VirtualBox

source: vbox/trunk/include/iprt/lock.h@ 19542

Last change on this file since 19542 was 8245, checked in by vboxsync, 17 years ago

rebranding: IPRT files again.

  • Property svn:eol-style set to native
File size: 3.4 KB
Line 
1/** @file
2 * IPRT - RTLock Classes for Scope-based Locking.
3 */
4
5/*
6 * Copyright (C) 2007 Sun Microsystems, Inc.
7 *
8 * This file is part of VirtualBox Open Source Edition (OSE), as
9 * available from http://www.virtualbox.org. This file is free software;
10 * you can redistribute it and/or modify it under the terms of the GNU
11 * General Public License (GPL) as published by the Free Software
12 * Foundation, in version 2 as it comes in the "COPYING" file of the
13 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
14 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
15 *
16 * The contents of this file may alternatively be used under the terms
17 * of the Common Development and Distribution License Version 1.0
18 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
19 * VirtualBox OSE distribution, in which case the provisions of the
20 * CDDL are applicable instead of those of the GPL.
21 *
22 * You may elect to license modified versions of this file under the
23 * terms and conditions of either the GPL or the CDDL or both.
24 *
25 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
26 * Clara, CA 95054 USA or visit http://www.sun.com if you need
27 * additional information or have any questions.
28 */
29
30#ifndef ___iprt_lock_h
31#define ___iprt_lock_h
32
33#include <iprt/critsect.h>
34
35__BEGIN_DECLS
36
37/** @defgroup grp_rt_lock RTLock - Scope-based Locking (C++).
38 * @ingroup grp_rt
39 * @{
40 */
41
42class RTLock;
43
44/**
45 * The mutex lock.
46 *
47 * This is used as a object data member if the intention is to lock
48 * a single object. This can also be used statically, initialized in
49 * a global variable, for class wide purposes.
50 *
51 * This is best used together with RTLock.
52 */
53class RTLockMtx
54{
55 friend class RTLock;
56
57 private:
58 RTCRITSECT mMtx;
59
60 public:
61 RTLockMtx()
62 {
63 RTCritSectInit(&mMtx);
64 }
65
66 ~RTLockMtx()
67 {
68 RTCritSectDelete(&mMtx);
69 }
70
71 // lock() and unlock() are private so that only
72 // friend RTLock can access them
73 private:
74 inline void lock()
75 {
76 RTCritSectEnter(&mMtx);
77 }
78
79 inline void unlock()
80 {
81 RTCritSectLeave(&mMtx);
82 }
83};
84
85
86/**
87 * The stack object for automatic locking and unlocking.
88 *
89 * This is a helper class for automatic locks, to simplify
90 * requesting a RTLockMtx and to not forget releasing it.
91 * To request a RTLockMtx, simply create an instance of RTLock
92 * on the stack and pass the mutex to it:
93 *
94 * @code
95 extern RTLockMtx gMtx; // wherever this is
96 ...
97 if (...)
98 {
99 RTLock lock(gMtx);
100 ... // do stuff
101 // when lock goes out of scope, destructor releases the mutex
102 }
103 @endcode
104 *
105 * You can also explicitly release the mutex by calling RTLock::release().
106 * This might be helpful if the lock doesn't go out of scope early enough
107 * for your mutex to be released.
108 */
109class RTLock
110{
111 private:
112 RTLockMtx &mMtx;
113 bool mfLocked;
114
115 public:
116 RTLock(RTLockMtx &aMtx)
117 : mMtx(aMtx)
118 {
119 mMtx.lock();
120 mfLocked = true;
121 }
122
123 ~RTLock()
124 {
125 if (mfLocked)
126 mMtx.unlock();
127 }
128
129 inline void release()
130 {
131 if (mfLocked)
132 {
133 mMtx.unlock();
134 mfLocked = false;
135 }
136 }
137};
138
139
140/** @} */
141
142__END_DECLS
143
144#endif
145
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