Akonadi

changerecorder.h
1 /*
2  SPDX-FileCopyrightText: 2007 Volker Krause <[email protected]>
3 
4  SPDX-License-Identifier: LGPL-2.0-or-later
5 */
6 
7 #pragma once
8 
9 #include "akonadicore_export.h"
10 #include "monitor.h"
11 
12 class QSettings;
13 
14 namespace Akonadi
15 {
16 class ChangeRecorderPrivate;
17 
18 /**
19  * @short Records and replays change notification.
20  *
21  * This class is responsible for recording change notifications while
22  * an agent is not online and replaying the notifications when the agent
23  * is online again. Therefore the agent doesn't have to care about
24  * online/offline mode in its synchronization algorithm.
25  *
26  * Unlike Akonadi::Monitor this class only emits one change signal at a
27  * time. To receive the next one you need to explicitly call replayNext().
28  * If a signal is emitted that has no receivers, it's automatically skipped,
29  * which means you only need to connect to signals you are actually interested
30  * in.
31  *
32  * @author Volker Krause <[email protected]>
33  */
34 class AKONADICORE_EXPORT ChangeRecorder : public Monitor
35 {
36  Q_OBJECT
37 public:
38  /**
39  * Creates a new change recorder.
40  */
41  explicit ChangeRecorder(QObject *parent = nullptr);
42 
43  /**
44  * Destroys the change recorder.
45  * All not yet processed changes are written back to the config file.
46  */
47  ~ChangeRecorder() override;
48 
49  /**
50  * Sets the QSettings object used for persistent recorded changes.
51  */
52  void setConfig(QSettings *settings);
53 
54  /**
55  * Returns whether there are recorded changes.
56  */
57  Q_REQUIRED_RESULT bool isEmpty() const;
58 
59  /**
60  * Removes the previously emitted change from the records.
61  */
62  void changeProcessed();
63 
64  /**
65  * Enables change recording. If change recording is disabled, this class
66  * behaves exactly like Akonadi::Monitor.
67  * Change recording is enabled by default.
68  * @param enable @c false to disable change recording. @c true by default
69  */
70  void setChangeRecordingEnabled(bool enable);
71 
72  /**
73  * Debugging: dump current list of notifications, as saved on disk.
74  */
75  Q_REQUIRED_RESULT QString dumpNotificationListToString() const;
76 
77 public Q_SLOTS:
78  /**
79  * Replay the next change notification and erase the previous one from the record.
80  */
81  void replayNext();
82 
83 Q_SIGNALS:
84  /**
85  * Emitted when new changes are recorded.
86  */
87  void changesAdded();
88 
89  /**
90  * Emitted when replayNext() was called, but there was no valid change to replay.
91  * This can happen when all pending changes have been filtered out, for example.
92  * You only need to connect to this signal if you rely on one signal being emitted
93  * as a result of calling replayNext().
94  */
95  void nothingToReplay();
96 
97 protected:
98  /// @cond PRIVATE
99  explicit ChangeRecorder(ChangeRecorderPrivate *d, QObject *parent = nullptr);
100  /// @endcond
101 
102 private:
103  /// @cond PRIVATE
104  Q_DECLARE_PRIVATE(ChangeRecorder)
105  /// @endcond
106 };
107 
108 }
109 
Monitors an item or collection for changes.
Definition: monitor.h:71
Records and replays change notification.
Helper integration between Akonadi and Qt.
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