Force QgsTask::run() to fully complete

Remove support for signal based completion/termination

Also unfortunately disable a lot of the test suite as a result,
since it's not easily translatable

Author: nyalldawson

python/core/__init__.py

@@ -214,15 +214,15 @@ def run(self):
         except Exception as ex:
             # report error
             self.exception = ex
-            return QgsTask.ResultFail
+            return False
 
-        return QgsTask.ResultSuccess
+        return True
 
     def finished(self, result):
         if not self.on_finished:
             return
 
-        if result == QgsTask.ResultFail and self.exception is None:
+        if not result and self.exception is None:
             self.exception = Exception('Task cancelled')
 
         try:

python/core/qgstaskmanager.sip

@@ -32,14 +32,6 @@ class QgsTask : QObject
       Terminated, /*!< Task was terminated or errored */
     };
 
-    //! Result of running the task
-    enum TaskResult
-    {
-      ResultSuccess, //!< Task completed successfully
-      ResultFail, //!< Task was terminated within completion
-      ResultPending, //!< Task is still running
-    };
-
     //! Task flags
     enum Flag
     {
@@ -154,8 +146,8 @@ class QgsTask : QObject
     /**
      * Will be emitted by task when its status changes.
      * @param status new task status
-     * @note derived classes should not emit this signal directly, instead they should call
-     * completed() or terminated()
+     * @note derived classes should not emit this signal directly, it will automatically
+     * be emitted
      */
     void statusChanged( int status );
 
@@ -168,17 +160,17 @@ class QgsTask : QObject
 
     /**
      * Will be emitted by task to indicate its successful completion.
-     * @note derived classes should not emit this signal directly, instead they should call
-     * completed()
+     * @note derived classes should not emit this signal directly, it will automatically
+     * be emitted
      */
     void taskCompleted();
 
     /**
      * Will be emitted by task if it has terminated for any reason
      * other then completion (eg when a task has been cancelled or encountered
      * an internal error).
-     * @note derived classes should not emit this signal directly, instead they should call
-     * terminated()
+     * @note derived classes should not emit this signal directly, it will automatically
+     * be emitted
      */
     void taskTerminated();
 
@@ -189,21 +181,10 @@ class QgsTask : QObject
      * (ie via calling start() ), and subclasses should implement the operation they
      * wish to perform in the background within this method.
      *
-     * A task can return a ResultSuccess and ResultFail value to indicate that the
-     * task has finished and was either completed successfully or terminated before
-     * completion.
-     *
-     * Alternatively, tasks can also return the ResultPending value
-     * to indicate that the task is still operating and will manually report its
-     * completion by calling completed() or terminated(). This may be useful for
-     * tasks which rely on external events for completion, eg downloading a
-     * file. In this case Qt slots could be created which are connected to the
-     * download completion or termination and which call completed() or terminated()
-     * to indicate the task has finished operations.
-     * @see completed()
-     * @see terminated()
+     * A task must return a boolean value to indicate whether the
+     * task was completed successfully or terminated before completion.
      */
-    virtual TaskResult run() = 0;
+    virtual bool run() = 0;
 
     /**
      * If the task is managed by a QgsTaskManager, this will be called after the
@@ -215,7 +196,7 @@ class QgsTask : QObject
      * for the duration of this method so tasks should avoid performing any
      * lengthy operations here.
      */
-    virtual void finished( TaskResult result );
+    virtual void finished( bool result );
 
     /**
      * Will return true if task should terminate ASAP. If the task reports the CanCancel
@@ -224,23 +205,6 @@ class QgsTask : QObject
      */
     bool isCancelled() const;
 
-    /**
-     * Sets the task as completed. Calling this is only required for tasks which
-     * returned the ResultPending value as a result of run(). This should be called
-     * when the task is complete. Calling will automatically emit the statusChanged
-     * and taskCompleted signals.
-     */
-    void completed();
-
-    /**
-     * Sets the task as terminated.  Calling this is only required for tasks which
-     * returned the ResultPending value as a result of run().
-     * Should be called whenever the task ends for any reason other than successful
-     * completion. Calling will automatically emit the statusChanged and taskTerminated
-     * signals.
-     */
-    void terminated();
-
   protected slots:
 
     /**

src/core/qgstaskmanager.cpp

@@ -62,22 +62,13 @@ void QgsTask::start()
   // force initial emission of progressChanged, but respect if task has had initial progress manually set
   setProgress( mProgress );
 
-  TaskResult result = run();
-  switch ( result )
+  if ( run() )
   {
-    case ResultSuccess:
-      completed();
-      break;
-
-    case ResultFail:
-      terminated();
-      break;
-
-    case ResultPending:
-      // nothing to do - task will call completed() or stopped()
-      // in it's own time
-      break;
-
+    completed();
+  }
+  else
+  {
+    terminated();
   }
 }
 
