glib/gthread-win32.c

   1 /* GLIB - Library of useful routines for C programming
   2  * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
   3  *
   4  * gthread.c: solaris thread system implementation
   5  * Copyright 1998-2001 Sebastian Wilhelmi; University of Karlsruhe
   6  * Copyright 2001 Hans Breuer
   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 /* The GMutex and GCond implementations in this file are some of the
  32  * lowest-level code in GLib.  All other parts of GLib (messages,
  33  * memory, slices, etc) assume that they can freely use these facilities
  34  * without risking recursion.
  35  *
  36  * As such, these functions are NOT permitted to call any other part of
  37  * GLib.
  38  *
  39  * The thread manipulation functions (create, exit, join, etc.) have
  40  * more freedom -- they can do as they please.
  41  */
  42
  43 #include "config.h"
  44
  45 #include "glib.h"
  46 #include "gthread.h"
  47 #include "gthreadprivate.h"
  48 #include "gslice.h"
  49
  50 #include <windows.h>
  51
  52 #include <process.h>
  53 #include <stdlib.h>
  54 #include <stdio.h>
  55
  56 static void
  57 g_thread_abort (gint         status,
  58                 const gchar *function)
  59 {
  60   fprintf (stderr, "GLib (gthread-win32.c): Unexpected error from C library during '%s': %s.  Aborting.\n",
  61            strerror (status), function);
  62   abort ();
  63 }
  64
  65 /* Starting with Vista and Windows 2008, we have access to the
  66  * CONDITION_VARIABLE and SRWLock primatives on Windows, which are
  67  * pretty reasonable approximations of the primatives specified in
  68  * POSIX 2001 (pthread_cond_t and pthread_mutex_t respectively).
  69  *
  70  * Both of these types are structs containing a single pointer.  That
  71  * pointer is used as an atomic bitfield to support user-space mutexes
  72  * that only get the kernel involved in cases of contention (similar
  73  * to how futex()-based mutexes work on Linux).  The biggest advantage
  74  * of these new types is that they can be statically initialised to
  75  * zero.  That means that they are completely ABI compatible with our
  76  * GMutex and GCond APIs.
  77  *
  78  * Unfortunately, Windows XP lacks these facilities and GLib still
  79  * needs to support Windows XP.  Our approach here is as follows:
  80  *
  81  *   - avoid depending on structure declarations at compile-time by
  82  *     declaring our own GMutex and GCond strutures to be
  83  *     ABI-compatible with SRWLock and CONDITION_VARIABLE and using
  84  *     those instead
  85  *
  86  *   - avoid a hard dependency on the symbols used to manipulate these
  87  *     structures by doing a dynamic lookup of those symbols at
  88  *     runtime
  89  *
  90  *   - if the symbols are not available, emulate them using other
  91  *     primatives
  92  *
  93  * Using this approach also allows us to easily build a GLib that lacks
  94  * support for Windows XP or to remove this code entirely when XP is no
  95  * longer supported (end of line is currently April 8, 2014).
  96  */
  97 typedef struct
  98 {
  99   void     (__stdcall * CallThisOnThreadExit)        (void);              /* fake */
 100
 101   void     (__stdcall * InitializeSRWLock)           (gpointer lock);
 102   void     (__stdcall * DeleteSRWLock)               (gpointer lock);     /* fake */
 103   void     (__stdcall * AcquireSRWLockExclusive)     (gpointer lock);
 104   BOOLEAN  (__stdcall * TryAcquireSRWLockExclusive)  (gpointer lock);
