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_rec_mutex_lock (GStaticRecMutex* mutex)
 164 {
 165   GSystemThread self;
 166
 167   g_return_if_fail (mutex);
 168
 169   if (!g_thread_supported ())
 170     return;
 171
 172   G_THREAD_UF (thread_self, (&self));
 173
 174   if (g_system_thread_equal (self, mutex->owner))
 175     {
 176       mutex->depth++;
 177       return;
 178     }
 179   g_static_mutex_lock (&mutex->mutex);
 180   g_system_thread_assign (mutex->owner, self);
 181   mutex->depth = 1;
 182 }
 183
 184 gboolean
 185 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
 186 {
 187   GSystemThread self;
 188
 189   g_return_val_if_fail (mutex, FALSE);
 190
 191   if (!g_thread_supported ())
 192     return TRUE;
 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 (!g_thread_supported ())
 216     return;
 217
 218   if (mutex->depth > 1)
 219     {
 220       mutex->depth--;
 221       return;
 222     }
 223   g_system_thread_assign (mutex->owner, zero_thread);
 224   g_static_mutex_unlock (&mutex->mutex);
 225 }
 226
 227 void
 228 g_static_rec_mutex_lock_full   (GStaticRecMutex *mutex,
 229                                 guint            depth)
 230 {
 231   g_return_if_fail (mutex);
 232
 233   if (!g_thread_supported ())
 234     return;
 235
 236   g_static_mutex_lock (&mutex->mutex);
 237   G_THREAD_UF (thread_self, (&mutex->owner));
 238   mutex->depth = depth;
 239 }
 240
 241 guint
 242 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
 243 {
 244   gint depth;
 245
 246   g_return_val_if_fail (mutex, 0);
 247
 248   if (!g_thread_supported ())
 249     return 1;
 250
 251   depth = mutex->depth;
 252
 253   g_system_thread_assign (mutex->owner, zero_thread);
 254   mutex->depth = 0;
 255   g_static_mutex_unlock (&mutex->mutex);
 256
 257   return depth;
 258 }
 259
 260
 261 gpointer
 262 g_static_private_get (GStaticPrivate *private_key)
 263 {
 264   return g_static_private_get_for_thread (private_key, g_thread_self ());
 265 }
 266
 267 gpointer
 268 g_static_private_get_for_thread (GStaticPrivate *private_key,
 269                                  GThread        *thread)
 270 {
 271   GArray *array;
 272   GRealThread *self = (GRealThread*) thread;
 273
 274   g_return_val_if_fail (thread, NULL);
 275
 276   array = self->private_data;
 277   if (!array)
 278     return NULL;
 279
 280   if (!private_key->index)
 281     return NULL;
 282   else if (private_key->index <= array->len)
 283     return g_array_index (array, GStaticPrivateNode, private_key->index - 1).data;
 284   else
 285     return NULL;
 286 }
 287
 288 void
 289 g_static_private_set (GStaticPrivate *private_key,
 290                       gpointer        data,
 291                       GDestroyNotify  notify)
 292 {
 293   g_static_private_set_for_thread (private_key, g_thread_self (),
 294                                    data, notify);
 295 }
 296
 297 void
 298 g_static_private_set_for_thread (GStaticPrivate *private_key,
 299                                  GThread        *thread,
 300                                  gpointer        data,
 301                                  GDestroyNotify  notify)
 302 {
 303   GArray *array;
 304   GRealThread *self =(GRealThread*) thread;
 305   static guint next_index = 0;
 306   GStaticPrivateNode *node;
 307
 308   g_return_if_fail (thread);
 309
 310   array = self->private_data;
 311   if (!array)
 312     {
 313       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 314       self->private_data = array;
 315     }
 316
 317   if (!private_key->index)
 318     {
 319       g_mutex_lock (g_thread_specific_mutex);
 320
 321       if (!private_key->index)
 322         private_key->index = ++next_index;
 323
 324       g_mutex_unlock (g_thread_specific_mutex);
 325     }
 326
 327   if (private_key->index > array->len)
 328     g_array_set_size (array, private_key->index);
 329
 330   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 331   if (node->destroy)
 332     {
 333       gpointer ddata = node->data;
 334       GDestroyNotify ddestroy = node->destroy;
 335
 336       node->data = data;
 337       node->destroy = notify;
 338
 339       ddestroy (ddata);
 340     }
 341   else
 342     {
 343       node->data = data;
 344       node->destroy = notify;
