gcc/gthr-win32.h

   1 /* Threads compatibility routines for libgcc2 and libobjc.  */
   2 /* Compile this one with gcc.  */
   3 /* Copyright (C) 1999, 2000, 2002, 2003, 2004  Free Software Foundation, Inc.
   4    Contributed by Mumit Khan <khan@xraylith.wisc.edu>.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 2, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING.  If not, write to the Free
  20 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  21 02111-1307, USA.  */
  22
  23 /* As a special exception, if you link this library with other files,
  24    some of which are compiled with GCC, to produce an executable,
  25    this library does not by itself cause the resulting executable
  26    to be covered by the GNU General Public License.
  27    This exception does not however invalidate any other reasons why
  28    the executable file might be covered by the GNU General Public License.  */
  29
  30 #ifndef GCC_GTHR_WIN32_H
  31 #define GCC_GTHR_WIN32_H
  32
  33 /* Windows32 threads specific definitions. The windows32 threading model
  34    does not map well into pthread-inspired gcc's threading model, and so
  35    there are caveats one needs to be aware of.
  36
  37    1. The destructor supplied to __gthread_key_create is ignored for
  38       generic x86-win32 ports. This will certainly cause memory leaks
  39       due to unreclaimed eh contexts (sizeof (eh_context) is at least
  40       24 bytes for x86 currently).
  41
  42       This memory leak may be significant for long-running applications
  43       that make heavy use of C++ EH.
  44
  45       However, Mingw runtime (version 0.3 or newer) provides a mechanism
  46       to emulate pthreads key dtors; the runtime provides a special DLL,
  47       linked in if -mthreads option is specified, that runs the dtors in
  48       the reverse order of registration when each thread exits. If
  49       -mthreads option is not given, a stub is linked in instead of the
  50       DLL, which results in memory leak. Other x86-win32 ports can use
  51       the same technique of course to avoid the leak.
  52
  53    2. The error codes returned are non-POSIX like, and cast into ints.
  54       This may cause incorrect error return due to truncation values on
  55       hw where sizeof (DWORD) > sizeof (int).
  56
  57    3. We are currently using a special mutex instead of the Critical
  58       Sections, since Win9x does not support TryEnterCriticalSection
  59       (while NT does).
  60
  61    The basic framework should work well enough. In the long term, GCC
  62    needs to use Structured Exception Handling on Windows32.  */
  63
  64 #define __GTHREADS 1
  65
  66 #include <errno.h>
  67 #ifdef __MINGW32__
  68 #include <_mingw.h>
  69 #endif
  70
  71 #ifdef _LIBOBJC
  72
  73 /* This is necessary to prevent windef.h (included from windows.h) from
  74    defining it's own BOOL as a typedef.  */
  75 #ifndef __OBJC__
  76 #define __OBJC__
  77 #endif
  78 #include <windows.h>
  79 /* Now undef the windows BOOL.  */
  80 #undef BOOL
  81
  82 /* Key structure for maintaining thread specific storage */
  83 static DWORD    __gthread_objc_data_tls = (DWORD) -1;
  84
  85 /* Backend initialization functions */
  86
  87 /* Initialize the threads subsystem.  */
  88 int
  89 __gthread_objc_init_thread_system (void)
  90 {
  91   /* Initialize the thread storage key */
  92   if ((__gthread_objc_data_tls = TlsAlloc ()) != (DWORD) -1)
  93     return 0;
  94   else
  95     return -1;