 105   void     (__stdcall * ReleaseSRWLockExclusive)     (gpointer lock);
 106   void     (__stdcall * AcquireSRWLockShared)        (gpointer lock);
 107   BOOLEAN  (__stdcall * TryAcquireSRWLockShared)     (gpointer lock);
 108   void     (__stdcall * ReleaseSRWLockShared)        (gpointer lock);
 109
 110   void     (__stdcall * InitializeConditionVariable) (gpointer cond);
 111   void     (__stdcall * DeleteConditionVariable)     (gpointer cond);     /* fake */
 112   BOOL     (__stdcall * SleepConditionVariableSRW)   (gpointer cond,
 113                                                       gpointer lock,
 114                                                       DWORD    timeout,
 115                                                       ULONG    flags);
 116   void     (__stdcall * WakeAllConditionVariable)    (gpointer cond);
 117   void     (__stdcall * WakeConditionVariable)       (gpointer cond);
 118 } GThreadImplVtable;
 119
 120 static GThreadImplVtable g_thread_impl_vtable;
 121
 122 /* {{{1 GMutex */
 123 void
 124 g_mutex_init (GMutex *mutex)
 125 {
 126   g_thread_impl_vtable.InitializeSRWLock (mutex);
 127 }
 128
 129 void
 130 g_mutex_clear (GMutex *mutex)
 131 {
 132   if (g_thread_impl_vtable.DeleteSRWLock != NULL)
 133     g_thread_impl_vtable.DeleteSRWLock (mutex);
 134 }
 135
 136 void
 137 g_mutex_lock (GMutex *mutex)
 138 {
 139   g_thread_impl_vtable.AcquireSRWLockExclusive (mutex);
 140 }
 141
 142 gboolean
 143 g_mutex_trylock (GMutex *mutex)
 144 {
 145   return g_thread_impl_vtable.TryAcquireSRWLockExclusive (mutex);
 146 }
 147
 148 void
 149 g_mutex_unlock (GMutex *mutex)
 150 {
 151   g_thread_impl_vtable.ReleaseSRWLockExclusive (mutex);
 152 }
 153
 154 /* {{{1 GRecMutex */
 155
 156 static CRITICAL_SECTION *
 157 g_rec_mutex_impl_new (void)
 158 {
 159   CRITICAL_SECTION *cs;
 160
 161   cs = g_slice_new (CRITICAL_SECTION);
 162   InitializeCriticalSection (cs);
 163
 164   return cs;
 165 }
 166
 167 static void
 168 g_rec_mutex_impl_free (CRITICAL_SECTION *cs)
 169 {
 170   DeleteCriticalSection (cs);
 171   g_slice_free (CRITICAL_SECTION, cs);
 172 }
 173
 174 static CRITICAL_SECTION *
 175 g_rec_mutex_get_impl (GRecMutex *mutex)
 176 {
 177   CRITICAL_SECTION *impl = mutex->p;
 178
 179   if G_UNLIKELY (mutex->p == NULL)
 180     {
 181       impl = g_rec_mutex_impl_new ();
 182       if (InterlockedCompareExchangePointer (&mutex->p, impl, NULL) != NULL)
 183         g_rec_mutex_impl_free (impl);
 184       impl = mutex->p;
 185     }
 186
 187   return impl;
 188 }
 189
 190 void
 191 g_rec_mutex_init (GRecMutex *mutex)
 192 {
 193   mutex->p = g_rec_mutex_impl_new ();
 194 }
 195
 196 void
 197 g_rec_mutex_clear (GRecMutex *mutex)
 198 {
 199   g_rec_mutex_impl_free (mutex->p);
 200 }
 201
 202 void
 203 g_rec_mutex_lock (GRecMutex *mutex)
 204 {
 205   EnterCriticalSection (g_rec_mutex_get_impl (mutex));
 206 }
 207
 208 void
 209 g_rec_mutex_unlock (GRecMutex *mutex)
 210 {
 211   LeaveCriticalSection (mutex->p);
 212 }
 213
 214 gboolean
 215 g_rec_mutex_trylock (GRecMutex *mutex)
 216 {
 217   return TryEnterCriticalSection (g_rec_mutex_get_impl (mutex));
 218 }
 219
 220 /* {{{1 GRWLock */
 221
 222 void
 223 g_rw_lock_init (GRWLock *lock)
 224 {
 225   g_thread_impl_vtable.InitializeSRWLock (lock);
 226 }
 227
 228 void
 229 g_rw_lock_clear (GRWLock *lock)
 230 {
 231   if (g_thread_impl_vtable.DeleteSRWLock != NULL)
 232     g_thread_impl_vtable.DeleteSRWLock (lock);
 233 }
 234
 235 void
 236 g_rw_lock_writer_lock (GRWLock *lock)
