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 Library 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  * Library General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Library 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 1997-1999.  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 typedef struct _GRealThread GRealThread;
  43
  44 struct  _GRealThread
  45 {
  46   GThread thread;
  47   GThreadFunc func;
  48   gpointer arg;
  49   gpointer system_thread;
  50   gpointer private_data;
  51 };
  52
  53 typedef struct _GStaticPrivateNode GStaticPrivateNode;
  54
  55 struct _GStaticPrivateNode
  56 {
  57   gpointer       data;
  58   GDestroyNotify destroy;
  59 };
  60
  61 static void g_thread_cleanup (gpointer data);
  62 static void g_thread_fail (void);
  63
  64 /* Global variables */
  65
  66 gboolean g_thread_use_default_impl = TRUE;
  67 gboolean g_threads_got_initialized = FALSE;
  68
  69 #if defined(G_OS_WIN32) && defined(__GNUC__)
  70 __declspec(dllexport)
  71 #endif
  72 GThreadFunctions g_thread_functions_for_glib_use = {
  73   (GMutex*(*)())g_thread_fail,                 /* mutex_new */
  74   NULL,                                        /* mutex_lock */
  75   NULL,                                        /* mutex_trylock */
  76   NULL,                                        /* mutex_unlock */
  77   NULL,                                        /* mutex_free */
  78   (GCond*(*)())g_thread_fail,                  /* cond_new */
  79   NULL,                                        /* cond_signal */
  80   NULL,                                        /* cond_broadcast */
  81   NULL,                                        /* cond_wait */
  82   NULL,                                        /* cond_timed_wait  */
  83   NULL,                                        /* cond_free */
  84   (GPrivate*(*)(GDestroyNotify))g_thread_fail, /* private_new */
  85   NULL,                                        /* private_get */
  86   NULL,                                        /* private_set */
  87   (gpointer(*)(GThreadFunc, gpointer, gulong,
  88                gboolean, gboolean,
  89                GThreadPriority))g_thread_fail, /* thread_create */
  90   NULL,                                        /* thread_yield */
  91   NULL,                                        /* thread_join */
  92   NULL,                                        /* thread_exit */
  93   NULL,                                        /* thread_set_priority */
  94   NULL                                         /* thread_self */
  95 };
  96
  97 /* Local data */
  98
  99 static GMutex   *g_mutex_protect_static_mutex_allocation = NULL;
 100 static GMutex   *g_thread_specific_mutex = NULL;
 101 static GPrivate *g_thread_specific_private = NULL;
 102
 103 /* This must be called only once, before any threads are created.
 104  * It will only be called from g_thread_init() in -lgthread.
 105  */
 106 void
 107 g_mutex_init (void)
 108 {
 109   gpointer private_old;
 110
 111   /* We let the main thread (the one that calls g_thread_init) inherit
 112    * the data, that it set before calling g_thread_init
 113    */
 114   private_old = g_thread_specific_private;
 115
 116   g_thread_specific_private = g_private_new (g_thread_cleanup);
 117
 118   /* we can not use g_private_set here, as g_threads_got_initialized is not
 119    * yet set TRUE, whereas the private_set function is already set.
 120    */
 121   g_thread_functions_for_glib_use.private_set (g_thread_specific_private,
 122                                                private_old);
 123
 124   g_mutex_protect_static_mutex_allocation = g_mutex_new();
 125   g_thread_specific_mutex = g_mutex_new();
 126
 127 }
 128
 129 GMutex *
 130 g_static_mutex_get_mutex_impl (GMutex** mutex)
 131 {
 132   if (!g_thread_supported ())
 133     return NULL;
 134
 135   g_assert (g_mutex_protect_static_mutex_allocation);
 136
 137   g_mutex_lock (g_mutex_protect_static_mutex_allocation);
 138
 139   if (!(*mutex))
 140     *mutex = g_mutex_new();
 141
 142   g_mutex_unlock (g_mutex_protect_static_mutex_allocation);
 143
 144   return *mutex;
 145 }
 146
 147 #ifndef g_static_rec_mutex_lock
 148 /* That means, that g_static_rec_mutex_lock is not defined to be
 149  * g_static_mutex_lock, we have to provide an implementation ourselves.
