for non-joinable threads is freed upon
 486      thread end. We free the memory here. This will leave loose end,
 487      if a joinable thread is not joined. */
 488
 489   g_free (thread);
 490 }
 491
 492 void
 493 g_thread_set_priority (GThread* thread,
 494                        GThreadPriority priority)
 495 {
 496   GRealThread* real = (GRealThread*) thread;
 497
 498   g_return_if_fail (thread);
 499   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 500   g_return_if_fail (priority >= G_THREAD_PRIORITY_LOW);
 501   g_return_if_fail (priority <= G_THREAD_PRIORITY_URGENT);
 502
 503   thread->priority = priority;
 504   G_THREAD_CF (thread_set_priority, (void)0, (&real->system_thread, priority));
 505 }
 506
 507 GThread*
 508 g_thread_self()
 509 {
 510   GRealThread* thread = g_private_get (g_thread_specific_private);
 511
 512   if (!thread)
 513     {
 514       /* If no thread data is available, provide and set one.  This
 515          can happen for the main thread and for threads, that are not
 516          created by GLib. */
 517       thread = g_new (GRealThread, 1);
 518       thread->thread.joinable = FALSE; /* This is a save guess */
 519       thread->thread.bound = TRUE; /* This isn't important at all */
 520       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 521                                                              just a guess */
 522       thread->func = NULL;
 523       thread->arg = NULL;
 524       thread->private_data = NULL;
 525
 526       if (g_thread_supported ())
 527         G_THREAD_UF (thread_self, (&thread->system_thread));
 528
 529       g_private_set (g_thread_specific_private, thread);
 530     }
 531
 532   return (GThread*)thread;
 533 }
 534
 535 static void inline g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 536 {
 537   if (!*cond)
 538       *cond = g_cond_new ();
 539   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 540 }
 541
 542 static void inline g_static_rw_lock_signal (GStaticRWLock* lock)
 543 {
 544   if (lock->want_to_write && lock->write_cond)
 545     g_cond_signal (lock->write_cond);
 546   else if (lock->read_cond)
 547     g_cond_broadcast (lock->read_cond);
 548 }
 549
 550 void g_static_rw_lock_reader_lock (GStaticRWLock* lock)
 551 {
 552   g_return_if_fail (lock);
 553
 554   if (!g_threads_got_initialized)
 555     return;
 556
 557   g_static_mutex_lock (&lock->mutex);
 558   while (lock->write || lock->want_to_write)
 559     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 560   lock->read_counter++;
 561   g_static_mutex_unlock (&lock->mutex);
 562 }
 563
 564 gboolean g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
 565 {
 566   gboolean ret_val = FALSE;
 567
 568   g_return_val_if_fail (lock, FALSE);
 569
 570   if (!g_threads_got_initialized)
 571     return TRUE;
 572
 573   g_static_mutex_lock (&lock->mutex);
 574   if (!lock->write && !lock->want_to_write)
 575     {
 576       lock->read_counter++;
 577       ret_val = TRUE;
 578     }
 579   g_static_mutex_unlock (&lock->mutex);
 580   return ret_val;
 581 }
 582
 583 void g_static_rw_lock_reader_unlock  (GStaticRWLock* lock)
 584 {
 585   g_return_if_fail (lock);
 586
 587   if (!g_threads_got_initialized)
 588     return;
 589
 590   g_static_mutex_lock (&lock->mutex);
 591   lock->read_counter--;
 592   if (lock->read_counter == 0)
 593     g_static_rw_lock_signal (lock);
 594   g_static_mutex_unlock (&lock->mutex);
 595 }
 596
 597 void g_static_rw_lock_writer_lock (GStaticRWLock* lock)
 598 {
 599   g_return_if_fail (lock);
 600
 601   if (!g_threads_got_initialized)
 602     return;
 603
 604   g_static_mutex_lock (&lock->mutex);
 605   lock->want_to_write++;
 606   while (lock->write || lock->read_counter)
 607     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 608   lock->want_to_write--;
 609   lock->write = TRUE;
 610   g_static_mutex_unlock (&lock->mutex);
 611 }
 612
 613 gboolean g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 614 {
 615   gboolean ret_val = FALSE;
 616
 617   g_return_val_if_fail (lock, FALSE);
 618
 619   if (!g_threads_got_initialized)
 620     return TRUE;
 621
 622   g_static_mutex_lock (&lock->mutex);
 623   if (!lock->write && !lock->read_counter)
 624     {
 625       lock->write = TRUE;
 626       ret_val = TRUE;
 627     }
 628   g_static_mutex_unlock (&lock->mutex);
 629   return ret_val;
 630 }
 631
 632 void g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
 633 {
 634   g_return_if_fail (lock);
 635
 636   if (!g_threads_got_initialized)
 637     return;
 638
 639   g_static_mutex_lock (&lock->mutex);
 640   lock->write = FALSE;
 641   g_static_rw_lock_signal (lock);
 642   g_static_mutex_unlock (&lock->mutex);
 643 }
 644
 645 void g_static_rw_lock_free (GStaticRWLock* lock)
 646 {
 647   g_return_if_fail (lock);
 648
 649   if (lock->read_cond)
 650     g_cond_free (lock->read_cond);
 651   if (lock->write_cond)
 652     g_cond_free (lock->write_cond);
 653
 654 }
 655