/*
* 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 com.hazelcast.config.EvictionPolicy;
import com.hazelcast.internal.eviction.impl.comparator.LFUEvictionPolicyComparator;
import com.hazelcast.internal.eviction.impl.comparator.LRUEvictionPolicyComparator;
import com.hazelcast.internal.eviction.impl.comparator.RandomEvictionPolicyComparator;
import com.hazelcast.internal.eviction.impl.evaluator.EvictionPolicyEvaluator;
import com.hazelcast.nio.ClassLoaderUtil;
import static com.hazelcast.util.ExceptionUtil.rethrow;
import static com.hazelcast.util.Preconditions.checkNotNull;
import static com.hazelcast.util.StringUtil.isNullOrEmpty;
/**
* Provider to get any kind ({@link EvictionPolicyType}) of {@link EvictionPolicyEvaluator}.
*/
public final class EvictionPolicyEvaluatorProvider {
private EvictionPolicyEvaluatorProvider() {
}
private static EvictionPolicyComparator createEvictionPolicyComparator(EvictionPolicy evictionPolicy) {
switch (evictionPolicy) {
case LRU:
return new LRUEvictionPolicyComparator();
case LFU:
return new LFUEvictionPolicyComparator();
case RANDOM:
return new RandomEvictionPolicyComparator();
case NONE:
return null;
default:
throw new IllegalArgumentException("Unsupported eviction policy: " + evictionPolicy);
}
}
/**
* Gets the {@link EvictionPolicyEvaluator} implementation specified with {@code evictionPolicy}.
*
* @param evictionConfig {@link EvictionConfiguration} for requested {@link EvictionPolicyEvaluator} implementation
* @param classLoader the {@link java.lang.ClassLoader} to be used
* while creating custom {@link EvictionPolicyComparator} if it is specified in the config
* @return the requested {@link EvictionPolicyEvaluator} implementation
*/
public static <A, E extends Evictable> EvictionPolicyEvaluator<A, E> getEvictionPolicyEvaluator(
EvictionConfiguration evictionConfig, ClassLoader classLoader) {
checkNotNull(evictionConfig);
EvictionPolicyComparator evictionPolicyComparator;
String evictionPolicyComparatorClassName = evictionConfig.getComparatorClassName();
if (!isNullOrEmpty(evictionPolicyComparatorClassName)) {
try {
evictionPolicyComparator = ClassLoaderUtil.newInstance(classLoader, evictionPolicyComparatorClassName);
} catch (Exception e) {
throw rethrow(e);
}
} else {
EvictionPolicyComparator comparator = evictionConfig.getComparator();
if (comparator != null) {
evictionPolicyComparator = comparator;
} else {
evictionPolicyComparator = createEvictionPolicyComparator(evictionConfig.getEvictionPolicy());
}
}
return new EvictionPolicyEvaluator<A, E>(evictionPolicyComparator);
}
}