 150  */
 151 void
 152 g_static_rec_mutex_lock (GStaticRecMutex* mutex)
 153 {
 154   guint counter = GPOINTER_TO_UINT (g_static_private_get (&mutex->counter));
 155   if (counter == 0)
 156     {
 157       g_static_mutex_lock (&mutex->mutex);
 158     }
 159   counter++;
 160   g_static_private_set (&mutex->counter, GUINT_TO_POINTER (counter), NULL);
 161 }
 162
 163 gboolean
 164 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
 165 {
 166   guint counter = GPOINTER_TO_UINT (g_static_private_get (&mutex->counter));
 167   if (counter == 0)
 168     {
 169       if (!g_static_mutex_trylock (&mutex->mutex)) return FALSE;
 170     }
 171   counter++;
 172   g_static_private_set (&mutex->counter, GUINT_TO_POINTER (counter), NULL);
 173   return TRUE;
 174 }
 175
 176 void
 177 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
 178 {
 179   guint counter = GPOINTER_TO_UINT (g_static_private_get (&mutex->counter));
 180   if (counter == 1)
 181     {
 182       g_static_mutex_unlock (&mutex->mutex);
 183     }
 184   counter--;
 185   g_static_private_set (&mutex->counter, GUINT_TO_POINTER (counter), NULL);
 186 }
 187 #endif /* g_static_rec_mutex_lock */
 188
 189 gpointer
 190 g_static_private_get (GStaticPrivate *private_key)
 191 {
 192   return g_static_private_get_for_thread (private_key, g_thread_self ());
 193 }
 194
 195 gpointer
 196 g_static_private_get_for_thread (GStaticPrivate *private_key,
 197                                  GThread        *thread)
 198 {
 199   GArray *array;
 200   GRealThread *self = (GRealThread*) thread;
 201
 202   g_return_val_if_fail (thread, NULL);
 203
 204   array = self->private_data;
 205   if (!array)
 206     return NULL;
 207
 208   if (!private_key->index)
 209     return NULL;
 210   else if (private_key->index <= array->len)
 211     return g_array_index (array, GStaticPrivateNode, private_key->index - 1).data;
 212   else
 213     return NULL;
 214 }
 215
 216 void
 217 g_static_private_set (GStaticPrivate *private_key,
 218                       gpointer        data,
 219                       GDestroyNotify  notify)
 220 {
 221   g_static_private_set_for_thread (private_key, g_thread_self (),
 222                                    data, notify);
 223 }
 224
 225 void
 226 g_static_private_set_for_thread (GStaticPrivate *private_key,
 227                                  GThread        *thread,
 228                                  gpointer        data,
 229                                  GDestroyNotify  notify)
 230 {
 231   GArray *array;
 232   GRealThread *self =(GRealThread*) thread;
 233   static guint next_index = 0;
 234   GStaticPrivateNode *node;
 235
 236   g_return_if_fail (thread);
 237
 238   array = self->private_data;
 239   if (!array)
 240     {
 241       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 242       self->private_data = array;
 243     }
 244
 245   if (!private_key->index)
 246     {
 247       g_mutex_lock (g_thread_specific_mutex);
 248
 249       if (!private_key->index)
 250         private_key->index = ++next_index;
 251
 252       g_mutex_unlock (g_thread_specific_mutex);
 253     }
 254
 255   if (private_key->index > array->len)
 256     g_array_set_size (array, private_key->index);
 257
 258   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 259   if (node->destroy)
 260     {
 261       gpointer ddata = node->data;
 262       GDestroyNotify ddestroy = node->destroy;
 263
 264       node->data = data;
 265       node->destroy = notify;
 266
 267       ddestroy (ddata);
 268     }
 269   else
 270     {
 271       node->data = data;
 272       node->destroy = notify;
 273     }
 274 }
 275
 276 static void
 277 g_thread_cleanup (gpointer data)
 278 {
 279   if (data)
 280     {
 281       GRealThread* thread = data;
 282       if (thread->private_data)
 283         {
 284           GArray* array = thread->private_data;
