denis-chudov commented on code in PR #7680: URL: https://github.com/apache/ignite-3/pull/7680#discussion_r3058856883
########## modules/core/src/main/java/org/apache/ignite/internal/util/retry/ExponentialBackoffTimeoutStrategy.java: ########## @@ -0,0 +1,134 @@ +/* + * 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.ignite.internal.util.retry; + +import java.util.concurrent.ThreadLocalRandom; + +/** + * A {@link TimeoutStrategy} that increases retry timeouts exponentially on each attempt. + * + * <p>Each call to {@link #next(int)} multiplies the current timeout by {@code backoffCoefficient}, + * capping the result at {@link #maxTimeout()}. Optionally, random jitter can be applied to spread + * retry attempts across time and avoid thundering herd problems under high concurrency. + * + * <p>When jitter is enabled, the returned timeout is randomized within the range + * {@code [raw / 2, raw * 1.5]}, then capped at {@link #maxTimeout()}. + * + * <p>This class is stateless and thread-safe. A single instance can be shared across + * multiple retry contexts. + */ +public class ExponentialBackoffTimeoutStrategy implements TimeoutStrategy { + /** Default backoff coefficient applied on each retry step. Doubles the timeout per attempt. */ + private static final double DEFAULT_BACKOFF_COEFFICIENT = 2.0; + + /** + * Multiplier applied to the current timeout on each call to {@link #next(int)}. + * Must be greater than {@code 1.0} to produce a growing sequence. + */ + private final double backoffCoefficient; + + /** + * Whether to apply random jitter to the computed timeout. + * When {@code true}, the result is randomized within {@code [raw / 2, raw * 1.5]}. + */ + private final boolean jitter; + + /** + * Upper bound for the timeout produced by this strategy, in milliseconds. + * The result of {@link #next(int)} is always capped at this value. + */ + private final int maxTimeout; + + /** + * Creates a strategy with default max timeout and backoff coefficient, and no jitter. + * + * @see TimeoutStrategy#DEFAULT_TIMEOUT_MS_MAX + */ + public ExponentialBackoffTimeoutStrategy() { + this(DEFAULT_TIMEOUT_MS_MAX, DEFAULT_BACKOFF_COEFFICIENT); + } + + /** + * Creates a strategy with the given max timeout and backoff coefficient, and no jitter. + * + * @param maxTimeout maximum timeout this strategy may produce, in milliseconds. + * @param backoffCoefficient multiplier applied to the current timeout on each step. + * Must be greater than {@code 1.0}. + */ + public ExponentialBackoffTimeoutStrategy( + int maxTimeout, + double backoffCoefficient + ) { + this(maxTimeout, backoffCoefficient, false); + } + + /** + * Creates a strategy with the given max timeout, backoff coefficient, and jitter setting. + * + * @param maxTimeout maximum timeout this strategy may produce, in milliseconds. + * @param backoffCoefficient multiplier applied to the current timeout on each step. + * Must be greater than {@code 1.0}. + * @param jitter if {@code true}, random jitter is applied to each computed timeout. + */ + public ExponentialBackoffTimeoutStrategy( + int maxTimeout, + double backoffCoefficient, + boolean jitter + ) { + this.maxTimeout = maxTimeout; + this.backoffCoefficient = backoffCoefficient; + this.jitter = jitter; + } + + /** + * Computes the next retry timeout by multiplying {@code currentTimeout} by + * {@link #backoffCoefficient}, then capping at {@link #maxTimeout}. + * If jitter is enabled, the result is further randomized via {@link #applyJitter(int)}. + * + * @param currentTimeout current retry timeout in milliseconds. + * @return next retry timeout in milliseconds, capped at {@link #maxTimeout}. + */ + @Override + public int next(int currentTimeout) { + int raw = (int) Math.min((currentTimeout * backoffCoefficient), maxTimeout); + + return jitter ? applyJitter(raw) : raw; Review Comment: It's still there... btw, how would it affect the actual values distribution? -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