 345     }
 346 }
 347
 348 static void
 349 g_thread_cleanup (gpointer data)
 350 {
 351   if (data)
 352     {
 353       GRealThread* thread = data;
 354       if (thread->private_data)
 355         {
 356           GArray* array = thread->private_data;
 357           guint i;
 358
 359           for (i = 0; i < array->len; i++ )
 360             {
 361               GStaticPrivateNode *node =
 362                 &g_array_index (array, GStaticPrivateNode, i);
 363               if (node->destroy)
 364                 node->destroy (node->data);
 365             }
 366           g_array_free (array, TRUE);
 367         }
 368       /* We only free the thread structure, if it isn't joinable. If
 369          it is, the structure is freed in g_thread_join */
 370       if (!thread->thread.joinable)
 371         {
 372           /* Just to make sure, this isn't used any more */
 373           g_system_thread_assign (thread->system_thread, zero_thread);
 374           g_free (thread);
 375         }
 376     }
 377 }
 378
 379 static void
 380 g_thread_fail (void)
 381 {
 382   g_error ("The thread system is not yet initialized.");
 383 }
 384
 385 G_LOCK_DEFINE_STATIC (g_thread_create);
 386
 387 static void
 388 g_thread_create_proxy (gpointer data)
 389 {
 390   GRealThread* thread = data;
 391
 392   g_assert (data);
 393
 394   /* This has to happen before G_LOCK, as that might call g_thread_self */
 395   g_private_set (g_thread_specific_private, data);
 396
 397   /* the lock makes sure, that thread->system_thread is written,
 398      before thread->func is called. See g_thread_create. */
 399   G_LOCK (g_thread_create);
 400   G_UNLOCK (g_thread_create);
 401
 402   thread->func (thread->arg);
 403 }
 404
 405 GThread*
 406 g_thread_create (GThreadFunc             thread_func,
 407                  gpointer                arg,
 408                  gulong                  stack_size,
 409                  gboolean                joinable,
 410                  gboolean                bound,
 411                  GThreadPriority         priority,
 412                  GError                **error)
 413 {
 414   GRealThread* result = g_new (GRealThread, 1);
 415   GError *local_error = NULL;
 416   g_return_val_if_fail (thread_func, NULL);
 417   g_return_val_if_fail (priority >= G_THREAD_PRIORITY_LOW, NULL);
 418   g_return_val_if_fail (priority <= G_THREAD_PRIORITY_URGENT, NULL);
 419
 420   result->thread.joinable = joinable;
 421   result->thread.bound = bound;
 422   result->thread.priority = priority;
 423   result->func = thread_func;
 424   result->arg = arg;
 425   result->private_data = NULL;
 426   G_LOCK (g_thread_create);
 427   G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
 428                                stack_size, joinable, bound, priority,
 429                                &result->system_thread, &local_error));
 430   G_UNLOCK (g_thread_create);
 431
 432   if (local_error)
 433     {
 434       g_propagate_error (error, local_error);
 435       g_free (result);
 436       return NULL;
 437     }
 438
 439   return (GThread*) result;
 440 }
 441
 442 void
 443 g_thread_join (GThread* thread)
 444 {
 445   GRealThread* real = (GRealThread*) thread;
 446
 447
 448   g_return_if_fail (thread);
 449   g_return_if_fail (thread->joinable);
 450   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 451
 452   G_THREAD_UF (thread_join, (&real->system_thread));
 453
 454   /* Just to make sure, this isn't used any more */
 455   thread->joinable = 0;
 456   g_system_thread_assign (real->system_thread, zero_thread);
 457
 458   /* the thread structure for non-joinable threads is freed upon
 459      thread end. We free the memory here. This will leave loose end,
 460      if a joinable thread is not joined. */
 461
 462   g_free (thread);
 463 }
 464
 465 void
 466 g_thread_set_priority (GThread* thread,
 467                        GThreadPriority priority)
 468 {
 469   GRealThread* real = (GRealThread*) thread;
 470
 471   g_return_if_fail (thread);
 472   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 473   g_return_if_fail (priority >= G_THREAD_PRIORITY_LOW);
 474   g_return_if_fail (priority <= G_THREAD_PRIORITY_URGENT);
 475
 476   thread->priority = priority;
