Index: src/main/java/org/apache/jackrabbit/oak/plugins/segment/CompactionMap.java
===================================================================
--- src/main/java/org/apache/jackrabbit/oak/plugins/segment/CompactionMap.java	(revision 1706957)
+++ src/main/java/org/apache/jackrabbit/oak/plugins/segment/CompactionMap.java	(working copy)
@@ -40,12 +40,20 @@
      * An empty map.
      */
     public static final CompactionMap EMPTY =
-            new CompactionMap(Collections.<PartialCompactionMap>emptyList());
+            new CompactionMap(Collections.<PartialCompactionMap>emptyList(), 0);
 
     private final List<PartialCompactionMap> maps;
 
-    private CompactionMap(@Nonnull List<PartialCompactionMap> maps) {
+    /**
+     * Generation represents the number of compaction cycles since the system
+     * came online. This is not persisted so it will be reset to 0 on each
+     * restart
+     */
+    private final int generation;
+
+    private CompactionMap(@Nonnull List<PartialCompactionMap> maps, int generation) {
         this.maps = maps;
+        this.generation = generation;
     }
 
     /**
@@ -122,7 +130,7 @@
                 maps.add(map);
             }
         }
-        return new CompactionMap(maps);
+        return new CompactionMap(maps, generation + 1);
     }
 
     /**
@@ -149,6 +157,10 @@
         return maps.size();
     }
 
+    public int getGeneration() {
+        return generation;
+    }
+
     /**
      * The weight of the compaction map is its  memory consumption bytes
      * @return Estimated weight of the compaction map