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 {-1, 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 /* The Windows95 kernel does not export InterlockedCompareExchange.
 361    This provides a substitute.   When building apps that reference
 362    gthread_mutex_try_lock, the  __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
 363    macro  must be defined if Windows95 is a target.  Currently
 364    gthread_mutex_try_lock is not referenced by libgcc or libstdc++.  */
 365 #ifdef __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
 366 static inline long
 367 __gthr_i486_lock_cmp_xchg(long *dest, long xchg, long comperand)
 368 {
 369   long result;
 370   __asm__ __volatile__ ("\n\
 371         lock\n\
 372         cmpxchg{l} {%4, %1|%1, %4}\n"
 373         : "=a" (result), "=m" (*dest)
 374         : "0" (comperand), "m" (*dest), "r" (xchg)
 375         : "cc");
 376   return result;
 377 }
 378 #define __GTHR_W32_InterlockedCompareExchange __gthr_i486_lock_cmp_xchg
 379 #else  /* __GTHREAD_I486_INLINE_LOCK_PRIMITIVES */
 380 #define __GTHR_W32_InterlockedCompareExchange InterlockedCompareExchange
 381 #endif /* __GTHREAD_I486_INLINE_LOCK_PRIMITIVES */
 382
 383 static inline int
 384 __gthread_active_p (void)
 385 {
 386 #ifdef MINGW32_SUPPORTS_MT_EH
 387   return _CRT_MT;
 388 #else
 389   return 1;
 390 #endif
 391 }
 392
 393 #if __GTHREAD_HIDE_WIN32API
 394
 395 /* The implementations are in config/i386/gthr-win32.c in libgcc.a.
 396    Only stubs are exposed to avoid polluting the C++ namespace with
 397    windows api definitions.  */
 398
 399 extern int __gthr_win32_once (__gthread_once_t *, void (*) (void));
 400 extern int __gthr_win32_key_create (__gthread_key_t *, void (*) (void*));
 401 extern int __gthr_win32_key_delete (__gthread_key_t);
 402 extern void * __gthr_win32_getspecific (__gthread_key_t);
 403 extern int __gthr_win32_setspecific (__gthread_key_t, const void *);
 404 extern void __gthr_win32_mutex_init_function (__gthread_mutex_t *);
 405 extern int __gthr_win32_mutex_lock (__gthread_mutex_t *);
 406 extern int __gthr_win32_mutex_trylock (__gthread_mutex_t *);
 407 extern int __gthr_win32_mutex_unlock (__gthread_mutex_t *);
 408
 409 static inline int
 410 __gthread_once (__gthread_once_t *once, void (*func) (void))
 411 {
 412   if (__gthread_active_p ())
 413     return __gthr_win32_once (once, func);
 414   else
 415     return -1;
 416 }
 417
 418 static inline int
 419 __gthread_key_create (__gthread_key_t *key, void (*dtor) (void *))
 420 {
 421   return __gthr_win32_key_create (key, dtor);
 422 }
 423
 424 static inline int
 425 __gthread_key_delete (__gthread_key_t key)
 426 {
 427   return __gthr_win32_key_delete (key);
 428 }
 429
 430 static inline void *
 431 __gthread_getspecific (__gthread_key_t key)
 432 {
 433   return __gthr_win32_getspecific (key);
 434 }
 435
 436 static inline int
 437 __gthread_setspecific (__gthread_key_t key, const void *ptr)
 438 {
 439   return __gthr_win32_setspecific (key, ptr);
 440 }
 441
 442 static inline void
 443 __gthread_mutex_init_function (__gthread_mutex_t *mutex)
 444 {
 445   __gthr_win32_mutex_init_function (mutex);
 446 }
 447
 448 static inline int
 449 __gthread_mutex_lock (__gthread_mutex_t *mutex)
 450 {
 451   if (__gthread_active_p ())
 452     return __gthr_win32_mutex_lock (mutex);
 453   else
 454     return 0;
 455 }
 456
 457 static inline int
 458 __gthread_mutex_trylock (__gthread_mutex_t *mutex)
 459 {
 460   if (__gthread_active_p ())
 461     return __gthr_win32_mutex_trylock (mutex);
 462   else
 463     return 0;
 464 }
 465
 466 static inline int
 467 __gthread_mutex_unlock (__gthread_mutex_t *mutex)
 468 {
 469   if (__gthread_active_p ())
 470     return __gthr_win32_mutex_unlock (mutex);
 471   else
 472     return 0;
 473 }
 474
 475 #else /* ! __GTHREAD_HIDE_WIN32API */
 476
 477 #include <windows.h>
 478 #include <errno.h>
 479
 480 static inline int
