com.hazelcast.internal.eviction.EvictionPolicyEvaluatorProvider Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2020, 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.internal.nio.ClassLoaderUtil;
import com.hazelcast.spi.eviction.EvictionPolicyComparator;
import static com.hazelcast.internal.util.ExceptionUtil.rethrow;
import static com.hazelcast.internal.util.Preconditions.checkNotNull;
import static com.hazelcast.internal.util.StringUtil.isNullOrEmpty;
/**
* Provider to get any kind ({@link EvictionPolicy}) of {@link EvictionPolicyEvaluator}.
*/
public final class EvictionPolicyEvaluatorProvider {
private EvictionPolicyEvaluatorProvider() {
}
/**
* 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 EvictionPolicyEvaluator
getEvictionPolicyEvaluator(EvictionConfiguration evictionConfig, ClassLoader classLoader) {
checkNotNull(evictionConfig);
return new EvictionPolicyEvaluator<>(getEvictionPolicyComparator(evictionConfig, classLoader));
}
/**
* @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 {@link
* EvictionPolicyComparator} instance if it is defined, otherwise
* returns null to indicate there is no comparator defined
*/
public static EvictionPolicyComparator getEvictionPolicyComparator(EvictionConfiguration evictionConfig,
ClassLoader classLoader) {
// 1. First check comparator class name
String evictionPolicyComparatorClassName = evictionConfig.getComparatorClassName();
if (!isNullOrEmpty(evictionPolicyComparatorClassName)) {
try {
return ClassLoaderUtil.newInstance(classLoader, evictionPolicyComparatorClassName);
} catch (Exception e) {
throw rethrow(e);
}
}
// 2. Then check comparator implementation
EvictionPolicyComparator comparator = evictionConfig.getComparator();
if (comparator != null) {
return comparator;
}
// 3. As a last resort, try to pick an out-of-the-box comparator implementation
return pickOutOfTheBoxComparator(evictionConfig.getEvictionPolicy());
}
private static EvictionPolicyComparator pickOutOfTheBoxComparator(EvictionPolicy evictionPolicy) {
switch (evictionPolicy) {
case LRU:
return LRUEvictionPolicyComparator.INSTANCE;
case LFU:
return LFUEvictionPolicyComparator.INSTANCE;
case RANDOM:
return RandomEvictionPolicyComparator.INSTANCE;
case NONE:
return null;
default:
throw new IllegalArgumentException("Unsupported eviction policy: " + evictionPolicy);
}
}
}