gcc/config/i386/gthr-win32.c

   1 /* Implementation of W32-specific threads compatibility routines for
   2    libgcc2.  */
   3
   4 /* Copyright (C) 1999, 2000, 2002, 2004 Free Software Foundation, Inc.
   5    Contributed by Mumit Khan <khan@xraylith.wisc.edu>.
   6    Modified and moved to separate file by Danny Smith
   7    <dannysmith@users.sourceforge.net>.
   8
   9 This file is part of GCC.
  10
  11 GCC is free software; you can redistribute it and/or modify it under
  12 the terms of the GNU General Public License as published by the Free
  13 Software Foundation; either version 2, or (at your option) any later
  14 version.
  15
  16 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  17 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  18 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  19 for more details.
  20
  21 You should have received a copy of the GNU General Public License
  22 along with GCC; see the file COPYING.  If not, write to the Free
  23 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  24 02110-1301, USA.  */
  25
  26 /* As a special exception, if you link this library with other files,
  27    some of which are compiled with GCC, to produce an executable,
  28    this library does not by itself cause the resulting executable
  29    to be covered by the GNU General Public License.
  30    This exception does not however invalidate any other reasons why
  31    the executable file might be covered by the GNU General Public License.  */
  32
  33
  34 #include <windows.h>
  35 #ifndef __GTHREAD_HIDE_WIN32API
  36 # define __GTHREAD_HIDE_WIN32API 1
  37 #endif
  38 #undef  __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
  39 #define __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
  40 #include <gthr-win32.h>
  41
  42 /* Windows32 threads specific definitions. The windows32 threading model
  43    does not map well into pthread-inspired gcc's threading model, and so
  44    there are caveats one needs to be aware of.
  45
  46    1. The destructor supplied to __gthread_key_create is ignored for
  47       generic x86-win32 ports. This will certainly cause memory leaks
  48       due to unreclaimed eh contexts (sizeof (eh_context) is at least
  49       24 bytes for x86 currently).
  50
  51       This memory leak may be significant for long-running applications
  52       that make heavy use of C++ EH.
  53
  54       However, Mingw runtime (version 0.3 or newer) provides a mechanism
  55       to emulate pthreads key dtors; the runtime provides a special DLL,
  56       linked in if -mthreads option is specified, that runs the dtors in
  57       the reverse order of registration when each thread exits. If
  58       -mthreads option is not given, a stub is linked in instead of the
  59       DLL, which results in memory leak. Other x86-win32 ports can use
  60       the same technique of course to avoid the leak.
  61
  62    2. The error codes returned are non-POSIX like, and cast into ints.
  63       This may cause incorrect error return due to truncation values on
  64       hw where sizeof (DWORD) > sizeof (int).
  65
  66    3. We are currently using a special mutex instead of the Critical
  67       Sections, since Win9x does not support TryEnterCriticalSection
  68       (while NT does).
  69
  70    The basic framework should work well enough. In the long term, GCC
  71    needs to use Structured Exception Handling on Windows32.  */
  72
  73 int
  74 __gthr_win32_once (__gthread_once_t *once, void (*func) (void))
  75 {
  76   if (once == NULL || func == NULL)
  77     return EINVAL;
  78
  79   if (! once->done)
  80     {
  81       if (InterlockedIncrement (&(once->started)) == 0)
  82         {
  83           (*func) ();
  84           once->done = TRUE;
  85         }
  86       else
  87         {
  88           /* Another thread is currently executing the code, so wait for it
  89              to finish; yield the CPU in the meantime.  If performance
  90              does become an issue, the solution is to use an Event that
  91              we wait on here (and set above), but that implies a place to
  92              create the event before this routine is called.  */
  93           while (! once->done)
  94             Sleep (0);
  95         }
  96     }
