After profiling, add another cache where it matters -- direcoryentries

src/main/java/org/forkalsrud/album/web/AlbumServlet.java

@@ -3,10 +3,11 @@ package org.forkalsrud.album.web;
 import java.io.File;
 import java.io.FileReader;
 import java.io.IOException;
-import java.util.Arrays;
 import java.util.Calendar;
 import java.util.Date;
 import java.util.Properties;
+import java.util.Timer;
+import java.util.TimerTask;
 import java.util.logging.Handler;
 import java.util.logging.Level;
 import java.util.logging.LogRecord;
@@ -91,6 +92,8 @@ public class AlbumServlet
     private Environment environment;
     ThumbnailDatabase thumbDb;
     DirectoryDatabase dirDb;
+    Timer timer;
+    Entry cachedRootNode = null;
 
     @Override
     public void init()
@@ -113,6 +116,16 @@ public class AlbumServlet
 
         log4jInit("/log4j.properties");
         log.info("in init of Album");
+        long minute = 60 * 1000L;
+        timer = new Timer("cache evictor");
+        timer.schedule(new TimerTask() {
+
+            @Override
+            public void run() {
+                clearDirCache();
+            }
+        }, minute, minute);
+
         base = new File(props.getProperty("base", "photos")).getAbsoluteFile();
         basePrefix = "/" + base.getName();
 
@@ -296,11 +309,19 @@ public class AlbumServlet
     Entry resolve(File file) {
 
     	if (base.equals(file.getAbsoluteFile())) {
-    		return new DirectoryEntry(dirDb, null, file);
+    	    synchronized (this) {
+    	        if (cachedRootNode == null) {
+    	            cachedRootNode = new DirectoryEntry(dirDb, null, file);
+    	        }
+    	    }
+    	    return cachedRootNode;
     	} else {
     		return ((DirectoryEntry)resolve(file.getParentFile())).get(file);
     	}
     }
+    public synchronized void clearDirCache() {
+        cachedRootNode = null;
+    }
 
 
     @Override