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_free (GStaticMutex* mutex)
 164 {
 165   GMutex **runtime_mutex;
 166
 167   g_return_if_fail (mutex);
 168
 169   /* The runtime_mutex is the first (or only) member of GStaticMutex,
 170    * see both versions (of glibconfig.h) in configure.in */
 171   runtime_mutex = ((GMutex**)mutex);
 172
 173   if (*runtime_mutex)
 174     g_mutex_free (*runtime_mutex);
 175
 176   *runtime_mutex = NULL;
 177 }
 178
 179 void
 180 g_static_rec_mutex_lock (GStaticRecMutex* mutex)
 181 {
 182   GSystemThread self;
 183
 184   g_return_if_fail (mutex);
 185
 186   if (!g_thread_supported ())
 187     return;
 188
 189   G_THREAD_UF (thread_self, (&self));
 190
 191   if (g_system_thread_equal (self, mutex->owner))
 192     {
 193       mutex->depth++;
 194       return;
 195     }
 196   g_static_mutex_lock (&mutex->mutex);
 197   g_system_thread_assign (mutex->owner, self);
 198   mutex->depth = 1;
 199 }
 200
 201 gboolean
 202 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
 203 {
 204   GSystemThread self;
 205
 206   g_return_val_if_fail (mutex, FALSE);
 207
 208   if (!g_thread_supported ())
 209     return TRUE;
 210
 211   G_THREAD_UF (thread_self, (&self));
 212
 213   if (g_system_thread_equal (self, mutex->owner))
 214     {
 215       mutex->depth++;
 216       return TRUE;
 217     }
 218
 219   if (!g_static_mutex_trylock (&mutex->mutex))
 220     return FALSE;
 221
 222   g_system_thread_assign (mutex->owner, self);
 223   mutex->depth = 1;
 224   return TRUE;
 225 }
 226
 227 void
 228 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
 229 {
 230   g_return_if_fail (mutex);
 231
 232   if (!g_thread_supported ())
 233     return;
 234
 235   if (mutex->depth > 1)
 236     {
 237       mutex->depth--;
 238       return;
 239     }
 240   g_system_thread_assign (mutex->owner, zero_thread);
 241   g_static_mutex_unlock (&mutex->mutex);
 242 }
 243
 244 void
 245 g_static_rec_mutex_lock_full   (GStaticRecMutex *mutex,
 246                                 guint            depth)
 247 {
 248   g_return_if_fail (mutex);
 249
 250   if (!g_thread_supported ())
 251     return;
 252
 253   g_static_mutex_lock (&mutex->mutex);
 254   G_THREAD_UF (thread_self, (&mutex->owner));
 255   mutex->depth = depth;
 256 }
 257
 258 guint
 259 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
 260 {
 261   gint depth;
 262
 263   g_return_val_if_fail (mutex, 0);
 264
 265   if (!g_thread_supported ())
 266     return 1;
 267
 268   depth = mutex->depth;
 269
 270   g_system_thread_assign (mutex->owner, zero_thread);
 271   mutex->depth = 0;
 272   g_static_mutex_unlock (&mutex->mutex);
 273
 274   return depth;
 275 }
 276
 277
 278 gpointer
 279 g_static_private_get (GStaticPrivate *private_key)
 280 {
 281   return g_static_private_get_for_thread (private_key, g_thread_self ());
 282 }
 283
 284 gpointer
 285 g_static_private_get_for_thread (GStaticPrivate *private_key,
 286                                  GThread        *thread)
 287 {
 288   GArray *array;
 289   GRealThread *self = (GRealThread*) thread;
 290
 291   g_return_val_if_fail (thread, NULL);
 292
 293   array = self->private_data;
 294   if (!array)
 295     return NULL;
 296
 297   if (!private_key->index)
 298     return NULL;
 299   else if (private_key->index <= array->len)
 300     return g_array_index (array, GStaticPrivateNode, private_key->index - 1).data;
 301   else
 302     return NULL;
 303 }
 304
 305 void
 306 g_static_private_set (GStaticPrivate *private_key,
 307                       gpointer        data,
 308                       GDestroyNotify  notify)
 309 {
 310   g_static_private_set_for_thread (private_key, g_thread_self (),
 311                                    data, notify);
 312 }
 313
 314 void
 315 g_static_private_set_for_thread (GStaticPrivate *private_key,
 316                                  GThread        *thread,
 317                                  gpointer        data,
 318                                  GDestroyNotify  notify)
 319 {
 320   GArray *array;
 321   GRealThread *self =(GRealThread*) thread;
 322   static guint next_index = 0;
 323   GStaticPrivateNode *node;
 324
 325   g_return_if_fail (thread);
 326
 327   array = self->private_data;
 328   if (!array)
 329     {
 330       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 331       self->private_data = array;
 332     }
 333
 334   if (!private_key->index)
 335     {
 336       g_mutex_lock (g_thread_specific_mutex);
 337
 338       if (!private_key->index)
