[processing] Add flag to indicate whether an algorithm is safe

nyalldawson · nyalldawson · commit 40e47e0fe75d · 2018-01-10T05:33:02.000+10:00
to run in a background thread
diff --git a/python/core/processing/qgsprocessingalgorithm.sip b/python/core/processing/qgsprocessingalgorithm.sip
@@ -44,6 +44,7 @@ Abstract base class for processing algorithms.
       FlagSupportsBatch,
       FlagCanCancel,
       FlagRequiresMatchingCrs,
+      FlagCanRunInBackground,
       FlagDeprecated,
     };
     typedef QFlags<QgsProcessingAlgorithm::Flag> Flags;
diff --git a/python/plugins/processing/gui/AlgorithmDialog.py b/python/plugins/processing/gui/AlgorithmDialog.py
@@ -53,7 +53,7 @@
 from processing.gui.ParametersPanel import ParametersPanel
 from processing.gui.BatchAlgorithmDialog import BatchAlgorithmDialog
 from processing.gui.AlgorithmDialogBase import AlgorithmDialogBase
-from processing.gui.AlgorithmExecutor import executeIterating
+from processing.gui.AlgorithmExecutor import executeIterating, execute
 from processing.gui.Postprocessing import handleAlgorithmResults
 
 from processing.tools import dataobjects
@@ -243,9 +243,14 @@ def on_complete(ok, results):
                     self.cancelButton().setEnabled(False)
                     self.finish(ok, results, context, feedback)
 
-                task = QgsProcessingAlgRunnerTask(self.algorithm(), parameters, context, feedback)
-                task.executed.connect(on_complete)
-                QgsApplication.taskManager().addTask(task)
+                if self.algorithm().flags() & QgsProcessingAlgorithm.FlagCanRunInBackground:
+                    task = QgsProcessingAlgRunnerTask(self.algorithm(), parameters, context, feedback)
+                    task.executed.connect(on_complete)
+                    QgsApplication.taskManager().addTask(task)
+                else:
+                    self.setWindowModality(Qt.ApplicationModal)
+                    ok, results = execute(self.algorithm(), parameters, context, feedback)
+                    on_complete(ok, results)
 
         except AlgorithmDialogBase.InvalidParameterValue as e:
             try:
diff --git a/src/core/processing/qgsprocessingalgorithm.h b/src/core/processing/qgsprocessingalgorithm.h
@@ -72,6 +72,7 @@ class CORE_EXPORT QgsProcessingAlgorithm
       FlagSupportsBatch = 1 << 3,  //!< Algorithm supports batch mode
       FlagCanCancel = 1 << 4, //!< Algorithm can be canceled
       FlagRequiresMatchingCrs = 1 << 5, //!< Algorithm requires that all input layers have matching coordinate reference systems
+      FlagCanRunInBackground = 1 << 6, //!< Algorithm is safe to run in a background thread
       FlagDeprecated = FlagHideFromToolbox | FlagHideFromModeler, //!< Algorithm is deprecated
     };
     Q_DECLARE_FLAGS( Flags, Flag )
