| /* |
| * 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.geode.internal.cache.eviction; |
| |
| |
| /** |
| * NewLIFOClockHand holds the behavior for LIFO logic , Overwriting getLRUEntry() to return most |
| * recently added Entry. |
| * |
| * @since GemFire 5.7 |
| */ |
| public class LIFOList extends AbstractEvictionList { |
| |
| public LIFOList(EvictionController controller) { |
| super(controller); |
| } |
| |
| /** |
| * Return the Entry that is considered most recently used and available to be evicted to overflow. |
| * Note that this implementation basically just returns the most recent thing added to the list. |
| * So, unlike the parent class, is does no scanning based on the recentlyUsed bit. This is a |
| * perfect implementation for our queues (gateway, client subscription) as long as they never |
| * update something already in the queue. Since updates simply set the recentlyUsed bit then the |
| * most recent node may be the one that was just updated and not moved to the tail of the list. |
| */ |
| @Override |
| public EvictableEntry getEvictableEntry() { |
| long evaluations = 0; |
| EvictionNode evictionNode; |
| // search for entry to return from list |
| for (;;) { |
| evictionNode = unlinkTailEntry(); |
| // end of Lifo list stop searching |
| if (evictionNode == null) { |
| break; |
| } |
| evaluations++; |
| synchronized (evictionNode) { |
| // if entry NOT used by transaction and NOT evicted return entry |
| if (!evictionNode.isInUseByTransaction() && !evictionNode.isEvicted()) { |
| break; |
| } |
| } |
| } |
| getStatistics().incEvaluations(evaluations); |
| return (EvictableEntry) evictionNode; |
| } |
| |
| @Override |
| public void incrementRecentlyUsed() { |
| // nothing |
| } |
| } |