Applying my patch from LANG-478 - moving StopWatch to using nanoTime under the hood.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/lang/trunk@749114 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/commons/lang/time/StopWatch.java

@@ -56,6 +56,8 @@
  */
 public class StopWatch {
 
+    private static final long NANO_2_MILLIS = 1000000L;
+
     // running states
     private static final int STATE_UNSTARTED = 0;
 
@@ -85,6 +87,13 @@ public class StopWatch {
      */
     private long startTime;
 
+    /**
+     * The start time in Millis - nanoTime is only for elapsed time so we 
+     * need to also store the currentTimeMillis to maintain the old 
+     * getStartTime API.
+     */
+    private long startTimeMillis;
+
     /**
      * The stop time.
      */
@@ -118,7 +127,8 @@ public void start() {
         if (this.runningState != STATE_UNSTARTED) {
             throw new IllegalStateException("Stopwatch already started. ");
         }
-        this.startTime = System.currentTimeMillis();
+        this.startTime = System.nanoTime();
+        this.startTimeMillis = System.currentTimeMillis();
         this.runningState = STATE_RUNNING;
     }
 
@@ -139,7 +149,7 @@ public void stop() {
             throw new IllegalStateException("Stopwatch is not running. ");
         }
         if (this.runningState == STATE_RUNNING) {
-            this.stopTime = System.currentTimeMillis();
+            this.stopTime = System.nanoTime();
         }
         this.runningState = STATE_STOPPED;
     }
@@ -175,7 +185,7 @@ public void split() {
         if (this.runningState != STATE_RUNNING) {
             throw new IllegalStateException("Stopwatch is not running. ");
         }
-        this.stopTime = System.currentTimeMillis();
+        this.stopTime = System.nanoTime();
         this.splitState = STATE_SPLIT;
     }
 
@@ -216,7 +226,7 @@ public void suspend() {
         if (this.runningState != STATE_RUNNING) {
             throw new IllegalStateException("Stopwatch must be running to suspend. ");
         }
-        this.stopTime = System.currentTimeMillis();
+        this.stopTime = System.nanoTime();
         this.runningState = STATE_SUSPENDED;
     }
 
@@ -237,7 +247,7 @@ public void resume() {
         if (this.runningState != STATE_SUSPENDED) {
             throw new IllegalStateException("Stopwatch must be suspended to resume. ");
         }
-        this.startTime += (System.currentTimeMillis() - this.stopTime);
+        this.startTime += (System.nanoTime() - this.stopTime);
         this.runningState = STATE_RUNNING;
     }
 
@@ -254,12 +264,28 @@ public void resume() {
      * @return the time in milliseconds
      */
     public long getTime() {
+        return getNanoTime() / NANO_2_MILLIS;
+    }
+    /**
+     * <p>
+     * Get the time on the stopwatch in nanoseconds.
+     * </p>
+     * 
+     * <p>
+     * This is either the time between the start and the moment this method is called, or the amount of time between
+     * start and stop.
+     * </p>
+     * 
+     * @return the time in nanoseconds
+     * @since 3.0
+     */
+    public long getNanoTime() {
         if (this.runningState == STATE_STOPPED || this.runningState == STATE_SUSPENDED) {
             return this.stopTime - this.startTime;
         } else if (this.runningState == STATE_UNSTARTED) {
             return 0;
         } else if (this.runningState == STATE_RUNNING) {
-            return System.currentTimeMillis() - this.startTime;
+            return System.nanoTime() - this.startTime;
         }
         throw new RuntimeException("Illegal running state has occured. ");
     }
@@ -280,6 +306,24 @@ public long getTime() {
      * @since 2.1
      */
     public long getSplitTime() {
+        return getSplitNanoTime() / NANO_2_MILLIS;
+    }
+    /**
+     * <p>
+     * Get the split time on the stopwatch in nanoseconds.
+     * </p>
+     * 
+     * <p>
+     * This is the time between start and latest split.
+     * </p>
+     * 
+     * @return the split time in nanoseconds
+     * 
+     * @throws IllegalStateException
+     *             if the StopWatch has not yet been split.
+     * @since 3.0
+     */
+    public long getSplitNanoTime() {
         if (this.splitState != STATE_SPLIT) {
             throw new IllegalStateException("Stopwatch must be split to get the split time. ");
         }
@@ -298,7 +342,8 @@ public long getStartTime() {
         if (this.runningState == STATE_UNSTARTED) {
             throw new IllegalStateException("Stopwatch has not been started");
         }
-        return this.startTime;
+        // System.nanoTime is for elapsed time
+        return this.startTimeMillis;
     }
 
     /**