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   G_THREAD_UF (thread_self, (&self));
 170
 171   if (g_system_thread_equal (self, mutex->owner))
 172     {
 173       mutex->depth++;
 174       return;
 175     }
 176   g_static_mutex_lock (&mutex->mutex);
 177   g_system_thread_assign (mutex->owner, self);
 178   mutex->depth = 1;
 179 }
 180
 181 gboolean
 182 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
 183 {
 184   GSystemThread self;
 185
 186   g_return_val_if_fail (mutex, FALSE);
 187
 188   G_THREAD_UF (thread_self, (&self));
 189
 190   if (g_system_thread_equal (self, mutex->owner))
 191     {
 192       mutex->depth++;
 193       return TRUE;
 194     }
 195
 196   if (!g_static_mutex_trylock (&mutex->mutex))
 197     return FALSE;
 198
 199   g_system_thread_assign (mutex->owner, self);
 200   mutex->depth = 1;
 201   return TRUE;
 202 }
 203
 204 void
 205 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
 206 {
 207   g_return_if_fail (mutex);
 208
 209   if (mutex->depth > 1)
 210     {
 211       mutex->depth--;
 212       return;
 213     }
 214   g_system_thread_assign (mutex->owner, zero_thread);
 215   g_static_mutex_unlock (&mutex->mutex);
 216 }
 217
 218 void
 219 g_static_rec_mutex_lock_full   (GStaticRecMutex *mutex,
 220                                 guint            depth)
 221 {
 222   g_return_if_fail (mutex);
 223
 224   g_static_mutex_lock (&mutex->mutex);
 225   G_THREAD_UF (thread_self, (&mutex->owner));
 226   mutex->depth = depth;
 227 }
 228
 229 guint
 230 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
 231 {
 232   gint depth = mutex->depth;
 233
 234   g_return_val_if_fail (mutex, 0);
 235
 236   g_system_thread_assign (mutex->owner, zero_thread);
 237   mutex->depth = 0;
 238   g_static_mutex_unlock (&mutex->mutex);
 239
 240   return depth;
 241 }
 242
 243
 244 gpointer
 245 g_static_private_get (GStaticPrivate *private_key)
 246 {
 247   return g_static_private_get_for_thread (private_key, g_thread_self ());
 248 }
 249
 250 gpointer
 251 g_static_private_get_for_thread (GStaticPrivate *private_key,
 252                                  GThread        *thread)
 253 {
 254   GArray *array;
 255   GRealThread *self = (GRealThread*) thread;
 256
 257   g_return_val_if_fail (thread, NULL);
 258
 259   array = self->private_data;
 260   if (!array)
 261     return NULL;
 262
 263   if (!private_key->index)
 264     return NULL;
 265   else if (private_key->index <= array->len)
 266     return g_array_index (array, GStaticPrivateNode, private_key->index - 1).data;
 267   else
 268     return NULL;
 269 }
 270
 271 void
 272 g_static_private_set (GStaticPrivate *private_key,
 273                       gpointer        data,
 274                       GDestroyNotify  notify)
 275 {
 276   g_static_private_set_for_thread (private_key, g_thread_self (),
 277                                    data, notify);
 278 }
 279
 280 void
 281 g_static_private_set_for_thread (GStaticPrivate *private_key,
 282                                  GThread        *thread,
 283                                  gpointer        data,
 284                                  GDestroyNotify  notify)
 285 {
 286   GArray *array;
 287   GRealThread *self =(GRealThread*) thread;
 288   static guint next_index = 0;
 289   GStaticPrivateNode *node;
 290
 291   g_return_if_fail (thread);
 292
 293   array = self->private_data;
 294   if (!array)
 295     {
 296       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 297       self->private_data = array;
 298     }
 299
 300   if (!private_key->index)
 301     {
 302       g_mutex_lock (g_thread_specific_mutex);
 303
 304       if (!private_key->index)
 305         private_key->index = ++next_index;
 306
 307       g_mutex_unlock (g_thread_specific_mutex);
 308     }
 309
 310   if (private_key->index > array->len)
 311     g_array_set_size (array, private_key->index);
 312
 313   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 314   if (node->destroy)
 315     {
 316       gpointer ddata = node->data;
 317       GDestroyNotify ddestroy = node->destroy;
 318
 319       node->data = data;
 320       node->destroy = notify;
 321
