gcc/gthr-win32.h

   1 /* Threads compatibility routines for libgcc2 and libobjc.  */
   2 /* Compile this one with gcc.  */
   3 /* Copyright (C) 1999, 2000 Free Software Foundation, Inc.
   4    Contributed by Mumit Khan <khan@xraylith.wisc.edu>.
   5
   6 This file is part of GNU CC.
   7
   8 GNU CC is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 2, or (at your option)
  11 any later version.
  12
  13 GNU CC 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
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GNU CC; see the file COPYING.  If not, write to
  20 the Free Software Foundation, 59 Temple Place - Suite 330,
  21 Boston, MA 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 __gthr_win32_h
  31 #define __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 <windows.h>
  68
  69 #ifdef _LIBOBJC
  70
  71 /* Key structure for maintaining thread specific storage */
  72 static DWORD    __gthread_objc_data_tls = (DWORD)-1;
  73
  74 /* Backend initialization functions */
  75
  76 /* Initialize the threads subsystem. */
  77 int
  78 __gthread_objc_init_thread_system(void)
  79 {
  80   /* Initialize the thread storage key */
  81   if ((__gthread_objc_data_tls = TlsAlloc()) != (DWORD)-1)
  82     return 0;
  83   else
  84     return -1;
  85 }
  86
  87 /* Close the threads subsystem. */
  88 int
  89 __gthread_objc_close_thread_system(void)
  90 {
  91   if (__gthread_objc_data_tls != (DWORD)-1)
  92     TlsFree(__gthread_objc_data_tls);
  93   return 0;
  94 }
  95
  96 /* Backend thread functions */
  97
  98 /* Create a new thread of execution. */
  99 objc_thread_t
 100 __gthread_objc_thread_detach(void (*func)(void *arg), void *arg)
 101 {
 102   DWORD thread_id = 0;
 103   HANDLE win32_handle;
 104
 105   if (!(win32_handle = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)func,
 106                                    arg, 0, &thread_id)))
 107     thread_id = 0;
 108
 109   return (objc_thread_t)thread_id;
 110 }
 111
 112 /* Set the current thread's priority. */
 113 int
 114 __gthread_objc_thread_set_priority(int priority)
 115 {
 116   int sys_priority = 0;
 117
 118   switch (priority)
 119     {
 120     case OBJC_THREAD_INTERACTIVE_PRIORITY:
 121       sys_priority = THREAD_PRIORITY_NORMAL;
 122       break;
 123     default:
 124     case OBJC_THREAD_BACKGROUND_PRIORITY:
 125       sys_priority = THREAD_PRIORITY_BELOW_NORMAL;
 126       break;
 127     case OBJC_THREAD_LOW_PRIORITY:
 128       sys_priority = THREAD_PRIORITY_LOWEST;
 129       break;
 130     }
 131
 132   /* Change priority */
 133   if (SetThreadPriority(GetCurrentThread(), sys_priority))
 134     return 0;
 135   else
 136     return -1;
 137 }
 138
 139 /* Return the current thread's priority. */
 140 int
 141 __gthread_objc_thread_get_priority(void)
 142 {
 143   int sys_priority;
 144
 145   sys_priority = GetThreadPriority(GetCurrentThread());
 146
 147   switch (sys_priority)
 148     {
 149     case THREAD_PRIORITY_HIGHEST:
 150     case THREAD_PRIORITY_TIME_CRITICAL:
 151     case THREAD_PRIORITY_ABOVE_NORMAL:
 152     case THREAD_PRIORITY_NORMAL:
 153       return OBJC_THREAD_INTERACTIVE_PRIORITY;
 154
 155     default:
 156     case THREAD_PRIORITY_BELOW_NORMAL:
 157       return OBJC_THREAD_BACKGROUND_PRIORITY;
 158
 159     case THREAD_PRIORITY_IDLE:
 160     case THREAD_PRIORITY_LOWEST:
 161       return OBJC_THREAD_LOW_PRIORITY;
 162     }
 163
 164   /* Couldn't get priority. */
 165   return -1;
 166 }
 167
 168 /* Yield our process time to another thread. */
 169 void
 170 __gthread_objc_thread_yield(void)
 171 {
 172   Sleep(0);
 173 }
 174
 175 /* Terminate the current thread. */
 176 int
 177 __gthread_objc_thread_exit(void)
 178 {
 179   /* exit the thread */
 180   ExitThread(__gthread_objc_thread_exit_status);
 181
 182   /* Failed if we reached here */
