| /* |
| * 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.twill.zookeeper; |
| |
| import com.google.common.base.Preconditions; |
| |
| import java.util.concurrent.TimeUnit; |
| |
| /** |
| * Factory for creating common {@link RetryStrategy} implementation. |
| */ |
| public final class RetryStrategies { |
| |
| /** |
| * @return A {@link RetryStrategy} that doesn't do any retry. |
| */ |
| public static RetryStrategy noRetry() { |
| return new RetryStrategy() { |
| @Override |
| public long nextRetry(int failureCount, long startTime, OperationType type, String path) { |
| return -1; |
| } |
| }; |
| } |
| |
| /** |
| * Creates a {@link RetryStrategy} that retries maximum given number of times, with the actual |
| * delay behavior delegated to another {@link RetryStrategy}. |
| * @param limit Maximum number of retries allowed. |
| * @param strategy When failure count is less than or equal to the limit, this strategy will be called. |
| * @return A {@link RetryStrategy}. |
| */ |
| public static RetryStrategy limit(final int limit, final RetryStrategy strategy) { |
| Preconditions.checkArgument(limit >= 0, "limit must be >= 0"); |
| return new RetryStrategy() { |
| @Override |
| public long nextRetry(int failureCount, long startTime, OperationType type, String path) { |
| return (failureCount <= limit) ? strategy.nextRetry(failureCount, startTime, type, path) : -1L; |
| } |
| }; |
| } |
| |
| /** |
| * Creates a {@link RetryStrategy} that imposes a fix delay between each retries. |
| * @param delay delay time |
| * @param delayUnit {@link TimeUnit} for the delay. |
| * @return A {@link RetryStrategy}. |
| */ |
| public static RetryStrategy fixDelay(final long delay, final TimeUnit delayUnit) { |
| Preconditions.checkArgument(delay >= 0, "delay must be >= 0"); |
| return new RetryStrategy() { |
| @Override |
| public long nextRetry(int failureCount, long startTime, OperationType type, String path) { |
| return TimeUnit.MILLISECONDS.convert(delay, delayUnit); |
| } |
| }; |
| } |
| |
| /** |
| * Creates a {@link RetryStrategy} that will increase delay exponentially between each retries. |
| * @param baseDelay delay to start with. |
| * @param maxDelay cap of the delay. |
| * @param delayUnit {@link TimeUnit} for the delays. |
| * @return A {@link RetryStrategy}. |
| */ |
| public static RetryStrategy exponentialDelay(final long baseDelay, final long maxDelay, final TimeUnit delayUnit) { |
| Preconditions.checkArgument(baseDelay >= 0, "base delay must be >= 0"); |
| Preconditions.checkArgument(maxDelay >= 0, "max delay must be >= 0"); |
| return new RetryStrategy() { |
| @Override |
| public long nextRetry(int failureCount, long startTime, OperationType type, String path) { |
| long power = failureCount > Long.SIZE ? Long.MAX_VALUE : (1L << (failureCount - 1)); |
| long delay = Math.min(baseDelay * power, maxDelay); |
| delay = delay < 0 ? maxDelay : delay; |
| return TimeUnit.MILLISECONDS.convert(delay, delayUnit); |
| } |
| }; |
| } |
| |
| /** |
| * Creates a {@link RetryStrategy} that will retry until maximum amount of time has been passed since the request, |
| * with the actual delay behavior delegated to another {@link RetryStrategy}. |
| * @param maxElapseTime Maximum amount of time until giving up retry. |
| * @param timeUnit {@link TimeUnit} for the max elapse time. |
| * @param strategy When time elapsed is less than or equal to the limit, this strategy will be called. |
| * @return A {@link RetryStrategy}. |
| */ |
| public static RetryStrategy timeLimit(long maxElapseTime, TimeUnit timeUnit, final RetryStrategy strategy) { |
| Preconditions.checkArgument(maxElapseTime >= 0, "max elapse time must be >= 0"); |
| final long maxElapseMs = TimeUnit.MILLISECONDS.convert(maxElapseTime, timeUnit); |
| return new RetryStrategy() { |
| @Override |
| public long nextRetry(int failureCount, long startTime, OperationType type, String path) { |
| long elapseTime = System.currentTimeMillis() - startTime; |
| return elapseTime <= maxElapseMs ? strategy.nextRetry(failureCount, startTime, type, path) : -1L; |
| } |
| }; |
| } |
| |
| private RetryStrategies() { |
| } |
| } |