268 lines
7.3 KiB
C
268 lines
7.3 KiB
C
/* Implementation of W32-specific threads compatibility routines for
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libgcc2. */
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/* Copyright (C) 1999-2019 Free Software Foundation, Inc.
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Contributed by Mumit Khan <khan@xraylith.wisc.edu>.
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Modified and moved to separate file by Danny Smith
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<dannysmith@users.sourceforge.net>.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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#include <windows.h>
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#ifndef __GTHREAD_HIDE_WIN32API
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# define __GTHREAD_HIDE_WIN32API 1
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#endif
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#undef __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
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#define __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
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#include "gthr-win32.h"
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/* Windows32 threads specific definitions. The windows32 threading model
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does not map well into pthread-inspired gcc's threading model, and so
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there are caveats one needs to be aware of.
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1. The destructor supplied to __gthread_key_create is ignored for
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generic x86-win32 ports. This will certainly cause memory leaks
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due to unreclaimed eh contexts (sizeof (eh_context) is at least
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24 bytes for x86 currently).
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This memory leak may be significant for long-running applications
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that make heavy use of C++ EH.
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However, Mingw runtime (version 0.3 or newer) provides a mechanism
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to emulate pthreads key dtors; the runtime provides a special DLL,
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linked in if -mthreads option is specified, that runs the dtors in
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the reverse order of registration when each thread exits. If
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-mthreads option is not given, a stub is linked in instead of the
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DLL, which results in memory leak. Other x86-win32 ports can use
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the same technique of course to avoid the leak.
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2. The error codes returned are non-POSIX like, and cast into ints.
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This may cause incorrect error return due to truncation values on
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hw where sizeof (DWORD) > sizeof (int).
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3. We are currently using a special mutex instead of the Critical
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Sections, since Win9x does not support TryEnterCriticalSection
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(while NT does).
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The basic framework should work well enough. In the long term, GCC
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needs to use Structured Exception Handling on Windows32. */
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int
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__gthr_win32_once (__gthread_once_t *once, void (*func) (void))
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{
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if (once == NULL || func == NULL)
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return EINVAL;
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if (! once->done)
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{
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if (InterlockedIncrement (&(once->started)) == 0)
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{
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(*func) ();
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once->done = TRUE;
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}
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else
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{
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/* Another thread is currently executing the code, so wait for it
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to finish; yield the CPU in the meantime. If performance
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does become an issue, the solution is to use an Event that
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we wait on here (and set above), but that implies a place to
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create the event before this routine is called. */
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while (! once->done)
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Sleep (0);
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}
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}
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return 0;
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}
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/* Windows32 thread local keys don't support destructors; this leads to
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leaks, especially in threaded applications making extensive use of
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C++ EH. Mingw uses a thread-support DLL to work-around this problem. */
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int
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__gthr_win32_key_create (__gthread_key_t *key,
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void (*dtor) (void *) __attribute__((unused)))
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{
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int status = 0;
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DWORD tls_index = TlsAlloc ();
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if (tls_index != 0xFFFFFFFF)
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{
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*key = tls_index;
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#ifdef MINGW32_SUPPORTS_MT_EH
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/* Mingw runtime will run the dtors in reverse order for each thread
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when the thread exits. */
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status = __mingwthr_key_dtor (*key, dtor);
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#endif
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}
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else
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status = (int) GetLastError ();
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return status;
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}
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int
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__gthr_win32_key_delete (__gthread_key_t key)
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{
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return (TlsFree (key) != 0) ? 0 : (int) GetLastError ();
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}
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void *
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__gthr_win32_getspecific (__gthread_key_t key)
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{
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DWORD lasterror;
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void *ptr;
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lasterror = GetLastError();
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ptr = TlsGetValue(key);
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SetLastError( lasterror );
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return ptr;
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}
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int
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__gthr_win32_setspecific (__gthread_key_t key, const void *ptr)
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{
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if (TlsSetValue (key, CONST_CAST2(void *, const void *, ptr)) != 0)
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return 0;
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else
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return GetLastError ();
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}
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void
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__gthr_win32_mutex_init_function (__gthread_mutex_t *mutex)
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{
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mutex->counter = -1;
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mutex->sema = CreateSemaphoreW (NULL, 0, 65535, NULL);
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}
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void
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__gthr_win32_mutex_destroy (__gthread_mutex_t *mutex)
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{
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CloseHandle ((HANDLE) mutex->sema);
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}
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int
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__gthr_win32_mutex_lock (__gthread_mutex_t *mutex)
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{
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if (InterlockedIncrement (&mutex->counter) == 0 ||
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WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0)
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return 0;
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else
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{
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/* WaitForSingleObject returns WAIT_FAILED, and we can only do
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some best-effort cleanup here. */
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InterlockedDecrement (&mutex->counter);
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return 1;
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}
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}
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int
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__gthr_win32_mutex_trylock (__gthread_mutex_t *mutex)
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{
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if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0)
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return 0;
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else
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return 1;
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}
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int
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__gthr_win32_mutex_unlock (__gthread_mutex_t *mutex)
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{
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if (InterlockedDecrement (&mutex->counter) >= 0)
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return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1;
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else
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return 0;
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}
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void
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__gthr_win32_recursive_mutex_init_function (__gthread_recursive_mutex_t *mutex)
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{
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mutex->counter = -1;
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mutex->depth = 0;
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mutex->owner = 0;
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mutex->sema = CreateSemaphoreW (NULL, 0, 65535, NULL);
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}
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int
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__gthr_win32_recursive_mutex_lock (__gthread_recursive_mutex_t *mutex)
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{
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DWORD me = GetCurrentThreadId();
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if (InterlockedIncrement (&mutex->counter) == 0)
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{
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mutex->depth = 1;
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mutex->owner = me;
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}
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else if (mutex->owner == me)
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{
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InterlockedDecrement (&mutex->counter);
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++(mutex->depth);
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}
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else if (WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0)
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{
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mutex->depth = 1;
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mutex->owner = me;
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}
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else
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{
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/* WaitForSingleObject returns WAIT_FAILED, and we can only do
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some best-effort cleanup here. */
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InterlockedDecrement (&mutex->counter);
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return 1;
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}
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return 0;
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}
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int
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__gthr_win32_recursive_mutex_trylock (__gthread_recursive_mutex_t *mutex)
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{
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DWORD me = GetCurrentThreadId();
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if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0)
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{
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mutex->depth = 1;
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mutex->owner = me;
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}
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else if (mutex->owner == me)
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++(mutex->depth);
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else
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return 1;
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return 0;
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}
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int
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__gthr_win32_recursive_mutex_unlock (__gthread_recursive_mutex_t *mutex)
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{
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--(mutex->depth);
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if (mutex->depth == 0)
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{
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mutex->owner = 0;
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if (InterlockedDecrement (&mutex->counter) >= 0)
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return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1;
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}
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return 0;
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}
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int
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__gthr_win32_recursive_mutex_destroy (__gthread_recursive_mutex_t *mutex)
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{
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CloseHandle ((HANDLE) mutex->sema);
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return 0;
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}
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