Support notification on entry removal

h2/src/tools/org/h2/dev/cache/CacheLIRS.java

@@ -106,7 +106,7 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> {
         long max = Math.max(1, maxMemory / segmentCount);
         for (int i = 0; i < segmentCount; i++) {
             segments[i] = new Segment<K, V>(
-                    max, averageMemory, stackMoveDistance);
+                    this, max, averageMemory, stackMoveDistance);
         }
     }
 
@@ -178,6 +178,16 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> {
     protected int sizeOf(K key, V value) {
         return averageMemory;
     }
+    
+    /**
+     * This method is called after the value for the given key was removed.
+     * It is not called on clear or put when replacing a value.
+     * 
+     * @param key the key
+     */
+    protected void onRemove(K key) {
+        // do nothing
+    }
 
     /**
      * Remove an entry. Both resident and non-resident entries can be
@@ -412,6 +422,8 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> {
      * @param <V> the value type
      */
     static class Segment<K, V> {
+        
+        final CacheLIRS<K, V> cache;
 
         /**
          * The number of (hot, cold, and non-resident) entries in the map.
@@ -500,7 +512,8 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> {
          * @param stackMoveDistance the number of other entries to be moved to
          *        the top of the stack before moving an entry to the top
          */
-        Segment(long maxMemory, int averageMemory, int stackMoveDistance) {
+        Segment(CacheLIRS<K, V> cache, long maxMemory, int averageMemory, int stackMoveDistance) {
+            this.cache = cache;
             setMaxMemory(maxMemory);
             setAverageMemory(averageMemory);
             this.stackMoveDistance = stackMoveDistance;
@@ -748,6 +761,7 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> {
                 Entry<K, V> e = queue.queuePrev;
                 usedMemory -= e.memory;
                 removeFromQueue(e);
+                cache.onRemove(e.key);
                 e.value = null;
                 e.memory = 0;
                 addToQueue(queue2, e);