  96 }
  97
  98 /* Close the threads subsystem.  */
  99 int
 100 __gthread_objc_close_thread_system (void)
 101 {
 102   if (__gthread_objc_data_tls != (DWORD) -1)
 103     TlsFree (__gthread_objc_data_tls);
 104   return 0;
 105 }
 106
 107 /* Backend thread functions */
 108
 109 /* Create a new thread of execution.  */
 110 objc_thread_t
 111 __gthread_objc_thread_detach (void (*func)(void *arg), void *arg)
 112 {
 113   DWORD thread_id = 0;
 114   HANDLE win32_handle;
 115
 116   if (!(win32_handle = CreateThread (NULL, 0, (LPTHREAD_START_ROUTINE) func,
 117                                      arg, 0, &thread_id)))
 118     thread_id = 0;
 119
 120   return (objc_thread_t) thread_id;
 121 }
 122
 123 /* Set the current thread's priority.  */
 124 int
 125 __gthread_objc_thread_set_priority (int priority)
 126 {
 127   int sys_priority = 0;
 128
 129   switch (priority)
 130     {
 131     case OBJC_THREAD_INTERACTIVE_PRIORITY:
 132       sys_priority = THREAD_PRIORITY_NORMAL;
 133       break;
 134     default:
 135     case OBJC_THREAD_BACKGROUND_PRIORITY:
 136       sys_priority = THREAD_PRIORITY_BELOW_NORMAL;
 137       break;
 138     case OBJC_THREAD_LOW_PRIORITY:
 139       sys_priority = THREAD_PRIORITY_LOWEST;
 140       break;
 141     }
 142
 143   /* Change priority */
 144   if (SetThreadPriority (GetCurrentThread (), sys_priority))
 145     return 0;
 146   else
 147     return -1;
 148 }
 149
 150 /* Return the current thread's priority.  */
 151 int
 152 __gthread_objc_thread_get_priority (void)
 153 {
 154   int sys_priority;
 155
 156   sys_priority = GetThreadPriority (GetCurrentThread ());
 157
 158   switch (sys_priority)
 159     {
 160     case THREAD_PRIORITY_HIGHEST:
 161     case THREAD_PRIORITY_TIME_CRITICAL:
 162     case THREAD_PRIORITY_ABOVE_NORMAL:
 163     case THREAD_PRIORITY_NORMAL:
 164       return OBJC_THREAD_INTERACTIVE_PRIORITY;
 165
 166     default:
 167     case THREAD_PRIORITY_BELOW_NORMAL:
 168       return OBJC_THREAD_BACKGROUND_PRIORITY;
 169
 170     case THREAD_PRIORITY_IDLE:
 171     case THREAD_PRIORITY_LOWEST:
 172       return OBJC_THREAD_LOW_PRIORITY;
 173     }
 174
 175   /* Couldn't get priority.  */
 176   return -1;
 177 }
 178
 179 /* Yield our process time to another thread.  */
 180 void
 181 __gthread_objc_thread_yield (void)
 182 {
 183   Sleep (0);
 184 }
 185
 186 /* Terminate the current thread.  */
 187 int
 188 __gthread_objc_thread_exit (void)
 189 {
 190   /* exit the thread */
 191   ExitThread (__objc_thread_exit_status);
 192
 193   /* Failed if we reached here */
 194   return -1;
 195 }
 196
 197 /* Returns an integer value which uniquely describes a thread.  */
 198 objc_thread_t
 199 __gthread_objc_thread_id (void)
 200 {
 201   return (objc_thread_t) GetCurrentThreadId ();
 202 }
 203
 204 /* Sets the thread's local storage pointer.  */
 205 int
 206 __gthread_objc_thread_set_data (void *value)
 207 {
 208   if (TlsSetValue (__gthread_objc_data_tls, value))
 209     return 0;
 210   else
 211     return -1;
 212 }
 213
 214 /* Returns the thread's local storage pointer.  */
 215 void *
 216 __gthread_objc_thread_get_data (void)
 217 {
 218   DWORD lasterror;
 219   void *ptr;
 220
 221   lasterror = GetLastError ();
 222
 223   ptr = TlsGetValue (__gthread_objc_data_tls);          /* Return thread data.  */
 224
 225   SetLastError (lasterror);
 226
 227   return ptr;
 228 }
 229
 230 /* Backend mutex functions */
 231
 232 /* Allocate a mutex.  */
 233 int
