Cleanup methods for providers (implemented for GDAL and OGR)

Fix #8932

Author: m-kuhn

src/core/qgsproviderregistry.cpp

@@ -199,8 +199,25 @@ QgsProviderRegistry::QgsProviderRegistry( QString pluginPath )
 } // QgsProviderRegistry ctor
 
 
+// typedef for the unload dataprovider function
+typedef void cleanupProviderFunction_t();
+
 QgsProviderRegistry::~QgsProviderRegistry()
 {
+  Providers::const_iterator it = mProviders.begin();
+
+  while ( it != mProviders.end() )
+  {
+    QString lib = it->second->library();
+    QLibrary myLib( lib );
+    if ( myLib.isLoaded() )
+    {
+      cleanupProviderFunction_t* cleanupFunc = ( cleanupProviderFunction_t* ) cast_to_fptr( myLib.resolve( "cleanupProvider" ) );
+      if ( cleanupFunc )
+        cleanupFunc();
+    }
+    it++;
+  }
 }
 
 
@@ -292,7 +309,6 @@ QDir const & QgsProviderRegistry::libraryDirectory() const
 typedef QgsDataProvider * classFactoryFunction_t( const QString * );
 
 
-
 /** Copied from QgsVectorLayer::setDataProvider
  *  TODO: Make it work in the generic environment
  *

src/providers/gdal/qgsgdalprovider.cpp

@@ -2767,3 +2767,8 @@ QGISEXTERN QList<QPair<QString, QString> > *pyramidResamplingMethods()
 
   return &methods;
 }
+
+QGISEXTERN void cleanupProvider()
+{
+  GDALDestroyDriverManager();
+}

src/providers/ogr/qgsogrprovider.cpp

@@ -2456,3 +2456,7 @@ QGISEXTERN QgsVectorLayerImport::ImportError createEmptyLayer(
          );
 }
 
+QGISEXTERN void cleanupProvider()
+{
+  OGRCleanupAll();
+}