| /* |
| * 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.servicecomb.qps.strategy; |
| |
| import java.util.concurrent.atomic.AtomicLong; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * leaky bucket algorithm include 2 implementation : |
| * 1. as a meter : it's same as the token bucket. |
| * 2. as a queue : the bucket size equal to qpsLimit. |
| * |
| **/ |
| public class LeakyBucketStrategy extends AbstractQpsStrategy { |
| |
| private static final Logger LOGGER = LoggerFactory.getLogger(LeakyBucketStrategy.class); |
| |
| // Request count between Interval begin and now in one interval |
| private final AtomicLong requestCount = new AtomicLong(); |
| |
| private volatile long lastTime; |
| |
| private long remainder = 0; |
| |
| private static final String STRATEGY_NAME = "LeakyBucket"; |
| |
| @Override |
| public boolean isLimitNewRequest() { |
| if (this.getQpsLimit() == null) { |
| throw new IllegalStateException("should not happen"); |
| } |
| if (this.getBucketLimit() == null) { |
| this.setBucketLimit(Math.max(2 * this.getQpsLimit(), Integer.MAX_VALUE)); |
| } |
| long nowTime = System.currentTimeMillis(); |
| //get the num of te period time |
| long leakCount = ((nowTime - lastTime + remainder) / 1000) * this.getQpsLimit(); |
| remainder = (nowTime - lastTime + remainder) % 1000; |
| // leak the request |
| if (requestCount.longValue() > leakCount) { |
| requestCount.addAndGet(-leakCount); |
| } else { |
| requestCount.set(0); |
| } |
| lastTime = nowTime; |
| //compute this time |
| if (requestCount.longValue() < this.getBucketLimit()) { |
| requestCount.incrementAndGet(); |
| return false; |
| } |
| LOGGER.warn("qps flowcontrol open, qpsLimit is {} and tps is {}", this.getQpsLimit(), requestCount.longValue() + 1); |
| return true; |
| } |
| |
| @Override |
| public String name() { |
| return STRATEGY_NAME; |
| } |
| } |