/* Implementation of W32-specific threads compatibility routines for libgcc2. */ /* Copyright (C) 1999, 2000, 2002, 2004 Free Software Foundation, Inc. Contributed by Mumit Khan <khan@xraylith.wisc.edu>. Modified and moved to separate file by Danny Smith <dannysmith@users.sourceforge.net>. This file is part of GCC. GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING. If not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /* As a special exception, if you link this library with other files, some of which are compiled with GCC, to produce an executable, this library does not by itself cause the resulting executable to be covered by the GNU General Public License. This exception does not however invalidate any other reasons why the executable file might be covered by the GNU General Public License. */ #include <windows.h> #ifndef __GTHREAD_HIDE_WIN32API # define __GTHREAD_HIDE_WIN32API 1 #endif #undef __GTHREAD_I486_INLINE_LOCK_PRIMITIVES #define __GTHREAD_I486_INLINE_LOCK_PRIMITIVES #include <gthr-win32.h> /* Windows32 threads specific definitions. The windows32 threading model does not map well into pthread-inspired gcc's threading model, and so there are caveats one needs to be aware of. 1. The destructor supplied to __gthread_key_create is ignored for generic x86-win32 ports. This will certainly cause memory leaks due to unreclaimed eh contexts (sizeof (eh_context) is at least 24 bytes for x86 currently). This memory leak may be significant for long-running applications that make heavy use of C++ EH. However, Mingw runtime (version 0.3 or newer) provides a mechanism to emulate pthreads key dtors; the runtime provides a special DLL, linked in if -mthreads option is specified, that runs the dtors in the reverse order of registration when each thread exits. If -mthreads option is not given, a stub is linked in instead of the DLL, which results in memory leak. Other x86-win32 ports can use the same technique of course to avoid the leak. 2. The error codes returned are non-POSIX like, and cast into ints. This may cause incorrect error return due to truncation values on hw where sizeof (DWORD) > sizeof (int). 3. We are currently using a special mutex instead of the Critical Sections, since Win9x does not support TryEnterCriticalSection (while NT does). The basic framework should work well enough. In the long term, GCC needs to use Structured Exception Handling on Windows32. */ int __gthr_win32_once (__gthread_once_t *once, void (*func) (void)) { if (once == NULL || func == NULL) return EINVAL; if (! once->done) { if (InterlockedIncrement (&(once->started)) == 0) { (*func) (); once->done = TRUE; } else { /* Another thread is currently executing the code, so wait for it to finish; yield the CPU in the meantime. If performance does become an issue, the solution is to use an Event that we wait on here (and set above), but that implies a place to create the event before this routine is called. */ while (! once->done) Sleep (0); } } return 0; } /* Windows32 thread local keys don't support destructors; this leads to leaks, especially in threaded applications making extensive use of C++ EH. Mingw uses a thread-support DLL to work-around this problem. */ int __gthr_win32_key_create (__gthread_key_t *key, void (*dtor) (void *)) { int status = 0; DWORD tls_index = TlsAlloc (); if (tls_index != 0xFFFFFFFF) { *key = tls_index; #ifdef MINGW32_SUPPORTS_MT_EH /* Mingw runtime will run the dtors in reverse order for each thread when the thread exits. */ status = __mingwthr_key_dtor (*key, dtor); #endif } else status = (int) GetLastError (); return status; } int __gthr_win32_key_delete (__gthread_key_t key) { return (TlsFree (key) != 0) ? 0 : (int) GetLastError (); } void * __gthr_win32_getspecific (__gthread_key_t key) { DWORD lasterror; void *ptr; lasterror = GetLastError(); ptr = TlsGetValue(key); SetLastError( lasterror ); return ptr; } int __gthr_win32_setspecific (__gthread_key_t key, const void *ptr) { return (TlsSetValue (key, (void*) ptr) != 0) ? 0 : (int) GetLastError (); } void __gthr_win32_mutex_init_function (__gthread_mutex_t *mutex) { mutex->counter = -1; mutex->sema = CreateSemaphore (NULL, 0, 65535, NULL); } int __gthr_win32_mutex_lock (__gthread_mutex_t *mutex) { if (InterlockedIncrement (&mutex->counter) == 0 || WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0) return 0; else { /* WaitForSingleObject returns WAIT_FAILED, and we can only do some best-effort cleanup here. */ InterlockedDecrement (&mutex->counter); return 1; } } int __gthr_win32_mutex_trylock (__gthread_mutex_t *mutex) { if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0) return 0; else return 1; } int __gthr_win32_mutex_unlock (__gthread_mutex_t *mutex) { if (InterlockedDecrement (&mutex->counter) >= 0) return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1; else return 0; } void __gthr_win32_recursive_mutex_init_function (__gthread_recursive_mutex_t *mutex) { mutex->counter = -1; mutex->depth = 0; mutex->owner = 0; mutex->sema = CreateSemaphore (NULL, 0, 65535, NULL); } int __gthr_win32_recursive_mutex_lock (__gthread_recursive_mutex_t *mutex) { DWORD me = GetCurrentThreadId(); if (InterlockedIncrement (&mutex->counter) == 0) { mutex->depth = 1; mutex->owner = me; } else if (mutex->owner == me) { InterlockedDecrement (&mutex->counter); ++(mutex->depth); } else if (WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0) { mutex->depth = 1; mutex->owner = me; } else { /* WaitForSingleObject returns WAIT_FAILED, and we can only do some best-effort cleanup here. */ InterlockedDecrement (&mutex->counter); return 1; } return 0; } int __gthr_win32_recursive_mutex_trylock (__gthread_recursive_mutex_t *mutex) { DWORD me = GetCurrentThreadId(); if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0) { mutex->depth = 1; mutex->owner = me; } else if (mutex->owner == me) ++(mutex->depth); else return 1; return 0; } int __gthr_win32_recursive_mutex_unlock (__gthread_recursive_mutex_t *mutex) { --(mutex->depth); if (mutex->depth == 0) { mutex->owner = 0; if (InterlockedDecrement (&mutex->counter) >= 0) return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1; } return 0; }