rmannibucau commented on code in PR #607: URL: https://github.com/apache/tomcat/pull/607#discussion_r1160616435
########## java/org/apache/catalina/util/TimeBucketCounter.java: ########## @@ -0,0 +1,217 @@ +/* + * 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.catalina.util; + +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.atomic.AtomicInteger; + +/** + * this class maintains a thread safe hash map that has timestamp-based buckets + * followed by a string for a key, and a counter for a value. each time the + * increment() method is called it adds the key if it does not exist, increments + * its value and returns it. + * + * a maintenance thread cleans up keys that are prefixed by previous timestamp + * buckets. + */ +public class TimeBucketCounter { + + /** + * Map to hold the buckets + */ + private final ConcurrentHashMap<String, AtomicInteger> map = new ConcurrentHashMap<>(); + + /** + * Milliseconds bucket size as a Power of 2 for bit shift math, e.g. + * 16 for 65_536ms which is about 1:05 minute + */ + private final int numBits; + + /** + * ratio of actual duration to config duration + */ + private final double ratio; + + /** + * flag for the maintenance thread + */ + volatile boolean isRunning = false; + + /** + * + * @param bucketDuration duration in seconds, e.g. for 1 minute pass 60 + */ + public TimeBucketCounter(int bucketDuration) { + + int durationMillis = bucketDuration * 1000; + + int bits = 0; + int pof2 = nextPowerOf2(durationMillis); + int bitCheck = pof2; + while (bitCheck > 1) { + bitCheck = pof2 >> ++bits; + } + + this.numBits = bits; + + this.ratio = ratioToPowerOf2(durationMillis); + + int cleanupsPerBucketDuration = (durationMillis >= 60_000) ? 6 : 3; + Thread mt = new MaintenanceThread(durationMillis / cleanupsPerBucketDuration); Review Comment: > I like it because it provides a standard way to pass scheduling services to the app. But no way to configure it, to define if it leaks between apps or not (here we want it leaks) and other common pitfalls :(. That said the way to link it to tomcat is JNDI and I guess the background scheduler could be made boundable in JNDI too quite easily so the solution can still converge. -- 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: dev-unsubscr...@tomcat.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@tomcat.apache.org For additional commands, e-mail: dev-h...@tomcat.apache.org
