backup MDL-24962 Backup, Restore, and Import all now explicitly destroy the UI, controller, and stage objects upon completion.

backup/backup.php

@@ -100,4 +100,6 @@ if ($backup->enforce_changed_dependencies()) {
 }
 echo $renderer->progress_bar($backup->get_progress_bar());
 echo $backup->display();
+$backup->destroy();
+unset($backup);
 echo $OUTPUT->footer();

backup/import.php

@@ -90,6 +90,8 @@ if ($backup->get_stage() == backup_ui::STAGE_CONFIRMATION) {
 if ($backup->get_stage() == backup_ui::STAGE_FINAL) {
     // First execute the backup
     $backup->execute();
+    $backup->destroy();
+    unset($backup);
 
     // Check whether the backup directory still exists. If missing, something
     // went really wrong in backup, throw error. Note that backup::MODE_IMPORT
@@ -156,4 +158,6 @@ if ($backup->enforce_changed_dependencies()) {
 }
 echo $renderer->progress_bar($backup->get_progress_bar());
 echo $backup->display();
-echo $OUTPUT->footer();
+$backup->destroy();
+unset($backup);
+echo $OUTPUT->footer();

backup/restore.php

@@ -54,4 +54,6 @@ if (!$restore->is_independent() && $restore->enforce_changed_dependencies()) {
 }
 echo $renderer->progress_bar($restore->get_progress_bar());
 echo $restore->display($renderer);
+$restore->destroy();
+unset($restore);
 echo $OUTPUT->footer();

backup/util/ui/base_ui.class.php

@@ -72,6 +72,17 @@ abstract class base_ui {
         // Process UI event before to be safe
         $this->controller->process_ui_event();
     }
+    /**
+     * Destorys the backup controller and the loaded stage.
+     */
+    public function destroy() {
+
+        if ($this->controller) {
+            $this->controller->destroy();
+        }
+        unset($this->stage);
+
+    }
     /**
      * Intialises what ever stage is requested. If none are requested we check
      * params for 'stage' and default to initial