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, see <http://www.gnu.org/licenses/>.
  20  */
  21
  22 /*
  23  * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
  24  * file for a list of people on the GLib Team.  See the ChangeLog
  25  * files for a list of changes.  These files are distributed with
  26  * GLib at ftp://ftp.gtk.org/pub/gtk/.
  27  */
  28
  29 /* The GMutex and GCond implementations in this file are some of the
  30  * lowest-level code in GLib.  All other parts of GLib (messages,
  31  * memory, slices, etc) assume that they can freely use these facilities
  32  * without risking recursion.
  33  *
  34  * As such, these functions are NOT permitted to call any other part of
  35  * GLib.
  36  *
  37  * The thread manipulation functions (create, exit, join, etc.) have
  38  * more freedom -- they can do as they please.
  39  */
  40
  41 #include "config.h"
  42
  43 #include "glib.h"
  44 #include "glib-init.h"
  45 #include "gthread.h"
  46 #include "gthreadprivate.h"
  47 #include "gslice.h"
  48
  49 #include <windows.h>
  50
  51 #include <process.h>
  52 #include <stdlib.h>
  53 #include <stdio.h>
  54
  55 static void
  56 g_thread_abort (gint         status,
  57                 const gchar *function)
  58 {
  59   fprintf (stderr, "GLib (gthread-win32.c): Unexpected error from C library during '%s': %s.  Aborting.\n",
  60            strerror (status), function);
  61   abort ();
  62 }
  63
  64 /* Starting with Vista and Windows 2008, we have access to the
  65  * CONDITION_VARIABLE and SRWLock primatives on Windows, which are
  66  * pretty reasonable approximations of the primatives specified in
  67  * POSIX 2001 (pthread_cond_t and pthread_mutex_t respectively).
  68  *
  69  * Both of these types are structs containing a single pointer.  That
  70  * pointer is used as an atomic bitfield to support user-space mutexes
  71  * that only get the kernel involved in cases of contention (similar
  72  * to how futex()-based mutexes work on Linux).  The biggest advantage
  73  * of these new types is that they can be statically initialised to
  74  * zero.  That means that they are completely ABI compatible with our
  75  * GMutex and GCond APIs.
  76  *
  77  * Unfortunately, Windows XP lacks these facilities and GLib still
  78  * needs to support Windows XP.  Our approach here is as follows:
  79  *
  80  *   - avoid depending on structure declarations at compile-time by
  81  *     declaring our own GMutex and GCond strutures to be
  82  *     ABI-compatible with SRWLock and CONDITION_VARIABLE and using
  83  *     those instead
  84  *
  85  *   - avoid a hard dependency on the symbols used to manipulate these
  86  *     structures by doing a dynamic lookup of those symbols at
  87  *     runtime
  88  *
  89  *   - if the symbols are not available, emulate them using other
  90  *     primatives
  91  *
  92  * Using this approach also allows us to easily build a GLib that lacks
  93  * support for Windows XP or to remove this code entirely when XP is no
  94  * longer supported (end of line is currently April 8, 2014).
  95  */
  96 typedef struct
  97 {
  98   void     (__stdcall * CallThisOnThreadExit)        (void);              /* fake */
  99
 100   void     (__stdcall * InitializeSRWLock)           (gpointer lock);
 101   void     (__stdcall * DeleteSRWLock)               (gpointer lock);     /* fake */
 102   void     (__stdcall * AcquireSRWLockExclusive)     (gpointer lock);
 103   BOOLEAN  (__stdcall * TryAcquireSRWLockExclusive)  (gpointer lock);