 183   return -1;
 184 }
 185
 186 /* Returns an integer value which uniquely describes a thread. */
 187 objc_thread_t
 188 __gthread_objc_thread_id(void)
 189 {
 190   return (objc_thread_t)GetCurrentThreadId();
 191 }
 192
 193 /* Sets the thread's local storage pointer. */
 194 int
 195 __gthread_objc_thread_set_data(void *value)
 196 {
 197   if (TlsSetValue(__gthread_objc_data_tls, value))
 198     return 0;
 199   else
 200     return -1;
 201 }
 202
 203 /* Returns the thread's local storage pointer. */
 204 void *
 205 __gthread_objc_thread_get_data(void)
 206 {
 207   return TlsGetValue(__gthread_objc_data_tls);          /* Return thread data.      */
 208 }
 209
 210 /* Backend mutex functions */
 211
 212 /* Allocate a mutex. */
 213 int
 214 __gthread_objc_mutex_allocate(objc_mutex_t mutex)
 215 {
 216   if ((mutex->backend = (void *)CreateMutex(NULL, 0, NULL)) == NULL)
 217     return -1;
 218   else
 219     return 0;
 220 }
 221
 222 /* Deallocate a mutex. */
 223 int
 224 __gthread_objc_mutex_deallocate(objc_mutex_t mutex)
 225 {
 226   CloseHandle((HANDLE)(mutex->backend));
 227   return 0;
 228 }
 229
 230 /* Grab a lock on a mutex. */
 231 int
 232 __gthread_objc_mutex_lock(objc_mutex_t mutex)
 233 {
 234   int status;
 235
 236   status = WaitForSingleObject((HANDLE)(mutex->backend), INFINITE);
 237   if (status != WAIT_OBJECT_0 && status != WAIT_ABANDONED)
 238     return -1;
 239   else
 240     return 0;
 241 }
 242
 243 /* Try to grab a lock on a mutex. */
 244 int
 245 __gthread_objc_mutex_trylock(objc_mutex_t mutex)
 246 {
 247   int status;
 248
 249   status = WaitForSingleObject((HANDLE)(mutex->backend), 0);
 250   if (status != WAIT_OBJECT_0 && status != WAIT_ABANDONED)
 251     return -1;
 252   else
 253     return 0;
 254 }
 255
 256 /* Unlock the mutex */
 257 int
 258 __gthread_objc_mutex_unlock(objc_mutex_t mutex)
 259 {
 260   if (ReleaseMutex((HANDLE)(mutex->backend)) == 0)
 261     return -1;
 262   else
 263     return 0;
 264 }
 265
 266 /* Backend condition mutex functions */
 267
 268 /* Allocate a condition. */
 269 int
 270 __gthread_objc_condition_allocate(objc_condition_t condition)
 271 {
 272   /* Unimplemented. */
 273   return -1;
 274 }
 275
 276 /* Deallocate a condition. */
 277 int
 278 __gthread_objc_condition_deallocate(objc_condition_t condition)
 279 {
 280   /* Unimplemented. */
 281   return -1;
 282 }
 283
 284 /* Wait on the condition */
 285 int
 286 __gthread_objc_condition_wait(objc_condition_t condition, objc_mutex_t mutex)
 287 {
 288   /* Unimplemented. */
 289   return -1;
 290 }
 291
 292 /* Wake up all threads waiting on this condition. */
 293 int
 294 __gthread_objc_condition_broadcast(objc_condition_t condition)
 295 {
 296   /* Unimplemented. */
 297   return -1;
 298 }
 299
 300 /* Wake up one thread waiting on this condition. */
 301 int
 302 __gthread_objc_condition_signal(objc_condition_t condition)
 303 {
 304   /* Unimplemented. */
 305   return -1;
 306 }
 307
 308 #else /* _LIBOBJC */
 309
 310 #ifdef __MINGW32__
 311 #include <_mingw.h>
 312 #endif
 313
 314 typedef DWORD __gthread_key_t;
 315
 316 typedef struct {
 317   int done;
 318   long started;
 319 } __gthread_once_t;
 320
 321 typedef HANDLE __gthread_mutex_t;
 322
 323 #define __GTHREAD_ONCE_INIT {FALSE, -1}
 324 #define __GTHREAD_MUTEX_INIT_FUNCTION __gthread_mutex_init_function
 325
 326 #if __MINGW32_MAJOR_VERSION >= 1 || \
 327   (__MINGW32_MAJOR_VERSION == 0 && __MINGW32_MINOR_VERSION > 2)
 328 #define MINGW32_SUPPORTS_MT_EH 1
 329 extern int __mingwthr_key_dtor PARAMS ((DWORD, void (*) (void *)));
 330 /* Mingw runtime >= v0.3 provides a magic variable that is set to non-zero
 331    if -mthreads option was specified, or 0 otherwise. This is to get around
 332    the lack of weak symbols in PE-COFF.  */
 333 extern int _CRT_MT;
 334 #endif
 335
