Akonadi

job.h
1/*
2 SPDX-FileCopyrightText: 2006 Tobias Koenig <tokoe@kde.org>
3 2006 Marc Mutz <mutz@kde.org>
4 2006 - 2007 Volker Krause <vkrause@kde.org>
5
6 SPDX-License-Identifier: LGPL-2.0-or-later
7*/
8
9#pragma once
10
11#include "akonadicore_export.h"
12
13#include <KCompositeJob>
14
15#include <memory>
16
17class QString;
18
19namespace Akonadi
20{
21namespace Protocol
22{
23class Command;
24using CommandPtr = QSharedPointer<Command>;
25}
26
27class JobPrivate;
28class Session;
29class SessionPrivate;
30
31/**
32 * @short Base class for all actions in the Akonadi storage.
33 *
34 * This class encapsulates a request to the pim storage service,
35 * the code looks like
36 *
37 * @code
38 *
39 * Akonadi::Job *job = new Akonadi::SomeJob( some parameter );
40 * connect( job, SIGNAL(result(KJob*)),
41 * this, SLOT(slotResult(KJob*)) );
42 *
43 * @endcode
44 *
45 * The job is queued for execution as soon as the event loop is entered
46 * again.
47 *
48 * And the slotResult is usually at least:
49 *
50 * @code
51 *
52 * if ( job->error() ) {
53 * // handle error...
54 * }
55 *
56 * @endcode
57 *
58 * With the synchronous interface the code looks like
59 *
60 * @code
61 * Akonadi::SomeJob *job = new Akonadi::SomeJob( some parameter );
62 * if ( !job->exec() ) {
63 * qDebug() << "Error:" << job->errorString();
64 * } else {
65 * // do something
66 * }
67 * @endcode
68 *
69 * @warning Using the synchronous method is error prone, use this only
70 * if the asynchronous access is not possible. See the documentation of
71 * KJob::exec() for more details.
72 *
73 * Subclasses must reimplement doStart().
74 *
75 * @note KJob-derived objects delete itself, it is thus not possible
76 * to create job objects on the stack!
77 *
78 * @author Volker Krause <vkrause@kde.org>, Tobias Koenig <tokoe@kde.org>, Marc Mutz <mutz@kde.org>
79 */
80class AKONADICORE_EXPORT Job : public KCompositeJob
81{
82 Q_OBJECT
83
84 friend class Session;
85 friend class SessionPrivate;
86
87public:
88 /**
89 * Describes a list of jobs.
90 */
92
93 /**
94 * Describes the error codes that can be emitted by this class.
95 * Subclasses can provide additional codes, starting from UserError
96 * onwards
97 */
98 enum Error {
99 ConnectionFailed = UserDefinedError, ///< The connection to the Akonadi server failed.
100 ProtocolVersionMismatch, ///< The server protocol version is too old or too new.
101 UserCanceled, ///< The user canceled this job.
102 Unknown, ///< Unknown error.
103 UserError = UserDefinedError + 42 ///< Starting point for error codes defined by sub-classes.
104 };
105
106 /**
107 * Creates a new job.
108 *
109 * If the parent object is a Job object, the new job will be a subjob of @p parent.
110 * If the parent object is a Session object, it will be used for server communication
111 * instead of the default session.
112 *
113 * @param parent The parent object, job or session.
114 */
115 explicit Job(QObject *parent = nullptr);
116
117 /**
118 * Destroys the job.
119 */
120 ~Job() override;
121
122 /**
123 * Jobs are started automatically once entering the event loop again, no need
124 * to explicitly call this.
125 */
126 void start() override;
127
128 /**
129 * Returns the error string, if there has been an error, an empty
130 * string otherwise.
131 */
132 [[nodiscard]] QString errorString() const final;
133
134Q_SIGNALS:
135 /**
136 * This signal is emitted directly before the job will be started.
137 *
138 * @param job The started job.
139 */
140 void aboutToStart(Akonadi::Job *job);
141
142 /**
143 * This signal is emitted if the job has finished all write operations, ie.
144 * if this signal is emitted, the job guarantees to not call writeData() again.
145 * Do not emit this signal directly, call emitWriteFinished() instead.
146 *
147 * @param job This job.
148 * @see emitWriteFinished()
149 */
150 void writeFinished(Akonadi::Job *job);
151
152protected:
153 /**
154 * This method must be reimplemented in the concrete jobs. It will be called
155 * after the job has been started and a connection to the Akonadi backend has
156 * been established.
157 */
158 virtual void doStart() = 0;
159
160 /**
161 * This method should be reimplemented in the concrete jobs in case you want
162 * to handle incoming data. It will be called on received data from the backend.
163 * The default implementation does nothing.
164 *
165 * @param tag The tag of the corresponding command, empty if this is an untagged response.
166 * @param response The received response
167 *
168 * @return Implementations should return true if the last response was processed and
169 * the job can emit result. Return false if more responses from server are expected.
170 */
171 virtual bool doHandleResponse(qint64 tag, const Protocol::CommandPtr &response);
172
173 /**
174 * Adds the given job as a subjob to this job. This method is automatically called
175 * if you construct a job using another job as parent object.
176 * The base implementation does the necessary setup to share the network connection
177 * with the backend.
178 *
179 * @param job The new subjob.
180 */
181 bool addSubjob(KJob *job) override;
182
183 /**
184 * Removes the given subjob of this job.
185 *
186 * @param job The subjob to remove.
187 */
188 bool removeSubjob(KJob *job) override;
189
190 /**
191 * Kills the execution of the job.
192 */
193 bool doKill() override;
194
195 /**
196 * Call this method to indicate that this job will not call writeData() again.
197 * @see writeFinished()
198 */
199 void emitWriteFinished();
200
201protected Q_SLOTS:
202 void slotResult(KJob *job) override;
203
204protected:
205 /// @cond PRIVATE
206 Job(JobPrivate *dd, QObject *parent);
207 std::unique_ptr<JobPrivate> const d_ptr;
208 /// @endcond
209
210private:
211 Q_DECLARE_PRIVATE(Job)
212
213 /// @cond PRIVATE
214 Q_PRIVATE_SLOT(d_func(), void startNext())
215 Q_PRIVATE_SLOT(d_func(), void signalCreationToJobTracker())
216 Q_PRIVATE_SLOT(d_func(), void signalStartedToJobTracker())
217 Q_PRIVATE_SLOT(d_func(), void delayedEmitResult())
218 /// @endcond
219};
220
221}
Base class for all actions in the Akonadi storage.
Definition job.h:81
Error
Describes the error codes that can be emitted by this class.
Definition job.h:98
@ Unknown
Unknown error.
Definition job.h:102
@ ProtocolVersionMismatch
The server protocol version is too old or too new.
Definition job.h:100
@ UserCanceled
The user canceled this job.
Definition job.h:101
A communication session with the Akonadi storage.
ASAP CLI session.
Q_SCRIPTABLE Q_NOREPLY void start()
Helper integration between Akonadi and Qt.
A glue between Qt and the standard library.
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