com.sap.cloud.alert.notification.client.internal.SimpleRetryPolicy Maven / Gradle / Ivy

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Means for out-of-the-box events management in SAP Alert Notification service for SAP BTP service.

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package com.sap.cloud.alert.notification.client.internal;

import com.sap.cloud.alert.notification.client.IRetryPolicy;
import com.sap.cloud.alert.notification.client.exceptions.ClientRequestException;

import java.time.Duration;
import java.util.function.Supplier;

import static java.lang.System.currentTimeMillis;

public class SimpleRetryPolicy implements IRetryPolicy {

    private final int maxRetries;
    private final Duration retryBackoff;

    public SimpleRetryPolicy() {
        this(0, Duration.ZERO);
    }

    public SimpleRetryPolicy(int maxRetries, Duration retryBackoff) {
        this.maxRetries = maxRetries;
        this.retryBackoff = retryBackoff;
    }

    public int getMaxRetries() {
        return maxRetries;
    }

    public Duration getRetryBackoff() {
        return retryBackoff;
    }

    @Override
    public  T executeWithRetry(Supplier supplier) {
        for (int i = 0; i < maxRetries; ++i) {
            try {
                return supplier.get();
            } catch (Exception exception) {
                sleepAtLeast(retryBackoff);
            }
        }

        return supplier.get();
    }

    private static void sleepAtLeast(Duration duration) {
        long sleepUntil = currentTimeMillis() + duration.toMillis();
        long currentTime;

        while ((currentTime = currentTimeMillis()) < sleepUntil) {
            trySleep(sleepUntil - currentTime);
        }
    }

    private static void trySleep(long durationMillis) {
        try {
            Thread.sleep(durationMillis);
        } catch (InterruptedException exception) {
            Thread.currentThread().interrupt();
            throw new ClientRequestException(exception);
        }
    }
}