 477   G_THREAD_CF (thread_set_priority, (void)0, (&real->system_thread, priority));
 478 }
 479
 480 GThread*
 481 g_thread_self()
 482 {
 483   GRealThread* thread = g_private_get (g_thread_specific_private);
 484
 485   if (!thread)
 486     {
 487       /* If no thread data is available, provide and set one.  This
 488          can happen for the main thread and for threads, that are not
 489          created by GLib. */
 490       thread = g_new (GRealThread, 1);
 491       thread->thread.joinable = FALSE; /* This is a save guess */
 492       thread->thread.bound = TRUE; /* This isn't important at all */
 493       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 494                                                              just a guess */
 495       thread->func = NULL;
 496       thread->arg = NULL;
 497       thread->private_data = NULL;
 498
 499       if (g_thread_supported ())
 500         G_THREAD_UF (thread_self, (&thread->system_thread));
 501
 502       g_private_set (g_thread_specific_private, thread);
 503     }
 504
 505   return (GThread*)thread;
 506 }
 507
 508 static void inline g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 509 {
 510   if (!*cond)
 511       *cond = g_cond_new ();
 512   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 513 }
 514
 515 static void inline g_static_rw_lock_signal (GStaticRWLock* lock)
 516 {
 517   if (lock->want_to_write && lock->write_cond)
 518     g_cond_signal (lock->write_cond);
 519   else if (lock->read_cond)
 520     g_cond_signal (lock->read_cond);
 521 }
 522
 523 void g_static_rw_lock_reader_lock (GStaticRWLock* lock)
 524 {
 525   g_return_if_fail (lock);
 526
 527   if (!g_threads_got_initialized)
 528     return;
 529
 530   g_static_mutex_lock (&lock->mutex);
 531   while (lock->write || lock->want_to_write)
 532     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 533   lock->read_counter++;
 534   g_static_mutex_unlock (&lock->mutex);
 535 }
 536
 537 gboolean g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
 538 {
 539   gboolean ret_val = FALSE;
 540
 541   g_return_val_if_fail (lock, FALSE);
 542
 543   if (!g_threads_got_initialized)
 544     return TRUE;
 545
 546   g_static_mutex_lock (&lock->mutex);
 547   if (!lock->write && !lock->want_to_write)
 548     {
 549       lock->read_counter++;
 550       ret_val = TRUE;
 551     }
 552   g_static_mutex_unlock (&lock->mutex);
 553   return ret_val;
 554 }
 555
 556 void g_static_rw_lock_reader_unlock  (GStaticRWLock* lock)
 557 {
 558   g_return_if_fail (lock);
 559
 560   if (!g_threads_got_initialized)
 561     return;
 562
 563   g_static_mutex_lock (&lock->mutex);
 564   lock->read_counter--;
 565   g_static_rw_lock_signal (lock);
 566   g_static_mutex_unlock (&lock->mutex);
 567 }
 568
 569 void g_static_rw_lock_writer_lock (GStaticRWLock* lock)
 570 {
 571   g_return_if_fail (lock);
 572
 573   if (!g_threads_got_initialized)
 574     return;
 575
 576   g_static_mutex_lock (&lock->mutex);
 577   lock->want_to_write++;
 578   while (lock->write || lock->read_counter)
 579     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 580   lock->want_to_write--;
 581   lock->write = TRUE;
 582   g_static_mutex_unlock (&lock->mutex);
 583 }
 584
 585 gboolean g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 586 {
 587   gboolean ret_val = FALSE;
 588
 589   g_return_val_if_fail (lock, FALSE);
 590
 591   if (!g_threads_got_initialized)
 592     return TRUE;
 593
 594   g_static_mutex_lock (&lock->mutex);
 595   if (!lock->write && !lock->read_counter)
 596     {
 597       lock->write = TRUE;
 598       ret_val = TRUE;
 599     }
 600   g_static_mutex_unlock (&lock->mutex);
 601   return ret_val;
 602 }
 603
 604 void g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
 605 {
 606   g_return_if_fail (lock);
 607
 608   if (!g_threads_got_initialized)
 609     return;
 610
 611   g_static_mutex_lock (&lock->mutex);
 612   lock->write = FALSE;
 613   g_static_rw_lock_signal (lock);
 614   g_static_mutex_unlock (&lock->mutex);
 615 }
 616
 617 void g_static_rw_lock_free (GStaticRWLock* lock)
 618 {
 619   g_return_if_fail (lock);
 620
 621   if (lock->read_cond)
 622     g_cond_free (lock->read_cond);
 623   if (lock->write_cond)
 624     g_cond_free (lock->write_cond);
 625
 626 }
 627