summaryrefslogtreecommitdiff
path: root/unotools/source/i18n/readwritemutexguard.cxx
blob: b60a392972d7b3577e8c22f3b900dbeb4d75e675 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
 * This file is part of the LibreOffice project.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * This file incorporates work covered by the following license notice:
 *
 *   Licensed to the Apache Software Foundation (ASF) under one or more
 *   contributor license agreements. See the NOTICE file distributed
 *   with this work for additional information regarding copyright
 *   ownership. The ASF licenses this file to you under the Apache
 *   License, Version 2.0 (the "License"); you may not use this file
 *   except in compliance with the License. You may obtain a copy of
 *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
 */

#include "unotools/readwritemutexguard.hxx"
#include <tools/debug.hxx>


namespace utl {

ReadWriteGuard::ReadWriteGuard( ReadWriteMutex& rMutexP,
            sal_Int32 nRequestMode )
        : rMutex( rMutexP )
{
    // don't do anything until a pending write completed (or another
    // ReadWriteGuard leaves the ctor phase)
    ::osl::MutexGuard aGuard( rMutex.pWriteMutex );
    nMode = nRequestMode;
    if ( nMode & ReadWriteGuardMode::nWrite )
    {
        rMutex.pWriteMutex->acquire();
        // wait for any read to complete
// TODO: set up a waiting thread instead of a loop
        sal_Bool bWait = sal_True;
        do
        {
            rMutex.pMutex->acquire();
            bWait = (rMutex.nReadCount != 0);
            if ( nMode & ReadWriteGuardMode::nCriticalChange )
                bWait |= (rMutex.nBlockCriticalCount != 0);
            rMutex.pMutex->release();
        } while ( bWait );
    }
    else if ( nMode & ReadWriteGuardMode::nBlockCritical )
    {
        rMutex.pMutex->acquire();
        ++rMutex.nBlockCriticalCount;
        rMutex.pMutex->release();
    }
    else
    {
        rMutex.pMutex->acquire();
        ++rMutex.nReadCount;
        rMutex.pMutex->release();
    }
}


ReadWriteGuard::~ReadWriteGuard()
{
    if ( nMode & ReadWriteGuardMode::nWrite )
        rMutex.pWriteMutex->release();
    else if ( nMode & ReadWriteGuardMode::nBlockCritical )
    {
        rMutex.pMutex->acquire();
        --rMutex.nBlockCriticalCount;
        rMutex.pMutex->release();
    }
    else
    {
        rMutex.pMutex->acquire();
        --rMutex.nReadCount;
        rMutex.pMutex->release();
    }
}


void ReadWriteGuard::changeReadToWrite()
{
    sal_Bool bOk = !(nMode & (ReadWriteGuardMode::nWrite | ReadWriteGuardMode::nBlockCritical));
    DBG_ASSERT( bOk, "ReadWriteGuard::changeReadToWrite: can't" );
    if ( bOk )
    {
        // MUST release read before acquiring write mutex or dead lock would
        // occur if there was a write in another thread waiting for this read
        // to complete.
        rMutex.pMutex->acquire();
        --rMutex.nReadCount;
        rMutex.pMutex->release();

        rMutex.pWriteMutex->acquire();
        nMode |= ReadWriteGuardMode::nWrite;
        // wait for any other read to complete
// TODO: set up a waiting thread instead of a loop
        sal_Bool bWait = sal_True;
        do
        {
            rMutex.pMutex->acquire();
            bWait = (rMutex.nReadCount != 0);
            rMutex.pMutex->release();
        } while ( bWait );
    }
}

}   // namespace utl

/* vim:set shiftwidth=4 softtabstop=4 expandtab: */