1/*
2 Copyright (c) 2007 Volker Krause <vkrause@kde.org>
3
4 This library is free software; you can redistribute it and/or modify it
5 under the terms of the GNU Library General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or (at your
7 option) any later version.
8
9 This library is distributed in the hope that it will be useful, but WITHOUT
10 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
12 License for more details.
13
14 You should have received a copy of the GNU Library General Public License
15 along with this library; see the file COPYING.LIB. If not, write to the
16 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17 02110-1301, USA.
18*/
19
20#ifndef AKONADI_CHANGERECORDER_H
21#define AKONADI_CHANGERECORDER_H
22
23#include <akonadi/monitor.h>
24
25class QSettings;
26
27namespace Akonadi {
28
29class ChangeRecorderPrivate;
30
31/**
32 * @short Records and replays change notification.
33 *
34 * This class is responsible for recording change notifications while
35 * an agent is not online and replaying the notifications when the agent
36 * is online again. Therefore the agent doesn't have to care about
37 * online/offline mode in its synchronization algorithm.
38 *
39 * Unlike Akonadi::Monitor this class only emits one change signal at a
40 * time. To receive the next one you need to explicitly call replayNext().
41 * If a signal is emitted that has no receivers, it's automatically skipped,
42 * which means you only need to connect to signals you are actually interested
43 * in.
44 *
45 * @author Volker Krause <vkrause@kde.org>
46 */
47class AKONADI_EXPORT ChangeRecorder : public Monitor
48{
49 Q_OBJECT
50public:
51 /**
52 * Creates a new change recorder.
53 */
54 explicit ChangeRecorder(QObject *parent = 0);
55
56 /**
57 * Destroys the change recorder.
58 * All not yet processed changes are written back to the config file.
59 */
60 ~ChangeRecorder();
61
62 /**
63 * Sets the QSettings object used for persistent recorded changes.
64 */
65 void setConfig(QSettings *settings);
66
67 /**
68 * Returns whether there are recorded changes.
69 */
70 bool isEmpty() const;
71
72 /**
73 * Removes the previously emitted change from the records.
74 */
75 void changeProcessed();
76
77 /**
78 * Enables change recording. If change recording is disabled, this class
79 * behaves exactly like Akonadi::Monitor.
80 * Change recording is enabled by default.
81 * @param enable @c false to disable change recording. @c true by default
82 */
83 void setChangeRecordingEnabled(bool enable);
84
85 /**
86 * Debugging: dump current list of notifications, as saved on disk.
87 */
88 QString dumpNotificationListToString() const;
89
90public Q_SLOTS:
91 /**
92 * Replay the next change notification and erase the previous one from the record.
93 */
94 void replayNext();
95
96Q_SIGNALS:
97 /**
98 * Emitted when new changes are recorded.
99 */
100 void changesAdded();
101
102 /**
103 * Emitted when replayNext() was called, but there was no valid change to replay.
104 * This can happen when all pending changes have been filtered out, for example.
105 * You only need to connect to this signal if you rely on one signal being emitted
106 * as a result of calling replayNext().
107 */
108 void nothingToReplay();
109
110protected:
111 //@cond PRIVATE
112 explicit ChangeRecorder(ChangeRecorderPrivate *d, QObject *parent = 0);
113 //@endcond
114
115private:
116 //@cond PRIVATE
117 Q_DECLARE_PRIVATE(ChangeRecorder)
118 //@endcond
119};
120
121}
122
123#endif
124