[DS-734] Cache columnNames in TableRowIterator, reduce database accesses in Item.update (getting metadatafields)

git-svn-id: http://scm.dspace.org/svn/repo/dspace/trunk@5721 9c30dcfa-912a-0410-8fc2-9e0234be79fd

dspace-api/src/main/java/org/dspace/content/Item.java

@@ -48,6 +48,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.StringTokenizer;
 
+import org.apache.commons.lang.StringUtils;
 import org.apache.log4j.Logger;
 import org.dspace.app.util.AuthorizeUtil;
 import org.dspace.authorize.AuthorizeConfiguration;
@@ -1770,10 +1771,29 @@ public class Item extends DSpaceObject
         }
     }
 
+    private transient MetadataField[] allMetadataFields = null;
     private MetadataField getMetadataField(DCValue dcv) throws SQLException, AuthorizeException
     {
-        return MetadataField.findByElement(ourContext,
-                        getMetadataSchemaID(dcv), dcv.element, dcv.qualifier);
+        if (allMetadataFields == null)
+        {
+            allMetadataFields = MetadataField.findAll(ourContext);
+        }
+
+        if (allMetadataFields != null)
+        {
+            int schemaID = getMetadataSchemaID(dcv);
+            for (MetadataField field : allMetadataFields)
+            {
+                if (field.getSchemaID() == schemaID &&
+                        StringUtils.equals(field.getElement(), dcv.element) &&
+                        StringUtils.equals(field.getQualifier(), dcv.qualifier))
+                {
+                    return field;
+                }
+            }
+        }
+
+        return null;
     }
 
     private int getMetadataSchemaID(DCValue dcv) throws SQLException

dspace-api/src/main/java/org/dspace/storage/rdbms/DatabaseManager.java

@@ -915,7 +915,7 @@ public class DatabaseManager
      * @exception SQLException
      *                If a database error occurs
      */
-    protected static List<String> getColumnNames(String table) throws SQLException
+    static List<String> getColumnNames(String table) throws SQLException
     {
         List<String> results = new ArrayList<String>();
         Collection<ColumnInfo> info = getColumnInfo(table);
@@ -938,8 +938,7 @@ public class DatabaseManager
      * @exception SQLException
      *                If a database error occurs
      */
-    protected static List<String> getColumnNames(ResultSetMetaData meta)
-            throws SQLException
+    static List<String> getColumnNames(ResultSetMetaData meta) throws SQLException
     {
         List<String> results = new ArrayList<String>();
         int columns = meta.getColumnCount();
@@ -1170,11 +1169,31 @@ public class DatabaseManager
      *                If a database error occurs
      */
     static TableRow process(ResultSet results, String table) throws SQLException
+    {
+        return process(results, table, null);
+    }
+
+    /**
+     * Convert the current row in a ResultSet into a TableRow object.
+     *
+     * @param results
+     *            A ResultSet to process
+     * @param table
+     *            The name of the table
+     * @param pColumnNames
+     *            The name of the columns in this resultset
+     * @return A TableRow object with the data from the ResultSet
+     * @exception SQLException
+     *                If a database error occurs
+     */
+    static TableRow process(ResultSet results, String table, List<String> pColumnNames) throws SQLException
     {
         ResultSetMetaData meta = results.getMetaData();
         int columns = meta.getColumnCount() + 1;
 
-        List<String> columnNames = (table == null) ? getColumnNames(meta) : getColumnNames(table);
+        // If we haven't been passed the column names try to generate them from the metadata / table
+        List<String> columnNames = pColumnNames != null ? pColumnNames :
+                                        ((table == null) ? getColumnNames(meta) : getColumnNames(table));
 
         TableRow row = new TableRow(canonicalize(table), columnNames);
 

dspace-api/src/main/java/org/dspace/storage/rdbms/TableRowIterator.java

@@ -45,6 +45,7 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 /**
@@ -81,6 +82,11 @@ public class TableRowIterator
      */
     private boolean hasAdvanced = false;
 
+    /**
+     * Column names for the results in this table
+     */
+    List<String> columnNames = null;
+
     /**
      * Constructor
      * 
@@ -102,9 +108,31 @@ public class TableRowIterator
      *            The name of the table
      */
     TableRowIterator(ResultSet results, String table)
+    {
+        this(results, table, null);
+        statemt = null;
+    }
+
+    TableRowIterator(ResultSet results, String table, List<String> columnNames)
     {
         this.results = results;
         this.table = table;
+        if (columnNames == null)
+        {
+            try
+            {
+                this.columnNames = (table == null) ? DatabaseManager.getColumnNames(results.getMetaData()) : DatabaseManager.getColumnNames(table);
+            }
+            catch (SQLException e)
+            {
+                this.columnNames = null;
+            }
+        }
+        else
+        {
+            this.columnNames = Collections.unmodifiableList(columnNames);
+        }
+        
         statemt = null;
     }
 
@@ -152,7 +180,7 @@ public class TableRowIterator
 
         hasAdvanced = false;
 
-        return DatabaseManager.process(results, table);
+        return DatabaseManager.process(results, table, columnNames);
     }
 
     /**