 481 __gthread_once (__gthread_once_t *once, void (*func) (void))
 482 {
 483   if (! __gthread_active_p ())
 484     return -1;
 485   else if (once == NULL || func == NULL)
 486     return EINVAL;
 487
 488   if (! once->done)
 489     {
 490       if (InterlockedIncrement (&(once->started)) == 0)
 491         {
 492           (*func) ();
 493           once->done = TRUE;
 494         }
 495       else
 496         {
 497           /* Another thread is currently executing the code, so wait for it
 498              to finish; yield the CPU in the meantime.  If performance
 499              does become an issue, the solution is to use an Event that
 500              we wait on here (and set above), but that implies a place to
 501              create the event before this routine is called.  */
 502           while (! once->done)
 503             Sleep (0);
 504         }
 505     }
 506
 507   return 0;
 508 }
 509
 510 /* Windows32 thread local keys don't support destructors; this leads to
 511    leaks, especially in threaded applications making extensive use of
 512    C++ EH. Mingw uses a thread-support DLL to work-around this problem.  */
 513 static inline int
 514 __gthread_key_create (__gthread_key_t *key, void (*dtor) (void *))
 515 {
 516   int status = 0;
 517   DWORD tls_index = TlsAlloc ();
 518   if (tls_index != 0xFFFFFFFF)
 519     {
 520       *key = tls_index;
 521 #ifdef MINGW32_SUPPORTS_MT_EH
 522       /* Mingw runtime will run the dtors in reverse order for each thread
 523          when the thread exits.  */
 524       status = __mingwthr_key_dtor (*key, dtor);
 525 #endif
 526     }
 527   else
 528     status = (int) GetLastError ();
 529   return status;
 530 }
 531
 532 static inline int
 533 __gthread_key_delete (__gthread_key_t key)
 534 {
 535   return (TlsFree (key) != 0) ? 0 : (int) GetLastError ();
 536 }
 537
 538 static inline void *
 539 __gthread_getspecific (__gthread_key_t key)
 540 {
 541   DWORD lasterror;
 542   void *ptr;
 543
 544   lasterror = GetLastError ();
 545
 546   ptr = TlsGetValue (key);
 547
 548   SetLastError (lasterror);
 549
 550   return ptr;
 551 }
 552
 553 static inline int
 554 __gthread_setspecific (__gthread_key_t key, const void *ptr)
 555 {
 556   return (TlsSetValue (key, (void*) ptr) != 0) ? 0 : (int) GetLastError ();
 557 }
 558
 559 static inline void
 560 __gthread_mutex_init_function (__gthread_mutex_t *mutex)
 561 {
 562   mutex->counter = -1;
 563   mutex->sema = CreateSemaphore (NULL, 0, 65535, NULL);
 564 }
 565
 566 static inline int
 567 __gthread_mutex_lock (__gthread_mutex_t *mutex)
 568 {
 569   int status = 0;
 570
 571   if (__gthread_active_p ())
 572     {
 573       if (InterlockedIncrement (&mutex->counter) == 0 ||
 574           WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0)
 575         status = 0;
 576       else
 577         {
 578           /* WaitForSingleObject returns WAIT_FAILED, and we can only do
 579              some best-effort cleanup here.  */
 580           InterlockedDecrement (&mutex->counter);
 581           status = 1;
 582         }
 583     }
 584   return status;
 585 }
 586
 587 static inline int
 588 __gthread_mutex_trylock (__gthread_mutex_t *mutex)
 589 {
 590   int status = 0;
 591
 592   if (__gthread_active_p ())
 593     {
 594       if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0)
 595         status = 0;
 596       else
 597         status = 1;
 598     }
 599   return status;
 600 }
 601
 602 static inline int
 603 __gthread_mutex_unlock (__gthread_mutex_t *mutex)
 604 {
 605   if (__gthread_active_p ())
 606     {
 607       if (InterlockedDecrement (&mutex->counter) >= 0)
 608         return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1;
 609     }
 610   return 0;
 611 }
 612
 613 #endif /*  __GTHREAD_HIDE_WIN32API */
 614
 615 #ifdef __cplusplus
 616 }
 617 #endif
 618
 619 #endif /* _LIBOBJC */
 620
 621 #endif /* ! GCC_GTHR_WIN32_H */