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}.<br>
026     * <br>
027     * You can obtain the instance of this for your web application by retrieving the {@link javax.servlet.ServletContext}
028     * attribute named {@code org.apache.logging.log4j.core.web.Log4jWebSupport.INSTANCE}. If needed, you can also obtain
029     * the {@link LoggerContext} instance for your web application by retrieving the {@code ServletContext} attribute named
030     * {@code org.apache.logging.log4j.spi.LoggerContext.INSTANCE}.
031     */
032    public interface Log4jWebSupport {
033        /**
034         * The {@link javax.servlet.ServletContext} parameter name for the name of the
035         * {@link org.apache.logging.log4j.core.LoggerContext}.
036         */
037        String LOG4J_CONTEXT_NAME = "log4jContextName";
038    
039        /**
040         * The {@link javax.servlet.ServletContext} parameter name for the location of the configuration.
041         */
042        String LOG4J_CONFIG_LOCATION = "log4jConfiguration";
043    
044        /**
045         * The {@link javax.servlet.ServletContext} parameter name for the JNDI flag.
046         */
047        String IS_LOG4J_CONTEXT_SELECTOR_NAMED = "isLog4jContextSelectorNamed";
048    
049        /**
050         * The {@link javax.servlet.ServletContext} parameter name for the flag that disables Log4j's auto-initialization
051         * in Servlet 3.0+ web applications. Set a context parameter with this name to "true" to disable
052         * auto-initialization.
053         */
054        String IS_LOG4J_AUTO_INITIALIZATION_DISABLED = "isLog4jAutoInitializationDisabled";
055    
056        /**
057         * The attribute key for the {@link javax.servlet.ServletContext} attribute that the singleton support instance
058         * is stored in.
059         */
060        String SUPPORT_ATTRIBUTE = Log4jWebSupport.class.getName() + ".INSTANCE";
061    
062        /**
063         * The attribute key for the {@link javax.servlet.ServletContext} attribute that the {@link LoggerContext}
064         * is stored in.
065         */
066        String CONTEXT_ATTRIBUTE = LoggerContext.class.getName() + ".INSTANCE";
067    
068        /**
069         * Sets the logger context so that code executing afterwards can easily and quickly access loggers via
070         * {@link org.apache.logging.log4j.LogManager#getLogger}.
071         */
072        void setLoggerContext();
073    
074        /**
075         * Clears the logger context set up in {@link #setLoggerContext}.
076         */
077        void clearLoggerContext();
078    
079        /**
080         * Sets the logger context by calling {@link #setLoggerContext}, executes the runnable argument, then clears the
081         * logger context by calling {@link #clearLoggerContext}.
082         *
083         * @param runnable The runnable to execute wrapped with a configured logger context
084         */
085        void wrapExecution(Runnable runnable);
086    }