glib/gthread.c

   1 /* GLIB - Library of useful routines for C programming
   2  * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
   3  *
   4  * gmutex.c: MT safety related functions
   5  * Copyright 1998 Sebastian Wilhelmi; University of Karlsruhe
   6  *                Owen Taylor
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2 of the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the
  20  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  21  * Boston, MA 02111-1307, USA.
  22  */
  23
  24 /*
  25  * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
  26  * file for a list of people on the GLib Team.  See the ChangeLog
  27  * files for a list of changes.  These files are distributed with
  28  * GLib at ftp://ftp.gtk.org/pub/gtk/.
  29  */
  30
  31 /*
  32  * MT safe
  33  */
  34
  35 #include "config.h"
  36 #include "glib.h"
  37
  38 #ifdef 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   G_LOCK_DEFINE_STATIC(lock);
  59   if (!quark)
  60   {
  61     G_LOCK (lock);
  62     if (!quark)
  63       quark = g_quark_from_static_string ("g-thread-error");
  64     G_UNLOCK (lock);
  65   }
  66   return quark;
  67 }
  68
  69 typedef struct _GRealThread GRealThread;
  70 struct  _GRealThread
  71 {
  72   GThread thread;
  73   GThreadFunc func;
  74   gpointer arg;
  75   gpointer private_data;
  76   GSystemThread system_thread;
  77 };
  78
  79 typedef struct _GStaticPrivateNode GStaticPrivateNode;
  80 struct _GStaticPrivateNode
  81 {
  82   gpointer       data;
  83   GDestroyNotify destroy;
  84 };
  85
  86 static void g_thread_cleanup (gpointer data);
  87 static void g_thread_fail (void);
  88
  89 /* Global variables */
  90
  91 static GSystemThread zero_thread; /* This is initialized to all zero */
  92 gboolean g_thread_use_default_impl = TRUE;
  93 gboolean g_threads_got_initialized = FALSE;
  94
  95 #if defined(G_OS_WIN32) && defined(__GNUC__)
  96 __declspec(dllexport)
  97 #endif
  98 GThreadFunctions g_thread_functions_for_glib_use = {
  99   (GMutex*(*)())g_thread_fail,                 /* mutex_new */
 100   NULL,                                        /* mutex_lock */
 101   NULL,                                        /* mutex_trylock */
 102   NULL,                                        /* mutex_unlock */
 103   NULL,                                        /* mutex_free */
 104   (GCond*(*)())g_thread_fail,                  /* cond_new */
 105   NULL,                                        /* cond_signal */
 106   NULL,                                        /* cond_broadcast */
 107   NULL,                                        /* cond_wait */
 108   NULL,                                        /* cond_timed_wait  */
 109   NULL,                                        /* cond_free */
 110   (GPrivate*(*)(GDestroyNotify))g_thread_fail, /* private_new */
 111   NULL,                                        /* private_get */
 112   NULL,                                        /* private_set */
 113   (void(*)(GThreadFunc, gpointer, gulong,
 114            gboolean, gboolean, GThreadPriority,
 115            gpointer, GError**))g_thread_fail,  /* thread_create */
 116   NULL,                                        /* thread_yield */
 117   NULL,                                        /* thread_join */
 118   NULL,                                        /* thread_exit */
 119   NULL,                                        /* thread_set_priority */
 120   NULL                                         /* thread_self */
 121 };
 122
 123 /* Local data */
 124
 125 static GMutex   *g_mutex_protect_static_mutex_allocation = NULL;
 126 static GMutex   *g_thread_specific_mutex = NULL;
 127 static GPrivate *g_thread_specific_private = NULL;
 128
 129 /* This must be called only once, before any threads are created.
 130  * It will only be called from g_thread_init() in -lgthread.