 322       ddestroy (ddata);
 323     }
 324   else
 325     {
 326       node->data = data;
 327       node->destroy = notify;
 328     }
 329 }
 330
 331 static void
 332 g_thread_cleanup (gpointer data)
 333 {
 334   if (data)
 335     {
 336       GRealThread* thread = data;
 337       if (thread->private_data)
 338         {
 339           GArray* array = thread->private_data;
 340           guint i;
 341
 342           for (i = 0; i < array->len; i++ )
 343             {
 344               GStaticPrivateNode *node =
 345                 &g_array_index (array, GStaticPrivateNode, i);
 346               if (node->destroy)
 347                 node->destroy (node->data);
 348             }
 349           g_array_free (array, TRUE);
 350         }
 351       /* We only free the thread structure, if it isn't joinable. If
 352          it is, the structure is freed in g_thread_join */
 353       if (!thread->thread.joinable)
 354         {
 355           /* Just to make sure, this isn't used any more */
 356           g_system_thread_assign (thread->system_thread, zero_thread);
 357           g_free (thread);
 358         }
 359     }
 360 }
 361
 362 static void
 363 g_thread_fail (void)
 364 {
 365   g_error ("The thread system is not yet initialized.");
 366 }
 367
 368 G_LOCK_DEFINE_STATIC (g_thread_create);
 369
 370 static void
 371 g_thread_create_proxy (gpointer data)
 372 {
 373   GRealThread* thread = data;
 374
 375   g_assert (data);
 376
 377   /* the lock makes sure, that thread->system_thread is written,
 378      before thread->func is called. See g_thread_create */
 379
 380   G_LOCK (g_thread_create);
 381   g_private_set (g_thread_specific_private, data);
 382   G_UNLOCK (g_thread_create);
 383
 384   thread->func (thread->arg);
 385 }
 386
 387 GThread*
 388 g_thread_create (GThreadFunc             thread_func,
 389                  gpointer                arg,
 390                  gulong                  stack_size,
 391                  gboolean                joinable,
 392                  gboolean                bound,
 393                  GThreadPriority         priority,
 394                  GError                **error)
 395 {
 396   GRealThread* result = g_new (GRealThread, 1);
 397   GError *local_error = NULL;
 398   g_return_val_if_fail (thread_func, NULL);
 399
 400   result->thread.joinable = joinable;
 401   result->thread.bound = bound;
 402   result->thread.priority = priority;
 403   result->func = thread_func;
 404   result->arg = arg;
 405   result->private_data = NULL;
 406   G_LOCK (g_thread_create);
 407   G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
 408                                stack_size, joinable, bound, priority,
 409                                &result->system_thread, &local_error));
 410   G_UNLOCK (g_thread_create);
 411
 412   if (local_error)
 413     {
 414       g_propagate_error (error, local_error);
 415       g_free (result);
 416       return NULL;
 417     }
 418
 419   return (GThread*) result;
 420 }
 421
 422 void
 423 g_thread_join (GThread* thread)
 424 {
 425   GRealThread* real = (GRealThread*) thread;
 426
 427
 428   g_return_if_fail (thread);
 429   g_return_if_fail (thread->joinable);
 430   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 431
 432   G_THREAD_UF (thread_join, (&real->system_thread));
 433
 434   /* Just to make sure, this isn't used any more */
 435   thread->joinable = 0;
 436   g_system_thread_assign (real->system_thread, zero_thread);
 437
 438   /* the thread structure for non-joinable threads is freed upon
 439      thread end. We free the memory here. This will leave loose end,
 440      if a joinable thread is not joined. */
 441
 442   g_free (thread);
 443 }
 444
 445 void
 446 g_thread_set_priority (GThread* thread,
 447                        GThreadPriority priority)
 448 {
 449   GRealThread* real = (GRealThread*) thread;
 450
 451   g_return_if_fail (thread);
 452   g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
 453
 454   thread->priority = priority;
 455   G_THREAD_CF (thread_set_priority, (void)0, (&real->system_thread, priority));
 456 }
 457
 458 GThread*
 459 g_thread_self()
