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/*
* SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
*
* SPDX-License-Identifier: EPL-2.0
*/
package tools.refinery.store.tuple;
import org.jetbrains.annotations.NotNull;
import tools.refinery.store.model.TupleHashProvider;
import java.util.Arrays;
import static tools.refinery.store.tuple.TupleConstants.TUPLE_BEGIN;
import static tools.refinery.store.tuple.TupleConstants.TUPLE_END;
public final class Tuple1 implements Tuple {
private final int value0;
private Tuple1(int value0) {
this.value0 = value0;
}
public int value0() {
return value0;
}
@Override
public int getSize() {
return 1;
}
@Override
public int get(int element) {
if (element == 0) {
return value0;
}
throw new IndexOutOfBoundsException(element);
}
@Override
public String toString() {
return TUPLE_BEGIN + value0 + TUPLE_END;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Tuple1 tuple1 = (Tuple1) o;
return value0 == tuple1.value0;
}
@Override
public int hashCode() {
return 31 + value0;
}
@Override
public int compareTo(@NotNull Tuple other) {
if (other instanceof Tuple1 other1) {
return Integer.compare(value0, other1.value0);
}
return Tuple.super.compareTo(other);
}
/**
* This class uses safe double-checked locking, see
* <a href="https://shipilev.net/blog/2014/safe-public-construction/">Safe Publication and Safe Initialization in
* Java</a> for details.
* <p>
* This class implements the singleton pattern to ensure only a single cache exists. This is thread-safe because
* of the locking of the cache.
*/
@SuppressWarnings("squid:S6548")
public static class Cache {
private static final int MIN_CACHE_SIZE = 256;
private static final int MAX_CACHE_SIZE = TupleHashProvider.MAX_MODEL_SIZE;
public static final Cache INSTANCE = new Cache();
private final Object lock = new Object();
// We don't want to synchronize the elements of the array, just the array reference itself, so an
// AtomicReferenceArray is not needed here and would degrade performance.
@SuppressWarnings("squid:S3077")
private volatile Tuple1[] tuple1Cache;
private Cache() {
reset();
}
public void reset() {
synchronized (lock) {
var newCache = new Tuple1[MIN_CACHE_SIZE];
for (int i = 0; i < newCache.length; i++) {
newCache[i] = new Tuple1(i);
}
tuple1Cache = newCache;
}
}
public Tuple1 getOrCreate(int value) {
if (value < 0 || value >= MAX_CACHE_SIZE) {
return new Tuple1(value);
}
var currentCache = tuple1Cache;
if (value < currentCache.length) {
return currentCache[value];
}
synchronized (lock) {
currentCache = tuple1Cache;
int currentSize = currentCache.length;
if (value < currentSize) {
return currentCache[value];
}
// We don't have to worry about currentSize + (currentSize >> 1) overflowing, because MAX_CACHE_SIZE
// is only 30 bits.
int newSize = Math.min(Math.max(value + 1, currentSize + (currentSize >> 1)), MAX_CACHE_SIZE);
var newCache = Arrays.copyOf(currentCache, newSize);
for (int i = currentSize; i < newSize; i++) {
newCache[i] = new Tuple1(i);
}
tuple1Cache = newCache;
return newCache[value];
}
}
}
}
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