 234 __gthread_objc_mutex_allocate (objc_mutex_t mutex)
 235 {
 236   if ((mutex->backend = (void *) CreateMutex (NULL, 0, NULL)) == NULL)
 237     return -1;
 238   else
 239     return 0;
 240 }
 241
 242 /* Deallocate a mutex.  */
 243 int
 244 __gthread_objc_mutex_deallocate (objc_mutex_t mutex)
 245 {
 246   CloseHandle ((HANDLE) (mutex->backend));
 247   return 0;
 248 }
 249
 250 /* Grab a lock on a mutex.  */
 251 int
 252 __gthread_objc_mutex_lock (objc_mutex_t mutex)
 253 {
 254   int status;
 255
 256   status = WaitForSingleObject ((HANDLE) (mutex->backend), INFINITE);
 257   if (status != WAIT_OBJECT_0 && status != WAIT_ABANDONED)
 258     return -1;
 259   else
 260     return 0;
 261 }
 262
 263 /* Try to grab a lock on a mutex.  */
 264 int
 265 __gthread_objc_mutex_trylock (objc_mutex_t mutex)
 266 {
 267   int status;
 268
 269   status = WaitForSingleObject ((HANDLE) (mutex->backend), 0);
 270   if (status != WAIT_OBJECT_0 && status != WAIT_ABANDONED)
 271     return -1;
 272   else
 273     return 0;
 274 }
 275
 276 /* Unlock the mutex */
 277 int
 278 __gthread_objc_mutex_unlock (objc_mutex_t mutex)
 279 {
 280   if (ReleaseMutex ((HANDLE) (mutex->backend)) == 0)
 281     return -1;
 282   else
 283     return 0;
 284 }
 285
 286 /* Backend condition mutex functions */
 287
 288 /* Allocate a condition.  */
 289 int
 290 __gthread_objc_condition_allocate (objc_condition_t condition)
 291 {
 292   /* Unimplemented.  */
 293   return -1;
 294 }
 295
 296 /* Deallocate a condition.  */
 297 int
 298 __gthread_objc_condition_deallocate (objc_condition_t condition)
 299 {
 300   /* Unimplemented.  */
 301   return -1;
 302 }
 303
 304 /* Wait on the condition */
 305 int
 306 __gthread_objc_condition_wait (objc_condition_t condition, objc_mutex_t mutex)
 307 {
 308   /* Unimplemented.  */
 309   return -1;
 310 }
 311
 312 /* Wake up all threads waiting on this condition.  */
 313 int
 314 __gthread_objc_condition_broadcast (objc_condition_t condition)
 315 {
 316   /* Unimplemented.  */
 317   return -1;
 318 }
 319
 320 /* Wake up one thread waiting on this condition.  */
 321 int
 322 __gthread_objc_condition_signal (objc_condition_t condition)
 323 {
 324   /* Unimplemented.  */
 325   return -1;
 326 }
 327
 328 #else /* _LIBOBJC */
 329
 330 #ifdef __cplusplus
 331 extern "C" {
 332 #endif
 333
 334 typedef unsigned long __gthread_key_t;
 335
 336 typedef struct {
 337   int done;
 338   long started;
 339 } __gthread_once_t;
 340
 341 typedef struct {
 342   long counter;
 343   void *sema;
 344 } __gthread_mutex_t;
 345
 346 #define __GTHREAD_ONCE_INIT {0, -1}
 347 #define __GTHREAD_MUTEX_INIT_FUNCTION __gthread_mutex_init_function
 348 #define __GTHREAD_MUTEX_INIT_DEFAULT {0, 0}
 349
 350 #if __MINGW32_MAJOR_VERSION >= 1 || \
 351   (__MINGW32_MAJOR_VERSION == 0 && __MINGW32_MINOR_VERSION > 2)
 352 #define MINGW32_SUPPORTS_MT_EH 1
 353 /* Mingw runtime >= v0.3 provides a magic variable that is set to nonzero
 354    if -mthreads option was specified, or 0 otherwise. This is to get around
 355    the lack of weak symbols in PE-COFF.  */
 356 extern int _CRT_MT;
 357 extern int __mingwthr_key_dtor (unsigned long, void (*) (void *));
 358 #endif /* __MINGW32__ version */
 359
 360 static inline int
 361 __gthread_active_p (void)
 362 {
 363 #ifdef MINGW32_SUPPORTS_MT_EH
 364   return _CRT_MT;
 365 #else
 366   return 1;
 367 #endif
 368 }
 369
 370 #if __GTHREAD_HIDE_WIN32API
 371
 372 /* The implementations are in config/i386/gthr-win32.c in libgcc.a.
