hsyuan commented on a change in pull request #1875: [CALCITE-3873] Use global caching for ReflectiveVisitDispatcher implementation URL: https://github.com/apache/calcite/pull/1875#discussion_r406600680
########## File path: core/src/main/java/org/apache/calcite/util/ReflectiveVisitDispatcherImpl.java ########## @@ -0,0 +1,134 @@ +/* + * 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.calcite.util; + +import org.apache.calcite.config.CalciteSystemProperty; + +import com.google.common.cache.Cache; +import com.google.common.cache.CacheBuilder; +import com.google.common.collect.ImmutableList; + +import java.lang.reflect.Method; +import java.util.Collections; +import java.util.List; + +/** + * Looking up methods relating to reflective visitation. Caching reflect + * method globally, every instance of the class shares the global cache to + * mitigate java reflection invocation overhead. + * + * @param <E> Argument type + * @param <R> Return type + */ +public class ReflectiveVisitDispatcherImpl<R extends ReflectiveVisitor, E> + implements ReflectiveVisitDispatcher<R, E> { + + /** + * Global singleton cache with limited size used to cache methods. Every instance + * of the class will share this cache to mitigate java reflection invocation + * overhead when looking up methods. + * <p>Note that there should be multiple ways to implement caching, for example, + * <p>1) Passing <em>Cache</em> between objects and hopefully using Java's + * <em>RAII (Resource Acquisition Is Initialization)</em> like try-finally to + * garbage collect. + * <p>2) Using <code>ThreadLocal</code> to store cache per thread. + * <p>3) Using global cache. + * <p>Solution 1) and 2) could introduce complexity to the main course and it only + * works per instance or per thread. + * Solution 3) which introduces a controllable global small sized cache is a + * better solution to balance memory usage and performance. + */ + private static final Cache<List<Object>, Method> GLOBAL_METHOD_CACHE = Review comment: Can we use `LoadingCache`? ---------------------------------------------------------------- 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: us...@infra.apache.org With regards, Apache Git Services
