File indexing completed on 2024-04-28 04:00:49

 /*
     SPDX-FileCopyrightText: 2014 Alejandro Fiestas Olivares <afiestas@kde.org>
 
     SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
 */
 
 #ifndef SOLID_JOB_H
 #define SOLID_JOB_H
 
 #include <QObject>
 
 #include "solid_export.h"
 
 namespace Solid
 {
 class JobPrivate;
 /**
  * This class represents an asynchronous job performed by Solid,
  * it is usually not used directly but instead it is inherited by some
  * other class, for example \See AcPluggedJob or \See StatesJob
  *
  * There are two ways of using this class, one is via exec() which will block
  * the thread until a result is fetched, the other is via connecting to the
  * signal result()
  *
  * Please, think twice before using exec(), it should be used only in either
  * unittest or cli apps.
  *
  * @note Job and its subclasses are meant to be used
  * in a fire-and-forget way. Jobs will delete themselves
  * when they finish using deleteLater()
  *
  * @note Even given their asynchronous nature, Jobs are still executed in the
  * main thread, so any blocking code executed in it will block the app calling it.
  */
 class SOLID_EXPORT Job : public QObject
 {
     Q_OBJECT
     Q_PROPERTY(int error READ error NOTIFY result)
     Q_PROPERTY(QString errorText READ errorText NOTIFY result)
 
 public:
     explicit Job(QObject *parent = nullptr);
     virtual ~Job();
 
     enum Error {
         /** Indicates there is no error */
         NoError = 0,
         /** Subclasses should define error codes starting at this value */
         UserDefinedError = 100,
     };
     Q_ENUM(Error)
 
     /**
      * Executes the job synchronously.
      *
      * This will start a nested QEventLoop internally. Nested event loop can be dangerous and
      * can have unintended side effects, you should avoid calling exec() whenever you can and use the
      * asynchronous interface of SolidJob instead.
      *
      * Should you indeed call this method, you need to make sure that all callers are reentrant,
      * so that events delivered by the inner event loop don't cause non-reentrant functions to be
      * called, which usually wreaks havoc.
      *
      * Note that the event loop started by this method does not process user input events, which means
      * your user interface will effectively be blocked. Other events like paint or network events are
      * still being processed. The advantage of not processing user input events is that the chance of
      * accidental reentrancy is greatly reduced. Still you should avoid calling this function.
      *
      * @return true if the job has been executed without error, false otherwise
      */
     bool exec();
 
     /**
      * Returns the error code, if there has been an error.
      *
      * Make sure to call this once result() has been emitted
      *
      * @return the error code for this job, 0 if no error.
      */
     int error() const;
 
     /**
      * Returns the error text if there has been an error.
      *
      * Only call if error is not 0.
      *
      * This is usually some extra data associated with the error,
      * such as a URL. Use errorString() to get a human-readable,
      * translated message.
      *
      * @return a string to help understand the error
      */
     QString errorText() const;
 
 public Q_SLOTS:
     /**
      * Starts the job asynchronously.
      *
      * This method will schedule doStart() to be executed in the next
      * loop. This is done so this method returns as soon as possible.
      *
      * When the job is finished, result() is emitted.
      */
     void start();
 
 private Q_SLOTS:
     /**
      * Implementation fo start() that will be executed in next loop
      *
      * This slot is always called in the next loop, triggered by start().
      *
      * When implementing this method it is important to remember that jobs
      * are not executed on a different thread (unless done that way), so any
      * blocking task has to be done in a different thread or process.
      */
     virtual void doStart() = 0;
 
 protected:
     /**
      * Sets the error code.
      *
      * It should be called when an error
      * is encountered in the job, just before calling emitResult().
      *
      * You should define an enum of error codes,
      * with values starting at KJob::UserDefinedError, and use
      * those. For example,
      * @code
      * enum ExampleErrors{
      *   InvalidFoo = UserDefinedError,
      *   BarNotFound
      * };
      * @endcode
      *
      * @param errorCode the error code
      * @see emitResult()
      */
     void setError(int errorCode);
 
     /**
      * Sets the error text.
      *
      * It should be called when an error
      * is encountered in the job, just before calling emitResult().
      *
      * Provides extra information about the error that cannot be
      * determined directly from the error code.  For example, a
      * URL or filename.  This string is not normally translatable.
      *
      * @param errorText the error text
      * @see emitResult(), setError()
      */
     void setErrorText(const QString &errorText);
 
     /**
      * Utility function to emit the result signal, and suicide this job.
      * @note Deletes this job using deleteLater().
      * @see result()
      */
     void emitResult();
 
     JobPrivate *const d_ptr;
     SOLID_NO_EXPORT Job(JobPrivate &dd, QObject *parent);
 
 private:
     Q_DECLARE_PRIVATE(Job)
 
 Q_SIGNALS:
     void result(Solid::Job *job);
 };
 }
 
 #endif // SOLID_JOB_H