 339         private_key->index = ++next_index;
 340
 341       g_mutex_unlock (g_thread_specific_mutex);
 342     }
 343
 344   if (private_key->index > array->len)
 345     g_array_set_size (array, private_key->index);
 346
 347   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 348   if (node->destroy)
 349     {
 350       gpointer ddata = node->data;
 351       GDestroyNotify ddestroy = node->destroy;
 352
 353       node->data = data;
 354       node->destroy = notify;
 355
 356       ddestroy (ddata);
 357     }
 358   else
 359     {
 360       node->data = data;
 361       node->destroy = notify;
 362     }
 363 }
 364
 365 static void
 366 g_thread_cleanup (gpointer data)
 367 {
 368   if (data)
 369     {
 370       GRealThread* thread = data;
 371       if (thread->private_data)
 372         {
 373           GArray* array = thread->private_data;
 374           guint i;
 375
 376           for (i = 0; i < array->len; i++ )
 377             {
 378               GStaticPrivateNode *node =
 379                 &g_array_index (array, GStaticPrivateNode, i);
 380               if (node->destroy)
 381                 node->destroy (node->data);
 382             }
 383           g_array_free (array, TRUE);
 384         }
 385       /* We only free the thread structure, if it isn't joinable. If
 386          it is, the structure is freed in g_thread_join */
 387       if (!thread->thread.joinable)
 388         {
 389           /* Just to make sure, this isn't used any more */
 390           g_system_thread_assign (thread->system_thread, zero_thread);
 391           g_free (thread);
 392         }
 393     }
 394 }
 395
 396 static void
 397 g_thread_fail (void)
 398 {
 399   g_error ("The thread system is not yet initialized.");
 400 }
 401
 402 G_LOCK_DEFINE_STATIC (g_thread_create);
 403
 404 static void
 405 g_thread_create_proxy (gpointer data)
 406 {
 407   GRealThread* thread = data;
 408
 409   g_assert (data);
 410
 411   /* This has to happen before G_LOCK, as that might call g_thread_self */
 412   g_private_set (g_thread_specific_private, data);
 413
 414   /* the lock makes sure, that thread->system_thread is written,
 415      before thread->func is called. See g_thread_create. */
 416   G_LOCK (g_thread_create);
 417   G_UNLOCK (g_thread_create);
 418
 419   thread->func (thread->arg);
 420 }
 421
 422 GThread*
 423 g_thread_create (GThreadFunc             thread_func,
 424                  gpointer                arg,
 425                  gulong                  stack_size,
 426                  gboolean                joinable,
 427                  gboolean                bound,
 428                  GThreadPriority         priority,
 429                  GError                **error)
 430 {
 431   GRealThread* result = g_new (GRealThread, 1);
 432   GError *local_error = NULL;
 433   g_return_val_if_fail (thread_func, NULL);
 434   g_return_val_if_fail (priority >= G_THREAD_PRIORITY_LOW, NULL);
 435   g_return_val_if_fail (priority <= G_THREAD_PRIORITY_URGENT, NULL);
 436
 437   result->thread.joinable = joinable;
 438   result->thread.bound = bound;
 439   result->thread.priority = priority;
 440   result->func = thread_func;
 441   result->arg = arg;
 442   result->private_data = NULL;
 443   G_LOCK (g_thread_create);
 444   G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
 445                                stack_size, joinable, bound, priority,
 446                                &result->system_thread, &local_error));
 447   G_UNLOCK (g_thread_create);
 448
 449   if (local_error)
 450     {
 451       g_propagate_error (error, local_error);
 452       g_free (result);
 453       return NULL;
 454     }
 455
 456   return (GThread*) result;
 457 }
 458
 459 void
 460 g_thread_join (GThread* thread)
 461 {
 462   GRealThread* real = (GRealThread*) thread;
 463
 464
 465   g_return_if_fail (thread);
 466   g_return_if_fail (thread->joinable);
 467   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 468
 469   G_THREAD_UF (thread_join, (&real->system_thread));
 470
 471   /* Just to make sure, this isn't used any more */
 472   thread->joinable = 0;
 473   g_system_thread_assign (real->system_thread, zero_thread);
 474
 475   /* the thread structure for non-joinable threads is freed upon
 476      thread end. We free the memory here. This will leave loose end,
 477      if a joinable thread is not joined. */
 478
 479   g_free (thread);
 480 }
 481
 482 void
 483 g_thread_set_priority (GThread* thread,
 484                        GThreadPriority priority)