 104   void     (__stdcall * ReleaseSRWLockExclusive)     (gpointer lock);
 105   void     (__stdcall * AcquireSRWLockShared)        (gpointer lock);
 106   BOOLEAN  (__stdcall * TryAcquireSRWLockShared)     (gpointer lock);
 107   void     (__stdcall * ReleaseSRWLockShared)        (gpointer lock);
 108
 109   void     (__stdcall * InitializeConditionVariable) (gpointer cond);
 110   void     (__stdcall * DeleteConditionVariable)     (gpointer cond);     /* fake */
 111   BOOL     (__stdcall * SleepConditionVariableSRW)   (gpointer cond,
 112                                                       gpointer lock,
 113                                                       DWORD    timeout,
 114                                                       ULONG    flags);
 115   void     (__stdcall * WakeAllConditionVariable)    (gpointer cond);
 116   void     (__stdcall * WakeConditionVariable)       (gpointer cond);
 117 } GThreadImplVtable;
 118
 119 static GThreadImplVtable g_thread_impl_vtable;
 120
 121 /* {{{1 GMutex */
 122 void
 123 g_mutex_init (GMutex *mutex)
 124 {
 125   g_thread_impl_vtable.InitializeSRWLock (mutex);
 126 }
 127
 128 void
 129 g_mutex_clear (GMutex *mutex)
 130 {
 131   if (g_thread_impl_vtable.DeleteSRWLock != NULL)
 132     g_thread_impl_vtable.DeleteSRWLock (mutex);
 133 }
 134
 135 void
 136 g_mutex_lock (GMutex *mutex)
 137 {
 138   g_thread_impl_vtable.AcquireSRWLockExclusive (mutex);
 139 }
 140
 141 gboolean
 142 g_mutex_trylock (GMutex *mutex)
 143 {
 144   return g_thread_impl_vtable.TryAcquireSRWLockExclusive (mutex);
 145 }
 146
 147 void
 148 g_mutex_unlock (GMutex *mutex)
 149 {
 150   g_thread_impl_vtable.ReleaseSRWLockExclusive (mutex);
 151 }
 152
 153 /* {{{1 GRecMutex */
 154
 155 static CRITICAL_SECTION *
 156 g_rec_mutex_impl_new (void)
 157 {
 158   CRITICAL_SECTION *cs;
 159
 160   cs = g_slice_new (CRITICAL_SECTION);
 161   InitializeCriticalSection (cs);
 162
 163   return cs;
 164 }
 165
 166 static void
 167 g_rec_mutex_impl_free (CRITICAL_SECTION *cs)
 168 {
 169   DeleteCriticalSection (cs);
 170   g_slice_free (CRITICAL_SECTION, cs);
 171 }
 172
 173 static CRITICAL_SECTION *
 174 g_rec_mutex_get_impl (GRecMutex *mutex)
 175 {
 176   CRITICAL_SECTION *impl = mutex->p;
 177
 178   if G_UNLIKELY (mutex->p == NULL)
 179     {
 180       impl = g_rec_mutex_impl_new ();
 181       if (InterlockedCompareExchangePointer (&mutex->p, impl, NULL) != NULL)
 182         g_rec_mutex_impl_free (impl);
 183       impl = mutex->p;
 184     }
 185
 186   return impl;
 187 }
 188
 189 void
 190 g_rec_mutex_init (GRecMutex *mutex)
 191 {
 192   mutex->p = g_rec_mutex_impl_new ();
 193 }
 194
 195 void
 196 g_rec_mutex_clear (GRecMutex *mutex)
 197 {
 198   g_rec_mutex_impl_free (mutex->p);
 199 }
 200
 201 void
 202 g_rec_mutex_lock (GRecMutex *mutex)
 203 {
 204   EnterCriticalSection (g_rec_mutex_get_impl (mutex));
 205 }
 206
 207 void
 208 g_rec_mutex_unlock (GRecMutex *mutex)
 209 {
 210   LeaveCriticalSection (mutex->p);
 211 }
 212
 213 gboolean
 214 g_rec_mutex_trylock (GRecMutex *mutex)
 215 {
 216   return TryEnterCriticalSection (g_rec_mutex_get_impl (mutex));
 217 }
 218
 219 /* {{{1 GRWLock */
 220
 221 void
 222 g_rw_lock_init (GRWLock *lock)
 223 {
 224   g_thread_impl_vtable.InitializeSRWLock (lock);
 225 }
 226
 227 void
 228 g_rw_lock_clear (GRWLock *lock)
 229 {
 230   if (g_thread_impl_vtable.DeleteSRWLock != NULL)
 231     g_thread_impl_vtable.DeleteSRWLock (lock);
 232 }
 233
 234 void