 237 {
 238   g_thread_impl_vtable.AcquireSRWLockExclusive (lock);
 239 }
 240
 241 gboolean
 242 g_rw_lock_writer_trylock (GRWLock *lock)
 243 {
 244   return g_thread_impl_vtable.TryAcquireSRWLockExclusive (lock);
 245 }
 246
 247 void
 248 g_rw_lock_writer_unlock (GRWLock *lock)
 249 {
 250   g_thread_impl_vtable.ReleaseSRWLockExclusive (lock);
 251 }
 252
 253 void
 254 g_rw_lock_reader_lock (GRWLock *lock)
 255 {
 256   g_thread_impl_vtable.AcquireSRWLockShared (lock);
 257 }
 258
 259 gboolean
 260 g_rw_lock_reader_trylock (GRWLock *lock)
 261 {
 262   return g_thread_impl_vtable.TryAcquireSRWLockShared (lock);
 263 }
 264
 265 void
 266 g_rw_lock_reader_unlock (GRWLock *lock)
 267 {
 268   g_thread_impl_vtable.ReleaseSRWLockShared (lock);
 269 }
 270
 271 /* {{{1 GCond */
 272 void
 273 g_cond_init (GCond *cond)
 274 {
 275   g_thread_impl_vtable.InitializeConditionVariable (cond);
 276 }
 277
 278 void
 279 g_cond_clear (GCond *cond)
 280 {
 281   if (g_thread_impl_vtable.DeleteConditionVariable)
 282     g_thread_impl_vtable.DeleteConditionVariable (cond);
 283 }
 284
 285 void
 286 g_cond_signal (GCond *cond)
 287 {
 288   g_thread_impl_vtable.WakeConditionVariable (cond);
 289 }
 290
 291 void
 292 g_cond_broadcast (GCond *cond)
 293 {
 294   g_thread_impl_vtable.WakeAllConditionVariable (cond);
 295 }
 296
 297 void
 298 g_cond_wait (GCond  *cond,
 299              GMutex *entered_mutex)
 300 {
 301   g_thread_impl_vtable.SleepConditionVariableSRW (cond, entered_mutex, INFINITE, 0);
 302 }
 303
 304 gboolean
 305 g_cond_wait_until (GCond  *cond,
 306                    GMutex *entered_mutex,
 307                    gint64  end_time)
 308 {
 309   gint64 span;
 310
 311   span = end_time - g_get_monotonic_time ();
 312
 313   if G_UNLIKELY (span < 0)
 314     span = 0;
 315
 316   if G_UNLIKELY (span > G_GINT64_CONSTANT (1000) * G_MAXINT32)
 317     span = INFINITE;
 318
 319   return g_thread_impl_vtable.SleepConditionVariableSRW (cond, entered_mutex, span / 1000, 0);
 320 }
 321
 322 /* {{{1 GPrivate */
 323
 324 typedef struct _GPrivateDestructor GPrivateDestructor;
 325
 326 struct _GPrivateDestructor
 327 {
 328   DWORD               index;
 329   GDestroyNotify      notify;
 330   GPrivateDestructor *next;
 331 };
 332
 333 static GPrivateDestructor * volatile g_private_destructors;
 334 static CRITICAL_SECTION g_private_lock;
 335
 336 static DWORD
 337 g_private_get_impl (GPrivate *key)
 338 {
 339   DWORD impl = (DWORD) key->p;
 340
 341   if G_UNLIKELY (impl == 0)
 342     {
 343       EnterCriticalSection (&g_private_lock);
 344       impl = (DWORD) key->p;
 345       if (impl == 0)
 346         {
 347           GPrivateDestructor *destructor;
 348
 349           impl = TlsAlloc ();
 350
 351           if (impl == TLS_OUT_OF_INDEXES)
 352             g_thread_abort (0, "TlsAlloc");
 353
 354           if (key->notify != NULL)
 355             {
 356               destructor = malloc (sizeof (GPrivateDestructor));
 357               if G_UNLIKELY (destructor == NULL)
 358                 g_thread_abort (errno, "malloc");
 359               destructor->index = impl;
 360               destructor->notify = key->notify;
 361               destructor->next = g_private_destructors;
 362
 363               /* We need to do an atomic store due to the unlocked
 364                * access to the destructor list from the thread exit
 365                * function.
 366                *
 367                * It can double as a sanity check...
