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   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   /* the lock makes sure, that thread->system_thread is written,
 395      before thread->func is called. See g_thread_create */
 396
 397   G_LOCK (g_thread_create);
 398   g_private_set (g_thread_specific_private, data);
 399   G_UNLOCK (g_thread_create);
 400
 401   thread->func (thread->arg);
 402 }
 403
 404 GThread*
 405 g_thread_create (GThreadFunc             thread_func,
 406                  gpointer                arg,
 407                  gulong                  stack_size,
 408                  gboolean                joinable,
 409                  gboolean                bound,
 410                  GThreadPriority         priority,
 411                  GError                **error)
 412 {
 413   GRealThread* result = g_new (GRealThread, 1);
 414   GError *local_error = NULL;
 415   g_return_val_if_fail (thread_func, NULL);
 416
 417   result->thread.joinable = joinable;
 418   result->thread.bound = bound;
 419   result->thread.priority = priority;
 420   result->func = thread_func;
 421   result->arg = arg;
 422   result->private_data = NULL;
 423   G_LOCK (g_thread_create);
 424   G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
 425                                stack_size, joinable, bound, priority,
 426                                &result->system_thread, &local_error));
 427   G_UNLOCK (g_thread_create);
 428
 429   if (local_error)
 430     {
 431       g_propagate_error (error, local_error);
 432       g_free (result);
 433       return NULL;
 434     }
 435
 436   return (GThread*) result;
 437 }
 438
 439 void
 440 g_thread_join (GThread* thread)
 441 {
 442   GRealThread* real = (GRealThread*) thread;
 443
 444
 445   g_return_if_fail (thread);
 446   g_return_if_fail (thread->joinable);
 447   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 448
 449   G_THREAD_UF (thread_join, (&real->system_thread));
 450
 451   /* Just to make sure, this isn't used any more */
 452   thread->joinable = 0;
 453   g_system_thread_assign (real->system_thread, zero_thread);
 454
 455   /* the thread structure for non-joinable threads is freed upon
 456      thread end. We free the memory here. This will leave loose end,
 457      if a joinable thread is not joined. */
 458
 459   g_free (thread);
 460 }
 461
 462 void
 463 g_thread_set_priority (GThread* thread,
 464                        GThreadPriority priority)
 465 {
 466   GRealThread* real = (GRealThread*) thread;
 467
 468   g_return_if_fail (thread);
 469   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 470
 471   thread->priority = priority;
 472   G_THREAD_CF (thread_set_priority, (void)0, (&real->system_thread, priority));
 473 }
 474
 475 GThread*
 476 g_thread_self()
 477 {
 478   GRealThread* thread = g_private_get (g_thread_specific_private);
 479
 480   if (!thread)
 481     {
 482       /* If no thread data is available, provide and set one.  This
 483          can happen for the main thread and for threads, that are not
 484          created by GLib. */
 485       thread = g_new (GRealThread, 1);
 486       thread->thread.joinable = FALSE; /* This is a save guess */
 487       thread->thread.bound = TRUE; /* This isn't important at all */
 488       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 489                                                              just a guess */
 490       thread->func = NULL;
 491       thread->arg = NULL;
 492       thread->private_data = NULL;
 493
 494       if (g_thread_supported ())
 495         G_THREAD_UF (thread_self, (&thread->system_thread));
 496
 497       g_private_set (g_thread_specific_private, thread);
 498     }
 499
 500   return (GThread*)thread;
 501 }
 502
 503 static void inline g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 504 {
 505   if (!*cond)
 506       *cond = g_cond_new ();
 507   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 508 }
 509
 510 static void inline g_static_rw_lock_signal (GStaticRWLock* lock)
 511 {
 512   if (lock->want_to_write && lock->write_cond)
 513     g_cond_signal (lock->write_cond);
 514   else if (lock->read_cond)
 515     g_cond_signal (lock->read_cond);
 516 }
 517
 518 void g_static_rw_lock_reader_lock (GStaticRWLock* lock)
 519 {
 520   g_return_if_fail (lock);
 521
 522   if (!g_threads_got_initialized)
 523     return;
 524
 525   g_static_mutex_lock (&lock->mutex);
 526   while (lock->write || lock->want_to_write)
 527     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 528   lock->read_counter++;
 529   g_static_mutex_unlock (&lock->mutex);
 530 }
 531
 532 gboolean g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
 533 {
 534   gboolean ret_val = FALSE;
 535
 536   g_return_val_if_fail (lock, FALSE);
 537
 538   if (!g_threads_got_initialized)
 539     return TRUE;
 540
 541   g_static_mutex_lock (&lock->mutex);
 542   if (!lock->write && !lock->want_to_write)
 543     {
 544       lock->read_counter++;
 545       ret_val = TRUE;
 546     }
 547   g_static_mutex_unlock (&lock->mutex);
 548   return ret_val;
 549 }
 550
 551 void g_static_rw_lock_reader_unlock  (GStaticRWLock* lock)
 552 {
 553   g_return_if_fail (lock);
 554
 555   if (!g_threads_got_initialized)
 556     return;
 557
 558   g_static_mutex_lock (&lock->mutex);
 559   lock->read_counter--;
 560   g_static_rw_lock_signal (lock);
 561   g_static_mutex_unlock (&lock->mutex);
 562 }
 563
 564 void g_static_rw_lock_writer_lock (GStaticRWLock* lock)
 565 {
 566   g_return_if_fail (lock);
 567
 568   if (!g_threads_got_initialized)
 569     return;
 570
 571   g_static_mutex_lock (&lock->mutex);
 572   lock->want_to_write++;
 573   while (lock->write || lock->read_counter)
 574     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 575   lock->want_to_write--;
 576   lock->write = TRUE;
 577   g_static_mutex_unlock (&lock->mutex);
 578 }
 579
 580 gboolean g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 581 {
 582   gboolean ret_val = FALSE;
 583
 584   g_return_val_if_fail (lock, FALSE);
 585
 586   if (!g_threads_got_initialized)
 587     return TRUE;
 588
 589   g_static_mutex_lock (&lock->mutex);
 590   if (!lock->write && !lock->read_counter)
 591     {
 592       lock->write = TRUE;
 593       ret_val = TRUE;
 594     }
 595   g_static_mutex_unlock (&lock->mutex);
 596   return ret_val;
 597 }
 598
 599 void g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
 600 {
 601   g_return_if_fail (lock);
 602
 603   if (!g_threads_got_initialized)
 604     return;
 605
 606   g_static_mutex_lock (&lock->mutex);
 607   lock->write = FALSE;
 608   g_static_rw_lock_signal (lock);
 609   g_static_mutex_unlock (&lock->mutex);
 610 }
 611
 612 void g_static_rw_lock_free (GStaticRWLock* lock)
 613 {
 614   g_return_if_fail (lock);
 615
 616   if (lock->read_cond)
 617     g_cond_free (lock->read_cond);
 618   if (lock->write_cond)
 619     g_cond_free (lock->write_cond);
 620
 621 }
 622