| /* |
| * 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.hadoop.util; |
| |
| import java.time.Duration; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.thirdparty.com.google.common.util.concurrent.RateLimiter; |
| |
| /** |
| * Factory for Rate Limiting. |
| * This should be only place in the code where the guava RateLimiter is imported. |
| */ |
| @InterfaceAudience.Private |
| @InterfaceStability.Unstable |
| public final class RateLimitingFactory { |
| |
| private static final RateLimiting UNLIMITED = new NoRateLimiting(); |
| |
| /** |
| * No waiting took place. |
| */ |
| private static final Duration INSTANTLY = Duration.ofMillis(0); |
| |
| private RateLimitingFactory() { |
| } |
| |
| /** |
| * No Rate Limiting. |
| */ |
| private static class NoRateLimiting implements RateLimiting { |
| |
| |
| @Override |
| public Duration acquire(int requestedCapacity) { |
| return INSTANTLY; |
| } |
| } |
| |
| /** |
| * Rate limiting restricted to that of a google rate limiter. |
| */ |
| private static final class RestrictedRateLimiting implements RateLimiting { |
| private final RateLimiter limiter; |
| |
| /** |
| * Constructor. |
| * @param capacityPerSecond capacity in permits/second. |
| */ |
| private RestrictedRateLimiting(int capacityPerSecond) { |
| this.limiter = RateLimiter.create(capacityPerSecond); |
| } |
| |
| @Override |
| public Duration acquire(int requestedCapacity) { |
| final double delayMillis = limiter.acquire(requestedCapacity); |
| return delayMillis == 0 |
| ? INSTANTLY |
| : Duration.ofMillis((long) (delayMillis * 1000)); |
| } |
| |
| } |
| |
| /** |
| * Get the unlimited rate. |
| * @return a rate limiter which always has capacity. |
| */ |
| public static RateLimiting unlimitedRate() { |
| return UNLIMITED; |
| } |
| |
| /** |
| * Create an instance. |
| * If the rate is 0; return the unlimited rate. |
| * @param capacity capacity in permits/second. |
| * @return limiter restricted to the given capacity. |
| */ |
| public static RateLimiting create(int capacity) { |
| |
| return capacity == 0 |
| ? unlimitedRate() |
| : new RestrictedRateLimiting(capacity); |
| } |
| |
| } |