 368                */
 369               if (InterlockedCompareExchangePointer (&g_private_destructors, destructor,
 370                                                      destructor->next) != destructor->next)
 371                 g_thread_abort (0, "g_private_get_impl(1)");
 372             }
 373
 374           /* Ditto, due to the unlocked access on the fast path */
 375           if (InterlockedCompareExchangePointer (&key->p, impl, NULL) != NULL)
 376             g_thread_abort (0, "g_private_get_impl(2)");
 377         }
 378       LeaveCriticalSection (&g_private_lock);
 379     }
 380
 381   return impl;
 382 }
 383
 384 gpointer
 385 g_private_get (GPrivate *key)
 386 {
 387   return TlsGetValue (g_private_get_impl (key));
 388 }
 389
 390 void
 391 g_private_set (GPrivate *key,
 392                gpointer  value)
 393 {
 394   TlsSetValue (g_private_get_impl (key), value);
 395 }
 396
 397 void
 398 g_private_replace (GPrivate *key,
 399                    gpointer  value)
 400 {
 401   DWORD impl = g_private_get_impl (key);
 402   gpointer old;
 403
 404   old = TlsGetValue (impl);
 405   if (old && key->notify)
 406     key->notify (old);
 407   TlsSetValue (impl, value);
 408 }
 409
 410 /* {{{1 GThread */
 411
 412 #define win32_check_for_error(what) G_STMT_START{                       \
 413   if (!(what))                                                          \
 414     g_error ("file %s: line %d (%s): error %s during %s",               \
 415              __FILE__, __LINE__, G_STRFUNC,                             \
 416              g_win32_error_message (GetLastError ()), #what);           \
 417   }G_STMT_END
 418
 419 #define G_MUTEX_SIZE (sizeof (gpointer))
 420
 421 typedef BOOL (__stdcall *GTryEnterCriticalSectionFunc) (CRITICAL_SECTION *);
 422
 423 typedef struct
 424 {
 425   GRealThread thread;
 426
 427   GThreadFunc proxy;
 428   HANDLE      handle;
 429 } GThreadWin32;
 430
 431 void
 432 g_system_thread_free (GRealThread *thread)
 433 {
 434   GThreadWin32 *wt = (GThreadWin32 *) thread;
 435
 436   win32_check_for_error (CloseHandle (wt->handle));
 437   g_slice_free (GThreadWin32, wt);
 438 }
 439
 440 void
 441 g_system_thread_exit (void)
 442 {
 443   _endthreadex (0);
 444 }
 445
 446 static guint __stdcall
 447 g_thread_win32_proxy (gpointer data)
 448 {
 449   GThreadWin32 *self = data;
 450
 451   self->proxy (self);
 452
 453   g_system_thread_exit ();
 454
 455   g_assert_not_reached ();
 456
 457   return 0;
 458 }
 459
 460 GRealThread *
 461 g_system_thread_new (GThreadFunc   func,
 462                      gulong        stack_size,
 463                      GError      **error)
 464 {
 465   GThreadWin32 *thread;
 466   guint ignore;
 467
 468   thread = g_slice_new0 (GThreadWin32);
 469   thread->proxy = func;
 470
 471   thread->handle = (HANDLE) _beginthreadex (NULL, stack_size, g_thread_win32_proxy, thread, 0, &ignore);
 472
 473   if (thread->handle == NULL)
 474     {
 475       gchar *win_error = g_win32_error_message (GetLastError ());
 476       g_set_error (error, G_THREAD_ERROR, G_THREAD_ERROR_AGAIN,
 477                    "Error creating thread: %s", win_error);
 478       g_free (win_error);
 479       g_slice_free (GThreadWin32, thread);
 480       return NULL;
 481     }
 482
 483   return (GRealThread *) thread;
 484 }
 485
 486 void
 487 g_thread_yield (void)
 488 {
 489   Sleep(0);
 490 }
 491
 492 void
 493 g_system_thread_wait (GRealThread *thread)
 494 {
 495   GThreadWin32 *wt = (GThreadWin32 *) thread;
 496
 497   win32_check_for_error (WAIT_FAILED != WaitForSingleObject (wt->handle, INFINITE));
 498 }
 499
 500 void
 501 g_system_thread_set_name (const gchar *name)
 502 {
 503   /* FIXME: implement */
 504 }
 505
 506 /* {{{1 SRWLock and CONDITION_VARIABLE emulation (for Windows XP) */
 507
 508 static CRITICAL_SECTION g_thread_xp_lock;
 509 static DWORD            g_thread_xp_waiter_tls;
 510
 511 /* {{{2 GThreadWaiter utility class for CONDITION_VARIABLE emulation */
 512 typedef struct _GThreadXpWaiter GThreadXpWaiter;
 513 struct _GThreadXpWaiter
 514 {
 515   HANDLE                     event;
 516   volatile GThreadXpWaiter  *next;
 517   volatile GThreadXpWaiter **my_owner;
 518 };
 519
 520 static GThreadXpWaiter *
 521 g_thread_xp_waiter_get (void)
 522 {
