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 "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_timedwait (GCond  *cond,
 305                   GMutex *entered_mutex,
 306                   gint64  abs_time)
 307 {
 308   gint64 span;
 309   FILETIME ft;
 310   gint64 now;
 311
 312   GetSystemTimeAsFileTime (&ft);
 313   memmove (&now, &ft, sizeof (FILETIME));
 314
 315   now -= G_GINT64_CONSTANT (116444736000000000);
 316   now /= 10;
 317
 318   span = abs_time - now;
 319
 320   if G_UNLIKELY (span < 0)
 321     span = 0;
 322
 323   if G_UNLIKELY (span > G_GINT64_CONSTANT (1000) * G_MAXINT32)
 324     span = INFINITE;
 325
 326   return g_thread_impl_vtable.SleepConditionVariableSRW (cond, entered_mutex, span / 1000, 0);
 327 }
 328
 329 gboolean
 330 g_cond_timed_wait (GCond    *cond,
 331                    GMutex   *entered_mutex,
 332                    GTimeVal *abs_time)
 333 {
 334   if (abs_time)
 335     {
 336       gint64 micros;
 337
 338       micros = abs_time->tv_sec;
 339       micros *= 1000000;
 340       micros += abs_time->tv_usec;
 341
 342       return g_cond_timedwait (cond, entered_mutex, micros);
 343     }
 344   else
 345     {
 346       g_cond_wait (cond, entered_mutex);
 347       return TRUE;
 348     }
 349 }
 350
 351 /* {{{1 GPrivate */
 352
 353 typedef struct _GPrivateDestructor GPrivateDestructor;
 354
 355 struct _GPrivateDestructor
 356 {
 357   DWORD               index;
 358   GDestroyNotify      notify;
 359   GPrivateDestructor *next;
 360 };
 361
 362 static GPrivateDestructor * volatile g_private_destructors;
 363 static CRITICAL_SECTION g_private_lock;
 364
 365 static DWORD
 366 g_private_get_impl (GPrivate *key)
 367 {
 368   DWORD impl = (DWORD) key->p;
 369
 370   if G_UNLIKELY (impl == 0)
 371     {
 372       EnterCriticalSection (&g_private_lock);
 373       impl = (DWORD) key->p;
 374       if (impl == 0)
 375         {
 376           GPrivateDestructor *destructor;
 377
 378           impl = TlsAlloc ();
 379
 380           if (impl == TLS_OUT_OF_INDEXES)
 381             g_thread_abort (0, "TlsAlloc");
 382
 383           if (key->notify != NULL)
 384             {
 385               destructor = malloc (sizeof (GPrivateDestructor));
 386               if G_UNLIKELY (destructor == NULL)
 387                 g_thread_abort (errno, "malloc");
 388               destructor->index = impl;
 389               destructor->notify = key->notify;
 390               destructor->next = g_private_destructors;
 391
 392               /* We need to do an atomic store due to the unlocked
 393                * access to the destructor list from the thread exit
 394                * function.
 395                *
 396                * It can double as a sanity check...
 397                */
 398               if (InterlockedCompareExchangePointer (&g_private_destructors, destructor,
 399                                                      destructor->next) != destructor->next)
 400                 g_thread_abort (0, "g_private_get_impl(1)");
 401             }
 402
 403           /* Ditto, due to the unlocked access on the fast path */
 404           if (InterlockedCompareExchangePointer (&key->p, impl, NULL) != NULL)
 405             g_thread_abort (0, "g_private_get_impl(2)");
 406         }
 407       LeaveCriticalSection (&g_private_lock);
 408     }
 409
 410   return impl;
 411 }
 412
 413 gpointer
 414 g_private_get (GPrivate *key)
 415 {
 416   return TlsGetValue (g_private_get_impl (key));
 417 }
 418
 419 void
 420 g_private_set (GPrivate *key,
 421                gpointer  value)
 422 {
 423   TlsSetValue (g_private_get_impl (key), value);
 424 }
 425
 426 void
 427 g_private_replace (GPrivate *key,
 428                    gpointer  value)
 429 {
 430   DWORD impl = g_private_get_impl (key);
 431   gpointer old;
 432
 433   old = TlsGetValue (impl);
 434   if (old && key->notify)
 435     key->notify (old);
 436   TlsSetValue (impl, value);
