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 9This file is part of GCC. 10 11GCC is free software; you can redistribute it and/or modify it under 12the terms of the GNU General Public License as published by the Free 13Software Foundation; either version 2, or (at your option) any later 14version. 15 16GCC is distributed in the hope that it will be useful, but WITHOUT ANY 17WARRANTY; without even the implied warranty of MERCHANTABILITY or 18FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 19for more details. 20 21You should have received a copy of the GNU General Public License 22along with GCC; see the file COPYING. If not, write to the Free 23Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 2402110-1301, 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 73int 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 104int 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 123int 124__gthr_win32_key_delete (__gthread_key_t key) 125{ 126 return (TlsFree (key) != 0) ? 0 : (int) GetLastError (); 127} 128 129void * 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 140int 141__gthr_win32_setspecific (__gthread_key_t key, const void *ptr) 142{ 143 return (TlsSetValue (key, (void*) ptr) != 0) ? 0 : (int) GetLastError (); 144} 145 146void 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 153int 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 168int 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 177int 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 186void 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 195int 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 224int 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 241int 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} 255