/*
* Copyright (c) 2008-2017, Hazelcast, Inc. All Rights Reserved.
*
* Licensed 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 com.hazelcast.internal.eviction;
import java.io.Serializable;
import java.util.Comparator;
/**
* A kind of {@link java.util.Comparator} to be used while comparing
* entries to be evicted.
*/
public abstract class EvictionPolicyComparator<K, V, E extends EvictableEntryView<K, V>>
implements Comparator<E>, Serializable {
/**
* Integer constant for representing behaviour for giving higher priority to first entry to be evicted.
*/
public static final int FIRST_ENTRY_HAS_HIGHER_PRIORITY_TO_BE_EVICTED = -1;
/**
* Integer constant for representing behaviour for giving higher priority to second entry to be evicted.
*/
public static final int SECOND_ENTRY_HAS_HIGHER_PRIORITY_TO_BE_EVICTED = +1;
/**
* Integer constant for representing behaviour for giving same priority to both of entry to be evicted.
*/
public static final int BOTH_OF_ENTRIES_HAVE_SAME_PRIORITY_TO_BE_EVICTED = 0;
/**
* Compares the given {@link EvictableEntryView} instances and returns the result.
* The result should be one of the
* <ul>
* <li>#FIRST_ENTRY_HAS_HIGHER_PRIORITY_TO_BE_EVICTED</li>
* <li>#SECOND_ENTRY_HAS_HIGHER_PRIORITY_TO_BE_EVICTED</li>
* <li>#BOTH_OF_ENTRIES_HAVE_SAME_PRIORITY_TO_BE_EVICTED</li>
* </ul>
*
* @param e1 the first {@link EvictableEntryView} instance to be compared
* @param e2 the second {@link EvictableEntryView} instance to be compared
*
* @return the result of comparison
*/
@Override
public abstract int compare(E e1, E e2);
}