 437 }
 438
 439 /* {{{1 GThread */
 440
 441 #include "glib.h"
 442 #include "gthreadprivate.h"
 443
 444 #define win32_check_for_error(what) G_STMT_START{                       \
 445   if (!(what))                                                          \
 446     g_error ("file %s: line %d (%s): error %s during %s",               \
 447              __FILE__, __LINE__, G_STRFUNC,                             \
 448              g_win32_error_message (GetLastError ()), #what);           \
 449   }G_STMT_END
 450
 451 #define G_MUTEX_SIZE (sizeof (gpointer))
 452
 453 static DWORD g_thread_self_tls;
 454
 455 typedef BOOL (__stdcall *GTryEnterCriticalSectionFunc) (CRITICAL_SECTION *);
 456
 457 typedef struct _GThreadData GThreadData;
 458 struct _GThreadData
 459 {
 460   GThreadFunc func;
 461   gpointer data;
 462   HANDLE thread;
 463   gboolean joinable;
 464 };
 465
 466 GRealThread *
 467 g_system_thread_new (void)
 468 {
 469   return g_slice_new0 (GRealThread);
 470 }
 471
 472 void
 473 g_system_thread_free (GRealThread *thread)
 474 {
 475   g_slice_free (GRealThread, thread);
 476 }
 477
 478 void
 479 g_system_thread_exit (void)
 480 {
 481   _endthreadex (0);
 482 }
 483
 484 static guint __stdcall
 485 g_thread_proxy (gpointer data)
 486 {
 487   GThreadData *self = (GThreadData*) data;
 488
 489   win32_check_for_error (TlsSetValue (g_thread_self_tls, self));
 490
 491   self->func (self->data);
 492
 493   g_system_thread_exit ();
 494
 495   g_assert_not_reached ();
 496
 497   return 0;
 498 }
 499
 500 void
 501 g_system_thread_create (GThreadFunc       func,
 502                         gpointer          data,
 503                         gulong            stack_size,
 504                         gboolean          joinable,
 505                         gpointer          thread,
 506                         GError          **error)
 507 {
 508   guint ignore;
 509   GThreadData *retval;
 510
 511   g_return_if_fail (func);
 512
 513   retval = g_new(GThreadData, 1);
 514   retval->func = func;
 515   retval->data = data;
 516
 517   retval->joinable = joinable;
 518
 519   retval->thread = (HANDLE) _beginthreadex (NULL, stack_size, g_thread_proxy,
 520                                             retval, 0, &ignore);
 521
 522   if (retval->thread == NULL)
 523     {
 524       gchar *win_error = g_win32_error_message (GetLastError ());
 525       g_set_error (error, G_THREAD_ERROR, G_THREAD_ERROR_AGAIN,
 526                    "Error creating thread: %s", win_error);
 527       g_free (retval);
 528       g_free (win_error);
 529       return;
 530     }
 531
 532   *(GThreadData **)thread = retval;
 533 }
 534
 535 void
 536 g_thread_yield (void)
 537 {
 538   Sleep(0);
 539 }
 540
 541 void
 542 g_system_thread_wait (GRealThread *thread)
 543 {
 544   GThreadData *target = *(GThreadData **)&(thread->system_thread);
 545
 546   g_return_if_fail (target->joinable);
 547
 548   win32_check_for_error (WAIT_FAILED !=
 549                          WaitForSingleObject (target->thread, INFINITE));
 550
 551   win32_check_for_error (CloseHandle (target->thread));
 552   g_free (target);
 553 }
 554
 555 void
 556 g_system_thread_set_name (const gchar *name)
 557 {
 558   /* FIXME: implement */
 559 }
 560
 561 /* {{{1 SRWLock and CONDITION_VARIABLE emulation (for Windows XP) */
 562
 563 static CRITICAL_SECTION g_thread_xp_lock;
 564 static DWORD            g_thread_xp_waiter_tls;
 565
 566 /* {{{2 GThreadWaiter utility class for CONDITION_VARIABLE emulation */
 567 typedef struct _GThreadXpWaiter GThreadXpWaiter;
 568 struct _GThreadXpWaiter
 569 {
 570   HANDLE                    event;
 571   volatile GThreadXpWaiter *next;
 572 };
 573
 574 static GThreadXpWaiter *
 575 g_thread_xp_waiter_get (void)
 576 {
 577   GThreadXpWaiter *waiter;
 578
 579   waiter = TlsGetValue (g_thread_xp_waiter_tls);
 580
 581   if G_UNLIKELY (waiter == NULL)
 582     {
 583       waiter = malloc (sizeof (GThreadXpWaiter));
