svn commit: r1374136 - /hama/trunk/core/src/main/java/org/apache/hama/util/LRUCache.java

[tj...@apache.org]

Author: tjungblut
Date: Fri Aug 17 05:03:59 2012
New Revision: 1374136

URL: http://svn.apache.org/viewvc?rev=1374136&view=rev
Log:
add missing class

Added:
    hama/trunk/core/src/main/java/org/apache/hama/util/LRUCache.java

Added: hama/trunk/core/src/main/java/org/apache/hama/util/LRUCache.java
URL: http://svn.apache.org/viewvc/hama/trunk/core/src/main/java/org/apache/hama/util/LRUCache.java?rev=1374136&view=auto
==============================================================================
--- hama/trunk/core/src/main/java/org/apache/hama/util/LRUCache.java (added)
+++ hama/trunk/core/src/main/java/org/apache/hama/util/LRUCache.java Fri Aug 17 05:03:59 2012
@@ -0,0 +1,57 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hama.util;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+/**
+ * Simple LinkedHashMap based LRU Cache for specified capacity.
+ * 
+ * @param <K> the type of keys maintained by this map
+ * @param <V> the type of mapped values
+ */
+public abstract class LRUCache<K, V> extends LinkedHashMap<K, V> {
+
+  private static final long serialVersionUID = -3347750474082019514L;
+  
+  /**
+   * The maximum size of the cache.
+   */
+  protected final int capacity;
+
+  /**
+   * Constructs an empty <tt>LinkedHashMap</tt> instance. Cache Capacity
+   * argument is used to ensure the size of the cache.
+   * 
+   * @param cacheCapacity
+   */
+  protected LRUCache(int cacheCapacity) {
+    super();
+    this.capacity = cacheCapacity;
+  }
+
+  /**
+   * @param eldest
+   * @return <tt>true</tt> if element insertion increases the size of the cache
+   *         than cache capacity.
+   */
+  @Override
+  protected abstract boolean removeEldestEntry(Map.Entry<K, V> eldest);
+}