 523   GThreadXpWaiter *waiter;
 524
 525   waiter = TlsGetValue (g_thread_xp_waiter_tls);
 526
 527   if G_UNLIKELY (waiter == NULL)
 528     {
 529       waiter = malloc (sizeof (GThreadXpWaiter));
 530       if (waiter == NULL)
 531         g_thread_abort (GetLastError (), "malloc");
 532       waiter->event = CreateEvent (0, FALSE, FALSE, NULL);
 533       if (waiter->event == NULL)
 534         g_thread_abort (GetLastError (), "CreateEvent");
 535       waiter->my_owner = NULL;
 536
 537       TlsSetValue (g_thread_xp_waiter_tls, waiter);
 538     }
 539
 540   return waiter;
 541 }
 542
 543 static void __stdcall
 544 g_thread_xp_CallThisOnThreadExit (void)
 545 {
 546   GThreadXpWaiter *waiter;
 547
 548   waiter = TlsGetValue (g_thread_xp_waiter_tls);
 549
 550   if (waiter != NULL)
 551     {
 552       TlsSetValue (g_thread_xp_waiter_tls, NULL);
 553       CloseHandle (waiter->event);
 554       free (waiter);
 555     }
 556 }
 557
 558 /* {{{2 SRWLock emulation */
 559 typedef struct
 560 {
 561   CRITICAL_SECTION  writer_lock;
 562   gboolean          ever_shared;    /* protected by writer_lock */
 563   gboolean          writer_locked;  /* protected by writer_lock */
 564
 565   /* below is only ever touched if ever_shared becomes true */
 566   CRITICAL_SECTION  atomicity;
 567   GThreadXpWaiter  *queued_writer; /* protected by atomicity lock */
 568   gint              num_readers;   /* protected by atomicity lock */
 569 } GThreadSRWLock;
 570
 571 static void __stdcall
 572 g_thread_xp_InitializeSRWLock (gpointer mutex)
 573 {
 574   *(GThreadSRWLock * volatile *) mutex = NULL;
 575 }
 576
 577 static void __stdcall
 578 g_thread_xp_DeleteSRWLock (gpointer mutex)
 579 {
 580   GThreadSRWLock *lock = *(GThreadSRWLock * volatile *) mutex;
 581
 582   if (lock)
 583     {
 584       if (lock->ever_shared)
 585         DeleteCriticalSection (&lock->atomicity);
 586
 587       DeleteCriticalSection (&lock->writer_lock);
 588       free (lock);
 589     }
 590 }
 591
 592 static GThreadSRWLock * __stdcall
 593 g_thread_xp_get_srwlock (GThreadSRWLock * volatile *lock)
 594 {
 595   GThreadSRWLock *result;
 596
 597   /* It looks like we're missing some barriers here, but this code only
 598    * ever runs on Windows XP, which in turn only ever runs on hardware
 599    * with a relatively rigid memory model.  The 'volatile' will take
 600    * care of the compiler.
 601    */
 602   result = *lock;
 603
 604   if G_UNLIKELY (result == NULL)
 605     {
 606       EnterCriticalSection (&g_thread_xp_lock);
 607
 608       /* Check again */
 609       result = *lock;
 610       if (result == NULL)
 611         {
 612           result = malloc (sizeof (GThreadSRWLock));
 613
 614           if (result == NULL)
 615             g_thread_abort (errno, "malloc");
 616
 617           InitializeCriticalSection (&result->writer_lock);
 618           result->writer_locked = FALSE;
 619           result->ever_shared = FALSE;
 620           *lock = result;
 621         }
 622
 623       LeaveCriticalSection (&g_thread_xp_lock);
 624     }
 625
 626   return result;
 627 }
 628
 629 static void __stdcall
 630 g_thread_xp_AcquireSRWLockExclusive (gpointer mutex)
 631 {
 632   GThreadSRWLock *lock = g_thread_xp_get_srwlock (mutex);
 633
 634   EnterCriticalSection (&lock->writer_lock);
 635
 636   /* CRITICAL_SECTION is reentrant, but SRWLock is not.
 637    * Detect the deadlock that would occur on later Windows version.
 638    */
 639   g_assert (!lock->writer_locked);
 640   lock->writer_locked = TRUE;
 641
 642   if (lock->ever_shared)
 643     {
 644       GThreadXpWaiter *waiter = NULL;
 645
 646       EnterCriticalSection (&lock->atomicity);
 647       if (lock->num_readers > 0)
 648         lock->queued_writer = waiter = g_thread_xp_waiter_get ();
 649       LeaveCriticalSection (&lock->atomicity);
 650
 651       if (waiter != NULL)
 652         WaitForSingleObject (waiter->event, INFINITE);
 653
 654       lock->queued_writer = NULL;
 655     }
 656 }
 657
 658 static BOOLEAN __stdcall
 659 g_thread_xp_TryAcquireSRWLockExclusive (gpointer mutex)
 660 {
 661   GThreadSRWLock *lock = g_thread_xp_get_srwlock (mutex);
 662
 663   if (!TryEnterCriticalSection (&lock->writer_lock))
 664     return FALSE;
 665
 666   /* CRITICAL_SECTION is reentrant, but SRWLock is not.