 584       if (waiter == NULL)
 585         g_thread_abort (GetLastError (), "malloc");
 586       waiter->event = CreateEvent (0, FALSE, FALSE, NULL);
 587       if (waiter->event == NULL)
 588         g_thread_abort (GetLastError (), "CreateEvent");
 589
 590       TlsSetValue (g_thread_xp_waiter_tls, waiter);
 591     }
 592
 593   return waiter;
 594 }
 595
 596 static void __stdcall
 597 g_thread_xp_CallThisOnThreadExit (void)
 598 {
 599   GThreadXpWaiter *waiter;
 600
 601   waiter = TlsGetValue (g_thread_xp_waiter_tls);
 602
 603   if (waiter != NULL)
 604     {
 605       TlsSetValue (g_thread_xp_waiter_tls, NULL);
 606       CloseHandle (waiter->event);
 607       free (waiter);
 608     }
 609 }
 610
 611 /* {{{2 SRWLock emulation */
 612 typedef struct
 613 {
 614   CRITICAL_SECTION  writer_lock;
 615   gboolean          ever_shared;    /* protected by writer_lock */
 616   gboolean          writer_locked;  /* protected by writer_lock */
 617
 618   /* below is only ever touched if ever_shared becomes true */
 619   CRITICAL_SECTION  atomicity;
 620   GThreadXpWaiter  *queued_writer; /* protected by atomicity lock */
 621   gint              num_readers;   /* protected by atomicity lock */
 622 } GThreadSRWLock;
 623
 624 static void __stdcall
 625 g_thread_xp_InitializeSRWLock (gpointer mutex)
 626 {
 627   *(GThreadSRWLock * volatile *) mutex = NULL;
 628 }
 629
 630 static void __stdcall
 631 g_thread_xp_DeleteSRWLock (gpointer mutex)
 632 {
 633   GThreadSRWLock *lock = *(GThreadSRWLock * volatile *) mutex;
 634
 635   if (lock)
 636     {
 637       if (lock->ever_shared)
 638         DeleteCriticalSection (&lock->atomicity);
 639
 640       DeleteCriticalSection (&lock->writer_lock);
 641       free (lock);
 642     }
 643 }
 644
 645 static GThreadSRWLock * __stdcall
 646 g_thread_xp_get_srwlock (GThreadSRWLock * volatile *lock)
 647 {
 648   GThreadSRWLock *result;
 649
 650   /* It looks like we're missing some barriers here, but this code only
 651    * ever runs on Windows XP, which in turn only ever runs on hardware
 652    * with a relatively rigid memory model.  The 'volatile' will take
 653    * care of the compiler.
 654    */
 655   result = *lock;
 656
 657   if G_UNLIKELY (result == NULL)
 658     {
 659       EnterCriticalSection (&g_thread_xp_lock);
 660
 661       result = malloc (sizeof (GThreadSRWLock));
 662
 663       if (result == NULL)
 664         g_thread_abort (errno, "malloc");
 665
 666       InitializeCriticalSection (&result->writer_lock);
 667       result->writer_locked = FALSE;
 668       result->ever_shared = FALSE;
 669       *lock = result;
 670
 671       LeaveCriticalSection (&g_thread_xp_lock);
 672     }
 673
 674   return result;
 675 }
 676
 677 static void __stdcall
 678 g_thread_xp_AcquireSRWLockExclusive (gpointer mutex)
 679 {
 680   GThreadSRWLock *lock = g_thread_xp_get_srwlock (mutex);
 681
 682   EnterCriticalSection (&lock->writer_lock);
 683
 684   /* CRITICAL_SECTION is reentrant, but SRWLock is not.
 685    * Detect the deadlock that would occur on later Windows version.
 686    */
 687   g_assert (!lock->writer_locked);
 688   lock->writer_locked = TRUE;
 689
 690   if (lock->ever_shared)
 691     {
 692       GThreadXpWaiter *waiter = NULL;
 693
 694       EnterCriticalSection (&lock->atomicity);
 695       if (lock->num_readers > 0)
 696         lock->queued_writer = waiter = g_thread_xp_waiter_get ();
 697       LeaveCriticalSection (&lock->atomicity);
 698
 699       if (waiter != NULL)
 700         WaitForSingleObject (waiter->event, INFINITE);
 701
 702       lock->queued_writer = NULL;
 703     }
 704 }
 705
 706 static BOOLEAN __stdcall
 707 g_thread_xp_TryAcquireSRWLockExclusive (gpointer mutex)
 708 {
 709   GThreadSRWLock *lock = g_thread_xp_get_srwlock (mutex);
 710
 711   if (!TryEnterCriticalSection (&lock->writer_lock))
 712     return FALSE;
 713
 714   /* CRITICAL_SECTION is reentrant, but SRWLock is not.
