1/*
2Open Tracker License
3
4Terms and Conditions
5
6Copyright (c) 1991-2000, Be Incorporated. All rights reserved.
7
8Permission is hereby granted, free of charge, to any person obtaining a copy of
9this software and associated documentation files (the "Software"), to deal in
10the Software without restriction, including without limitation the rights to
11use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
12of the Software, and to permit persons to whom the Software is furnished to do
13so, subject to the following conditions:
14
15The above copyright notice and this permission notice applies to all licensees
16and shall be included in all copies or substantial portions of the Software.
17
18THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF TITLE, MERCHANTABILITY,
20FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
21BE INCORPORATED BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
22AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF, OR IN CONNECTION
23WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
24
25Except as contained in this notice, the name of Be Incorporated shall not be
26used in advertising or otherwise to promote the sale, use or other dealings in
27this Software without prior written authorization from Be Incorporated.
28
29Tracker(TM), Be(R), BeOS(R), and BeIA(TM) are trademarks or registered trademarks
30of Be Incorporated in the United States and other countries. Other brand product
31names are registered trademarks or trademarks of their respective holders.
32All rights reserved.
33*/
34
35#ifndef _AUTO_LOCK_H
36#define _AUTO_LOCK_H
37
38template<class T>
39class AutoLock
40{
41
42// exception safe locking mechanism, allocate on stack and have
43// destructor unlock for you whenever the lock goes out of scope
44
45public:
46	AutoLock(T *lock, bool lockNow = true)
47		// use <lockLater> for lazy locking
48		:	fLock(lock),
49			fHasLock(false)
50		{
51			if (lockNow)
52				fHasLock = fLock->Lock();
53		}
54
55	AutoLock(T &lock, bool lockNow = true)
56		:	fLock(&lock),
57			fHasLock(false)
58		{
59			if (lockNow)
60				fHasLock = fLock->Lock();
61		}
62
63	~AutoLock()
64		{
65			if (fHasLock)
66				fLock->Unlock();
67		}
68
69	bool operator!() const
70		{ return !fHasLock; }
71
72	bool IsLocked() const
73		{ return fHasLock; }
74
75	// explicit Lock/Unlock calls are only used in special cases
76	// for unlocking before lock goes out of scope and successive
77	// re-locking
78	// usually constructor/destructor locks/unlocks are sufficient
79	void Unlock()
80		{
81			if (fHasLock) {
82				fLock->Unlock();
83				fHasLock = false;
84			}
85		}
86
87	bool Lock()
88		{
89			if (!fHasLock)
90				fHasLock = fLock->Lock();
91
92			return fHasLock;
93		}
94
95	// convenience call used when passing the AutoLock and the locked object
96	// around
97	T *LockedItem() const
98		{ return fLock; }
99
100private:
101	T *fLock;
102	bool fHasLock;
103};
104
105#endif
106