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