 715    * Ensure that this properly returns FALSE (as SRWLock would).
 716    */
 717   if G_UNLIKELY (lock->writer_locked)
 718     {
 719       LeaveCriticalSection (&lock->writer_lock);
 720       return FALSE;
 721     }
 722
 723   lock->writer_locked = TRUE;
 724
 725   if (lock->ever_shared)
 726     {
 727       gboolean available;
 728
 729       EnterCriticalSection (&lock->atomicity);
 730       available = lock->num_readers == 0;
 731       LeaveCriticalSection (&lock->atomicity);
 732
 733       if (!available)
 734         {
 735           LeaveCriticalSection (&lock->writer_lock);
 736           return FALSE;
 737         }
 738     }
 739
 740   return TRUE;
 741 }
 742
 743 static void __stdcall
 744 g_thread_xp_ReleaseSRWLockExclusive (gpointer mutex)
 745 {
 746   GThreadSRWLock *lock = *(GThreadSRWLock * volatile *) mutex;
 747
 748   lock->writer_locked = FALSE;
 749
 750   /* We need this until we fix some weird parts of GLib that try to
 751    * unlock freshly-allocated mutexes.
 752    */
 753   if (lock != NULL)
 754     LeaveCriticalSection (&lock->writer_lock);
 755 }
 756
 757 static void
 758 g_thread_xp_srwlock_become_reader (GThreadSRWLock *lock)
 759 {
 760   if G_UNLIKELY (!lock->ever_shared)
 761     {
 762       InitializeCriticalSection (&lock->atomicity);
 763       lock->queued_writer = NULL;
 764       lock->num_readers = 0;
 765
 766       lock->ever_shared = TRUE;
 767     }
 768
 769   EnterCriticalSection (&lock->atomicity);
 770   lock->num_readers++;
 771   LeaveCriticalSection (&lock->atomicity);
 772 }
 773
 774 static void __stdcall
 775 g_thread_xp_AcquireSRWLockShared (gpointer mutex)
 776 {
 777   GThreadSRWLock *lock = g_thread_xp_get_srwlock (mutex);
 778
 779   EnterCriticalSection (&lock->writer_lock);
 780
 781   /* See g_thread_xp_AcquireSRWLockExclusive */
 782   g_assert (!lock->writer_locked);
 783
 784   g_thread_xp_srwlock_become_reader (lock);
 785
 786   LeaveCriticalSection (&lock->writer_lock);
 787 }
 788
 789 static BOOLEAN __stdcall
 790 g_thread_xp_TryAcquireSRWLockShared (gpointer mutex)
 791 {
 792   GThreadSRWLock *lock = g_thread_xp_get_srwlock (mutex);
 793
 794   if (!TryEnterCriticalSection (&lock->writer_lock))
 795     return FALSE;
 796
 797   /* See g_thread_xp_AcquireSRWLockExclusive */
 798   if G_UNLIKELY (lock->writer_locked)
 799     {
 800       LeaveCriticalSection (&lock->writer_lock);
 801       return FALSE;
 802     }
 803
 804   g_thread_xp_srwlock_become_reader (lock);
 805
 806   LeaveCriticalSection (&lock->writer_lock);
 807
 808   return TRUE;
 809 }
 810
 811 static void __stdcall
 812 g_thread_xp_ReleaseSRWLockShared (gpointer mutex)
 813 {
 814   GThreadSRWLock *lock = g_thread_xp_get_srwlock (mutex);
 815
 816   EnterCriticalSection (&lock->atomicity);
 817
 818   lock->num_readers--;
 819
 820   if (lock->num_readers == 0 && lock->queued_writer)
 821     SetEvent (lock->queued_writer->event);
 822
 823   LeaveCriticalSection (&lock->atomicity);
 824 }
 825
 826 /* {{{2 CONDITION_VARIABLE emulation */
 827 typedef struct
 828 {
 829   volatile GThreadXpWaiter  *first;
 830   volatile GThreadXpWaiter **last_ptr;
 831 } GThreadXpCONDITION_VARIABLE;
 832
 833 static void __stdcall
 834 g_thread_xp_InitializeConditionVariable (gpointer cond)
 835 {
 836   *(GThreadXpCONDITION_VARIABLE * volatile *) cond = NULL;
 837 }
 838
 839 static void __stdcall
 840 g_thread_xp_DeleteConditionVariable (gpointer cond)
 841 {
 842   GThreadXpCONDITION_VARIABLE *cv = *(GThreadXpCONDITION_VARIABLE * volatile *) cond;
 843
 844   if (cv)
 845     free (cv);
 846 }
 847
 848 static GThreadXpCONDITION_VARIABLE * __stdcall
 849 g_thread_xp_get_condition_variable (GThreadXpCONDITION_VARIABLE * volatile *cond)
 850 {
 851   GThreadXpCONDITION_VARIABLE *result;
 852
 853   /* It looks like we're missing some barriers here, but this code only
 854    * ever runs on Windows XP, which in turn only ever runs on hardware
 855    * with a relatively rigid memory model.  The 'volatile' will take
 856    * care of the compiler.
