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Easy Redis Java client and Real-Time Data Platform. Valkey compatible. Sync/Async/RxJava3/Reactive API. Client side caching. Over 50 Redis based Java objects and services: JCache API, Apache Tomcat, Hibernate, Spring, Set, Multimap, SortedSet, Map, List, Queue, Deque, Semaphore, Lock, AtomicLong, Map Reduce, Bloom filter, Scheduler, RPC
/**
* Copyright (c) 2013-2024 Nikita Koksharov
*
* 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 org.redisson.cache;
import java.util.Map;
import java.util.concurrent.ConcurrentNavigableMap;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.atomic.AtomicLong;
/**
* LFU (least frequently used) cache.
*
* @author Nikita Koksharov
*
* @param key
* @param value
*/
public class LFUCacheMap extends AbstractCacheMap {
public static class MapKey implements Comparable {
private Long accessCount;
private LFUCachedValue cachedValue;
public MapKey(Long accessCount, LFUCachedValue cachedValue) {
super();
this.accessCount = accessCount;
this.cachedValue = cachedValue;
}
@Override
public int compareTo(MapKey o) {
int compare = accessCount.compareTo(o.accessCount);
if (compare == 0) {
return cachedValue.id.compareTo(o.cachedValue.id);
}
return compare;
}
@Override
public String toString() {
return "MapKey [accessCount=" + accessCount + "]";
}
}
public static class LFUCachedValue extends StdCachedValue {
private final Long id;
private long accessCount;
public LFUCachedValue(long id, K key, V value, long ttl, long maxIdleTime) {
super(key, value, ttl, maxIdleTime);
this.id = id;
}
public void addAccessCount(long value) {
accessCount += value;
}
}
private final AtomicLong idGenerator = new AtomicLong();
private final ConcurrentNavigableMap> accessMap = new ConcurrentSkipListMap<>();
public LFUCacheMap(int size, long timeToLiveInMillis, long maxIdleInMillis) {
super(size, timeToLiveInMillis, maxIdleInMillis);
}
@Override
protected CachedValue create(K key, V value, long ttl, long maxIdleTime) {
return new LFUCachedValue(idGenerator.incrementAndGet(), key, value, ttl, maxIdleTime);
}
@Override
protected void onValueCreate(CachedValue value) {
MapKey key = toKey((LFUCachedValue) value);
accessMap.put(key, (LFUCachedValue) value);
}
@Override
protected void onValueRead(CachedValue value) {
addAccessCount((LFUCachedValue) value, 1);
}
private MapKey toKey(LFUCachedValue value) {
return new MapKey(value.accessCount, value);
}
@Override
protected void onValueRemove(CachedValue value) {
value.getLock().execute(() -> {
MapKey key = toKey((LFUCachedValue) value);
accessMap.remove(key);
});
super.onValueRemove(value);
}
private void addAccessCount(LFUCachedValue value, long c) {
value.getLock().execute(() -> {
long count = c;
if (count < 0 && value.accessCount == 0) {
return;
}
MapKey key = toKey(value);
if (accessMap.remove(key) == null) {
return;
}
if (count < 0) {
count = -Math.min(value.accessCount, -count);
}
value.addAccessCount(count);
key = toKey(value);
accessMap.put(key, value);
});
}
@Override
protected void onMapFull() {
Map.Entry> entry = accessMap.pollFirstEntry();
if (entry == null) {
return;
}
if (map.remove(entry.getValue().getKey(), entry.getValue())) {
super.onValueRemove(entry.getValue());
}
if (entry.getValue().accessCount == 0) {
return;
}
// TODO optimize
// decrease all values
for (LFUCachedValue value : accessMap.values()) {
addAccessCount(value, -entry.getValue().accessCount);
}
}
@Override
public void clear() {
accessMap.clear();
super.clear();
}
}
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