 235 g_rw_lock_writer_lock (GRWLock *lock)
 236 {
 237   g_thread_impl_vtable.AcquireSRWLockExclusive (lock);
 238 }
 239
 240 gboolean
 241 g_rw_lock_writer_trylock (GRWLock *lock)
 242 {
 243   return g_thread_impl_vtable.TryAcquireSRWLockExclusive (lock);
 244 }
 245
 246 void
 247 g_rw_lock_writer_unlock (GRWLock *lock)
 248 {
 249   g_thread_impl_vtable.ReleaseSRWLockExclusive (lock);
 250 }
 251
 252 void
 253 g_rw_lock_reader_lock (GRWLock *lock)
 254 {
 255   g_thread_impl_vtable.AcquireSRWLockShared (lock);
 256 }
 257
 258 gboolean
 259 g_rw_lock_reader_trylock (GRWLock *lock)
 260 {
 261   return g_thread_impl_vtable.TryAcquireSRWLockShared (lock);
 262 }
 263
 264 void
 265 g_rw_lock_reader_unlock (GRWLock *lock)
 266 {
 267   g_thread_impl_vtable.ReleaseSRWLockShared (lock);
 268 }
 269
 270 /* {{{1 GCond */
 271 void
 272 g_cond_init (GCond *cond)
 273 {
 274   g_thread_impl_vtable.InitializeConditionVariable (cond);
 275 }
 276
 277 void
 278 g_cond_clear (GCond *cond)
 279 {
 280   if (g_thread_impl_vtable.DeleteConditionVariable)
 281     g_thread_impl_vtable.DeleteConditionVariable (cond);
 282 }
 283
 284 void
 285 g_cond_signal (GCond *cond)
 286 {
 287   g_thread_impl_vtable.WakeConditionVariable (cond);
 288 }
 289
 290 void
 291 g_cond_broadcast (GCond *cond)
 292 {
 293   g_thread_impl_vtable.WakeAllConditionVariable (cond);
 294 }
 295
 296 void
 297 g_cond_wait (GCond  *cond,
 298              GMutex *entered_mutex)
 299 {
 300   g_thread_impl_vtable.SleepConditionVariableSRW (cond, entered_mutex, INFINITE, 0);
 301 }
 302
 303 gboolean
 304 g_cond_wait_until (GCond  *cond,
 305                    GMutex *entered_mutex,
 306                    gint64  end_time)
 307 {
 308   gint64 span;
 309
 310   span = end_time - g_get_monotonic_time ();
 311
 312   if G_UNLIKELY (span < 0)
 313     span = 0;
 314
 315   if G_UNLIKELY (span > G_GINT64_CONSTANT (1000) * G_MAXINT32)
 316     span = INFINITE;
 317
 318   return g_thread_impl_vtable.SleepConditionVariableSRW (cond, entered_mutex, span / 1000, 0);
 319 }
 320
 321 /* {{{1 GPrivate */
 322
 323 typedef struct _GPrivateDestructor GPrivateDestructor;
 324
 325 struct _GPrivateDestructor
 326 {
 327   DWORD               index;
 328   GDestroyNotify      notify;
 329   GPrivateDestructor *next;
 330 };
 331
 332 static GPrivateDestructor * volatile g_private_destructors;
 333 static CRITICAL_SECTION g_private_lock;
 334
 335 static DWORD
 336 g_private_get_impl (GPrivate *key)
 337 {
 338   DWORD impl = (DWORD) key->p;
 339
 340   if G_UNLIKELY (impl == 0)
 341     {
 342       EnterCriticalSection (&g_private_lock);
 343       impl = (DWORD) key->p;
 344       if (impl == 0)
 345         {
 346           GPrivateDestructor *destructor;
 347
 348           impl = TlsAlloc ();
 349
 350           if (impl == TLS_OUT_OF_INDEXES)
 351             g_thread_abort (0, "TlsAlloc");
 352
 353           if (key->notify != NULL)
 354             {
 355               destructor = malloc (sizeof (GPrivateDestructor));
 356               if G_UNLIKELY (destructor == NULL)
 357                 g_thread_abort (errno, "malloc");
 358               destructor->index = impl;
 359               destructor->notify = key->notify;
 360               destructor->next = g_private_destructors;
 361
 362               /* We need to do an atomic store due to the unlocked
 363                * access to the destructor list from the thread exit
 364                * function.
 365                *
 366                * It can double as a sanity check...
