bdelacretaz commented on a change in pull request #18: URL: https://github.com/apache/sling-org-apache-sling-jcr-repoinit/pull/18#discussion_r646639611
########## File path: src/main/java/org/apache/sling/jcr/repoinit/impl/RetryableOperation.java ########## @@ -0,0 +1,120 @@ +/* + * 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.sling.jcr.repoinit.impl; + +import java.util.concurrent.TimeUnit; +import java.util.function.Supplier; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * A simple implementation of retryable operations. + * Use the builder class to create an instance of it. + * + */ +public class RetryableOperation { + + private static final Logger LOG = LoggerFactory.getLogger(RetryableOperation.class); + + int backoffBase; + int maxRetries; + int jitter; + + int retryCount = 0; + + RetryableOperation(int backoff, int maxRetries, int jitter) { + this.backoffBase = backoff; + this.maxRetries = maxRetries; + this.jitter = jitter; + } + /** + * Execute the operation with the defined retry until it returns true or + * the retry aborts; in case the operation is retried, a log message is logged on INFO with the + * provided logMessage and the current number of retries + * @param operation + * @param logMessage the log message + * @return true if the supplier was eventually successful, false if it failed despite all retries + */ + public boolean apply(Supplier<Boolean> operation, String logMessage) { + + boolean successful = false; + successful = operation.get(); + while (! successful && retryCount < maxRetries) { + retryCount++; + LOG.info("%s (retry %d/%d)", logMessage, retryCount, maxRetries); + delay(retryCount); + successful = operation.get(); + } + return successful; + } + + private void delay(int retryCount) { + + int j = (int) (Math.random() * (jitter)); + int delayInMilis = (backoffBase * retryCount) + j; + try { + TimeUnit.MILLISECONDS.sleep(delayInMilis); + } catch (InterruptedException e) { + Thread.currentThread().interrupt(); + } + } + + + + public static class Builder { + + int exponentialBackoff = 1000; // default + int maxRetries = 3; // default + int jitter = 200; + + /** + * The backoff time + * @param msec backoff time in miliseconds + * @return the builder + */ + Builder withBackoffBase(int msec) { + exponentialBackoff = msec; + return this; + } + + /** + * Configures the number of retries; + * @param retries number of retries + * @return the builder + */ + Builder withMaxRetries(int retries) { + this.maxRetries= retries; + return this; + } + + /** + * configures the jitter + * @param msec the jitter in miliseconds + * @return the builder + */ + Builder withJitter(int msec) { Review comment: Same as above, I would call this `withJitterMsec` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
