util: LinkedHashMapRemoveEldest refactored with BiConsumer

common/util/src/main/java/org/thingsboard/common/util/LinkedHashMapRemoveEldest.java

@@ -36,48 +36,33 @@ import lombok.ToString;
 
 import java.util.LinkedHashMap;
 import java.util.Map;
+import java.util.function.BiConsumer;
 
 /**
- * HashMap that removed eldest (by put order) entries
+ * LinkedHashMap that removed eldest entries (by insert order)
  * It guaranteed that size is not greater then maxEntries parameter. And remove time is constant O(1).
- * Use withMaxEntries to setup maxEntries.
- * Because overloaded constructor will look similar to LinkedHashMap(initCapacity)
  * Example:
- *   new LinkedHashMapRemoveEldest<Long, String>().withMaxEntries(100L)
+ *   LinkedHashMapRemoveEldest<Long, String> map =
+ *                 new LinkedHashMapRemoveEldest<>(MAX_ENTRIES, this::removeConsumer);
  * */
 @Getter
 @ToString(callSuper = true)
 @EqualsAndHashCode(callSuper = true)
-public class LinkedHashMapRemoveEldest<K,V> extends LinkedHashMap<K,V> {
+public class LinkedHashMapRemoveEldest<K, V> extends LinkedHashMap<K, V> {
-    long maxEntries = Long.MAX_VALUE;
+    final long maxEntries;
+    final BiConsumer<K, V> removeConsumer;
 
-    public LinkedHashMapRemoveEldest() {
+    public LinkedHashMapRemoveEldest(long maxEntries, BiConsumer<K, V> removeConsumer) {
-        super();
-    }
-
-    public LinkedHashMapRemoveEldest(int initialCapacity) {
-        super(initialCapacity);
-    }
-
-    public LinkedHashMapRemoveEldest(int initialCapacity, float loadFactor) {
-        super(initialCapacity, loadFactor);
-    }
-
-    public LinkedHashMapRemoveEldest(Map<? extends K, ? extends V> m) {
-        super(m);
-    }
-
-    public LinkedHashMapRemoveEldest(int initialCapacity, float loadFactor, boolean accessOrder) {
-        super(initialCapacity, loadFactor, accessOrder);
-    }
-
-    public LinkedHashMapRemoveEldest<K,V> withMaxEntries(long maxEntries) {
         this.maxEntries = maxEntries;
-        return this;
+        this.removeConsumer = removeConsumer;
     }
 
     @Override
-    protected boolean removeEldestEntry(Map.Entry eldest) {
+    protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
-        return size() > maxEntries;
+        if (size() <= maxEntries) {
+            return false;
+        }
+        removeConsumer.accept(eldest.getKey(), eldest.getValue());
+        return true;
     }
 }

common/util/src/test/java/org/thingsboard/common/util/LinkedHashMapRemoveEldestTest.java

@@ -30,7 +30,7 @@
  */
 package org.thingsboard.common.util;
 
-import org.junit.Before;
+import org.hamcrest.Matchers;
 import org.junit.Test;
 
 import java.util.LinkedHashMap;
@@ -42,26 +42,33 @@ import static org.hamcrest.MatcherAssert.assertThat;
 public class LinkedHashMapRemoveEldestTest {
 
     public static final long MAX_ENTRIES = 10L;
-    LinkedHashMapRemoveEldest<Long, String> map;
+    long removeCount = 0;
 
-    @Before
+    void removeConsumer(Long id, String name) {
-    public void setUp() throws Exception {
+        removeCount++;
-        map = new LinkedHashMapRemoveEldest<Long, String>().withMaxEntries(MAX_ENTRIES);
+        assertThat(id, is(Matchers.lessThan(MAX_ENTRIES)));
+        assertThat(name, is(id.toString()));
     }
 
     @Test
     public void givenMap_whenOverSized_thenVerifyRemovedEldest() {
+        //given
+        LinkedHashMapRemoveEldest<Long, String> map =
+                new LinkedHashMapRemoveEldest<>(MAX_ENTRIES, this::removeConsumer);
+
         assertThat(map.getMaxEntries(), is(MAX_ENTRIES));
         assertThat(map, instanceOf(LinkedHashMap.class));
         assertThat(map, instanceOf(LinkedHashMapRemoveEldest.class));
         assertThat(map.size(), is(0));
 
+        //when
         for (long i = 0; i < MAX_ENTRIES * 2; i++) {
             map.put(i, String.valueOf(i));
         }
 
-        assertThat(map.size(), is((int) MAX_ENTRIES));
+        //then
-
+        assertThat((long) map.size(), is(MAX_ENTRIES));
+        assertThat(removeCount, is(MAX_ENTRIES));
         for (long i = MAX_ENTRIES; i < MAX_ENTRIES * 2; i++) {
             assertThat(map.get(i), is(String.valueOf(i)));
         }