 367                */
 368               if (InterlockedCompareExchangePointer (&g_private_destructors, destructor,
 369                                                      destructor->next) != destructor->next)
 370                 g_thread_abort (0, "g_private_get_impl(1)");
 371             }
 372
 373           /* Ditto, due to the unlocked access on the fast path */
 374           if (InterlockedCompareExchangePointer (&key->p, impl, NULL) != NULL)
 375             g_thread_abort (0, "g_private_get_impl(2)");
 376         }
 377       LeaveCriticalSection (&g_private_lock);
 378     }
 379
 380   return impl;
 381 }
 382
 383 gpointer
 384 g_private_get (GPrivate *key)
 385 {
 386   return TlsGetValue (g_private_get_impl (key));
 387 }
 388
 389 void
 390 g_private_set (GPrivate *key,
 391                gpointer  value)
 392 {
 393   TlsSetValue (g_private_get_impl (key), value);
 394 }
 395
 396 void
 397 g_private_replace (GPrivate *key,
 398                    gpointer  value)
 399 {
 400   DWORD impl = g_private_get_impl (key);
 401   gpointer old;
 402
 403   old = TlsGetValue (impl);
 404   if (old && key->notify)
 405     key->notify (old);
 406   TlsSetValue (impl, value);
 407 }
 408
 409 /* {{{1 GThread */
 410
 411 #define win32_check_for_error(what) G_STMT_START{                       \
 412   if (!(what))                                                          \
 413     g_error ("file %s: line %d (%s): error %s during %s",               \
 414              __FILE__, __LINE__, G_STRFUNC,                             \
 415              g_win32_error_message (GetLastError ()), #what);           \
 416   }G_STMT_END
 417
 418 #define G_MUTEX_SIZE (sizeof (gpointer))
 419
 420 typedef BOOL (__stdcall *GTryEnterCriticalSectionFunc) (CRITICAL_SECTION *);
 421
 422 typedef struct
 423 {
 424   GRealThread thread;
 425
 426   GThreadFunc proxy;
 427   HANDLE      handle;
 428 } GThreadWin32;
 429
 430 void
 431 g_system_thread_free (GRealThread *thread)
 432 {
 433   GThreadWin32 *wt = (GThreadWin32 *) thread;
 434
 435   win32_check_for_error (CloseHandle (wt->handle));
 436   g_slice_free (GThreadWin32, wt);
 437 }
 438
 439 void
 440 g_system_thread_exit (void)
 441 {
 442   _endthreadex (0);
 443 }
 444
 445 static guint __stdcall
 446 g_thread_win32_proxy (gpointer data)
 447 {
 448   GThreadWin32 *self = data;
 449
 450   self->proxy (self);
 451
 452   g_system_thread_exit ();
 453
 454   g_assert_not_reached ();
 455
 456   return 0;
 457 }
 458
 459 GRealThread *
 460 g_system_thread_new (GThreadFunc   func,
 461                      gulong        stack_size,
 462                      GError      **error)
 463 {
 464   GThreadWin32 *thread;
 465   guint ignore;
 466
 467   thread = g_slice_new0 (GThreadWin32);
 468   thread->proxy = func;
 469
 470   thread->handle = (HANDLE) _beginthreadex (NULL, stack_size, g_thread_win32_proxy, thread, 0, &ignore);
 471
 472   if (thread->handle == NULL)
 473     {
 474       gchar *win_error = g_win32_error_message (GetLastError ());
 475       g_set_error (error, G_THREAD_ERROR, G_THREAD_ERROR_AGAIN,
 476                    "Error creating thread: %s", win_error);
 477       g_free (win_error);
 478       g_slice_free (GThreadWin32, thread);
 479       return NULL;
 480     }
 481
 482   return (GRealThread *) thread;
 483 }
 484
 485 void
 486 g_thread_yield (void)
 487 {
 488   Sleep(0);
 489 }
 490
 491 void
 492 g_system_thread_wait (GRealThread *thread)
 493 {
 494   GThreadWin32 *wt = (GThreadWin32 *) thread;
 495
 496   win32_check_for_error (WAIT_FAILED != WaitForSingleObject (wt->handle, INFINITE));
 497 }
 498
 499 void
 500 g_system_thread_set_name (const gchar *name)
 501 {
 502   /* FIXME: implement */
 503 }
 504
 505 /* {{{1 SRWLock and CONDITION_VARIABLE emulation (for Windows XP) */
 506
 507 static CRITICAL_SECTION g_thread_xp_lock;
 508 static DWORD            g_thread_xp_waiter_tls;
 509
 510 /* {{{2 GThreadWaiter utility class for CONDITION_VARIABLE emulation */
 511 typedef struct _GThreadXpWaiter GThreadXpWaiter;
 512 struct _GThreadXpWaiter
 513 {
 514   HANDLE                     event;
 515   volatile GThreadXpWaiter  *next;
 516   volatile GThreadXpWaiter **my_owner;
 517 };
 518
 519 static GThreadXpWaiter *
 520 g_thread_xp_waiter_get (void)
 521 {