 131  */
 132 void
 133 g_mutex_init (void)
 134 {
 135   GRealThread* main_thread;
 136
 137   /* We let the main thread (the one that calls g_thread_init) inherit
 138    * the data, that it set before calling g_thread_init
 139    */
 140   main_thread = (GRealThread*) g_thread_self ();
 141
 142   g_thread_specific_private = g_private_new (g_thread_cleanup);
 143   G_THREAD_UF (private_set, (g_thread_specific_private, main_thread));
 144   G_THREAD_UF (thread_self, (&main_thread->system_thread));
 145
 146   g_mutex_protect_static_mutex_allocation = g_mutex_new();
 147   g_thread_specific_mutex = g_mutex_new();
 148 }
 149
 150 GMutex *
 151 g_static_mutex_get_mutex_impl (GMutex** mutex)
 152 {
 153   if (!g_thread_supported ())
 154     return NULL;
 155
 156   g_assert (g_mutex_protect_static_mutex_allocation);
 157
 158   g_mutex_lock (g_mutex_protect_static_mutex_allocation);
 159
 160   if (!(*mutex))
 161     *mutex = g_mutex_new();
 162
 163   g_mutex_unlock (g_mutex_protect_static_mutex_allocation);
 164
 165   return *mutex;
 166 }
 167
 168 void
 169 g_static_rec_mutex_lock (GStaticRecMutex* mutex)
 170 {
 171   GSystemThread self;
 172
 173   g_return_if_fail (mutex);
 174
 175   G_THREAD_UF (thread_self, (&self));
 176
 177   if (g_system_thread_equal (self, mutex->owner))
 178     {
 179       mutex->depth++;
 180       return;
 181     }
 182   g_static_mutex_lock (&mutex->mutex);
 183   g_system_thread_assign (mutex->owner, self);
 184   mutex->depth = 1;
 185 }
 186
 187 gboolean
 188 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
 189 {
 190   GSystemThread self;
 191
 192   g_return_val_if_fail (mutex, FALSE);
 193
 194   G_THREAD_UF (thread_self, (&self));
 195
 196   if (g_system_thread_equal (self, mutex->owner))
 197     {
 198       mutex->depth++;
 199       return TRUE;
 200     }
 201
 202   if (!g_static_mutex_trylock (&mutex->mutex))
 203     return FALSE;
 204
 205   g_system_thread_assign (mutex->owner, self);
 206   mutex->depth = 1;
 207   return TRUE;
 208 }
 209
 210 void
 211 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
 212 {
 213   g_return_if_fail (mutex);
 214
 215   if (mutex->depth > 1)
 216     {
 217       mutex->depth--;
 218       return;
 219     }
 220   g_system_thread_assign (mutex->owner, zero_thread);
 221   g_static_mutex_unlock (&mutex->mutex);
 222 }
 223
 224 void
 225 g_static_rec_mutex_lock_full   (GStaticRecMutex *mutex,
 226                                 guint            depth)
 227 {
 228   g_return_if_fail (mutex);
 229
 230   g_static_mutex_lock (&mutex->mutex);
 231   G_THREAD_UF (thread_self, (&mutex->owner));
 232   mutex->depth = depth;
 233 }
 234
 235 guint
 236 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
 237 {
 238   gint depth = mutex->depth;
 239
 240   g_return_val_if_fail (mutex, 0);
 241
 242   g_system_thread_assign (mutex->owner, zero_thread);
 243   mutex->depth = 0;
 244   g_static_mutex_unlock (&mutex->mutex);
 245
 246   return depth;
 247 }
 248
 249
 250 gpointer
 251 g_static_private_get (GStaticPrivate *private_key)
 252 {
 253   return g_static_private_get_for_thread (private_key, g_thread_self ());
 254 }
 255
 256 gpointer
 257 g_static_private_get_for_thread (GStaticPrivate *private_key,
 258                                  GThread        *thread)
 259 {
 260   GArray *array;
 261   GRealThread *self = (GRealThread*) thread;
 262
 263   g_return_val_if_fail (thread, NULL);
 264
 265   array = self->private_data;
 266   if (!array)
 267     return NULL;
 268
 269   if (!private_key->index)
 270     return NULL;
 271   else if (private_key->index <= array->len)
 272     return g_array_index (array, GStaticPrivateNode, private_key->index - 1).data;
 273   else
 274     return NULL;
 275 }
 276
 277 void
 278 g_static_private_set (GStaticPrivate *private_key,
 279                       gpointer        data,
 280                       GDestroyNotify  notify)
 281 {
 282   g_static_private_set_for_thread (private_key, g_thread_self (),
 283                                    data, notify);
 284 }
 285
 286 void
 287 g_static_private_set_for_thread (GStaticPrivate *private_key,
 288                                  GThread        *thread,
 289                                  gpointer        data,
 290                                  GDestroyNotify  notify)
 291 {
 292   GArray *array;
 293   GRealThread *self =(GRealThread*) thread;
 294   static guint next_index = 0;
 295   GStaticPrivateNode *node;
 296
 297   g_return_if_fail (thread);
 298
 299   array = self->private_data;