 373    Only stubs are exposed to avoid polluting the C++ namespace with
 374    windows api definitions.  */
 375
 376 extern int __gthr_win32_once (__gthread_once_t *, void (*) (void));
 377 extern int __gthr_win32_key_create (__gthread_key_t *, void (*) (void*));
 378 extern int __gthr_win32_key_delete (__gthread_key_t);
 379 extern void * __gthr_win32_getspecific (__gthread_key_t);
 380 extern int __gthr_win32_setspecific (__gthread_key_t, const void *);
 381 extern void __gthr_win32_mutex_init_function (__gthread_mutex_t *);
 382 extern int __gthr_win32_mutex_lock (__gthread_mutex_t *);
 383 extern int __gthr_win32_mutex_trylock (__gthread_mutex_t *);
 384 extern int __gthr_win32_mutex_unlock (__gthread_mutex_t *);
 385
 386 static inline int
 387 __gthread_once (__gthread_once_t *once, void (*func) (void))
 388 {
 389   if (__gthread_active_p ())
 390     return __gthr_win32_once (once, func);
 391   else
 392     return -1;
 393 }
 394
 395 static inline int
 396 __gthread_key_create (__gthread_key_t *key, void (*dtor) (void *))
 397 {
 398   return __gthr_win32_key_create (key, dtor);
 399 }
 400
 401 static inline int
 402 __gthread_key_delete (__gthread_key_t key)
 403 {
 404   return __gthr_win32_key_delete (key);
 405 }
 406
 407 static inline void *
 408 __gthread_getspecific (__gthread_key_t key)
 409 {
 410   return __gthr_win32_getspecific (key);
 411 }
 412
 413 static inline int
 414 __gthread_setspecific (__gthread_key_t key, const void *ptr)
 415 {
 416   return __gthr_win32_setspecific (key, ptr);
 417 }
 418
 419 static inline void
 420 __gthread_mutex_init_function (__gthread_mutex_t *mutex)
 421 {
 422   __gthr_win32_mutex_init_function (mutex);
 423 }
 424
 425 static inline int
 426 __gthread_mutex_lock (__gthread_mutex_t *mutex)
 427 {
 428   if (__gthread_active_p ())
 429     return __gthr_win32_mutex_lock (mutex);
 430   else
 431     return 0;
 432 }
 433
 434 static inline int
 435 __gthread_mutex_trylock (__gthread_mutex_t *mutex)
 436 {
 437   if (__gthread_active_p ())
 438     return __gthr_win32_mutex_trylock (mutex);
 439   else
 440     return 0;
 441 }
 442
 443 static inline int
 444 __gthread_mutex_unlock (__gthread_mutex_t *mutex)
 445 {
 446   if (__gthread_active_p ())
 447     return __gthr_win32_mutex_unlock (mutex);
 448   else
 449     return 0;
 450 }
 451
 452 #else /* ! __GTHREAD_HIDE_WIN32API */
 453
 454 #include <windows.h>
 455 #include <errno.h>
 456
 457 static inline int
 458 __gthread_once (__gthread_once_t *once, void (*func) (void))
 459 {
 460   if (! __gthread_active_p ())
 461     return -1;
 462   else if (once == NULL || func == NULL)
 463     return EINVAL;
 464
 465   if (! once->done)
 466     {
 467       if (InterlockedIncrement (&(once->started)) == 0)
 468         {
 469           (*func) ();
 470           once->done = TRUE;
 471         }
 472       else
 473         {
 474           /* Another thread is currently executing the code, so wait for it
 475              to finish; yield the CPU in the meantime.  If performance
 476              does become an issue, the solution is to use an Event that
 477              we wait on here (and set above), but that implies a place to
