io.evitadb.utils.RandomUtils Maven / Gradle / Ivy
/*
*
* _ _ ____ ____
* _____ _(_) |_ __ _| _ \| __ )
* / _ \ \ / / | __/ _` | | | | _ \
* | __/\ V /| | || (_| | |_| | |_) |
* \___| \_/ |_|\__\__,_|____/|____/
*
* Copyright (c) 2024
*
* Licensed under the Business Source License, Version 1.1 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://github.com/FgForrest/evitaDB/blob/master/LICENSE
*
* 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 io.evitadb.utils;
import io.evitadb.exception.GenericEvitaInternalError;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Random;
import java.util.concurrent.ThreadLocalRandom;
import static java.util.Optional.ofNullable;
/**
* This class contains utility methods for working with random numbers.
*
* @author Jan Novotný ([email protected]), FG Forrest a.s. (c) 2024
*/
public class RandomUtils {
/**
* Method retrieves frozen internal state of the {@link Random} function that can be used as a stable SEED for
* randomized logic.
*/
public static byte[] getFrozenRandom() {
final ByteArrayOutputStream bos = new ByteArrayOutputStream(200);
try (var os = new ObjectOutputStream(bos)) {
os.writeObject(new Random());
return bos.toByteArray();
} catch (IOException e) {
throw new GenericEvitaInternalError("Unexpected error during debug mode evaluation!", e);
}
}
/**
* Returns {@link Random} instance based on the provided frozen state. If the state is null, it returns
* {@link ThreadLocalRandom#current()}.
*
* @param frozenRandom frozen state of the random function
* @return {@link Random} instance
*/
@Nonnull
public static Random getRandom(@Nullable byte[] frozenRandom) {
return ofNullable(frozenRandom)
.map(it -> {
try (var is = new ObjectInputStream(new ByteArrayInputStream(it))) {
return (Random) is.readObject();
} catch (IOException | ClassNotFoundException e) {
throw new GenericEvitaInternalError("Unexpected error during debug mode evaluation!", e);
}
})
.orElseGet(ThreadLocalRandom::current);
}
}