com.lambdaworks.redis.resource.FullJitterDelay Maven / Gradle / Ivy

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Advanced and thread-safe Java Redis client for synchronous, asynchronous, and reactive usage. Supports Cluster, Sentinel, Pipelining, Auto-Reconnect, Codecs and much more.

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/*
 * Copyright 2011-2016 the original author or authors.
 *
 * 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 com.lambdaworks.redis.resource;

import java.util.concurrent.TimeUnit;

/**
 * Delay that increases using full jitter strategy.
 *
 * 
 * Considering retry attempts start at 1, attempt 0 would be the initial call and will always yield 0 (or the lower). Then, each
 * retry step will by default yield {@code temp / 2 + random_between(0, temp / 2)} and temp is
 * {@code temp = min(upper, base * 2 ** attempt)}.
 *
 * This strategy is based on Exponential Backoff and
 * Jitter.
 * 
 *
 * @author Jongyeol Choi
 * @since 4.2
 */
class FullJitterDelay extends ExponentialDelay {

    private final long base;
    private final long upper;

    FullJitterDelay(long lower, long upper, long base, TimeUnit unit) {
        super(lower, upper, unit, 2);
        this.upper = upper;
        this.base = base;
    }

    @Override
    public long createDelay(long attempt) {
        long temp = Math.min(upper, base * calculatePowerOfTwo(attempt));
        long delay = temp / 2 + randomBetween(0, temp / 2);
        return applyBounds(delay);
    }
}