Implement a primitive cache for XMLReaders. Construction of them is pretty expensive so we cache at most 10 of them an reuse them. If more than 10 are needed at any given time, they will be created though not cached.

core/src/net/sf/openrocket/file/simplesax/SimpleSAX.java

@@ -1,6 +1,8 @@
 package net.sf.openrocket.file.simplesax;
 
 import java.io.IOException;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
 
 import net.sf.openrocket.aerodynamics.WarningSet;
 
@@ -23,7 +25,9 @@ import org.xml.sax.helpers.XMLReaderFactory;
  * @author Sampo Niskanen <sampo.niskanen@iki.fi>
  */
 public class SimpleSAX {
-	
+
+	static final XMLReaderCache cache = new XMLReaderCache(10);
+
 	/**
 	 * Read a simple XML file.
 	 * 
@@ -35,13 +39,35 @@ public class SimpleSAX {
 	 */
 	public static void readXML(InputSource source, ElementHandler initialHandler,
 			WarningSet warnings) throws IOException, SAXException {
-		
+
 		DelegatorHandler xmlhandler = new DelegatorHandler(initialHandler, warnings);
-		
-		XMLReader reader = XMLReaderFactory.createXMLReader();
+
+		XMLReader reader = cache.createXMLReader();
 		reader.setContentHandler(xmlhandler);
 		reader.setErrorHandler(xmlhandler);
 		reader.parse(source);
+		cache.releaseXMLReader(reader);
 	}
-	
+
+	private static class XMLReaderCache {
+
+		private final BlockingQueue<XMLReader> queue;
+		private XMLReaderCache( int maxSize ) {
+			this.queue = new LinkedBlockingQueue<XMLReader>(maxSize);
+		}
+
+		private XMLReader createXMLReader() throws SAXException {
+
+			XMLReader reader = queue.poll();
+			if ( reader == null ) {
+				reader = XMLReaderFactory.createXMLReader();
+			}
+			return reader;
+		}
+
+		private void releaseXMLReader( XMLReader reader ) {
+			queue.offer( reader );
+		}
+	}
+
 }