/[pcsx2_0.9.7]/trunk/3rdparty/w32pthreads/ptw32_mutex_check_need_init.c
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Revision 31 - (show annotations) (download)
Tue Sep 7 03:24:11 2010 UTC (9 years, 11 months ago) by william
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committing r3113 initial commit again...
1 /*
2 * ptw32_mutex_check_need_init.c
3 *
4 * Description:
5 * This translation unit implements mutual exclusion (mutex) primitives.
6 *
7 * --------------------------------------------------------------------------
8 *
9 * Pthreads-win32 - POSIX Threads Library for Win32
10 * Copyright(C) 1998 John E. Bossom
11 * Copyright(C) 1999,2005 Pthreads-win32 contributors
12 *
13 * Contact Email: rpj@callisto.canberra.edu.au
14 *
15 * The current list of contributors is contained
16 * in the file CONTRIBUTORS included with the source
17 * code distribution. The list can also be seen at the
18 * following World Wide Web location:
19 * http://sources.redhat.com/pthreads-win32/contributors.html
20 *
21 * This library is free software; you can redistribute it and/or
22 * modify it under the terms of the GNU Lesser General Public
23 * License as published by the Free Software Foundation; either
24 * version 2 of the License, or (at your option) any later version.
25 *
26 * This library is distributed in the hope that it will be useful,
27 * but WITHOUT ANY WARRANTY; without even the implied warranty of
28 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
29 * Lesser General Public License for more details.
30 *
31 * You should have received a copy of the GNU Lesser General Public
32 * License along with this library in the file COPYING.LIB;
33 * if not, write to the Free Software Foundation, Inc.,
34 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
35 */
36
37 #include "ptw32pch.h"
38 #include <assert.h>
39
40 static struct pthread_mutexattr_t_ ptw32_recursive_mutexattr_s =
41 {PTHREAD_PROCESS_PRIVATE, PTHREAD_MUTEX_RECURSIVE};
42 static struct pthread_mutexattr_t_ ptw32_errorcheck_mutexattr_s =
43 {PTHREAD_PROCESS_PRIVATE, PTHREAD_MUTEX_ERRORCHECK};
44 static pthread_mutexattr_t ptw32_recursive_mutexattr = &ptw32_recursive_mutexattr_s;
45 static pthread_mutexattr_t ptw32_errorcheck_mutexattr = &ptw32_errorcheck_mutexattr_s;
46
47
48 INLINE int
49 ptw32_mutex_check_need_init (pthread_mutex_t * mutex)
50 {
51 register int result = 0;
52 register pthread_mutex_t mtx;
53
54 // Make sure static mutexes are enabled.
55 assert( ptw32_static_mutex_enable );
56
57 /*
58 * The following guarded test is specifically for statically
59 * initialised mutexes (via PTHREAD_MUTEX_INITIALIZER).
60 *
61 * Note that by not providing this synchronisation we risk
62 * introducing race conditions into applications which are
63 * correctly written.
64 *
65 * Approach
66 * --------
67 * We know that static mutexes will not be PROCESS_SHARED
68 * so we can serialise access to internal state using
69 * Win32 Critical Sections rather than Win32 Mutexes.
70 *
71 * If using a single global lock slows applications down too much,
72 * multiple global locks could be created and hashed on some random
73 * value associated with each mutex, the pointer perhaps. At a guess,
74 * a good value for the optimal number of global locks might be
75 * the number of processors + 1.
76 *
77 */
78
79 EnterCriticalSection (&ptw32_mutex_test_init_lock);
80
81 /*
82 * We got here possibly under race
83 * conditions. Check again inside the critical section
84 * and only initialise if the mutex is valid (not been destroyed).
85 * If a static mutex has been destroyed, the application can
86 * re-initialise it only by calling pthread_mutex_init()
87 * explicitly.
88 */
89 mtx = *mutex;
90
91 if (mtx == PTHREAD_MUTEX_INITIALIZER)
92 {
93 result = pthread_mutex_init (mutex, NULL);
94 }
95 else if (mtx == PTHREAD_RECURSIVE_MUTEX_INITIALIZER)
96 {
97 result = pthread_mutex_init (mutex, &ptw32_recursive_mutexattr);
98 }
99 else if (mtx == PTHREAD_ERRORCHECK_MUTEX_INITIALIZER)
100 {
101 result = pthread_mutex_init (mutex, &ptw32_errorcheck_mutexattr);
102 }
103 else if (mtx == NULL)
104 {
105 /*
106 * The mutex has been destroyed while we were waiting to
107 * initialise it, so the operation that caused the
108 * auto-initialisation should fail.
109 */
110 result = EINVAL;
111 }
112
113 LeaveCriticalSection (&ptw32_mutex_test_init_lock);
114
115 return (result);
116 }

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