@@ -625,8 +616,7 @@ void QgsTaskManager::taskStatusChanged( int status )
 
   if ( status == QgsTask::Terminated || status == QgsTask::Complete )
   {
-    QgsTask::TaskResult result = status == QgsTask::Complete ? QgsTask::ResultSuccess
-                                 : QgsTask::ResultFail;
+    bool result = status == QgsTask::Complete;
     task->finished( result );
   }
 

src/core/qgstaskmanager.h

@@ -61,14 +61,6 @@ class CORE_EXPORT QgsTask : public QObject
       Terminated, //!< Task was terminated or errored
     };
 
-    //! Result of running the task
-    enum TaskResult
-    {
-      ResultSuccess = 0, //!< Task completed successfully
-      ResultFail, //!< Task was terminated within completion
-      ResultPending, //!< Task is still running
-    };
-
     //! Task flags
     enum Flag
     {
@@ -186,8 +178,8 @@ class CORE_EXPORT QgsTask : public QObject
     /**
      * Will be emitted by task when its status changes.
      * @param status new task status
-     * @note derived classes should not emit this signal directly, instead they should call
-     * completed() or terminated()
+     * @note derived classes should not emit this signal directly, it will automatically
+     * be emitted
      */
     void statusChanged( int status );
 
@@ -200,17 +192,17 @@ class CORE_EXPORT QgsTask : public QObject
 
     /**
      * Will be emitted by task to indicate its successful completion.
-     * @note derived classes should not emit this signal directly, instead they should call
-     * completed()
+     * @note derived classes should not emit this signal directly, it will automatically
+     * be emitted
      */
     void taskCompleted();
 
     /**
      * Will be emitted by task if it has terminated for any reason
      * other then completion (eg when a task has been cancelled or encountered
      * an internal error).
-     * @note derived classes should not emit this signal directly, instead they should call
-     * terminated()
+     * @note derived classes should not emit this signal directly, it will automatically
+     * be emitted
      */
     void taskTerminated();
 
@@ -221,21 +213,10 @@ class CORE_EXPORT QgsTask : public QObject
      * (ie via calling start() ), and subclasses should implement the operation they
      * wish to perform in the background within this method.
      *
-     * A task can return a ResultSuccess and ResultFail value to indicate that the
-     * task has finished and was either completed successfully or terminated before
-     * completion.
-     *
-     * Alternatively, tasks can also return the ResultPending value
-     * to indicate that the task is still operating and will manually report its
-     * completion by calling completed() or terminated(). This may be useful for
-     * tasks which rely on external events for completion, eg downloading a
-     * file. In this case Qt slots could be created which are connected to the
-     * download completion or termination and which call completed() or terminated()
-     * to indicate the task has finished operations.
-     * @see completed()
-     * @see terminated()
-     */
-    virtual TaskResult run() = 0;
+     * A task must return a boolean value to indicate whether the
+     * task was completed successfully or terminated before completion.
+     */
+    virtual bool run() = 0;
 
     /**
      * If the task is managed by a QgsTaskManager, this will be called after the
@@ -247,7 +228,7 @@ class CORE_EXPORT QgsTask : public QObject
      * for the duration of this method so tasks should avoid performing any
      * lengthy operations here.
      */
-    virtual void finished( TaskResult result ) { Q_UNUSED( result ); }
+    virtual void finished( bool result ) { Q_UNUSED( result ); }
 
     /**
      * Will return true if task should terminate ASAP. If the task reports the CanCancel
@@ -256,29 +237,11 @@ class CORE_EXPORT QgsTask : public QObject
      */
     bool isCancelled() const { return mShouldTerminate; }
 
-    /**
-     * Sets the task as completed. Calling this is only required for tasks which
-     * returned the ResultPending value as a result of run(). This should be called
-     * when the task is complete. Calling will automatically emit the statusChanged
-     * and taskCompleted signals.
-     */
-    void completed();
-
-    /**
-     * Sets the task as terminated.  Calling this is only required for tasks which
-     * returned the ResultPending value as a result of run().
-     * Should be called whenever the task ends for any reason other than successful
-     * completion. Calling will automatically emit the statusChanged and taskTerminated
-     * signals.
-     */
-    void terminated();
-
   protected slots:
 
     /**
-     * Sets the task's current progress. If task reports the CanReportProgress flag then
-     * the derived class should call this method whenever the task wants to update its
-     * progress. Calling will automatically emit the progressChanged signal.
+     * Sets the task's current progress. The derived class should call this method whenever
+     * the task wants to update its progress. Calling will automatically emit the progressChanged signal.
      * @param progress percent of progress, from 0.0 - 100.0
      */
     void setProgress( double progress );
@@ -321,6 +284,16 @@ class CORE_EXPORT QgsTask : public QObject
      */
     void start();
 
+    /**
+     * Called when the task has completed successfully.
+     */
+    void completed();
+
+    /**
+     * Called when the task has failed, as either a result of an internal failure or via cancellation.
+     */
+    void terminated();
+
     void processSubTasksForCompletion();
 
     void processSubTasksForTermination();