com.wandoulabs.nedis.codis.BoundedExponentialBackoffRetryUntilElapsed Maven / Gradle / Ivy

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/**
 * Copyright (c) 2015 Wandoujia Inc.
 *
 * 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.wandoulabs.nedis.codis;

import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.TimeUnit;

import org.apache.curator.RetryPolicy;
import org.apache.curator.RetrySleeper;

/**
 * Similar to {@link org.apache.curator.retry.BoundedExponentialBackoffRetry},
 * but limit the retry elapsed time, not retry number.
 * 
 * @author Apache9
 */
public class BoundedExponentialBackoffRetryUntilElapsed implements RetryPolicy {

    private final int baseSleepTimeMs;

    private final int maxSleepTimeMs;

    private final long maxElapsedTimeMs;

    /**
     * @param baseSleepTimeMs
     *            initial amount of time to wait between retries
     * @param maxSleepTimeMs
     *            max time in ms to sleep on each retry
     * @param maxElapsedTimeMs
     *            total time in ms to retry
     */
    public BoundedExponentialBackoffRetryUntilElapsed(int baseSleepTimeMs, int maxSleepTimeMs,
            long maxElapsedTimeMs) {
        this.baseSleepTimeMs = baseSleepTimeMs;
        this.maxSleepTimeMs = maxSleepTimeMs;
        if (maxElapsedTimeMs < 0) {
            this.maxElapsedTimeMs = Long.MAX_VALUE;
        } else {
            this.maxElapsedTimeMs = maxElapsedTimeMs;
        }
    }

    private long getSleepTimeMs(int retryCount, long elapsedTimeMs) {
        return Math.min(
                maxSleepTimeMs,
                (long) baseSleepTimeMs
                        * Math.max(
                                1,
                                ThreadLocalRandom.current().nextInt(
                                        1 << Math.min(30, retryCount + 1))));
    }

    @Override
    public boolean allowRetry(int retryCount, long elapsedTimeMs, RetrySleeper sleeper) {
        if (elapsedTimeMs >= maxElapsedTimeMs) {
            return false;
        }
        long sleepTimeMs = Math.min(maxElapsedTimeMs - elapsedTimeMs,
                getSleepTimeMs(retryCount, elapsedTimeMs));
        try {
            sleeper.sleepFor(sleepTimeMs, TimeUnit.MILLISECONDS);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            return false;
        }
        return true;
    }
}