 336 static inline int
 337 __gthread_active_p (void)
 338 {
 339 #ifdef MINGW32_SUPPORTS_MT_EH
 340   return _CRT_MT;
 341 #else
 342   return 1;
 343 #endif
 344 }
 345
 346 static inline int
 347 __gthread_once (__gthread_once_t *once, void (*func) (void))
 348 {
 349   if (! __gthread_active_p ())
 350     return -1;
 351   else if (once == NULL || func == NULL)
 352     return EINVAL;
 353
 354   if (! once->done)
 355     {
 356       if (InterlockedIncrement (&(once->started)) == 0)
 357         {
 358           (*func) ();
 359           once->done = TRUE;
 360         }
 361       else
 362         {
 363           /* Another thread is currently executing the code, so wait for it
 364              to finish; yield the CPU in the meantime.  If performance
 365              does become an issue, the solution is to use an Event that
 366              we wait on here (and set above), but that implies a place to
 367              create the event before this routine is called.  */
 368           while (! once->done)
 369             Sleep (0);
 370         }
 371     }
 372
 373   return 0;
 374 }
 375
 376 /* Windows32 thread local keys don't support destructors; this leads to
 377    leaks, especially in threaded applications making extensive use of
 378    C++ EH. Mingw uses a thread-support DLL to work-around this problem.  */
 379 static inline int
 380 __gthread_key_create (__gthread_key_t *key, void (*dtor) (void *))
 381 {
 382   int status = 0;
 383   DWORD tls_index = TlsAlloc ();
 384   if (tls_index != 0xFFFFFFFF)
 385     {
 386       *key = tls_index;
 387 #ifdef MINGW32_SUPPORTS_MT_EH
 388       /* Mingw runtime will run the dtors in reverse order for each thread
 389          when the thread exits.  */
 390       status = __mingwthr_key_dtor (*key, dtor);
 391 #endif
 392     }
 393   else
 394     status = (int) GetLastError ();
 395   return status;
 396 }
 397
 398 /* Currently, this routine is called only for Mingw runtime, and if
 399    -mthreads option is chosen to link in the thread support DLL.  */
 400 static inline int
 401 __gthread_key_dtor (__gthread_key_t key, void *ptr)
 402 {
 403   /* Nothing needed. */
 404   return 0;
 405 }
 406
 407 static inline int
 408 __gthread_key_delete (__gthread_key_t key)
 409 {
 410   return (TlsFree (key) != 0) ? 0 : (int) GetLastError ();
 411 }
 412
 413 static inline void *
 414 __gthread_getspecific (__gthread_key_t key)
 415 {
 416   return TlsGetValue (key);
 417 }
 418
 419 static inline int
 420 __gthread_setspecific (__gthread_key_t key, const void *ptr)
 421 {
 422   return (TlsSetValue (key, (void*) ptr) != 0) ? 0 : (int) GetLastError ();
 423 }
 424
 425 static inline void
 426 __gthread_mutex_init_function (__gthread_mutex_t *mutex)
 427 {
 428   /* Create unnamed mutex with default security attr and no initial owner.  */
 429   *mutex = CreateMutex (NULL, 0, NULL);
 430 }
 431
 432 static inline int
 433 __gthread_mutex_lock (__gthread_mutex_t *mutex)
 434 {
 435   int status = 0;
 436
 437   if (__gthread_active_p ())
 438     {
 439       if (WaitForSingleObject (*mutex, INFINITE) == WAIT_OBJECT_0)
 440         status = 0;
 441       else
 442         status = 1;
 443     }
 444   return status;
 445 }
 446
 447 static inline int
 448 __gthread_mutex_trylock (__gthread_mutex_t *mutex)
 449 {
 450   int status = 0;
 451
 452   if (__gthread_active_p ())
 453     {
 454       if (WaitForSingleObject (*mutex, 0) == WAIT_OBJECT_0)
 455         status = 0;
 456       else
 457         status = 1;
 458     }
 459   return status;
 460 }
 461
 462 static inline int
 463 __gthread_mutex_unlock (__gthread_mutex_t *mutex)
 464 {
 465   if (__gthread_active_p ())
 466     return (ReleaseMutex (*mutex) != 0) ? 0 : 1;
 467   else
 468     return 0;
 469 }
 470
 471 #endif /* _LIBOBJC */
 472
 473 #endif /* not __gthr_win32_h */
 474