MCR-3049 prevent unnecessary indexing of mods child documents by chec…

…king a property (#2075)

* MCR-3049 prevent unnecessary indexing of mods child documents by checking a property

* MCR-3049 better TODO message

mycore-mods/src/main/java/org/mycore/mods/MCRMODSLinksEventHandler.java

@@ -23,6 +23,7 @@
 
 import org.jdom2.Element;
 import org.mycore.common.MCRConstants;
+import org.mycore.common.config.MCRConfiguration2;
 import org.mycore.common.events.MCREvent;
 import org.mycore.common.events.MCREventHandlerBase;
 import org.mycore.common.events.MCREventManager;
@@ -42,6 +43,11 @@
  */
 public class MCRMODSLinksEventHandler extends MCREventHandlerBase {
 
+    public static final String INDEX_ALL_CHILDREN_PROPERTY_NAME = "MCR.MODS.LinksEventHandler.IndexAllChildren";
+    private static final boolean INDEX_ALL_CHILDREN
+        = MCRConfiguration2.getBoolean(INDEX_ALL_CHILDREN_PROPERTY_NAME)
+            .orElseThrow(() -> MCRConfiguration2.createConfigurationException(INDEX_ALL_CHILDREN_PROPERTY_NAME));
+
     /* (non-Javadoc)
      * @see org.mycore.common.events.MCREventHandlerBase
      * #handleObjectCreated(org.mycore.common.events.MCREvent, org.mycore.datamodel.metadata.MCRObject)
@@ -87,11 +93,12 @@ protected void handleObjectUpdated(final MCREvent evt, final MCRObject obj) {
         }
         handleObjectCreated(evt, obj);
         //may have to reindex children, if they inherit any information
+        // TODO: remove this code, it is not part of this classes responsibility. if information is inherited, i.e.
+        //  because of a metadata share agent, that process should, in turn, cause a reindexing of affected objects
         for (MCRMetaLinkID childLinkID : obj.getStructure().getChildren()) {
             MCRObjectID childID = childLinkID.getXLinkHrefID();
-            if (MCRMetadataManager.exists(childID)) {
-                MCREvent childEvent
-                    = new MCREvent(MCREvent.ObjectType.OBJECT, MCREvent.EventType.INDEX);
+            if (MCRMetadataManager.exists(childID) && INDEX_ALL_CHILDREN) {
+                MCREvent childEvent = new MCREvent(MCREvent.ObjectType.OBJECT, MCREvent.EventType.INDEX);
                 childEvent.put(MCREvent.OBJECT_KEY, MCRMetadataManager.retrieve(childID));
                 MCREventManager.instance().handleEvent(childEvent);
             }

mycore-mods/src/main/resources/components/mods/config/mycore.properties

@@ -239,3 +239,6 @@ MCR.ContentTransformer.migrate-extension-display.Class=org.mycore.common.content
 MCR.ContentTransformer.migrate-extension-display.TransformerFactoryClass=net.sf.saxon.TransformerFactoryImpl
 MCR.ContentTransformer.migrate-extension-display.Stylesheet=xsl/migrate-extension-display.xsl
 
+# if somebody wants to index all children of a mods object without checking if their metadata is changed,
+# then the following property can be set to true
+MCR.MODS.LinksEventHandler.IndexAllChildren=false