remkop commented on a change in pull request #284: LOG4J2-2639 - Allow logging calls to be constructed using a builder pattern URL: https://github.com/apache/logging-log4j2/pull/284#discussion_r296923818
########## File path: log4j-api/src/main/java/org/apache/logging/log4j/internal/DefaultLogBuilder.java ########## @@ -0,0 +1,179 @@ +/* + * 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.logging.log4j.internal; + +import org.apache.logging.log4j.Level; +import org.apache.logging.log4j.Logger; +import org.apache.logging.log4j.Marker; +import org.apache.logging.log4j.message.Message; +import org.apache.logging.log4j.message.SimpleMessage; +import org.apache.logging.log4j.status.StatusLogger; +import org.apache.logging.log4j.util.StackLocatorUtil; +import org.apache.logging.log4j.util.Supplier; + + +/** + * Collects data for a log event and then logs it. + */ +public class DefaultLogBuilder implements LogBuilder { + private static Message EMPTY_MESSAGE = new SimpleMessage(""); + private static final String FQCN = DefaultLogBuilder.class.getName(); + private static final Logger LOGGER = StatusLogger.getLogger(); + + private final Logger logger; + private Level level; + private Marker marker; + private Throwable throwable; + private StackTraceElement location; + private Object object; + private Message msg; + private String textMessage; + private Supplier<Message> supplier; + private Object[] parameters; + private volatile boolean inUse; + private long threadId; + + public DefaultLogBuilder(Logger logger) { + this.logger = logger; + this.inUse = false; + this.threadId = Thread.currentThread().getId(); + } + + public LogBuilder setLevel(Level level) { + this.inUse = true; + this.level = level; + this.marker = null; + this.throwable = null; + this.location = null; + this.object = null; + this.msg = null; + this.textMessage = null; + this.supplier = null; + this.parameters = null; + return this; Review comment: I believe the `setLevel` method should be moved to `Logger` (and renamed to `atLevel`), and removed from the `LogBuilder` class. That will allow all of the remaining methods to skip processing if the log level is not applicable. That is one of the value propositions of [fluent logging APIs like this](https://google.github.io/flogger/benefits). We lose that benefit if we allow users to change the log level later in the call chain: for example, this usage is possible: ```java // assume log level is WARN logger.trace().withMessage("This {} should {} be {} ignored {}") .withParameters("statement", "immediately", "completely", "for better performance") .setLevel(Level.TRACE) // oops, we cannot ignore the above after all .log(); ``` ---------------------------------------------------------------- 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
