/*
* 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.impl.comparator;
import com.hazelcast.internal.eviction.EvictableEntryView;
import com.hazelcast.internal.eviction.EvictionPolicyComparator;
import com.hazelcast.nio.serialization.SerializableByConvention;
/**
* {@link com.hazelcast.config.EvictionPolicy#LFU} policy based {@link EvictionPolicyComparator}.
*/
@SerializableByConvention
public class LFUEvictionPolicyComparator extends EvictionPolicyComparator {
@Override
public int compare(EvictableEntryView e1, EvictableEntryView e2) {
long hits1 = e1.getAccessHit();
long hits2 = e2.getAccessHit();
if (hits2 < hits1) {
return SECOND_ENTRY_HAS_HIGHER_PRIORITY_TO_BE_EVICTED;
} else if (hits1 < hits2) {
return FIRST_ENTRY_HAS_HIGHER_PRIORITY_TO_BE_EVICTED;
} else {
long creationTime1 = e1.getCreationTime();
long creationTime2 = e2.getCreationTime();
// if hits are same, we select the oldest entry to evict
if (creationTime2 < creationTime1) {
return SECOND_ENTRY_HAS_HIGHER_PRIORITY_TO_BE_EVICTED;
} else if (creationTime2 > creationTime1) {
return FIRST_ENTRY_HAS_HIGHER_PRIORITY_TO_BE_EVICTED;
} else {
return BOTH_OF_ENTRIES_HAVE_SAME_PRIORITY_TO_BE_EVICTED;
}
}
}
}