diff -N TimerDriver.java
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ TimerDriver.java	8 Aug 2012 01:02:21 -0000	1.1
@@ -0,0 +1,38 @@

+package org.lcsim.hps.util;
+
+import org.lcsim.event.EventHeader;
+import org.lcsim.util.Driver;
+
+/**
+ * Lightweight timer driver. Add one copy of this driver to measure time per event; add multiple copies to measure time between two points in the execute list.
+ * @author Sho Uemura <[log in to unmask]>
+ * @version $Id: TimerDriver.java,v 1.1 2012/08/08 01:02:21 meeg Exp $
+ */
+public class TimerDriver extends Driver {
+
+    private static long time = Long.MIN_VALUE;
+    private long timeElapsed;
+    private int count = 0;
+    private String name = "unnamed";
+    private boolean verbose = false;
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    @Override
+    public void process(EventHeader event) {
+        long oldTime = time;
+        time = System.nanoTime();
+        if (oldTime != Long.MIN_VALUE) {
+            long dt = time - oldTime;
+            timeElapsed += dt;
+            count++;
+            if (verbose) {
+                System.out.format("Timer %s: dt %f, timeElapsed %d, count %d, mean time %f ms\n", name, dt / 1.0e6, timeElapsed, count, (timeElapsed / 1.0e6) / count);
+            } else {
+                System.out.format("Timer %s: dt %f, mean time %f ms\n", name, dt / 1.0e6, (timeElapsed / 1.0e6) / count);
+            }
+        }
+    }
+}