1 /* Implementation of W32-specific threads compatibility routines for 2 libgcc2. */ 3 4 /* Copyright (C) 1999-2018 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 3, 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 Under Section 7 of GPL version 3, you are granted additional 22 permissions described in the GCC Runtime Library Exception, version 23 3.1, as published by the Free Software Foundation. 24 25 You should have received a copy of the GNU General Public License and 26 a copy of the GCC Runtime Library Exception along with this program; 27 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 28 <http://www.gnu.org/licenses/>. */ 29 30 #include <windows.h> 31 #ifndef __GTHREAD_HIDE_WIN32API 32 # define __GTHREAD_HIDE_WIN32API 1 33 #endif 34 #undef __GTHREAD_I486_INLINE_LOCK_PRIMITIVES 35 #define __GTHREAD_I486_INLINE_LOCK_PRIMITIVES 36 #include "gthr-win32.h" 37 38 /* Windows32 threads specific definitions. The windows32 threading model 39 does not map well into pthread-inspired gcc's threading model, and so 40 there are caveats one needs to be aware of. 41 42 1. The destructor supplied to __gthread_key_create is ignored for 43 generic x86-win32 ports. This will certainly cause memory leaks 44 due to unreclaimed eh contexts (sizeof (eh_context) is at least 45 24 bytes for x86 currently). 46 47 This memory leak may be significant for long-running applications 48 that make heavy use of C++ EH. 49 50 However, Mingw runtime (version 0.3 or newer) provides a mechanism 51 to emulate pthreads key dtors; the runtime provides a special DLL, 52 linked in if -mthreads option is specified, that runs the dtors in 53 the reverse order of registration when each thread exits. If 54 -mthreads option is not given, a stub is linked in instead of the 55 DLL, which results in memory leak. Other x86-win32 ports can use 56 the same technique of course to avoid the leak. 57 58 2. The error codes returned are non-POSIX like, and cast into ints. 59 This may cause incorrect error return due to truncation values on 60 hw where sizeof (DWORD) > sizeof (int). 61 62 3. We are currently using a special mutex instead of the Critical 63 Sections, since Win9x does not support TryEnterCriticalSection 64 (while NT does). 65 66 The basic framework should work well enough. In the long term, GCC 67 needs to use Structured Exception Handling on Windows32. */ 68 69 int 70 __gthr_win32_once (__gthread_once_t *once, void (*func) (void)) 71 { 72 if (once == NULL || func == NULL) 73 return EINVAL; 74 75 if (! once->done) 76 { 77 if (InterlockedIncrement (&(once->started)) == 0) 78 { 79 (*func) (); 80 once->done = TRUE; 81 } 82 else 83 { 84 /* Another thread is currently executing the code, so wait for it 85 to finish; yield the CPU in the meantime. If performance 86 does become an issue, the solution is to use an Event that 87 we wait on here (and set above), but that implies a place to 88 create the event before this routine is called. */ 89 while (! once->done) 90 Sleep (0); 91 } 92 } 93 return 0; 94 } 95 96 /* Windows32 thread local keys don't support destructors; this leads to 97 leaks, especially in threaded applications making extensive use of 98 C++ EH. Mingw uses a thread-support DLL to work-around this problem. */ 99 100 int 101 __gthr_win32_key_create (__gthread_key_t *key, 102 void (*dtor) (void *) __attribute__((unused))) 103 { 104 int status = 0; 105 DWORD tls_index = TlsAlloc (); 106 if (tls_index != 0xFFFFFFFF) 107 { 108 *key = tls_index; 109 #ifdef MINGW32_SUPPORTS_MT_EH 110 /* Mingw runtime will run the dtors in reverse order for each thread 111 when the thread exits. */ 112 status = __mingwthr_key_dtor (*key, dtor); 113 #endif 114 } 115 else 116 status = (int) GetLastError (); 117 return status; 118 } 119 120 int 121 __gthr_win32_key_delete (__gthread_key_t key) 122 { 123 return (TlsFree (key) != 0) ? 