 300   if (!array)
 301     {
 302       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 303       self->private_data = array;
 304     }
 305
 306   if (!private_key->index)
 307     {
 308       g_mutex_lock (g_thread_specific_mutex);
 309
 310       if (!private_key->index)
 311         private_key->index = ++next_index;
 312
 313       g_mutex_unlock (g_thread_specific_mutex);
 314     }
 315
 316   if (private_key->index > array->len)
 317     g_array_set_size (array, private_key->index);
 318
 319   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 320   if (node->destroy)
 321     {
 322       gpointer ddata = node->data;
 323       GDestroyNotify ddestroy = node->destroy;
 324
 325       node->data = data;
 326       node->destroy = notify;
 327
 328       ddestroy (ddata);
 329     }
 330   else
 331     {
 332       node->data = data;
 333       node->destroy = notify;
 334     }
 335 }
 336
 337 static void
 338 g_thread_cleanup (gpointer data)
 339 {
 340   if (data)
 341     {
 342       GRealThread* thread = data;
 343       if (thread->private_data)
 344         {
 345           GArray* array = thread->private_data;
 346           guint i;
 347
 348           for (i = 0; i < array->len; i++ )
 349             {
 350               GStaticPrivateNode *node =
 351                 &g_array_index (array, GStaticPrivateNode, i);
 352               if (node->destroy)
 353                 node->destroy (node->data);
 354             }
 355           g_array_free (array, TRUE);
 356         }
 357       /* We only free the thread structure, if it isn't joinable. If
 358          it is, the structure is freed in g_thread_join */
 359       if (!thread->thread.joinable)
 360         {
 361           /* Just to make sure, this isn't used any more */
 362           g_system_thread_assign (thread->system_thread, zero_thread);
 363           g_free (thread);
 364         }
 365     }
 366 }
 367
 368 static void
 369 g_thread_fail (void)
 370 {
 371   g_error ("The thread system is not yet initialized.");
 372 }
 373
 374 G_LOCK_DEFINE_STATIC (g_thread_create);
 375
 376 static void
 377 g_thread_create_proxy (gpointer data)
 378 {
 379   GRealThread* thread = data;
 380
 381   g_assert (data);
 382
 383   /* the lock makes sure, that thread->system_thread is written,
 384      before thread->func is called. See g_thread_create */
 385
 386   G_LOCK (g_thread_create);
 387   g_private_set (g_thread_specific_private, data);
 388   G_UNLOCK (g_thread_create);
 389
 390   thread->func (thread->arg);
 391 }
 392
 393 GThread*
 394 g_thread_create (GThreadFunc             thread_func,
 395                  gpointer                arg,
 396                  gulong                  stack_size,
 397                  gboolean                joinable,
 398                  gboolean                bound,
 399                  GThreadPriority         priority,
 400                  GError                **error)
 401 {
 402   GRealThread* result = g_new (GRealThread, 1);
 403   GError *local_error = NULL;
 404   g_return_val_if_fail (thread_func, NULL);
 405
 406   result->thread.joinable = joinable;
 407   result->thread.bound = bound;
 408   result->thread.priority = priority;
 409   result->func = thread_func;
 410   result->arg = arg;
 411   result->private_data = NULL;
 412   G_LOCK (g_thread_create);
 413   G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
 414                                stack_size, joinable, bound, priority,
 415                                &result->system_thread, &local_error));
 416   G_UNLOCK (g_thread_create);
 417
 418   if (local_error)
 419     {
 420       g_propagate_error (error, local_error);
 421       g_free (result);
 422       return NULL;
 423     }
 424
 425   return (GThread*) result;
 426 }
 427
 428 void
 429 g_thread_join (GThread* thread)
 430 {
 431   GRealThread* real = (GRealThread*) thread;
 432
 433
 434   g_return_if_fail (thread);
 435   g_return_if_fail (thread->joinable);
 436   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 437
 438   G_THREAD_UF (thread_join, (&real->system_thread));
 439
 440   /* Just to make sure, this isn't used any more */
 441   thread->joinable = 0;
 442   g_system_thread_assign (real->system_thread, zero_thread);
 443
 444   /* the thread structure for non-joinable threads is freed upon
 445      thread end. We free the memory here. This will leave loose end,
 446      if a joinable thread is not joined. */
 447
 448   g_free (thread);
 449 }
 450
 451 void
 452 g_thread_set_priority (GThread* thread,
