001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements. See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache license, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License. You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the license for the specific language governing permissions and
015     * limitations under the license.
016     */
017    package org.apache.logging.log4j.web;
018    
019    import org.apache.logging.log4j.spi.LoggerContext;
020    
021    /**
022     * Specifies an interface for setting and clearing a thread-bound {@link LoggerContext} in a Java EE web application.
023     * Also defines constants for context parameter and attribute names. In most cases you will never need to use this
024     * directly because the Log4j filter handles this task automatically. However, in async operations you should wrap
025     * code that executes in separate threads with {@link #setLoggerContext} and {@link #clearLoggerContext}.
026     *
027     * <p>
028     * You can obtain the instance of this for your web application by retrieving the {@link javax.servlet.ServletContext}
029     * attribute named {@code org.apache.logging.log4j.core.web.Log4jWebSupport.INSTANCE}. If needed, you can also obtain
030     * the {@link LoggerContext} instance for your web application by retrieving the {@code ServletContext} attribute named
031     * {@code org.apache.logging.log4j.spi.LoggerContext.INSTANCE}.
032     * </p>
033     */
034    public interface Log4jWebSupport {
035        /**
036         * The {@link javax.servlet.ServletContext} parameter name for the name of the
037         * {@link org.apache.logging.log4j.core.LoggerContext}.
038         */
039        String LOG4J_CONTEXT_NAME = "log4jContextName";
040    
041        /**
042         * The {@link javax.servlet.ServletContext} parameter name for the location of the configuration.
043         */
044        String LOG4J_CONFIG_LOCATION = "log4jConfiguration";
045    
046        /**
047         * The {@link javax.servlet.ServletContext} parameter name for the JNDI flag.
048         */
049        String IS_LOG4J_CONTEXT_SELECTOR_NAMED = "isLog4jContextSelectorNamed";
050    
051        /**
052         * The {@link javax.servlet.ServletContext} parameter name for the flag that disables Log4j's auto-initialization
053         * in Servlet 3.0+ web applications. Set a context parameter with this name to "true" to disable
054         * auto-initialization.
055         */
056        String IS_LOG4J_AUTO_INITIALIZATION_DISABLED = "isLog4jAutoInitializationDisabled";
057    
058        /**
059         * The attribute key for the {@link javax.servlet.ServletContext} attribute that the singleton support instance
060         * is stored in.
061         */
062        String SUPPORT_ATTRIBUTE = Log4jWebSupport.class.getName() + ".INSTANCE";
063    
064        /**
065         * The attribute key for the {@link javax.servlet.ServletContext} attribute that the {@link LoggerContext}
066         * is stored in.
067         */
068        String CONTEXT_ATTRIBUTE = LoggerContext.class.getName() + ".INSTANCE";
069    
070        /**
071         * Sets the logger context so that code executing afterwards can easily and quickly access loggers via
072         * {@link org.apache.logging.log4j.LogManager#getLogger}.
073         */
074        void setLoggerContext();
075    
076        /**
077         * Clears the logger context set up in {@link #setLoggerContext}.
078         */
079        void clearLoggerContext();
080    
081        /**
082         * Sets the logger context by calling {@link #setLoggerContext}, executes the runnable argument, then clears the
083         * logger context by calling {@link #clearLoggerContext}.
084         *
085         * @param runnable The runnable to execute wrapped with a configured logger context
086         */
087        void wrapExecution(Runnable runnable);
088    }