 667    * Ensure that this properly returns FALSE (as SRWLock would).
 668    */
 669   if G_UNLIKELY (lock->writer_locked)
 670     {
 671       LeaveCriticalSection (&lock->writer_lock);
 672       return FALSE;
 673     }
 674
 675   lock->writer_locked = TRUE;
 676
 677   if (lock->ever_shared)
 678     {
 679       gboolean available;
 680
 681       EnterCriticalSection (&lock->atomicity);
 682       available = lock->num_readers == 0;
 683       LeaveCriticalSection (&lock->atomicity);
 684
 685       if (!available)
 686         {
 687           LeaveCriticalSection (&lock->writer_lock);
 688           return FALSE;
 689         }
 690     }
 691
 692   return TRUE;
 693 }
 694
 695 static void __stdcall
 696 g_thread_xp_ReleaseSRWLockExclusive (gpointer mutex)
 697 {
 698   GThreadSRWLock *lock = *(GThreadSRWLock * volatile *) mutex;
 699
 700   lock->writer_locked = FALSE;
 701
 702   /* We need this until we fix some weird parts of GLib that try to
 703    * unlock freshly-allocated mutexes.
 704    */
 705   if (lock != NULL)
 706     LeaveCriticalSection (&lock->writer_lock);
 707 }
 708
 709 static void
 710 g_thread_xp_srwlock_become_reader (GThreadSRWLock *lock)
 711 {
 712   if G_UNLIKELY (!lock->ever_shared)
 713     {
 714       InitializeCriticalSection (&lock->atomicity);
 715       lock->queued_writer = NULL;
 716       lock->num_readers = 0;
 717
 718       lock->ever_shared = TRUE;
 719     }
 720
 721   EnterCriticalSection (&lock->atomicity);
 722   lock->num_readers++;
 723   LeaveCriticalSection (&lock->atomicity);
 724 }
 725
 726 static void __stdcall
 727 g_thread_xp_AcquireSRWLockShared (gpointer mutex)
 728 {
 729   GThreadSRWLock *lock = g_thread_xp_get_srwlock (mutex);
 730
 731   EnterCriticalSection (&lock->writer_lock);
 732
 733   /* See g_thread_xp_AcquireSRWLockExclusive */
 734   g_assert (!lock->writer_locked);
 735
 736   g_thread_xp_srwlock_become_reader (lock);
 737
 738   LeaveCriticalSection (&lock->writer_lock);
 739 }
 740
 741 static BOOLEAN __stdcall
 742 g_thread_xp_TryAcquireSRWLockShared (gpointer mutex)
 743 {
 744   GThreadSRWLock *lock = g_thread_xp_get_srwlock (mutex);
 745
 746   if (!TryEnterCriticalSection (&lock->writer_lock))
 747     return FALSE;
 748
 749   /* See g_thread_xp_AcquireSRWLockExclusive */
 750   if G_UNLIKELY (lock->writer_locked)
 751     {
 752       LeaveCriticalSection (&lock->writer_lock);
 753       return FALSE;
 754     }
 755
 756   g_thread_xp_srwlock_become_reader (lock);
 757
 758   LeaveCriticalSection (&lock->writer_lock);
 759
 760   return TRUE;
 761 }
 762
 763 static void __stdcall
 764 g_thread_xp_ReleaseSRWLockShared (gpointer mutex)
 765 {
 766   GThreadSRWLock *lock = g_thread_xp_get_srwlock (mutex);
 767
 768   EnterCriticalSection (&lock->atomicity);
 769
 770   lock->num_readers--;
 771
 772   if (lock->num_readers == 0 && lock->queued_writer)
 773     SetEvent (lock->queued_writer->event);
 774
 775   LeaveCriticalSection (&lock->atomicity);
 776 }
 777
 778 /* {{{2 CONDITION_VARIABLE emulation */
 779 typedef struct
 780 {
 781   volatile GThreadXpWaiter  *first;
 782   volatile GThreadXpWaiter **last_ptr;
 783 } GThreadXpCONDITION_VARIABLE;
 784
 785 static void __stdcall
 786 g_thread_xp_InitializeConditionVariable (gpointer cond)
 787 {
 788   *(GThreadXpCONDITION_VARIABLE * volatile *) cond = NULL;
 789 }
 790
 791 static void __stdcall
 792 g_thread_xp_DeleteConditionVariable (gpointer cond)
 793 {
 794   GThreadXpCONDITION_VARIABLE *cv = *(GThreadXpCONDITION_VARIABLE * volatile *) cond;
 795
 796   if (cv)
 797     free (cv);
 798 }
 799
 800 static GThreadXpCONDITION_VARIABLE * __stdcall
 801 g_thread_xp_get_condition_variable (GThreadXpCONDITION_VARIABLE * volatile *cond)
 802 {
 803   GThreadXpCONDITION_VARIABLE *result;
 804
 805   /* It looks like we're missing some barriers here, but this code only
 806    * ever runs on Windows XP, which in turn only ever runs on hardware
 807    * with a relatively rigid memory model.  The 'volatile' will take
 808    * care of the compiler.
