Add method to copy thread safe settings between processing contexts

Author: nyalldawson

python/core/processing/qgsprocessingcontext.sip

@@ -38,6 +38,12 @@ class QgsProcessingContext
 %End
 
 
+    void copyThreadSafeSettings( const QgsProcessingContext &other );
+%Docstring
+ Copies all settings which are safe for use across different threads from
+ ``other`` to this context.
+%End
+
     QgsProcessingContext::Flags flags() const;
 %Docstring
  Returns any flags set in the context.

src/core/processing/qgsprocessingcontext.h

@@ -66,6 +66,22 @@ class CORE_EXPORT QgsProcessingContext
     //! QgsProcessingContext cannot be copied
     QgsProcessingContext &operator=( const QgsProcessingContext &other ) = delete;
 
+    /**
+     * Copies all settings which are safe for use across different threads from
+     * \a other to this context.
+     */
+    void copyThreadSafeSettings( const QgsProcessingContext &other )
+    {
+      mFlags = other.mFlags;
+      mProject = other.mProject;
+      mExpressionContext = other.mExpressionContext;
+      mInvalidGeometryCallback = other.mInvalidGeometryCallback;
+      mInvalidGeometryCheck = other.mInvalidGeometryCheck;
+      mTransformErrorCallback = other.mTransformErrorCallback;
+      mDefaultEncoding = other.mDefaultEncoding;
+      mFeedback = other.mFeedback;
+    }
+
     /**
      * Returns any flags set in the context.
      * \see setFlags()

tests/src/core/testqgsprocessing.cpp

@@ -583,6 +583,13 @@ void TestQgsProcessing::context()
   context.setInvalidGeometryCheck( QgsFeatureRequest::GeometrySkipInvalid );
   QCOMPARE( context.invalidGeometryCheck(), QgsFeatureRequest::GeometrySkipInvalid );
 
+  QgsProcessingContext context2;
+  context2.copyThreadSafeSettings( context );
+  QCOMPARE( context2.defaultEncoding(), context.defaultEncoding() );
+  QCOMPARE( context2.invalidGeometryCheck(), context.invalidGeometryCheck() );
+  QCOMPARE( context2.flags(), context.flags() );
+  QCOMPARE( context2.project(), context.project() );
+
   // layers to load on completion
   QgsVectorLayer *v1 = new QgsVectorLayer( "Polygon", "V1", "memory" );
   QgsVectorLayer *v2 = new QgsVectorLayer( "Polygon", "V2", "memory" );