gcc/gthr-win32.h

   1 /* Threads compatibility routines for libgcc2 and libobjc.  */
   2 /* Compile this one with gcc.  */
   3 /* Copyright (C) 1999, 2000, 2002 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 might consider using Critical Sections instead of Windows32
  58       mutexes for better performance, but emulating __gthread_mutex_trylock
  59       interface becomes more complicated (Win9x does not support
  60       TryEnterCriticalSectioni, while NT does).
  61
  62    The basic framework should work well enough. In the long term, GCC
  63    needs to use Structured Exception Handling on Windows32.  */
  64
  65 #define __GTHREADS 1
  66
  67 #include <errno.h>
  68 #ifdef __MINGW32__
  69 #include <_mingw.h>
  70 #endif
  71
  72 #ifdef _LIBOBJC
  73
  74 /* This is necessary to prevent windef.h (included from windows.h) from
  75    defining it's own BOOL as a typedef.  */
  76 #ifndef __OBJC__
  77 #define __OBJC__
  78 #endif
  79 #include <windows.h>
  80 /* Now undef the windows BOOL.  */
  81 #undef BOOL
  82
  83 /* Key structure for maintaining thread specific storage */
  84 static DWORD    __gthread_objc_data_tls = (DWORD)-1;
  85
  86 /* Backend initialization functions */
  87
  88 /* Initialize the threads subsystem.  */
  89 int
  90 __gthread_objc_init_thread_system(void)
  91 {
  92   /* Initialize the thread storage key */
  93   if ((__gthread_objc_data_tls = TlsAlloc()) != (DWORD)-1)
  94     return 0;
  95   else
  96     return -1;
  97 }
  98
  99 /* Close the threads subsystem.  */
 100 int
 101 __gthread_objc_close_thread_system(void)
 102 {
 103   if (__gthread_objc_data_tls != (DWORD)-1)
 104     TlsFree(__gthread_objc_data_tls);
 105   return 0;
 106 }
 107
 108 /* Backend thread functions */
 109
 110 /* Create a new thread of execution.  */
 111 objc_thread_t
 112 __gthread_objc_thread_detach(void (*func)(void *arg), void *arg)
 113 {
 114   DWORD thread_id = 0;
 115   HANDLE win32_handle;
 116
 117   if (!(win32_handle = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)func,
 118                                    arg, 0, &thread_id)))
 119     thread_id = 0;
 120
 121   return (objc_thread_t)thread_id;
 122 }
 123
 124 /* Set the current thread's priority.  */
 125 int
 126 __gthread_objc_thread_set_priority(int priority)
 127 {
 128   int sys_priority = 0;
 129
 130   switch (priority)
 131     {
 132     case OBJC_THREAD_INTERACTIVE_PRIORITY:
 133       sys_priority = THREAD_PRIORITY_NORMAL;
 134       break;
 135     default:
 136     case OBJC_THREAD_BACKGROUND_PRIORITY:
 137       sys_priority = THREAD_PRIORITY_BELOW_NORMAL;
 138       break;
 139     case OBJC_THREAD_LOW_PRIORITY:
 140       sys_priority = THREAD_PRIORITY_LOWEST;
 141       break;
 142     }
 143
 144   /* Change priority */
 145   if (SetThreadPriority(GetCurrentThread(), sys_priority))
 146     return 0;
 147   else
 148     return -1;
 149 }
 150
 151 /* Return the current thread's priority.  */
 152 int
 153 __gthread_objc_thread_get_priority(void)
 154 {
 155   int sys_priority;
 156
 157   sys_priority = GetThreadPriority(GetCurrentThread());
 158
 159   switch (sys_priority)
 160     {
 161     case THREAD_PRIORITY_HIGHEST:
 162     case THREAD_PRIORITY_TIME_CRITICAL:
 163     case THREAD_PRIORITY_ABOVE_NORMAL:
 164     case THREAD_PRIORITY_NORMAL:
 165       return OBJC_THREAD_INTERACTIVE_PRIORITY;
 166
 167     default:
 168     case THREAD_PRIORITY_BELOW_NORMAL:
 169       return OBJC_THREAD_BACKGROUND_PRIORITY;
 170
 171     case THREAD_PRIORITY_IDLE:
 172     case THREAD_PRIORITY_LOWEST:
 173       return OBJC_THREAD_LOW_PRIORITY;
 174     }
 175
 176   /* Couldn't get priority.  */
 177   return -1;
 178 }
 179
 180 /* Yield our process time to another thread.  */
 181 void
 182 __gthread_objc_thread_yield(void)
 183 {
 184   Sleep(0);
 185 }
 186
 187 /* Terminate the current thread.  */
 188 int
 189 __gthread_objc_thread_exit(void)
 190 {
 191   /* exit the thread */
 192   ExitThread(__objc_thread_exit_status);
 193
 194   /* Failed if we reached here */