 857    */
 858   result = *cond;
 859
 860   if G_UNLIKELY (result == NULL)
 861     {
 862       result = malloc (sizeof (GThreadXpCONDITION_VARIABLE));
 863
 864       if (result == NULL)
 865         g_thread_abort (errno, "malloc");
 866
 867       result->first = NULL;
 868       result->last_ptr = &result->first;
 869
 870       if (InterlockedCompareExchangePointer (cond, result, NULL) != NULL)
 871         {
 872           free (result);
 873           result = *cond;
 874         }
 875     }
 876
 877   return result;
 878 }
 879
 880 static BOOL __stdcall
 881 g_thread_xp_SleepConditionVariableSRW (gpointer cond,
 882                                        gpointer mutex,
 883                                        DWORD    timeout,
 884                                        ULONG    flags)
 885 {
 886   GThreadXpCONDITION_VARIABLE *cv = g_thread_xp_get_condition_variable (cond);
 887   GThreadXpWaiter *waiter = g_thread_xp_waiter_get ();
 888   DWORD status;
 889
 890   waiter->next = NULL;
 891
 892   EnterCriticalSection (&g_thread_xp_lock);
 893   *cv->last_ptr = waiter;
 894   cv->last_ptr = &waiter->next;
 895   LeaveCriticalSection (&g_thread_xp_lock);
 896
 897   g_mutex_unlock (mutex);
 898   status = WaitForSingleObject (waiter->event, timeout);
 899
 900   if (status != WAIT_TIMEOUT && status != WAIT_OBJECT_0)
 901     g_thread_abort (GetLastError (), "WaitForSingleObject");
 902
 903   g_mutex_lock (mutex);
 904
 905   return status == WAIT_OBJECT_0;
 906 }
 907
 908 static void __stdcall
 909 g_thread_xp_WakeConditionVariable (gpointer cond)
 910 {
 911   GThreadXpCONDITION_VARIABLE *cv = g_thread_xp_get_condition_variable (cond);
 912   volatile GThreadXpWaiter *waiter;
 913
 914   EnterCriticalSection (&g_thread_xp_lock);
 915   waiter = cv->first;
 916   if (waiter != NULL)
 917     {
 918       cv->first = waiter->next;
 919       if (cv->first == NULL)
 920         cv->last_ptr = &cv->first;
 921     }
 922   LeaveCriticalSection (&g_thread_xp_lock);
 923
 924   if (waiter != NULL)
 925     SetEvent (waiter->event);
 926 }
 927
 928 static void __stdcall
 929 g_thread_xp_WakeAllConditionVariable (gpointer cond)
 930 {
 931   GThreadXpCONDITION_VARIABLE *cv = g_thread_xp_get_condition_variable (cond);
 932   volatile GThreadXpWaiter *waiter;
 933
 934   EnterCriticalSection (&g_thread_xp_lock);
 935   waiter = cv->first;
 936   cv->first = NULL;
 937   cv->last_ptr = &cv->first;
 938   LeaveCriticalSection (&g_thread_xp_lock);
 939
 940   while (waiter != NULL)
 941     {
 942       volatile GThreadXpWaiter *next;
 943
 944       next = waiter->next;
 945       SetEvent (waiter->event);
 946       waiter = next;
 947     }
 948 }
 949
 950 /* {{{2 XP Setup */
 951 static void
 952 g_thread_xp_init (void)
 953 {
 954   static const GThreadImplVtable g_thread_xp_impl_vtable = {
 955     g_thread_xp_CallThisOnThreadExit,
 956     g_thread_xp_InitializeSRWLock,
 957     g_thread_xp_DeleteSRWLock,
 958     g_thread_xp_AcquireSRWLockExclusive,
 959     g_thread_xp_TryAcquireSRWLockExclusive,
 960     g_thread_xp_ReleaseSRWLockExclusive,
 961     g_thread_xp_AcquireSRWLockShared,
 962     g_thread_xp_TryAcquireSRWLockShared,
 963     g_thread_xp_ReleaseSRWLockShared,
 964     g_thread_xp_InitializeConditionVariable,