 485 {
 486   GRealThread* real = (GRealThread*) thread;
 487
 488   g_return_if_fail (thread);
 489   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 490   g_return_if_fail (priority >= G_THREAD_PRIORITY_LOW);
 491   g_return_if_fail (priority <= G_THREAD_PRIORITY_URGENT);
 492
 493   thread->priority = priority;
 494   G_THREAD_CF (thread_set_priority, (void)0, (&real->system_thread, priority));
 495 }
 496
 497 GThread*
 498 g_thread_self()
 499 {
 500   GRealThread* thread = g_private_get (g_thread_specific_private);
 501
 502   if (!thread)
 503     {
 504       /* If no thread data is available, provide and set one.  This
 505          can happen for the main thread and for threads, that are not
 506          created by GLib. */
 507       thread = g_new (GRealThread, 1);
 508       thread->thread.joinable = FALSE; /* This is a save guess */
 509       thread->thread.bound = TRUE; /* This isn't important at all */
 510       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 511                                                              just a guess */
 512       thread->func = NULL;
 513       thread->arg = NULL;
 514       thread->private_data = NULL;
 515
 516       if (g_thread_supported ())
 517         G_THREAD_UF (thread_self, (&thread->system_thread));
 518
 519       g_private_set (g_thread_specific_private, thread);
 520     }
 521
 522   return (GThread*)thread;
 523 }
 524
 525 static void inline g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 526 {
 527   if (!*cond)
 528       *cond = g_cond_new ();
 529   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 530 }
 531
 532 static void inline g_static_rw_lock_signal (GStaticRWLock* lock)
 533 {
 534   if (lock->want_to_write && lock->write_cond)
 535     g_cond_signal (lock->write_cond);
 536   else if (lock->read_cond)
 537     g_cond_broadcast (lock->read_cond);
 538 }
 539
 540 void g_static_rw_lock_reader_lock (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   while (lock->write || lock->want_to_write)
 549     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 550   lock->read_counter++;
 551   g_static_mutex_unlock (&lock->mutex);
 552 }
 553
 554 gboolean g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
 555 {
 556   gboolean ret_val = FALSE;
 557
 558   g_return_val_if_fail (lock, FALSE);
 559
 560   if (!g_threads_got_initialized)
 561     return TRUE;
 562
 563   g_static_mutex_lock (&lock->mutex);
 564   if (!lock->write && !lock->want_to_write)
 565     {
 566       lock->read_counter++;
 567       ret_val = TRUE;
 568     }
 569   g_static_mutex_unlock (&lock->mutex);
 570   return ret_val;
 571 }
 572
 573 void g_static_rw_lock_reader_unlock  (GStaticRWLock* lock)
 574 {
 575   g_return_if_fail (lock);
 576
 577   if (!g_threads_got_initialized)
 578     return;
 579
 580   g_static_mutex_lock (&lock->mutex);
 581   lock->read_counter--;
 582   if (lock->read_counter == 0)
 583     g_static_rw_lock_signal (lock);
 584   g_static_mutex_unlock (&lock->mutex);
 585 }
 586
 587 void g_static_rw_lock_writer_lock (GStaticRWLock* lock)
 588 {
 589   g_return_if_fail (lock);
 590
 591   if (!g_threads_got_initialized)
 592     return;
 593
 594   g_static_mutex_lock (&lock->mutex);
 595   lock->want_to_write++;
 596   while (lock->write || lock->read_counter)
 597     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 598   lock->want_to_write--;
 599   lock->write = TRUE;
 600   g_static_mutex_unlock (&lock->mutex);
 601 }
 602
 603 gboolean g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 604 {
 605   gboolean ret_val = FALSE;
 606
 607   g_return_val_if_fail (lock, FALSE);
 608
 609   if (!g_threads_got_initialized)
 610     return TRUE;
 611
 612   g_static_mutex_lock (&lock->mutex);
 613   if (!lock->write && !lock->read_counter)
 614     {
 615       lock->write = TRUE;
 616       ret_val = TRUE;
 617     }
 618   g_static_mutex_unlock (&lock->mutex);
 619   return ret_val;
 620 }
 621
 622 void g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
 623 {
 624   g_return_if_fail (lock);
 625
 626   if (!g_threads_got_initialized)
 627     return;
 628
 629   g_static_mutex_lock (&lock->mutex);
 630   lock->write = FALSE;
 631   g_static_rw_lock_signal (lock);
 632   g_static_mutex_unlock (&lock->mutex);
 633 }
 634
 635 void g_static_rw_lock_free (GStaticRWLock* lock)
 636 {
 637   g_return_if_fail (lock);
 638
 639   if (lock->read_cond)
 640     g_cond_free (lock->read_cond);
 641   if (lock->write_cond)
 642     g_cond_free (lock->write_cond);
 643
 644 }
 645