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Implementation of blocking (IO-Bound) cancellable java.util.concurrent.CompletionStage and related extensions to java.util.concurrent.ExecutorService-s

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/**
 * Original work: copyright 2013 Tomasz Nurkiewicz
 * https://github.com/nurkiewicz/async-retry
 * 
 * This class is based on the work create by Tomasz Nurkiewicz 
 * under the Apache License, Version 2.0. Please see 
 * https://github.com/nurkiewicz/async-retry/blob/master/src/main/java/com/nurkiewicz/asyncretry/backoff/RandomBackoff.java
 * 
 * Modified work: copyright 2015-2019 Valery Silaev (http://vsilaev.com)
 * 
 * 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 net.tascalate.concurrent.delays;

import java.time.Duration;
import java.util.Random;
import java.util.concurrent.ThreadLocalRandom;
import java.util.function.Supplier;

import net.tascalate.concurrent.DelayPolicy;
import net.tascalate.concurrent.RetryContext;

abstract public class RandomDelayPolicy extends DelayPolicyWrapper {
    private final Supplier randomSource;

    protected RandomDelayPolicy(DelayPolicy target) {
        this(target, ThreadLocalRandom::current);
    }

    protected RandomDelayPolicy(DelayPolicy target, Random randomSource) {
        this(target, () -> randomSource);
    }

    private RandomDelayPolicy(DelayPolicy target, Supplier randomSource) {
        super(target);
        this.randomSource = randomSource;
    }
    
    @Override
    public Duration delay(RetryContext context) {
        double randomizer = random().nextDouble();
        return DurationCalcs.safeTransform(
            target.delay(context), 
            (amount, dimIdx) -> DurationCalcs.toBoolean(checkBounds(amount, randomizer, (int)dimIdx)), 
            (amount, dimIdx) -> addRandomJitter(amount, randomizer, (int)dimIdx)
        );
    }
    
    abstract long addRandomJitter(long amount, double randomizer, int dimIdx);
    abstract boolean checkBounds(long amount, double randomizer, int dimIdx);
    
    protected Random random() {
        return randomSource.get();
    }
}