JAVA-621: Make BSONTimestamp Comparable

Author: Steve Briskin

src/main/org/bson/types/BSONTimestamp.java

@@ -27,7 +27,7 @@
  * <b>time</b> is seconds since epoch
  * <b>inc<b> is an ordinal
  */
-public class BSONTimestamp implements Serializable {
+public class BSONTimestamp implements Comparable<BSONTimestamp>, Serializable {
 
     private static final long serialVersionUID = -3268482672267936464L;
 
@@ -60,6 +60,16 @@ public String toString(){
         return "TS time:" + _time + " inc:" + _inc;
     }
 
+    @Override
+    public int compareTo(BSONTimestamp ts) {
+        if(getTime() != ts.getTime()) {
+            return getTime() - ts.getTime();
+        }
+        else{
+            return getInc() - ts.getInc();
+        }
+    }
+    
     @Override
     public boolean equals(Object obj) {
         if (obj == this)
@@ -73,4 +83,5 @@ public boolean equals(Object obj) {
 
     final int _inc;
     final Date _time;
+
 }

src/test/org/bson/BSONTimestampTest.java

@@ -0,0 +1,29 @@
+package org.bson;
+
+import org.bson.types.BSONTimestamp;
+import org.testng.Assert;
+import org.testng.annotations.Test;
+
+public class BSONTimestampTest extends Assert{
+
+    @Test
+    public void testComparable(){
+        
+        int currTime = (int)(System.currentTimeMillis() / 1000);
+        
+        BSONTimestamp t1 = new BSONTimestamp(currTime, 1);
+        BSONTimestamp t2 = new BSONTimestamp(currTime, 1);
+        
+        assertEquals(0, t1.compareTo(t2));
+        
+        t2 = new BSONTimestamp(currTime,  2);
+        
+        assertTrue(t1.compareTo(t2) < 0);
+        assertTrue(t2.compareTo(t1) > 0);
+        
+        t2 = new BSONTimestamp(currTime + 1, 1);
+        
+        assertTrue(t1.compareTo(t2) < 0);
+        assertTrue(t2.compareTo(t1) > 0);
+    }
+}