 522   GThreadXpWaiter *waiter;
 523
 524   waiter = TlsGetValue (g_thread_xp_waiter_tls);
 525
 526   if G_UNLIKELY (waiter == NULL)
 527     {
 528       waiter = malloc (sizeof (GThreadXpWaiter));
 529       if (waiter == NULL)
 530         g_thread_abort (GetLastError (), "malloc");
 531       waiter->event = CreateEvent (0, FALSE, FALSE, NULL);
 532       if (waiter->event == NULL)
 533         g_thread_abort (GetLastError (), "CreateEvent");
 534       waiter->my_owner = NULL;
 535
 536       TlsSetValue (g_thread_xp_waiter_tls, waiter);
 537     }
 538
 539   return waiter;
 540 }
 541
 542 static void __stdcall
 543 g_thread_xp_CallThisOnThreadExit (void)
 544 {
 545   GThreadXpWaiter *waiter;
 546
 547   waiter = TlsGetValue (g_thread_xp_waiter_tls);
 548
 549   if (waiter != NULL)
 550     {
 551       TlsSetValue (g_thread_xp_waiter_tls, NULL);
 552       CloseHandle (waiter->event);
 553       free (waiter);
 554     }
 555 }
 556
 557 /* {{{2 SRWLock emulation */
 558 typedef struct
 559 {
 560   CRITICAL_SECTION  writer_lock;
 561   gboolean          ever_shared;    /* protected by writer_lock */
 562   gboolean          writer_locked;  /* protected by writer_lock */
 563
 564   /* below is only ever touched if ever_shared becomes true */
 565   CRITICAL_SECTION  atomicity;
 566   GThreadXpWaiter  *queued_writer; /* protected by atomicity lock */
 567   gint              num_readers;   /* protected by atomicity lock */
 568 } GThreadSRWLock;
 569
 570 static void __stdcall
 571 g_thread_xp_InitializeSRWLock (gpointer mutex)
 572 {
 573   *(GThreadSRWLock * volatile *) mutex = NULL;
 574 }
 575
 576 static void __stdcall
 577 g_thread_xp_DeleteSRWLock (gpointer mutex)
 578 {
 579   GThreadSRWLock *lock = *(GThreadSRWLock * volatile *) mutex;
 580
 581   if (lock)
 582     {
 583       if (lock->ever_shared)
 584         DeleteCriticalSection (&lock->atomicity);
 585
 586       DeleteCriticalSection (&lock->writer_lock);
 587       free (lock);
 588     }
 589 }
 590
 591 static GThreadSRWLock * __stdcall
 592 g_thread_xp_get_srwlock (GThreadSRWLock * volatile *lock)
 593 {
 594   GThreadSRWLock *result;
 595
 596   /* It looks like we're missing some barriers here, but this code only
 597    * ever runs on Windows XP, which in turn only ever runs on hardware
 598    * with a relatively rigid memory model.  The 'volatile' will take
 599    * care of the compiler.
 600    */
 601   result = *lock;
 602
 603   if G_UNLIKELY (result == NULL)
 604     {
 605       EnterCriticalSection (&g_thread_xp_lock);
 606
 607       /* Check again */
 608       result = *lock;
 609       if (result == NULL)
 610         {
 611           result = malloc (sizeof (GThreadSRWLock));
 612
 613           if (result == NULL)
 614             g_thread_abort (errno, "malloc");
 615
 616           InitializeCriticalSection (&result->writer_lock);
 617           result->writer_locked = FALSE;
 618           result->ever_shared = FALSE;
 619           *lock = result;
 620         }
 621
 622       LeaveCriticalSection (&g_thread_xp_lock);
 623     }
 624
 625   return result;
 626 }
 627
 628 static void __stdcall
 629 g_thread_xp_AcquireSRWLockExclusive (gpointer mutex)
 630 {
 631   GThreadSRWLock *lock = g_thread_xp_get_srwlock (mutex);
 632
 633   EnterCriticalSection (&lock->writer_lock);
 634
 635   /* CRITICAL_SECTION is reentrant, but SRWLock is not.
 636    * Detect the deadlock that would occur on later Windows version.
 637    */
 638   g_assert (!lock->writer_locked);
 639   lock->writer_locked = TRUE;
 640
 641   if (lock->ever_shared)
 642     {
 643       GThreadXpWaiter *waiter = NULL;
 644
 645       EnterCriticalSection (&lock->atomicity);
 646       if (lock->num_readers > 0)
 647         lock->queued_writer = waiter = g_thread_xp_waiter_get ();
 648       LeaveCriticalSection (&lock->atomicity);
 649
 650       if (waiter != NULL)
 651         WaitForSingleObject (waiter->event, INFINITE);
 652
 653       lock->queued_writer = NULL;
 654     }
 655 }
 656
 657 static BOOLEAN __stdcall
 658 g_thread_xp_TryAcquireSRWLockExclusive (gpointer mutex)
 659 {
 660   GThreadSRWLock *lock = g_thread_xp_get_srwlock (mutex);
 661
 662   if (!TryEnterCriticalSection (&lock->writer_lock))
 663     return FALSE;
 664
 665   /* CRITICAL_SECTION is reentrant, but SRWLock is not.
