pulsar-client/src/main/java/org/apache/pulsar/client/util/RetryUtil.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.pulsar.client.util;

import org.apache.pulsar.client.impl.Backoff;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.function.Supplier;

public class RetryUtil {
    private static final Logger log = LoggerFactory.getLogger(RetryUtil.class);

    public static <T> void retryAsynchronously(Supplier<T> supplier, Backoff backoff,
                                               ScheduledExecutorService scheduledExecutorService,
                                               CompletableFuture<T> callback) {
        if (backoff.getMax() <= 0) {
            throw new IllegalArgumentException("Illegal max retry time");
        }
        if (backoff.getInitial() <= 0) {
            throw new IllegalArgumentException("Illegal initial time");
        }
        scheduledExecutorService.execute(() ->
                executeWithRetry(supplier, backoff, scheduledExecutorService, callback));
    }

    private static <T> void executeWithRetry(Supplier<T> supplier, Backoff backoff,
                                             ScheduledExecutorService scheduledExecutorService,
                                             CompletableFuture<T> callback) {
        try {
            T result = supplier.get();
            callback.complete(result);
        } catch (Exception e) {
            long next = backoff.next();
            boolean isMandatoryStop = backoff.isMandatoryStopMade();
            if (isMandatoryStop) {
                callback.completeExceptionally(e);
            } else {
                if (log.isDebugEnabled()) {
                    log.debug("execute with retry fail, will retry in {} ms", next, e);
                }
                log.info("Because of {}, will retry in {} ms", e.getMessage(), next);
                scheduledExecutorService.schedule(() ->
                                executeWithRetry(supplier, backoff, scheduledExecutorService, callback),
                        next, TimeUnit.MILLISECONDS);
            }
        }
    }
}