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, 59 Temple Place - Suite 330, Boston, MA
24 02111-1307, 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
__gthr_win32_once(__gthread_once_t * once,void (* func)(void))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
__gthr_win32_key_create(__gthread_key_t * key,void (* dtor)(void *))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
__gthr_win32_key_delete(__gthread_key_t key)124 __gthr_win32_key_delete (__gthread_key_t key)
125 {
126 return (TlsFree (key) != 0) ? 0 : (int) GetLastError ();
127 }
128
129 void *
__gthr_win32_getspecific(__gthread_key_t key)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
__gthr_win32_setspecific(__gthread_key_t key,const void * ptr)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
__gthr_win32_mutex_init_function(__gthread_mutex_t * mutex)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
__gthr_win32_mutex_lock(__gthread_mutex_t * mutex)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
__gthr_win32_mutex_trylock(__gthread_mutex_t * mutex)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
__gthr_win32_mutex_unlock(__gthread_mutex_t * mutex)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