 666    * Ensure that this properly returns FALSE (as SRWLock would).
 667    */
 668   if G_UNLIKELY (lock->writer_locked)
 669     {
 670       LeaveCriticalSection (&lock->writer_lock);
 671       return FALSE;
 672     }
 673
 674   lock->writer_locked = TRUE;
 675
 676   if (lock->ever_shared)
 677     {
 678       gboolean available;
 679
 680       EnterCriticalSection (&lock->atomicity);
 681       available = lock->num_readers == 0;
 682       LeaveCriticalSection (&lock->atomicity);
 683
 684       if (!available)
 685         {
 686           LeaveCriticalSection (&lock->writer_lock);
 687           return FALSE;
 688         }
 689     }
 690
 691   return TRUE;
 692 }
 693
 694 static void __stdcall
 695 g_thread_xp_ReleaseSRWLockExclusive (gpointer mutex)
 696 {
 697   GThreadSRWLock *lock = *(GThreadSRWLock * volatile *) mutex;
 698
 699   lock->writer_locked = FALSE;
 700
 701   /* We need this until we fix some weird parts of GLib that try to
 702    * unlock freshly-allocated mutexes.
 703    */
 704   if (lock != NULL)
 705     LeaveCriticalSection (&lock->writer_lock);
 706 }
 707
 708 static void
 709 g_thread_xp_srwlock_become_reader (GThreadSRWLock *lock)
 710 {
 711   if G_UNLIKELY (!lock->ever_shared)
 712     {
 713       InitializeCriticalSection (&lock->atomicity);
 714       lock->queued_writer = NULL;
 715       lock->num_readers = 0;
 716
 717       lock->ever_shared = TRUE;
 718     }
 719
 720   EnterCriticalSection (&lock->atomicity);
 721   lock->num_readers++;
 722   LeaveCriticalSection (&lock->atomicity);
 723 }
 724
 725 static void __stdcall
 726 g_thread_xp_AcquireSRWLockShared (gpointer mutex)
 727 {
 728   GThreadSRWLock *lock = g_thread_xp_get_srwlock (mutex);
 729
 730   EnterCriticalSection (&lock->writer_lock);
 731
 732   /* See g_thread_xp_AcquireSRWLockExclusive */
 733   g_assert (!lock->writer_locked);
 734
 735   g_thread_xp_srwlock_become_reader (lock);
 736
 737   LeaveCriticalSection (&lock->writer_lock);
 738 }
 739
 740 static BOOLEAN __stdcall
 741 g_thread_xp_TryAcquireSRWLockShared (gpointer mutex)
 742 {
 743   GThreadSRWLock *lock = g_thread_xp_get_srwlock (mutex);
 744
 745   if (!TryEnterCriticalSection (&lock->writer_lock))
 746     return FALSE;
 747
 748   /* See g_thread_xp_AcquireSRWLockExclusive */
 749   if G_UNLIKELY (lock->writer_locked)
 750     {
 751       LeaveCriticalSection (&lock->writer_lock);
 752       return FALSE;
 753     }
 754
 755   g_thread_xp_srwlock_become_reader (lock);
 756
 757   LeaveCriticalSection (&lock->writer_lock);
 758
 759   return TRUE;
 760 }
 761
 762 static void __stdcall
 763 g_thread_xp_ReleaseSRWLockShared (gpointer mutex)
 764 {
 765   GThreadSRWLock *lock = g_thread_xp_get_srwlock (mutex);
 766
 767   EnterCriticalSection (&lock->atomicity);
 768
 769   lock->num_readers--;
 770
 771   if (lock->num_readers == 0 && lock->queued_writer)
 772     SetEvent (lock->queued_writer->event);
 773
 774   LeaveCriticalSection (&lock->atomicity);
 775 }
 776
 777 /* {{{2 CONDITION_VARIABLE emulation */
 778 typedef struct
 779 {
 780   volatile GThreadXpWaiter  *first;
 781   volatile GThreadXpWaiter **last_ptr;
 782 } GThreadXpCONDITION_VARIABLE;
 783
 784 static void __stdcall
 785 g_thread_xp_InitializeConditionVariable (gpointer cond)
 786 {
 787   *(GThreadXpCONDITION_VARIABLE * volatile *) cond = NULL;
 788 }
 789
 790 static void __stdcall
 791 g_thread_xp_DeleteConditionVariable (gpointer cond)
 792 {
 793   GThreadXpCONDITION_VARIABLE *cv = *(GThreadXpCONDITION_VARIABLE * volatile *) cond;
 794
 795   if (cv)
 796     free (cv);
 797 }
 798
 799 static GThreadXpCONDITION_VARIABLE * __stdcall
 800 g_thread_xp_get_condition_variable (GThreadXpCONDITION_VARIABLE * volatile *cond)
 801 {
 802   GThreadXpCONDITION_VARIABLE *result;
 803
 804   /* It looks like we're missing some barriers here, but this code only
 805    * ever runs on Windows XP, which in turn only ever runs on hardware
 806    * with a relatively rigid memory model.  The 'volatile' will take
 807    * care of the compiler.
