Changeset 11240 for trunk

Timestamp:

2006-02-14T09:58:38+13:00 (18 years ago)

Author:

mdewsnip

Message:

Huge speed improvement when namespacing metadata.xml files -- why is setting the value of a Node so slow in Java?

File:

• trunk/gli/src/org/greenstone/gatherer/metadata/MetadataXMLFile.java (modified) (2 diffs)

trunk/gli/src/org/greenstone/gatherer/metadata/MetadataXMLFile.java

@@ -504 +504 @@
 
     // Read all the Metadata elements in the file
+    HashMap target_metadata_element_name_attrs_cache = new HashMap();
     NodeList metadata_elements_nodelist = document.getElementsByTagName(METADATA_ELEMENT);
     for (int i = 0; i < metadata_elements_nodelist.getLength(); i++) {
@@ -524 +525 @@
         }
 
-        // Update the metadata.xml file to have the new element name
-        current_metadata_element.setAttribute("name", target_metadata_element_name_full);
+        // Update the metadata.xml file to have the new (namespaced) element name
+        // Instead of using current_metadata_element.setAttribute("name", target_metadata_element_name_full)
+        //   we create an Attr object for each target metadata element name, and cache them
+        // This makes a *huge* difference (namespacing a metadata.xml file with 45000 metadata entries now
+        //   takes 45 seconds instead of 30 minutes!) -- why is setting the value of a Node so slow?
+        Attr target_metadata_element_name_attr = (Attr) target_metadata_element_name_attrs_cache.get(target_metadata_element_name_full);
+        if (target_metadata_element_name_attr == null) {
+            target_metadata_element_name_attr = document.createAttribute("name");
+            target_metadata_element_name_attr.setValue(target_metadata_element_name_full);
+            target_metadata_element_name_attrs_cache.put(target_metadata_element_name_full, target_metadata_element_name_attr);
+        }
+
+        // Remove the old name attribute and add the new (namespaced) one
+        current_metadata_element.removeAttribute("name");
+        current_metadata_element.setAttributeNode((Attr) target_metadata_element_name_attr.cloneNode(false));
         file_changed = true;