 285           guint i;
 286
 287           for (i = 0; i < array->len; i++ )
 288             {
 289               GStaticPrivateNode *node =
 290                 &g_array_index (array, GStaticPrivateNode, i);
 291               if (node->destroy)
 292                 node->destroy (node->data);
 293             }
 294           g_array_free (array, TRUE);
 295         }
 296       /* We only free the thread structure, if it isn't joinable. If
 297          it is, the structure is freed in g_thread_join */
 298       if (!thread->thread.joinable)
 299         {
 300           /* Just to make sure, this isn't used any more */
 301           thread->system_thread = NULL;
 302           g_free (thread);
 303         }
 304     }
 305 }
 306
 307 static void
 308 g_thread_fail (void)
 309 {
 310   g_error ("The thread system is not yet initialized.");
 311 }
 312
 313 G_LOCK_DEFINE_STATIC (g_thread_create);
 314
 315 static void
 316 g_thread_create_proxy (gpointer data)
 317 {
 318   GRealThread* thread = data;
 319
 320   g_assert (data);
 321
 322   /* the lock makes sure, that thread->system_thread is written,
 323      before thread->func is called. See g_thread_create */
 324
 325   G_LOCK (g_thread_create);
 326   g_private_set (g_thread_specific_private, data);
 327   G_UNLOCK (g_thread_create);
 328
 329   thread->func (thread->arg);
 330 }
 331
 332 GThread*
 333 g_thread_create (GThreadFunc             thread_func,
 334                  gpointer                arg,
 335                  gulong                  stack_size,
 336                  gboolean                joinable,
 337                  gboolean                bound,
 338                  GThreadPriority         priority)
 339 {
 340   GRealThread* result = g_new0 (GRealThread,1);
 341
 342   g_return_val_if_fail (thread_func, NULL);
 343
 344   result->thread.joinable = joinable;
 345   result->thread.bound = bound;
 346   result->thread.priority = priority;
 347   result->func = thread_func;
 348   result->arg = arg;
 349   G_LOCK (g_thread_create);
 350   result->system_thread = G_THREAD_UF (thread_create, (g_thread_create_proxy,
 351                                                        result, stack_size,
 352                                                        joinable, bound,
 353                                                        priority));
 354   G_UNLOCK (g_thread_create);
 355   return (GThread*) result;
 356 }
 357
 358 void
 359 g_thread_join (GThread* thread)
 360 {
 361   GRealThread* real = (GRealThread*) thread;
 362
 363   g_return_if_fail (thread);
 364   g_return_if_fail (thread->joinable);
 365   g_return_if_fail (real->system_thread);
 366
 367   G_THREAD_UF (thread_join, (real->system_thread));
 368
 369   /* Just to make sure, this isn't used any more */
 370   thread->joinable = 0;
 371   real->system_thread = NULL;
 372
 373   /* the thread structure for non-joinable threads is freed upon
 374      thread end. We free the memory here. This will leave loose end,
 375      if a joinable thread is not joined. */
 376
 377   g_free (thread);
 378 }
 379
 380 void
 381 g_thread_set_priority (GThread* thread,
 382                        GThreadPriority priority)
 383 {
 384   GRealThread* real = (GRealThread*) thread;
 385
 386   g_return_if_fail (thread);
 387   g_return_if_fail (real->system_thread);
 388
 389   thread->priority = priority;
 390   G_THREAD_CF (thread_set_priority, (void)0, (real->system_thread, priority));
 391 }
 392
 393 GThread*
 394 g_thread_self()
 395 {
 396   GRealThread* thread = g_private_get (g_thread_specific_private);
 397
 398   if (!thread)
 399     {
 400       /* If no thread data is available, provide and set one.  This
 401          can happen for the main thread and for threads, that are not
 402          created by glib. */
 403       thread = g_new (GRealThread,1);
 404       thread->thread.joinable = FALSE; /* This is a save guess */
