/[pcsx2_0.9.7]/trunk/3rdparty/w32pthreads/ptw32_cond_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_cond_check_need_init.c
3 *
4 * Description:
5 * This translation unit implements condition variables and their primitives.
6 *
7 *
8 * --------------------------------------------------------------------------
9 *
10 * Pthreads-win32 - POSIX Threads Library for Win32
11 * Copyright(C) 1998 John E. Bossom
12 * Copyright(C) 1999,2005 Pthreads-win32 contributors
13 *
14 * Contact Email: rpj@callisto.canberra.edu.au
15 *
16 * The current list of contributors is contained
17 * in the file CONTRIBUTORS included with the source
18 * code distribution. The list can also be seen at the
19 * following World Wide Web location:
20 * http://sources.redhat.com/pthreads-win32/contributors.html
21 *
22 * This library is free software; you can redistribute it and/or
23 * modify it under the terms of the GNU Lesser General Public
24 * License as published by the Free Software Foundation; either
25 * version 2 of the License, or (at your option) any later version.
26 *
27 * This library is distributed in the hope that it will be useful,
28 * but WITHOUT ANY WARRANTY; without even the implied warranty of
29 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
30 * Lesser General Public License for more details.
31 *
32 * You should have received a copy of the GNU Lesser General Public
33 * License along with this library in the file COPYING.LIB;
34 * if not, write to the Free Software Foundation, Inc.,
35 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
36 */
37
38 #include "ptw32pch.h"
39
40
41 INLINE int
42 ptw32_cond_check_need_init (pthread_cond_t * cond)
43 {
44 int result = 0;
45
46 /*
47 * The following guarded test is specifically for statically
48 * initialised condition variables (via PTHREAD_OBJECT_INITIALIZER).
49 *
50 * Note that by not providing this synchronisation we risk
51 * introducing race conditions into applications which are
52 * correctly written.
53 *
54 * Approach
55 * --------
56 * We know that static condition variables will not be PROCESS_SHARED
57 * so we can serialise access to internal state using
58 * Win32 Critical Sections rather than Win32 Mutexes.
59 *
60 * If using a single global lock slows applications down too much,
61 * multiple global locks could be created and hashed on some random
62 * value associated with each mutex, the pointer perhaps. At a guess,
63 * a good value for the optimal number of global locks might be
64 * the number of processors + 1.
65 *
66 */
67 EnterCriticalSection (&ptw32_cond_test_init_lock);
68
69 /*
70 * We got here possibly under race
71 * conditions. Check again inside the critical section.
72 * If a static cv has been destroyed, the application can
73 * re-initialise it only by calling pthread_cond_init()
74 * explicitly.
75 */
76 if (*cond == PTHREAD_COND_INITIALIZER)
77 {
78 result = pthread_cond_init (cond, NULL);
79 }
80 else if (*cond == NULL)
81 {
82 /*
83 * The cv has been destroyed while we were waiting to
84 * initialise it, so the operation that caused the
85 * auto-initialisation should fail.
86 */
87 result = EINVAL;
88 }
89
90 LeaveCriticalSection (&ptw32_cond_test_init_lock);
91
92 return result;
93 }

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