 453                        GThreadPriority priority)
 454 {
 455   GRealThread* real = (GRealThread*) thread;
 456
 457   g_return_if_fail (thread);
 458   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 459
 460   thread->priority = priority;
 461   G_THREAD_CF (thread_set_priority, (void)0, (&real->system_thread, priority));
 462 }
 463
 464 GThread*
 465 g_thread_self()
 466 {
 467   GRealThread* thread = g_private_get (g_thread_specific_private);
 468
 469   if (!thread)
 470     {
 471       /* If no thread data is available, provide and set one.  This
 472          can happen for the main thread and for threads, that are not
 473          created by GLib. */
 474       thread = g_new (GRealThread, 1);
 475       thread->thread.joinable = FALSE; /* This is a save guess */
 476       thread->thread.bound = TRUE; /* This isn't important at all */
 477       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 478                                                              just a guess */
 479       thread->func = NULL;
 480       thread->arg = NULL;
 481       thread->private_data = NULL;
 482
 483       if (g_thread_supported ())
 484         G_THREAD_UF (thread_self, (&thread->system_thread));
 485
 486       g_private_set (g_thread_specific_private, thread);
 487     }
 488
 489   return (GThread*)thread;
 490 }
 491
 492 static void inline g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 493 {
 494   if (!*cond)
 495       *cond = g_cond_new ();
 496   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 497 }
 498
 499 static void inline g_static_rw_lock_signal (GStaticRWLock* lock)
 500 {
 501   if (lock->want_to_write && lock->write_cond)
 502     g_cond_signal (lock->write_cond);
 503   else if (lock->read_cond)
 504     g_cond_signal (lock->read_cond);
 505 }
 506
 507 void g_static_rw_lock_reader_lock (GStaticRWLock* lock)
 508 {
 509   g_return_if_fail (lock);
 510
 511   if (!g_threads_got_initialized)
 512     return;
 513
 514   g_static_mutex_lock (&lock->mutex);
 515   while (lock->write || lock->want_to_write)
 516     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 517   lock->read_counter++;
 518   g_static_mutex_unlock (&lock->mutex);
 519 }
 520
 521 gboolean g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
 522 {
 523   gboolean ret_val = FALSE;
 524
 525   g_return_val_if_fail (lock, FALSE);
 526
 527   if (!g_threads_got_initialized)
 528     return TRUE;
 529
 530   g_static_mutex_lock (&lock->mutex);
 531   if (!lock->write && !lock->want_to_write)
 532     {
 533       lock->read_counter++;
 534       ret_val = TRUE;
 535     }
 536   g_static_mutex_unlock (&lock->mutex);
 537   return ret_val;
 538 }
 539
 540 void g_static_rw_lock_reader_unlock  (GStaticRWLock* lock)
 541 {
 542   g_return_if_fail (lock);
 543
 544   if (!g_threads_got_initialized)
 545     return;
 546
 547   g_static_mutex_lock (&lock->mutex);
 548   lock->read_counter--;
 549   g_static_rw_lock_signal (lock);
 550   g_static_mutex_unlock (&lock->mutex);
 551 }
 552
 553 void g_static_rw_lock_writer_lock (GStaticRWLock* lock)
 554 {
 555   g_return_if_fail (lock);
 556
 557   if (!g_threads_got_initialized)
 558     return;
 559
 560   g_static_mutex_lock (&lock->mutex);
 561   lock->want_to_write++;
 562   while (lock->write || lock->read_counter)
 563     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 564   lock->want_to_write--;
 565   lock->write = TRUE;
 566   g_static_mutex_unlock (&lock->mutex);
 567 }
 568
 569 gboolean g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 570 {
 571   gboolean ret_val = FALSE;
 572
 573   g_return_val_if_fail (lock, FALSE);
 574
 575   if (!g_threads_got_initialized)
 576     return TRUE;
 577
 578   g_static_mutex_lock (&lock->mutex);
 579   if (!lock->write && !lock->read_counter)
 580     {
 581       lock->write = TRUE;
 582       ret_val = TRUE;
 583     }
 584   g_static_mutex_unlock (&lock->mutex);
 585   return ret_val;
 586 }
 587
 588 void g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
 589 {
 590   g_return_if_fail (lock);
 591
 592   if (!g_threads_got_initialized)
 593     return;
 594
 595   g_static_mutex_lock (&lock->mutex);
 596   lock->write = FALSE;
 597   g_static_rw_lock_signal (lock);
 598   g_static_mutex_unlock (&lock->mutex);
 599 }
 600
 601 void g_static_rw_lock_free (GStaticRWLock* lock)
 602 {
 603   g_return_if_fail (lock);
 604
 605   if (lock->read_cond)
 606     g_cond_free (lock->read_cond);
 607   if (lock->write_cond)
 608     g_cond_free (lock->write_cond);
 609
 610 }
 611