1 | /* |
2 | This file is part of the KDE libraries |
3 | Copyright (C) 2008 Christian Ehrlicher <ch.ehrlicher@gmx.de> |
4 | |
5 | This library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Library General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2 of the License, or (at your option) any later version. |
9 | |
10 | This library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Library General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Library General Public License |
16 | along with this library; see the file COPYING.LIB. If not, write to |
17 | the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, |
18 | Boston, MA 02110-1301, USA. |
19 | */ |
20 | |
21 | #ifndef KMEMFILE_H |
22 | #define KMEMFILE_H |
23 | |
24 | #ifndef QT_NO_SHAREDMEMORY |
25 | |
26 | #include <QtCore/QIODevice> |
27 | #include <kdecore_export.h> |
28 | |
29 | /** |
30 | * @internal |
31 | * Simple QIODevice for QSharedMemory to keep ksycoca cache in memory only once |
32 | * The first call to open() loads the file into a shm segment. Every |
33 | * subsequent call only attaches to this segment. When the file content changed, |
34 | * you have to execute KMemFile::fileContentsChanged() to update the internal |
35 | * structures. The next call to open() creates a new shm segment. The old one |
36 | * is automatically destroyed when the last process closed KMemFile. |
37 | */ |
38 | |
39 | class KDECORE_EXPORT KMemFile : public QIODevice |
40 | { |
41 | public: |
42 | /** |
43 | * ctor |
44 | * |
45 | * @param filename the file to load into memory |
46 | * @param parent our parent |
47 | */ |
48 | explicit KMemFile ( const QString &filename, QObject *parent = 0 ); |
49 | /** |
50 | * dtor |
51 | */ |
52 | virtual ~KMemFile(); |
53 | /** |
54 | * closes the KMemFile |
55 | * |
56 | * @reimp |
57 | */ |
58 | virtual void close (); |
59 | /** |
60 | * As KMemFile is a random access device, it returns false |
61 | * |
62 | * @reimp |
63 | */ |
64 | virtual bool isSequential () const; |
65 | /** |
66 | * @reimp |
67 | * @param mode only QIODevice::ReadOnly is accepted |
68 | */ |
69 | virtual bool open ( OpenMode mode ); |
70 | /** |
71 | * Sets the current read/write position to pos |
72 | * @reimp |
73 | * @param pos the new read/write position |
74 | */ |
75 | virtual bool seek ( qint64 pos ); |
76 | /** |
77 | * Returns the size of the file |
78 | * @reimp |
79 | */ |
80 | virtual qint64 size () const; |
81 | /** |
82 | * This static function updates the internal information about the file |
83 | * loaded into shared memory. The next time the file is opened, the file is |
84 | * reread from the file system. |
85 | */ |
86 | static void fileContentsChanged ( const QString &filename ); |
87 | protected: |
88 | /** @reimp */ |
89 | virtual qint64 readData ( char * data, qint64 maxSize ); |
90 | /** @reimp */ |
91 | virtual qint64 writeData ( const char * data, qint64 maxSize ); |
92 | private: |
93 | class Private; |
94 | friend class Private; |
95 | Private * const d; |
96 | }; |
97 | |
98 | #endif //QT_NO_SHAREDMEMORY |
99 | |
100 | #endif // KMEMFILE_H |
101 | |