 460 {
 461   GRealThread* thread = g_private_get (g_thread_specific_private);
 462
 463   if (!thread)
 464     {
 465       /* If no thread data is available, provide and set one.  This
 466          can happen for the main thread and for threads, that are not
 467          created by GLib. */
 468       thread = g_new (GRealThread, 1);
 469       thread->thread.joinable = FALSE; /* This is a save guess */
 470       thread->thread.bound = TRUE; /* This isn't important at all */
 471       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 472                                                              just a guess */
 473       thread->func = NULL;
 474       thread->arg = NULL;
 475       thread->private_data = NULL;
 476
 477       if (g_thread_supported ())
 478         G_THREAD_UF (thread_self, (&thread->system_thread));
 479
 480       g_private_set (g_thread_specific_private, thread);
 481     }
 482
 483   return (GThread*)thread;
 484 }
 485
 486 static void inline g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 487 {
 488   if (!*cond)
 489       *cond = g_cond_new ();
 490   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 491 }
 492
 493 static void inline g_static_rw_lock_signal (GStaticRWLock* lock)
 494 {
 495   if (lock->want_to_write && lock->write_cond)
 496     g_cond_signal (lock->write_cond);
 497   else if (lock->read_cond)
 498     g_cond_signal (lock->read_cond);
 499 }
 500
 501 void g_static_rw_lock_reader_lock (GStaticRWLock* lock)
 502 {
 503   g_return_if_fail (lock);
 504
 505   if (!g_threads_got_initialized)
 506     return;
 507
 508   g_static_mutex_lock (&lock->mutex);
 509   while (lock->write || lock->want_to_write)
 510     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 511   lock->read_counter++;
 512   g_static_mutex_unlock (&lock->mutex);
 513 }
 514
 515 gboolean g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
 516 {
 517   gboolean ret_val = FALSE;
 518
 519   g_return_val_if_fail (lock, FALSE);
 520
 521   if (!g_threads_got_initialized)
 522     return TRUE;
 523
 524   g_static_mutex_lock (&lock->mutex);
 525   if (!lock->write && !lock->want_to_write)
 526     {
 527       lock->read_counter++;
 528       ret_val = TRUE;
 529     }
 530   g_static_mutex_unlock (&lock->mutex);
 531   return ret_val;
 532 }
 533
 534 void g_static_rw_lock_reader_unlock  (GStaticRWLock* lock)
 535 {
 536   g_return_if_fail (lock);
 537
 538   if (!g_threads_got_initialized)
 539     return;
 540
 541   g_static_mutex_lock (&lock->mutex);
 542   lock->read_counter--;
 543   g_static_rw_lock_signal (lock);
 544   g_static_mutex_unlock (&lock->mutex);
 545 }
 546
 547 void g_static_rw_lock_writer_lock (GStaticRWLock* lock)
 548 {
 549   g_return_if_fail (lock);
 550
 551   if (!g_threads_got_initialized)
 552     return;
 553
 554   g_static_mutex_lock (&lock->mutex);
 555   lock->want_to_write++;
 556   while (lock->write || lock->read_counter)
 557     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 558   lock->want_to_write--;
 559   lock->write = TRUE;
 560   g_static_mutex_unlock (&lock->mutex);
 561 }
 562
 563 gboolean g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 564 {
 565   gboolean ret_val = FALSE;
 566
 567   g_return_val_if_fail (lock, FALSE);
 568
 569   if (!g_threads_got_initialized)
 570     return TRUE;
 571
 572   g_static_mutex_lock (&lock->mutex);
 573   if (!lock->write && !lock->read_counter)
 574     {
 575       lock->write = TRUE;
 576       ret_val = TRUE;
 577     }
 578   g_static_mutex_unlock (&lock->mutex);
 579   return ret_val;
 580 }
 581
 582 void g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
 583 {
 584   g_return_if_fail (lock);
 585
 586   if (!g_threads_got_initialized)
 587     return;
 588
 589   g_static_mutex_lock (&lock->mutex);
 590   lock->write = FALSE;
 591   g_static_rw_lock_signal (lock);
 592   g_static_mutex_unlock (&lock->mutex);
 593 }
 594
 595 void g_static_rw_lock_free (GStaticRWLock* lock)
 596 {
 597   g_return_if_fail (lock);
 598
 599   if (lock->read_cond)
 600     g_cond_free (lock->read_cond);
 601   if (lock->write_cond)
 602     g_cond_free (lock->write_cond);
 603
 604 }
 605