Akonadi

job.h
1 /*
2  SPDX-FileCopyrightText: 2006 Tobias Koenig <[email protected]>
3  2006 Marc Mutz <[email protected]>
4  2006 - 2007 Volker Krause <[email protected]>
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 
17 class QString;
18 
19 namespace Akonadi
20 {
21 namespace Protocol
22 {
23 class Command;
24 using CommandPtr = QSharedPointer<Command>;
25 }
26 
27 class JobPrivate;
28 class Session;
29 class 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 <[email protected]>, Tobias Koenig <[email protected]>, Marc Mutz <[email protected]>
79  */
80 class AKONADICORE_EXPORT Job : public KCompositeJob
81 {
82  Q_OBJECT
83 
84  friend class Session;
85  friend class SessionPrivate;
86 
87 public:
88  /**
89  * Describes a list of jobs.
90  */
91  using List = QList<Job *>;
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  Q_REQUIRED_RESULT QString errorString() const final;
133 
134 Q_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 
152 protected:
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 
201 protected Q_SLOTS:
202  void slotResult(KJob *job) override;
203 
204 protected:
205  /// @cond PRIVATE
206  Job(JobPrivate *dd, QObject *parent);
207  std::unique_ptr<JobPrivate> const d_ptr;
208  /// @endcond
209 
210 private:
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 }
222 
The server protocol version is too old or too new.
Definition: job.h:100
Unknown error.
Definition: job.h:102
A glue between Qt and the standard library.
Base class for all actions in the Akonadi storage.
Definition: job.h:80
A communication session with the Akonadi storage.
Definition: core/session.h:55
ASAP CLI session.
Helper integration between Akonadi and Qt.
The user canceled this job.
Definition: job.h:101
Error
Describes the error codes that can be emitted by this class.
Definition: job.h:98
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