 405       thread->thread.bound = TRUE; /* This isn't important at all */
 406       thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
 407                                                              just a guess */
 408       thread->func = NULL;
 409       thread->arg = NULL;
 410       thread->system_thread = NULL;
 411       thread->private_data = NULL;
 412       g_private_set (g_thread_specific_private, thread);
 413     }
 414
 415   if (g_thread_supported () && !thread->system_thread)
 416     {
 417       thread->system_thread = g_thread_functions_for_glib_use.thread_self();
 418     }
 419
 420   return (GThread*)thread;
 421 }
 422
 423 static void inline g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
 424 {
 425   if (!*cond)
 426       *cond = g_cond_new ();
 427   g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
 428 }
 429
 430 static void inline g_static_rw_lock_signal (GStaticRWLock* lock)
 431 {
 432   if (lock->want_to_write && lock->write_cond)
 433     g_cond_signal (lock->write_cond);
 434   else if (lock->read_cond)
 435     g_cond_signal (lock->read_cond);
 436 }
 437
 438 void g_static_rw_lock_reader_lock (GStaticRWLock* lock)
 439 {
 440   g_return_if_fail (lock);
 441
 442   if (!g_threads_got_initialized)
 443     return;
 444
 445   g_static_mutex_lock (&lock->mutex);
 446   while (lock->write || lock->want_to_write)
 447     g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
 448   lock->read_counter++;
 449   g_static_mutex_unlock (&lock->mutex);
 450 }
 451
 452 gboolean g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
 453 {
 454   gboolean ret_val = FALSE;
 455
 456   g_return_val_if_fail (lock, FALSE);
 457
 458   if (!g_threads_got_initialized)
 459     return TRUE;
 460
 461   g_static_mutex_lock (&lock->mutex);
 462   if (!lock->write && !lock->want_to_write)
 463     {
 464       lock->read_counter++;
 465       ret_val = TRUE;
 466     }
 467   g_static_mutex_unlock (&lock->mutex);
 468   return ret_val;
 469 }
 470
 471 void g_static_rw_lock_reader_unlock  (GStaticRWLock* lock)
 472 {
 473   g_return_if_fail (lock);
 474
 475   if (!g_threads_got_initialized)
 476     return;
 477
 478   g_static_mutex_lock (&lock->mutex);
 479   lock->read_counter--;
 480   g_static_rw_lock_signal (lock);
 481   g_static_mutex_unlock (&lock->mutex);
 482 }
 483
 484 void g_static_rw_lock_writer_lock (GStaticRWLock* lock)
 485 {
 486   g_return_if_fail (lock);
 487
 488   if (!g_threads_got_initialized)
 489     return;
 490
 491   g_static_mutex_lock (&lock->mutex);
 492   lock->want_to_write++;
 493   while (lock->write || lock->read_counter)
 494     g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
 495   lock->want_to_write--;
 496   lock->write = TRUE;
 497   g_static_mutex_unlock (&lock->mutex);
 498 }
 499
 500 gboolean g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
 501 {
 502   gboolean ret_val = FALSE;
 503
 504   g_return_val_if_fail (lock, FALSE);
 505
 506   if (!g_threads_got_initialized)
 507     return TRUE;
 508
 509   g_static_mutex_lock (&lock->mutex);
 510   if (!lock->write && !lock->read_counter)
 511     {
 512       lock->write = TRUE;
 513       ret_val = TRUE;
 514     }
 515   g_static_mutex_unlock (&lock->mutex);
 516   return ret_val;
 517 }
 518
 519 void g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
 520 {
 521   g_return_if_fail (lock);
 522
 523   if (!g_threads_got_initialized)
 524     return;
 525
 526   g_static_mutex_lock (&lock->mutex);
 527   lock->write = FALSE;
 528   g_static_rw_lock_signal (lock);
 529   g_static_mutex_unlock (&lock->mutex);
 530 }
 531
 532 void g_static_rw_lock_free (GStaticRWLock* lock)
 533 {
 534   g_return_if_fail (lock);
 535
 536   if (lock->read_cond)
 537     g_cond_free (lock->read_cond);
 538   if (lock->write_cond)
 539     g_cond_free (lock->write_cond);
 540
 541 }
 542