[processing] More responsive cancelation for dissolve algorithm

nyalldawson · nyalldawson · commit 05933ef02fd9 · 2019-02-12T16:36:10.000+10:00
(cherry picked from commit 916805c)
diff --git a/src/analysis/processing/qgsalgorithmdissolve.cpp b/src/analysis/processing/qgsalgorithmdissolve.cpp
@@ -220,11 +220,16 @@ QVariantMap QgsDissolveAlgorithm::processAlgorithm( const QVariantMap &parameter
     // See: https://issues.qgis.org/issues/20591 - Dissolve tool failing to produce outputs
     if ( ! result.lastError().isEmpty() && parts.count() >  2 )
     {
+      if ( feedback->isCanceled() )
+        return result;
+
       feedback->pushDebugInfo( QStringLiteral( "GEOS exception: taking the slower route ..." ) );
       result = QgsGeometry();
       for ( const auto &p : parts )
       {
         result = QgsGeometry::unaryUnion( QVector< QgsGeometry >() << result << p );
+        if ( feedback->isCanceled() )
+          return result;
       }
     }
     if ( ! result.lastError().isEmpty() )

Original file line number	Diff line number	Diff line change
`@@ -220,11 +220,16 @@ QVariantMap QgsDissolveAlgorithm::processAlgorithm( const QVariantMap &parameter`
`220`	`220`	`// See: https://issues.qgis.org/issues/20591 - Dissolve tool failing to produce outputs`
`221`	`221`	`if ( ! result.lastError().isEmpty() && parts.count() > 2 )`
`222`	`222`	`{`
	`223`	`+ if ( feedback->isCanceled() )`
	`224`	`+ return result;`
	`225`	`+`
`223`	`226`	`feedback->pushDebugInfo( QStringLiteral( "GEOS exception: taking the slower route ..." ) );`
`224`	`227`	`result = QgsGeometry();`
`225`	`228`	`for ( const auto &p : parts )`
`226`	`229`	`{`
`227`	`230`	`result = QgsGeometry::unaryUnion( QVector< QgsGeometry >() << result << p );`
	`231`	`+ if ( feedback->isCanceled() )`
	`232`	`+ return result;`
`228`	`233`	`}`
`229`	`234`	`}`
`230`	`235`	`if ( ! result.lastError().isEmpty() )`