 195   return -1;
 196 }
 197
 198 /* Returns an integer value which uniquely describes a thread.  */
 199 objc_thread_t
 200 __gthread_objc_thread_id(void)
 201 {
 202   return (objc_thread_t)GetCurrentThreadId();
 203 }
 204
 205 /* Sets the thread's local storage pointer.  */
 206 int
 207 __gthread_objc_thread_set_data(void *value)
 208 {
 209   if (TlsSetValue(__gthread_objc_data_tls, value))
 210     return 0;
 211   else
 212     return -1;
 213 }
 214
 215 /* Returns the thread's local storage pointer.  */
 216 void *
 217 __gthread_objc_thread_get_data(void)
 218 {
 219   DWORD lasterror;
 220   void *ptr;
 221
 222   lasterror = GetLastError();
 223
 224   ptr = TlsGetValue(__gthread_objc_data_tls);          /* Return thread data.  */
 225
 226   SetLastError( lasterror );
 227
 228   return ptr;
 229 }
 230
 231 /* Backend mutex functions */
 232
 233 /* Allocate a mutex.  */
 234 int
 235 __gthread_objc_mutex_allocate(objc_mutex_t mutex)
 236 {
 237   if ((mutex->backend = (void *)CreateMutex(NULL, 0, NULL)) == NULL)
 238     return -1;
 239   else
 240     return 0;
 241 }
 242
 243 /* Deallocate a mutex.  */
 244 int
 245 __gthread_objc_mutex_deallocate(objc_mutex_t mutex)
 246 {
 247   CloseHandle((HANDLE)(mutex->backend));
 248   return 0;
 249 }
 250
 251 /* Grab a lock on a mutex.  */
 252 int
 253 __gthread_objc_mutex_lock(objc_mutex_t mutex)
 254 {
 255   int status;
 256
 257   status = WaitForSingleObject((HANDLE)(mutex->backend), INFINITE);
 258   if (status != WAIT_OBJECT_0 && status != WAIT_ABANDONED)
 259     return -1;
 260   else
 261     return 0;
 262 }
 263
 264 /* Try to grab a lock on a mutex.  */
 265 int
 266 __gthread_objc_mutex_trylock(objc_mutex_t mutex)
 267 {
 268   int status;
 269
 270   status = WaitForSingleObject((HANDLE)(mutex->backend), 0);
 271   if (status != WAIT_OBJECT_0 && status != WAIT_ABANDONED)
 272     return -1;
 273   else
 274     return 0;
 275 }
 276
 277 /* Unlock the mutex */
 278 int
 279 __gthread_objc_mutex_unlock(objc_mutex_t mutex)
 280 {
 281   if (ReleaseMutex((HANDLE)(mutex->backend)) == 0)
 282     return -1;
 283   else
 284     return 0;
 285 }
 286
 287 /* Backend condition mutex functions */
 288
 289 /* Allocate a condition.  */
 290 int
 291 __gthread_objc_condition_allocate(objc_condition_t condition)
 292 {
 293   /* Unimplemented.  */
 294   return -1;
 295 }
 296
 297 /* Deallocate a condition.  */
 298 int
 299 __gthread_objc_condition_deallocate(objc_condition_t condition)
 300 {
 301   /* Unimplemented.  */
 302   return -1;
 303 }
 304
 305 /* Wait on the condition */
 306 int
 307 __gthread_objc_condition_wait(objc_condition_t condition, objc_mutex_t mutex)
 308 {
 309   /* Unimplemented.  */
 310   return -1;
 311 }
 312
 313 /* Wake up all threads waiting on this condition.  */
 314 int
 315 __gthread_objc_condition_broadcast(objc_condition_t condition)
 316 {
 317   /* Unimplemented.  */
 318   return -1;
 319 }
 320
 321 /* Wake up one thread waiting on this condition.  */
 322 int
 323 __gthread_objc_condition_signal(objc_condition_t condition)
 324 {
 325   /* Unimplemented.  */
 326   return -1;
 327 }
 328
 329 #else /* _LIBOBJC */
 330
 331 #include <windows.h>
 332
 333 typedef DWORD __gthread_key_t;
 334
 335 typedef struct {
 336   int done;
 337   long started;
 338 } __gthread_once_t;
 339
 340 typedef HANDLE __gthread_mutex_t;
 341
 342 #define __GTHREAD_ONCE_INIT {FALSE, -1}
 343 #define __GTHREAD_MUTEX_INIT_FUNCTION __gthread_mutex_init_function
 344
 345 #if __MINGW32_MAJOR_VERSION >= 1 || \
 346   (__MINGW32_MAJOR_VERSION == 0 && __MINGW32_MINOR_VERSION > 2)
 347 #define MINGW32_SUPPORTS_MT_EH 1
 348 #ifdef __cplusplus
 349 extern "C" {
 350 #endif
 351 extern int __mingwthr_key_dtor (DWORD, void (*) (void *));
 352 #ifdef __cplusplus
 353 }
 354 #endif
 355
 356 /* Mingw runtime >= v0.3 provides a magic variable that is set to non-zero
 357    if -mthreads option was specified, or 0 otherwise. This is to get around
 358    the lack of weak symbols in PE-COFF.  */
