b-slim commented on a change in pull request #944: [Hive-22760] Adding Clock based eviction strategy. URL: https://github.com/apache/hive/pull/944#discussion_r396638475
########## File path: llap-server/src/java/org/apache/hadoop/hive/llap/cache/ClockCachePolicy.java ########## @@ -0,0 +1,264 @@ +/* + * 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.hive.llap.cache; + +import com.google.common.annotations.VisibleForTesting; +import com.google.common.base.Preconditions; + +import javax.annotation.concurrent.GuardedBy; +import java.util.Iterator; +import java.util.NoSuchElementException; +import java.util.concurrent.locks.Lock; +import java.util.concurrent.locks.ReentrantLock; + +/** + * Clock eviction policy. Uses a simple circular list to keep a ring of current used buffers. + * New entries are added to tail of the clock hand AKA (clockHand.prev) + * Eviction start at the current clock hand following the next pointer. + * + */ +public class ClockCachePolicy implements LowLevelCachePolicy { Review comment: In theory i totally agree with you, although in practice i benchmarked with lock free FIFO implementations and I can not see anything that really moves the needle, but am up to work on second patch that makes this 100 lock free. ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
