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/*
* Copyright (C) 2022 NotEnoughUpdates contributors
*
* This file is part of NotEnoughUpdates.
*
* NotEnoughUpdates is free software: you can redistribute it
* and/or modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation, either
* version 3 of the License, or (at your option) any later version.
*
* NotEnoughUpdates is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with NotEnoughUpdates. If not, see <https://www.gnu.org/licenses/>.
*/
package io.github.moulberry.notenoughupdates.util;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.function.Function;
import java.util.function.IntSupplier;
public interface LRUCache<K, V> extends Function<K, V> {
static <K, V> LRUCache<K, V> memoize(Function<K, V> mapper, int maxCacheSize) {
return memoize(mapper, () -> maxCacheSize);
}
static <K, V> LRUCache<K, V> memoize(Function<K, V> mapper, IntSupplier maxCacheSize) {
Map<K, Object> cache = new LinkedHashMap<K, Object>(10, 0.75F, true) {
@Override
protected boolean removeEldestEntry(Map.Entry<K, Object> eldest) {
return this.size() > maxCacheSize.getAsInt();
}
};
Object SENTINEL_CACHE_RESULT_NULL = new Object();
Function<K, Object> sentinelAwareMapper = mapper.andThen(it -> it == null ? SENTINEL_CACHE_RESULT_NULL : it);
Map<K, Object> synchronizedCache = Collections.synchronizedMap(cache);
return new LRUCache<K, V>() {
@Override
public void clearCache() {
synchronizedCache.clear();
}
@Override
public int size() {
return synchronizedCache.size();
}
@Override
public V apply(K k) {
Object value = synchronizedCache.computeIfAbsent(k, sentinelAwareMapper);
return value == SENTINEL_CACHE_RESULT_NULL ? null : (V) value;
}
};
}
int size();
void clearCache();
}
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