 359 extern int _CRT_MT;
 360 #endif
 361
 362 static inline int
 363 __gthread_active_p (void)
 364 {
 365 #ifdef MINGW32_SUPPORTS_MT_EH
 366   return _CRT_MT;
 367 #else
 368   return 1;
 369 #endif
 370 }
 371
 372 static inline int
 373 __gthread_once (__gthread_once_t *once, void (*func) (void))
 374 {
 375   if (! __gthread_active_p ())
 376     return -1;
 377   else if (once == NULL || func == NULL)
 378     return EINVAL;
 379
 380   if (! once->done)
 381     {
 382       if (InterlockedIncrement (&(once->started)) == 0)
 383         {
 384           (*func) ();
 385           once->done = TRUE;
 386         }
 387       else
 388         {
 389           /* Another thread is currently executing the code, so wait for it
 390              to finish; yield the CPU in the meantime.  If performance
 391              does become an issue, the solution is to use an Event that
 392              we wait on here (and set above), but that implies a place to
 393              create the event before this routine is called.  */
 394           while (! once->done)
 395             Sleep (0);
 396         }
 397     }
 398
 399   return 0;
 400 }
 401
 402 /* Windows32 thread local keys don't support destructors; this leads to
 403    leaks, especially in threaded applications making extensive use of
 404    C++ EH. Mingw uses a thread-support DLL to work-around this problem.  */
 405 static inline int
 406 __gthread_key_create (__gthread_key_t *key, void (*dtor) (void *))
 407 {
 408   int status = 0;
 409   DWORD tls_index = TlsAlloc ();
 410   if (tls_index != 0xFFFFFFFF)
 411     {
 412       *key = tls_index;
 413 #ifdef MINGW32_SUPPORTS_MT_EH
 414       /* Mingw runtime will run the dtors in reverse order for each thread
 415          when the thread exits.  */
 416       status = __mingwthr_key_dtor (*key, dtor);
 417 #endif
 418     }
 419   else
 420     status = (int) GetLastError ();
 421   return status;
 422 }
 423
 424 /* Currently, this routine is called only for Mingw runtime, and if
 425    -mthreads option is chosen to link in the thread support DLL.  */
 426 static inline int
 427 __gthread_key_dtor (__gthread_key_t key, void *ptr)
 428 {
 429   /* Nothing needed.  */
 430   return 0;
 431 }
 432
 433 static inline int
 434 __gthread_key_delete (__gthread_key_t key)
 435 {
 436   return (TlsFree (key) != 0) ? 0 : (int) GetLastError ();
 437 }
 438
 439 static inline void *
 440 __gthread_getspecific (__gthread_key_t key)
 441 {
 442   DWORD lasterror;
 443   void *ptr;
 444
 445   lasterror = GetLastError();
 446
 447   ptr = TlsGetValue(key);
 448
 449   SetLastError( lasterror );
 450
 451   return ptr;
 452 }
 453
 454 static inline int
 455 __gthread_setspecific (__gthread_key_t key, const void *ptr)
 456 {
 457   return (TlsSetValue (key, (void*) ptr) != 0) ? 0 : (int) GetLastError ();
 458 }
 459
 460 static inline void
 461 __gthread_mutex_init_function (__gthread_mutex_t *mutex)
 462 {
 463   /* Create unnamed mutex with default security attr and no initial owner.  */
 464   *mutex = CreateMutex (NULL, 0, NULL);
 465 }
 466
 467 static inline int
 468 __gthread_mutex_lock (__gthread_mutex_t *mutex)
 469 {
 470   int status = 0;
 471
 472   if (__gthread_active_p ())
 473     {
 474       if (WaitForSingleObject (*mutex, INFINITE) == WAIT_OBJECT_0)
 475         status = 0;
 476       else
 477         status = 1;
 478     }
 479   return status;
 480 }
 481
 482 static inline int
 483 __gthread_mutex_trylock (__gthread_mutex_t *mutex)
 484 {
 485   int status = 0;
 486
 487   if (__gthread_active_p ())
 488     {
 489       if (WaitForSingleObject (*mutex, 0) == WAIT_OBJECT_0)
 490         status = 0;
 491       else
 492         status = 1;
 493     }
 494   return status;
 495 }
 496
 497 static inline int
 498 __gthread_mutex_unlock (__gthread_mutex_t *mutex)
 499 {
 500   if (__gthread_active_p ())
 501     return (ReleaseMutex (*mutex) != 0) ? 0 : 1;
 502   else
 503     return 0;
 504 }
 505
 506 #endif /* _LIBOBJC */
 507
 508 #endif /* ! GCC_GTHR_WIN32_H */
 509