  97   return 0;
  98 }
  99
 100 /* Windows32 thread local keys don't support destructors; this leads to
 101    leaks, especially in threaded applications making extensive use of
 102    C++ EH. Mingw uses a thread-support DLL to work-around this problem.  */
 103
 104 int
 105 __gthr_win32_key_create (__gthread_key_t *key, void (*dtor) (void *))
 106 {
 107   int status = 0;
 108   DWORD tls_index = TlsAlloc ();
 109   if (tls_index != 0xFFFFFFFF)
 110     {
 111       *key = tls_index;
 112 #ifdef MINGW32_SUPPORTS_MT_EH
 113       /* Mingw runtime will run the dtors in reverse order for each thread
 114          when the thread exits.  */
 115       status = __mingwthr_key_dtor (*key, dtor);
 116 #endif
 117     }
 118   else
 119     status = (int) GetLastError ();
 120   return status;
 121 }
 122
 123 int
 124 __gthr_win32_key_delete (__gthread_key_t key)
 125 {
 126   return (TlsFree (key) != 0) ? 0 : (int) GetLastError ();
 127 }
 128
 129 void *
 130 __gthr_win32_getspecific (__gthread_key_t key)
 131 {
 132   DWORD lasterror;
 133   void *ptr;
 134   lasterror = GetLastError();
 135   ptr = TlsGetValue(key);
 136   SetLastError( lasterror );
 137   return ptr;
 138 }
 139
 140 int
 141 __gthr_win32_setspecific (__gthread_key_t key, const void *ptr)
 142 {
 143   return (TlsSetValue (key, (void*) ptr) != 0) ? 0 : (int) GetLastError ();
 144 }
 145
 146 void
 147 __gthr_win32_mutex_init_function (__gthread_mutex_t *mutex)
 148 {
 149   mutex->counter = -1;
 150   mutex->sema = CreateSemaphore (NULL, 0, 65535, NULL);
 151 }
 152
 153 int
 154 __gthr_win32_mutex_lock (__gthread_mutex_t *mutex)
 155 {
 156   if (InterlockedIncrement (&mutex->counter) == 0 ||
 157       WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0)
 158     return 0;
 159   else
 160     {
 161       /* WaitForSingleObject returns WAIT_FAILED, and we can only do
 162          some best-effort cleanup here.  */
 163       InterlockedDecrement (&mutex->counter);
 164       return 1;
 165     }
 166 }
 167
 168 int
 169 __gthr_win32_mutex_trylock (__gthread_mutex_t *mutex)
 170 {
 171   if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0)
 172     return 0;
 173   else
 174     return 1;
 175 }
 176
 177 int
 178 __gthr_win32_mutex_unlock (__gthread_mutex_t *mutex)
 179 {
 180   if (InterlockedDecrement (&mutex->counter) >= 0)
 181     return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1;
 182   else
 183     return 0;
 184 }
 185
 186 void
 187 __gthr_win32_recursive_mutex_init_function (__gthread_recursive_mutex_t *mutex)
 188 {
 189   mutex->counter = -1;
 190   mutex->depth = 0;
 191   mutex->owner = 0;
 192   mutex->sema = CreateSemaphore (NULL, 0, 65535, NULL);
 193 }
 194
 195 int
 196 __gthr_win32_recursive_mutex_lock (__gthread_recursive_mutex_t *mutex)
 197 {
 198   DWORD me = GetCurrentThreadId();
 199   if (InterlockedIncrement (&mutex->counter) == 0)
 200     {
 201       mutex->depth = 1;
 202       mutex->owner = me;
 203     }
 204   else if (mutex->owner == me)
 205     {
 206       InterlockedDecrement (&mutex->counter);
 207       ++(mutex->depth);
 208     }
 209   else if (WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0)
 210     {
 211       mutex->depth = 1;
 212       mutex->owner = me;
 213     }
 214   else
 215     {
 216       /* WaitForSingleObject returns WAIT_FAILED, and we can only do
 217          some best-effort cleanup here.  */
 218       InterlockedDecrement (&mutex->counter);
 219       return 1;
 220     }
 221   return 0;
 222 }
 223
 224 int
 225 __gthr_win32_recursive_mutex_trylock (__gthread_recursive_mutex_t *mutex)
 226 {
 227   DWORD me = GetCurrentThreadId();
 228   if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0)
 229     {
 230       mutex->depth = 1;
 231       mutex->owner = me;
 232     }
 233   else if (mutex->owner == me)
 234     ++(mutex->depth);
 235   else
 236     return 1;
 237
 238   return 0;
 239 }
 240
 241 int
 242 __gthr_win32_recursive_mutex_unlock (__gthread_recursive_mutex_t *mutex)
 243 {
 244   --(mutex->depth);
 245   if (mutex->depth == 0)
 246     {
 247       mutex->owner = 0;
 248
 249       if (InterlockedDecrement (&mutex->counter) >= 0)
 250         return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1;
 251     }
 252
 253   return 0;
 254 }