 809    */
 810   result = *cond;
 811
 812   if G_UNLIKELY (result == NULL)
 813     {
 814       result = malloc (sizeof (GThreadXpCONDITION_VARIABLE));
 815
 816       if (result == NULL)
 817         g_thread_abort (errno, "malloc");
 818
 819       result->first = NULL;
 820       result->last_ptr = &result->first;
 821
 822       if (InterlockedCompareExchangePointer (cond, result, NULL) != NULL)
 823         {
 824           free (result);
 825           result = *cond;
 826         }
 827     }
 828
 829   return result;
 830 }
 831
 832 static BOOL __stdcall
 833 g_thread_xp_SleepConditionVariableSRW (gpointer cond,
 834                                        gpointer mutex,
 835                                        DWORD    timeout,
 836                                        ULONG    flags)
 837 {
 838   GThreadXpCONDITION_VARIABLE *cv = g_thread_xp_get_condition_variable (cond);
 839   GThreadXpWaiter *waiter = g_thread_xp_waiter_get ();
 840   DWORD status;
 841
 842   waiter->next = NULL;
 843
 844   EnterCriticalSection (&g_thread_xp_lock);
 845   waiter->my_owner = cv->last_ptr;
 846   *cv->last_ptr = waiter;
 847   cv->last_ptr = &waiter->next;
 848   LeaveCriticalSection (&g_thread_xp_lock);
 849
 850   g_mutex_unlock (mutex);
 851   status = WaitForSingleObject (waiter->event, timeout);
 852
 853   if (status != WAIT_TIMEOUT && status != WAIT_OBJECT_0)
 854     g_thread_abort (GetLastError (), "WaitForSingleObject");
 855   g_mutex_lock (mutex);
 856
 857   if (status == WAIT_TIMEOUT)
 858     {
 859       EnterCriticalSection (&g_thread_xp_lock);
 860       if (waiter->my_owner)
 861         {
 862           if (waiter->next)
 863             waiter->next->my_owner = waiter->my_owner;
 864           else
 865             cv->last_ptr = waiter->my_owner;
 866           *waiter->my_owner = waiter->next;
 867           waiter->my_owner = NULL;
 868         }
 869       LeaveCriticalSection (&g_thread_xp_lock);
 870     }
 871
 872   return status == WAIT_OBJECT_0;
 873 }
 874
 875 static void __stdcall
 876 g_thread_xp_WakeConditionVariable (gpointer cond)
 877 {
 878   GThreadXpCONDITION_VARIABLE *cv = g_thread_xp_get_condition_variable (cond);
 879   volatile GThreadXpWaiter *waiter;
 880
 881   EnterCriticalSection (&g_thread_xp_lock);
 882
 883   waiter = cv->first;
 884   if (waiter != NULL)
 885     {
 886       waiter->my_owner = NULL;
 887       cv->first = waiter->next;
 888       if (cv->first != NULL)
 889         cv->first->my_owner = &cv->first;
 890       else
 891         cv->last_ptr = &cv->first;
 892     }
 893
 894   if (waiter != NULL)
 895     SetEvent (waiter->event);
 896
 897   LeaveCriticalSection (&g_thread_xp_lock);
 898 }
 899
 900 static void __stdcall
 901 g_thread_xp_WakeAllConditionVariable (gpointer cond)
 902 {
 903   GThreadXpCONDITION_VARIABLE *cv = g_thread_xp_get_condition_variable (cond);
 904   volatile GThreadXpWaiter *waiter;
 905
 906   EnterCriticalSection (&g_thread_xp_lock);
 907
 908   waiter = cv->first;
 909   cv->first = NULL;
 910   cv->last_ptr = &cv->first;
 911
 912   while (waiter != NULL)
 913     {
 914       volatile GThreadXpWaiter *next;
 915
 916       next = waiter->next;
 917       SetEvent (waiter->event);
 918       waiter->my_owner = NULL;
 919       waiter = next;
 920     }
 921
 922   LeaveCriticalSection (&g_thread_xp_lock);
