1 /*************************************************************************
2  *
3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4  *
5  * Copyright 2000, 2010 Oracle and/or its affiliates.
6  *
7  * OpenOffice.org - a multi-platform office productivity suite
8  *
9  * This file is part of OpenOffice.org.
10  *
11  * OpenOffice.org is free software: you can redistribute it and/or modify
12  * it under the terms of the GNU Lesser General Public License version 3
13  * only, as published by the Free Software Foundation.
14  *
15  * OpenOffice.org is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18  * GNU Lesser General Public License version 3 for more details
19  * (a copy is included in the LICENSE file that accompanied this code).
20  *
21  * You should have received a copy of the GNU Lesser General Public License
22  * version 3 along with OpenOffice.org.  If not, see
23  * <http://www.openoffice.org/license.html>
24  * for a copy of the LGPLv3 License.
25  *
26  ************************************************************************/
27 
28 #ifndef __FRAMEWORK_THREADHELP_READGUARD_HXX_
29 #define __FRAMEWORK_THREADHELP_READGUARD_HXX_
30 
31 //_________________________________________________________________________________________________________________
32 //	my own includes
33 //_________________________________________________________________________________________________________________
34 
35 #include <threadhelp/inoncopyable.h>
36 #include <threadhelp/irwlock.h>
37 
38 //#ifndef __FRAMEWORK_THREADHELP_THREADHELPBASE_HXX_
39 //#include <threadhelp/threadhelpbase.hxx>
40 //#endif
41 
42 //_________________________________________________________________________________________________________________
43 //	interface includes
44 //_________________________________________________________________________________________________________________
45 
46 //_________________________________________________________________________________________________________________
47 //	other includes
48 //_________________________________________________________________________________________________________________
49 #include <sal/types.h>
50 
51 //_________________________________________________________________________________________________________________
52 //	namespace
53 //_________________________________________________________________________________________________________________
54 
55 namespace framework{
56 
57 //_________________________________________________________________________________________________________________
58 //	const
59 //_________________________________________________________________________________________________________________
60 
61 //_________________________________________________________________________________________________________________
62 //	declarations
63 //_________________________________________________________________________________________________________________
64 
65 /*-************************************************************************************************************//**
66 	@short          implement a guard to set read locks
67 	@descr			This guard should be used to set a lock for reading object internal member.
68 					Nobody can control it but don't use member after successfuly locking for writing!
69 					We never need a own mutex to safe our internal member access - because
70 					a guard is used as function-local member only. There exist no multithreaded access to it realy ...
71 
72     @attention      a) To prevent us against wrong using, the default ctor, copy ctor and the =operator are maked private!
73                     b) Use interface "IRWLock" of set LockHelper only - because we must support a finer granularity of locking.
74                        Interface "IMutex" should be used by easier guard implementations ... like "ResetableGuard"!
75 
76 	@implements		-
77     @base           INonCopyable
78 
79 	@devstatus		ready to use
80 *//*-*************************************************************************************************************/
81 class ReadGuard : private INonCopyable
82 {
83 	//-------------------------------------------------------------------------------------------------------------
84 	//	public methods
85 	//-------------------------------------------------------------------------------------------------------------
86 	public:
87 
88         /*-****************************************************************************************************//**
89             @short      ctor
90             @descr      These ctors initialize the guard with a reference to used lock member of object to protect.
91                         Null isn't allowed as value!
92 
93             @seealso    -
94 
95             @param      "pLock" ,reference to used lock member of object to protect
96             @param      "rLock" ,reference to used lock member of object to protect
97             @return     -
98 
99             @onerror    -
100         *//*-*****************************************************************************************************/
101         inline ReadGuard( IRWLock* pLock )
102             :   m_pLock     ( pLock     )
103             ,   m_bLocked   ( sal_False )
104         {
105             lock();
106         }
107 
108         //*********************************************************************************************************
109         inline ReadGuard( IRWLock& rLock )
110             :   m_pLock     ( &rLock    )
111             ,   m_bLocked   ( sal_False )
112         {
113             lock();
114         }
115 
116         /*-****************************************************************************************************//**
117             @short      dtor
118             @descr      We unlock the used lock member automaticly if user forget it.
119 
120             @seealso    -
121 
122             @param      -
123             @return     -
124 
125             @onerror    -
126         *//*-*****************************************************************************************************/
127         inline ~ReadGuard()
128         {
129             unlock();
130         }
131 
132         /*-****************************************************************************************************//**
133             @short      set read lock
134             @descr      Call this method to set the read lock. The call will block till all current threads are synchronized!
135 
136             @seealso    method unlock()
137 
138             @param      -
139             @return     -
140 
141             @onerror    -
142         *//*-*****************************************************************************************************/
143         inline void lock()
144         {
145             if( m_bLocked == sal_False )
146             {
147                 m_pLock->acquireReadAccess();
148                 m_bLocked = sal_True;
149             }
150         }
151 
152         /*-****************************************************************************************************//**
153             @short      unset read lock
154             @descr      Call this method to unlock the rw-lock temp.!
155                         Normaly we do it at dtor automaticly for you ...
156 
157             @seealso    method lock()
158 
159             @param      -
160             @return     -
161 
162             @onerror    -
163         *//*-*****************************************************************************************************/
164         inline void unlock()
165         {
166             if( m_bLocked == sal_True )
167             {
168                 m_pLock->releaseReadAccess();
169                 m_bLocked = sal_False;
170             }
171         }
172 
173 	//-------------------------------------------------------------------------------------------------------------
174 	//	private methods
175 	//-------------------------------------------------------------------------------------------------------------
176 	private:
177 
178 		/*-****************************************************************************************************//**
179 			@short		disable using of these functions!
180 			@descr		It's not allowed to use this methods. Different problem can occure otherwise.
181 						Thats why we disable it by make it private.
182 
183 			@seealso	other ctor
184 
185 			@param		-
186 			@return		-
187 
188 			@onerror	-
189 		*//*-*****************************************************************************************************/
190 		ReadGuard();
191 
192 	//-------------------------------------------------------------------------------------------------------------
193 	//	private member
194 	//-------------------------------------------------------------------------------------------------------------
195 	private:
196 
197         IRWLock*    m_pLock     ;   /// reference to lock-member of protected object
198 		sal_Bool	m_bLocked	;	/// protection against multiple lock calls without unlock!
199 
200 };		//	class ReadGuard
201 
202 }		//	namespace framework
203 
204 #endif	//	#ifndef __FRAMEWORK_THREADHELP_READGUARD_HXX_
205