 965     g_thread_xp_DeleteConditionVariable,
 966     g_thread_xp_SleepConditionVariableSRW,
 967     g_thread_xp_WakeAllConditionVariable,
 968     g_thread_xp_WakeConditionVariable
 969   };
 970
 971   InitializeCriticalSection (&g_thread_xp_lock);
 972   g_thread_xp_waiter_tls = TlsAlloc ();
 973
 974   g_thread_impl_vtable = g_thread_xp_impl_vtable;
 975 }
 976
 977 /* {{{1 Epilogue */
 978
 979 static gboolean
 980 g_thread_lookup_native_funcs (void)
 981 {
 982   GThreadImplVtable native_vtable = { 0, };
 983   HMODULE kernel32;
 984
 985   kernel32 = GetModuleHandle ("KERNEL32.DLL");
 986
 987   if (kernel32 == NULL)
 988     return FALSE;
 989
 990 #define GET_FUNC(name) if ((native_vtable.name = (void *) GetProcAddress (kernel32, #name)) == NULL) return FALSE
 991   GET_FUNC(InitializeSRWLock);
 992   GET_FUNC(AcquireSRWLockExclusive);
 993   GET_FUNC(TryAcquireSRWLockExclusive);
 994   GET_FUNC(ReleaseSRWLockExclusive);
 995   GET_FUNC(AcquireSRWLockShared);
 996   GET_FUNC(TryAcquireSRWLockShared);
 997   GET_FUNC(ReleaseSRWLockShared);
 998
 999   GET_FUNC(InitializeConditionVariable);
1000   GET_FUNC(SleepConditionVariableSRW);
1001   GET_FUNC(WakeAllConditionVariable);
1002   GET_FUNC(WakeConditionVariable);
1003 #undef GET_FUNC
1004
1005   g_thread_impl_vtable = native_vtable;
1006
1007   return TRUE;
1008 }
1009
1010 G_GNUC_INTERNAL void
1011 g_thread_win32_init (void)
1012 {
1013   if (g_thread_lookup_native_funcs ())
1014     fprintf (stderr, "(debug) GThread using native mode\n");
1015   else
1016     {
1017       fprintf (stderr, "(debug) GThread using Windows XP mode\n");
1018       g_thread_xp_init ();
1019     }
1020
1021   win32_check_for_error (TLS_OUT_OF_INDEXES != (g_thread_self_tls = TlsAlloc ()));
1022   InitializeCriticalSection (&g_private_lock);
1023 }
1024
1025 G_GNUC_INTERNAL void
1026 g_thread_win32_thread_detach (void)
1027 {
1028   GThreadData *self = TlsGetValue (g_thread_self_tls);
1029   gboolean dtors_called;
1030
1031   do
1032     {
1033       GPrivateDestructor *dtor;
1034
1035       /* We go by the POSIX book on this one.
1036        *
1037        * If we call a destructor then there is a chance that some new
1038        * TLS variables got set by code called in that destructor.
1039        *
1040        * Loop until nothing is left.
1041        */
1042       dtors_called = FALSE;
1043
1044       for (dtor = g_private_destructors; dtor; dtor = dtor->next)
1045         {
1046           gpointer value;
1047
1048           value = TlsGetValue (dtor->index);
1049           if (value != NULL && dtor->notify != NULL)
1050             {
1051               /* POSIX says to clear this before the call */
1052               TlsSetValue (dtor->index, NULL);
1053               dtor->notify (value);
1054               dtors_called = TRUE;
1055             }
1056         }
1057     }
1058   while (dtors_called);
1059
1060   if (self)
1061     {
1062       if (!self->joinable)
1063         {
1064           win32_check_for_error (CloseHandle (self->thread));
1065           g_free (self);
1066         }
1067       win32_check_for_error (TlsSetValue (g_thread_self_tls, NULL));
1068     }
1069
1070   if (g_thread_impl_vtable.CallThisOnThreadExit)
1071     g_thread_impl_vtable.CallThisOnThreadExit ();
1072 }
1073
1074 /* vim:set foldmethod=marker: */