ojasvajain commented on code in PR #23696: URL: https://github.com/apache/kafka/pull/23696#discussion_r4228774949
########## server/src/main/java/org/apache/kafka/server/metrics/ClientMatchPattern.java: ########## @@ -0,0 +1,66 @@ +/* + * 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.kafka.server.metrics; + +/** + * A compiled client-metrics match pattern, backed by RE2/J. java.util.regex is supported only as + * a deprecated, temporary fallback for patterns that predate RE2/J validation. See + * {@link #ofLegacy}. + * <p> + * RE2/J's {@code Pattern} and {@code java.util.regex.Pattern} share no common supertype, so this + * interface gives both a uniform shape wherever a compiled match pattern is stored or evaluated. + */ +public interface ClientMatchPattern { + + boolean matches(String input); + + String pattern(); + + static ClientMatchPattern ofRe2(com.google.re2j.Pattern pattern) { + return new ClientMatchPattern() { + @Override + public boolean matches(String input) { + return pattern.matcher(input).matches(); + } + + @Override + public String pattern() { + return pattern.pattern(); + } + }; + } + + /** + * Wraps a pattern compiled with the legacy java.util.regex engine, for a match pattern that + * predates RE2/J validation and would otherwise be rejected (e.g. one relying on backreferences + * or lookaround). This fallback support is temporary and will be removed in Apache Kafka 5.0. + */ + @Deprecated(since = "4.5", forRemoval = true) + static ClientMatchPattern ofLegacy(java.util.regex.Pattern pattern) { Review Comment: > Can you please provide me example when this will be used i.e. scenario? This is used in the fallback path of `compileLenient`. We first try to compile the pattern using RE2, if it does not succeed we try using the existing library. If it succeeds, we log a warning. `compileLenient` gets called in two flows: 1. When a config is altered and the change is propagated to the brokers, all brokers call it when updating their subscriptions. 2. When a broker rebuilds its state using the metadata log (for eg. during startup). -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