 808    */
 809   result = *cond;
 810
 811   if G_UNLIKELY (result == NULL)
 812     {
 813       result = malloc (sizeof (GThreadXpCONDITION_VARIABLE));
 814
 815       if (result == NULL)
 816         g_thread_abort (errno, "malloc");
 817
 818       result->first = NULL;
 819       result->last_ptr = &result->first;
 820
 821       if (InterlockedCompareExchangePointer (cond, result, NULL) != NULL)
 822         {
 823           free (result);
 824           result = *cond;
 825         }
 826     }
 827
 828   return result;
 829 }
 830
 831 static BOOL __stdcall
 832 g_thread_xp_SleepConditionVariableSRW (gpointer cond,
 833                                        gpointer mutex,
 834                                        DWORD    timeout,
 835                                        ULONG    flags)
 836 {
 837   GThreadXpCONDITION_VARIABLE *cv = g_thread_xp_get_condition_variable (cond);
 838   GThreadXpWaiter *waiter = g_thread_xp_waiter_get ();
 839   DWORD status;
 840
 841   waiter->next = NULL;
 842
 843   EnterCriticalSection (&g_thread_xp_lock);
 844   waiter->my_owner = cv->last_ptr;
 845   *cv->last_ptr = waiter;
 846   cv->last_ptr = &waiter->next;
 847   LeaveCriticalSection (&g_thread_xp_lock);
 848
 849   g_mutex_unlock (mutex);
 850   status = WaitForSingleObject (waiter->event, timeout);
 851
 852   if (status != WAIT_TIMEOUT && status != WAIT_OBJECT_0)
 853     g_thread_abort (GetLastError (), "WaitForSingleObject");
 854   g_mutex_lock (mutex);
 855
 856   if (status == WAIT_TIMEOUT)
 857     {
 858       EnterCriticalSection (&g_thread_xp_lock);
 859       if (waiter->my_owner)
 860         {
 861           if (waiter->next)
 862             waiter->next->my_owner = waiter->my_owner;
 863           else
 864             cv->last_ptr = waiter->my_owner;
 865           *waiter->my_owner = waiter->next;
 866           waiter->my_owner = NULL;
 867         }
 868       LeaveCriticalSection (&g_thread_xp_lock);
 869     }
 870
 871   return status == WAIT_OBJECT_0;
 872 }
 873
 874 static void __stdcall
 875 g_thread_xp_WakeConditionVariable (gpointer cond)
 876 {
 877   GThreadXpCONDITION_VARIABLE *cv = g_thread_xp_get_condition_variable (cond);
 878   volatile GThreadXpWaiter *waiter;
 879
 880   EnterCriticalSection (&g_thread_xp_lock);
 881
 882   waiter = cv->first;
 883   if (waiter != NULL)
 884     {
 885       waiter->my_owner = NULL;
 886       cv->first = waiter->next;
 887       if (cv->first != NULL)
 888         cv->first->my_owner = &cv->first;
 889       else
 890         cv->last_ptr = &cv->first;
 891     }
 892
 893   if (waiter != NULL)
 894     SetEvent (waiter->event);
 895
 896   LeaveCriticalSection (&g_thread_xp_lock);
 897 }
 898
 899 static void __stdcall
 900 g_thread_xp_WakeAllConditionVariable (gpointer cond)
 901 {
 902   GThreadXpCONDITION_VARIABLE *cv = g_thread_xp_get_condition_variable (cond);
 903   volatile GThreadXpWaiter *waiter;
 904
 905   EnterCriticalSection (&g_thread_xp_lock);
 906
 907   waiter = cv->first;
 908   cv->first = NULL;
 909   cv->last_ptr = &cv->first;
 910
 911   while (waiter != NULL)
 912     {
 913       volatile GThreadXpWaiter *next;
 914
 915       next = waiter->next;
 916       SetEvent (waiter->event);
 917       waiter->my_owner = NULL;
 918       waiter = next;
 919     }
 920