 478              create the event before this routine is called.  */
 479           while (! once->done)
 480             Sleep (0);
 481         }
 482     }
 483
 484   return 0;
 485 }
 486
 487 /* Windows32 thread local keys don't support destructors; this leads to
 488    leaks, especially in threaded applications making extensive use of
 489    C++ EH. Mingw uses a thread-support DLL to work-around this problem.  */
 490 static inline int
 491 __gthread_key_create (__gthread_key_t *key, void (*dtor) (void *))
 492 {
 493   int status = 0;
 494   DWORD tls_index = TlsAlloc ();
 495   if (tls_index != 0xFFFFFFFF)
 496     {
 497       *key = tls_index;
 498 #ifdef MINGW32_SUPPORTS_MT_EH
 499       /* Mingw runtime will run the dtors in reverse order for each thread
 500          when the thread exits.  */
 501       status = __mingwthr_key_dtor (*key, dtor);
 502 #endif
 503     }
 504   else
 505     status = (int) GetLastError ();
 506   return status;
 507 }
 508
 509 static inline int
 510 __gthread_key_delete (__gthread_key_t key)
 511 {
 512   return (TlsFree (key) != 0) ? 0 : (int) GetLastError ();
 513 }
 514
 515 static inline void *
 516 __gthread_getspecific (__gthread_key_t key)
 517 {
 518   DWORD lasterror;
 519   void *ptr;
 520
 521   lasterror = GetLastError ();
 522
 523   ptr = TlsGetValue (key);
 524
 525   SetLastError (lasterror);
 526
 527   return ptr;
 528 }
 529
 530 static inline int
 531 __gthread_setspecific (__gthread_key_t key, const void *ptr)
 532 {
 533   return (TlsSetValue (key, (void*) ptr) != 0) ? 0 : (int) GetLastError ();
 534 }
 535
 536 static inline void
 537 __gthread_mutex_init_function (__gthread_mutex_t *mutex)
 538 {
 539   mutex->counter = 0;
 540   mutex->sema = CreateSemaphore (NULL, 0, 65535, NULL);
 541 }
 542
 543 static inline int
 544 __gthread_mutex_lock (__gthread_mutex_t *mutex)
 545 {
 546   int status = 0;
 547
 548   if (__gthread_active_p ())
 549     {
 550       if (InterlockedIncrement (&mutex->counter) == 1 ||
 551           WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0)
 552         status = 0;
 553       else
 554         {
 555           // WaitForSingleObject returns WAIT_FAILED, and we can only do
 556           // some best-effort cleanup here.
 557           InterlockedDecrement (&mutex->counter);
 558           status = 1;
 559         }
 560     }
 561   return status;
 562 }
 563
 564 static inline int
 565 __gthread_mutex_trylock (__gthread_mutex_t *mutex)
 566 {
 567   int status = 0;
 568
 569   if (__gthread_active_p ())
 570     {
 571       if (InterlockedCompareExchange (&mutex->counter, 1, 0 ) == 0)
 572         status = 0;
 573       else
 574         status = 1;
 575     }
 576   return status;
 577 }
 578
 579 static inline int
 580 __gthread_mutex_unlock (__gthread_mutex_t *mutex)
 581 {
 582   if (__gthread_active_p ())
 583     {
 584       if (InterlockedDecrement (&mutex->counter))
 585         return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1;
 586     }
 587   return 0;
 588 }
 589
 590 #endif /*  __GTHREAD_HIDE_WIN32API */
 591
 592 #ifdef __cplusplus
 593 }
 594 #endif
 595
 596 #endif /* _LIBOBJC */
 597
 598 #endif /* ! GCC_GTHR_WIN32_H */