 923 }
 924
 925 /* {{{2 XP Setup */
 926 static void
 927 g_thread_xp_init (void)
 928 {
 929   static const GThreadImplVtable g_thread_xp_impl_vtable = {
 930     g_thread_xp_CallThisOnThreadExit,
 931     g_thread_xp_InitializeSRWLock,
 932     g_thread_xp_DeleteSRWLock,
 933     g_thread_xp_AcquireSRWLockExclusive,
 934     g_thread_xp_TryAcquireSRWLockExclusive,
 935     g_thread_xp_ReleaseSRWLockExclusive,
 936     g_thread_xp_AcquireSRWLockShared,
 937     g_thread_xp_TryAcquireSRWLockShared,
 938     g_thread_xp_ReleaseSRWLockShared,
 939     g_thread_xp_InitializeConditionVariable,
 940     g_thread_xp_DeleteConditionVariable,
 941     g_thread_xp_SleepConditionVariableSRW,
 942     g_thread_xp_WakeAllConditionVariable,
 943     g_thread_xp_WakeConditionVariable
 944   };
 945
 946   InitializeCriticalSection (&g_thread_xp_lock);
 947   g_thread_xp_waiter_tls = TlsAlloc ();
 948
 949   g_thread_impl_vtable = g_thread_xp_impl_vtable;
 950 }
 951
 952 /* {{{1 Epilogue */
 953
 954 static gboolean
 955 g_thread_lookup_native_funcs (void)
 956 {
 957   GThreadImplVtable native_vtable = { 0, };
 958   HMODULE kernel32;
 959
 960   kernel32 = GetModuleHandle ("KERNEL32.DLL");
 961
 962   if (kernel32 == NULL)
 963     return FALSE;
 964
 965 #define GET_FUNC(name) if ((native_vtable.name = (void *) GetProcAddress (kernel32, #name)) == NULL) return FALSE
 966   GET_FUNC(InitializeSRWLock);
 967   GET_FUNC(AcquireSRWLockExclusive);
 968   GET_FUNC(TryAcquireSRWLockExclusive);
 969   GET_FUNC(ReleaseSRWLockExclusive);
 970   GET_FUNC(AcquireSRWLockShared);
 971   GET_FUNC(TryAcquireSRWLockShared);
 972   GET_FUNC(ReleaseSRWLockShared);
 973
 974   GET_FUNC(InitializeConditionVariable);
 975   GET_FUNC(SleepConditionVariableSRW);
 976   GET_FUNC(WakeAllConditionVariable);
 977   GET_FUNC(WakeConditionVariable);
 978 #undef GET_FUNC
 979
 980   g_thread_impl_vtable = native_vtable;
 981
 982   return TRUE;
 983 }
 984
 985 G_GNUC_INTERNAL void
 986 g_thread_win32_init (void)
 987 {
 988   if (!g_thread_lookup_native_funcs ())
 989     g_thread_xp_init ();
 990
 991   InitializeCriticalSection (&g_private_lock);
 992 }
 993
 994 G_GNUC_INTERNAL void
 995 g_thread_win32_thread_detach (void)
 996 {
 997   gboolean dtors_called;
 998
 999   do
1000     {
1001       GPrivateDestructor *dtor;
1002
1003       /* We go by the POSIX book on this one.
1004        *
1005        * If we call a destructor then there is a chance that some new
1006        * TLS variables got set by code called in that destructor.
1007        *
1008        * Loop until nothing is left.
1009        */
1010       dtors_called = FALSE;
1011
1012       for (dtor = g_private_destructors; dtor; dtor = dtor->next)
1013         {
1014           gpointer value;
1015
1016           value = TlsGetValue (dtor->index);
1017           if (value != NULL && dtor->notify != NULL)
1018             {
1019               /* POSIX says to clear this before the call */
1020               TlsSetValue (dtor->index, NULL);
1021               dtor->notify (value);
1022               dtors_called = TRUE;
1023             }
1024         }
1025     }
1026   while (dtors_called);
1027
1028   if (g_thread_impl_vtable.CallThisOnThreadExit)
1029     g_thread_impl_vtable.CallThisOnThreadExit ();
1030 }
1031
1032 /* vim:set foldmethod=marker: */