 921   LeaveCriticalSection (&g_thread_xp_lock);
 922 }
 923
 924 /* {{{2 XP Setup */
 925 static void
 926 g_thread_xp_init (void)
 927 {
 928   static const GThreadImplVtable g_thread_xp_impl_vtable = {
 929     g_thread_xp_CallThisOnThreadExit,
 930     g_thread_xp_InitializeSRWLock,
 931     g_thread_xp_DeleteSRWLock,
 932     g_thread_xp_AcquireSRWLockExclusive,
 933     g_thread_xp_TryAcquireSRWLockExclusive,
 934     g_thread_xp_ReleaseSRWLockExclusive,
 935     g_thread_xp_AcquireSRWLockShared,
 936     g_thread_xp_TryAcquireSRWLockShared,
 937     g_thread_xp_ReleaseSRWLockShared,
 938     g_thread_xp_InitializeConditionVariable,
 939     g_thread_xp_DeleteConditionVariable,
 940     g_thread_xp_SleepConditionVariableSRW,
 941     g_thread_xp_WakeAllConditionVariable,
 942     g_thread_xp_WakeConditionVariable
 943   };
 944
 945   InitializeCriticalSection (&g_thread_xp_lock);
 946   g_thread_xp_waiter_tls = TlsAlloc ();
 947
 948   g_thread_impl_vtable = g_thread_xp_impl_vtable;
 949 }
 950
 951 /* {{{1 Epilogue */
 952
 953 static gboolean
 954 g_thread_lookup_native_funcs (void)
 955 {
 956   GThreadImplVtable native_vtable = { 0, };
 957   HMODULE kernel32;
 958
 959   kernel32 = GetModuleHandle ("KERNEL32.DLL");
 960
 961   if (kernel32 == NULL)
 962     return FALSE;
 963
 964 #define GET_FUNC(name) if ((native_vtable.name = (void *) GetProcAddress (kernel32, #name)) == NULL) return FALSE
 965   GET_FUNC(InitializeSRWLock);
 966   GET_FUNC(AcquireSRWLockExclusive);
 967   GET_FUNC(TryAcquireSRWLockExclusive);
 968   GET_FUNC(ReleaseSRWLockExclusive);
 969   GET_FUNC(AcquireSRWLockShared);
 970   GET_FUNC(TryAcquireSRWLockShared);
 971   GET_FUNC(ReleaseSRWLockShared);
 972
 973   GET_FUNC(InitializeConditionVariable);
 974   GET_FUNC(SleepConditionVariableSRW);
 975   GET_FUNC(WakeAllConditionVariable);
 976   GET_FUNC(WakeConditionVariable);
 977 #undef GET_FUNC
 978
 979   g_thread_impl_vtable = native_vtable;
 980
 981   return TRUE;
 982 }
 983
 984 void
 985 g_thread_win32_init (void)
 986 {
 987   if (!g_thread_lookup_native_funcs ())
 988     g_thread_xp_init ();
 989
 990   InitializeCriticalSection (&g_private_lock);
 991 }
 992
 993 void
 994 g_thread_win32_thread_detach (void)
 995 {
 996   gboolean dtors_called;
 997
 998   do
 999     {
1000       GPrivateDestructor *dtor;
1001
1002       /* We go by the POSIX book on this one.
1003        *
1004        * If we call a destructor then there is a chance that some new
1005        * TLS variables got set by code called in that destructor.
1006        *
1007        * Loop until nothing is left.
1008        */
1009       dtors_called = FALSE;
1010
1011       for (dtor = g_private_destructors; dtor; dtor = dtor->next)
1012         {
1013           gpointer value;
1014
1015           value = TlsGetValue (dtor->index);
1016           if (value != NULL && dtor->notify != NULL)
1017             {
1018               /* POSIX says to clear this before the call */
1019               TlsSetValue (dtor->index, NULL);
1020               dtor->notify (value);
1021               dtors_called = TRUE;
1022             }
1023         }
1024     }
1025   while (dtors_called);
1026
1027   if (g_thread_impl_vtable.CallThisOnThreadExit)
1028     g_thread_impl_vtable.CallThisOnThreadExit ();
1029 }
1030
1031 /* vim:set foldmethod=marker: */