0 : (int) GetLastError (); 124 } 125 126 void * 127 __gthr_win32_getspecific (__gthread_key_t key) 128 { 129 DWORD lasterror; 130 void *ptr; 131 lasterror = GetLastError(); 132 ptr = TlsGetValue(key); 133 SetLastError( lasterror ); 134 return ptr; 135 } 136 137 int 138 __gthr_win32_setspecific (__gthread_key_t key, const void *ptr) 139 { 140 if (TlsSetValue (key, CONST_CAST2(void *, const void *, ptr)) != 0) 141 return 0; 142 else 143 return GetLastError (); 144 } 145 146 void 147 __gthr_win32_mutex_init_function (__gthread_mutex_t *mutex) 148 { 149 mutex->counter = -1; 150 mutex->sema = CreateSemaphoreW (NULL, 0, 65535, NULL); 151 } 152 153 void 154 __gthr_win32_mutex_destroy (__gthread_mutex_t *mutex) 155 { 156 CloseHandle ((HANDLE) mutex->sema); 157 } 158 159 int 160 __gthr_win32_mutex_lock (__gthread_mutex_t *mutex) 161 { 162 if (InterlockedIncrement (&mutex->counter) == 0 || 163 WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0) 164 return 0; 165 else 166 { 167 /* WaitForSingleObject returns WAIT_FAILED, and we can only do 168 some best-effort cleanup here. */ 169 InterlockedDecrement (&mutex->counter); 170 return 1; 171 } 172 } 173 174 int 175 __gthr_win32_mutex_trylock (__gthread_mutex_t *mutex) 176 { 177 if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0) 178 return 0; 179 else 180 return 1; 181 } 182 183 int 184 __gthr_win32_mutex_unlock (__gthread_mutex_t *mutex) 185 { 186 if (InterlockedDecrement (&mutex->counter) >= 0) 187 return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1; 188 else 189 return 0; 190 } 191 192 void 193 __gthr_win32_recursive_mutex_init_function (__gthread_recursive_mutex_t *mutex) 194 { 195 mutex->counter = -1; 196 mutex->depth = 0; 197 mutex->owner = 0; 198 mutex->sema = CreateSemaphoreW (NULL, 0, 65535, NULL); 199 } 200 201 int 202 __gthr_win32_recursive_mutex_lock (__gthread_recursive_mutex_t *mutex) 203 { 204 DWORD me = GetCurrentThreadId(); 205 if (InterlockedIncrement (&mutex->counter) == 0) 206 { 207 mutex->depth = 1; 208 mutex->owner = me; 209 } 210 else if (mutex->owner == me) 211 { 212 InterlockedDecrement (&mutex->counter); 213 ++(mutex->depth); 214 } 215 else if (WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0) 216 { 217 mutex->depth = 1; 218 mutex->owner = me; 219 } 220 else 221 { 222 /* WaitForSingleObject returns WAIT_FAILED, and we can only do 223 some best-effort cleanup here. */ 224 InterlockedDecrement (&mutex->counter); 225 return 1; 226 } 227 return 0; 228 } 229 230 int 231 __gthr_win32_recursive_mutex_trylock (__gthread_recursive_mutex_t *mutex) 232 { 233 DWORD me = GetCurrentThreadId(); 234 if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0) 235 { 236 mutex->depth = 1; 237 mutex->owner = me; 238 } 239 else if (mutex->owner == me) 240 ++(mutex->depth); 241 else 242 return 1; 243 244 return 0; 245 } 246 247 int 248 __gthr_win32_recursive_mutex_unlock (__gthread_recursive_mutex_t *mutex) 249 { 250 --(mutex->depth); 251 if (mutex->depth == 0) 252 { 253 mutex->owner = 0; 254 255 if (InterlockedDecrement (&mutex->counter) >= 0) 256 return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1; 257 } 258 259 return 0; 260 } 261 262 int 263 __gthr_win32_recursive_mutex_destroy (__gthread_recursive_mutex_t *mutex) 264 { 265 CloseHandle ((HANDLE) mutex->sema); 266 return 0; 267 } 268