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1 : : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
2 : : /*
3 : : * This file is part of the LibreOffice project.
4 : : *
5 : : * This Source Code Form is subject to the terms of the Mozilla Public
6 : : * License, v. 2.0. If a copy of the MPL was not distributed with this
7 : : * file, You can obtain one at http://mozilla.org/MPL/2.0/.
8 : : *
9 : : * This file incorporates work covered by the following license notice:
10 : : *
11 : : * Licensed to the Apache Software Foundation (ASF) under one or more
12 : : * contributor license agreements. See the NOTICE file distributed
13 : : * with this work for additional information regarding copyright
14 : : * ownership. The ASF licenses this file to you under the Apache
15 : : * License, Version 2.0 (the "License"); you may not use this file
16 : : * except in compliance with the License. You may obtain a copy of
17 : : * the License at http://www.apache.org/licenses/LICENSE-2.0 .
18 : : */
19 : :
20 : : #ifndef INCLUDED_UNOTOOLS_READWRITEMUTEXGUARD_HXX
21 : : #define INCLUDED_UNOTOOLS_READWRITEMUTEXGUARD_HXX
22 : :
23 : : #include <osl/mutex.hxx>
24 : :
25 : : namespace utl {
26 : :
27 : : class ReadWriteGuard;
28 : : class ReadWriteMutex
29 : : {
30 : : friend class ReadWriteGuard;
31 : :
32 : : sal_uInt32 nReadCount;
33 : : sal_uInt32 nBlockCriticalCount;
34 : : ::osl::Mutex* pMutex;
35 : : ::osl::Mutex* pWriteMutex;
36 : :
37 : : public:
38 : 23318 : ReadWriteMutex()
39 : : : nReadCount(0)
40 : : , nBlockCriticalCount(0)
41 [ + - ]: 23318 : , pMutex( new ::osl::Mutex )
42 [ + - ]: 46636 : , pWriteMutex( new ::osl::Mutex )
43 : 23318 : {}
44 : 23205 : ~ReadWriteMutex()
45 : : {
46 [ + - ]: 23205 : delete pMutex;
47 [ + - ]: 23205 : delete pWriteMutex;
48 : 23205 : }
49 : : };
50 : :
51 : :
52 : : namespace ReadWriteGuardMode {
53 : : const sal_Int32 nWrite = 0x01;
54 : : const sal_Int32 nCriticalChange = 0x02 | nWrite;
55 : : const sal_Int32 nBlockCritical = 0x04; // only a block, not a read, exclusive flag!
56 : : }
57 : :
58 : : /** Enable multiple threads to read simultaneously, but a write blocks all
59 : : other reads and writes, and a read blocks any write.
60 : : Used in I18N wrappers to be able to maintain a single instance of a wrapper
61 : : for the standard Office locale.
62 : : NEVER construct a writing guard if there is already a reading guard in the
63 : : same context, the following will dead lock EVEN IN THE SAME THREAD!
64 : : void foo()
65 : : {
66 : : ReadWriteGuard aGuard1( aMutex );
67 : : bar();
68 : : }
69 : : void bar()
70 : : {
71 : : // waits forever for aGuard1
72 : : ReadWriteGuard aGuard2( aMutex, ReadWriteGuardMode::nWrite );
73 : : }
74 : : */
75 : : class ReadWriteGuard
76 : : {
77 : : ReadWriteMutex& rMutex;
78 : : sal_Int32 nMode;
79 : : public:
80 : : ReadWriteGuard(
81 : : ReadWriteMutex& rMutex,
82 : : sal_Int32 nRequestMode = 0 // read only
83 : : );
84 : : ~ReadWriteGuard();
85 : :
86 : : /** Be careful with this, it does wait for ANY read to complete.
87 : : The following will dead lock EVEN IN THE SAME THREAD!
88 : : void foo()
89 : : {
90 : : ReadWriteGuard aGuard1( aMutex );
91 : : bar();
92 : : }
93 : : void bar()
94 : : {
95 : : ReadWriteGuard aGuard2( aMutex );
96 : : aGuard2.changeReadToWrite(); // waits forever for aGuard1
97 : : }
98 : : */
99 : : void changeReadToWrite();
100 : : };
101 : :
102 : : } // namespace utl
103 : :
104 : : #endif // INCLUDED_UNOTOOLS_READWRITEMUTEXGUARD_HXX
105 : :
106 : : /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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