org.apache.logging.log4j.core.selector.JndiContextSelector Maven / Gradle / Ivy

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The Apache Log4j Implementation
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/*
 * 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.core.selector;

import java.net.URI;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import javax.naming.NamingException;

import org.apache.logging.log4j.core.LoggerContext;
import org.apache.logging.log4j.core.impl.ContextAnchor;
import org.apache.logging.log4j.core.net.JndiManager;
import org.apache.logging.log4j.core.util.Constants;
import org.apache.logging.log4j.status.StatusLogger;

/**
 * This class can be used to define a custom logger repository. It makes use of the fact that in J2EE environments, each
 * web-application is guaranteed to have its own JNDI context relative to the java:comp/env context. In
 * EJBs, each enterprise bean (albeit not each application) has its own context relative to the
 * java:comp/env context. An env-entry in a deployment descriptor provides the information to
 * the JNDI context. Once the env-entry is set, a repository selector can query the JNDI application
 * context to look up the value of the entry. The logging context of the web-application will depend on the value the
 * env-entry. The JNDI context which is looked up by this class is java:comp/env/log4j/context-name.
 *
 * 
 * Here is an example of an env-entry:
 * 
 * 
 * 
 *  * <env-entry>
 *   <description>JNDI logging context name for this app</description>
 *   <env-entry-name>log4j/context-name</env-entry-name>
 *   <env-entry-value>aDistinctiveLoggingContextName</env-entry-value>
 *   <env-entry-type>java.lang.String</env-entry-type>
 * </env-entry>
 * 
 * 
 * 
 *
 * 
 * If multiple applications use the same logging context name, then they
 * will share the same logging context.
 * 
 *
 * 
 * You can also specify the URL for this context's configuration resource. This repository selector
 * (ContextJNDISelector) will use this resource to automatically configure the log4j repository.
 * 
 ** 
 * 
 *  * <env-entry>
 *   <description>URL for configuring log4j context</description>
 *   <env-entry-name>log4j/configuration-resource</env-entry-name>
 *   <env-entry-value>urlOfConfigurationResource</env-entry-value>
 *   <env-entry-type>java.lang.String</env-entry-type>
 * </env-entry>
 * 
 * 
 * 
 *
 * 
 * It usually good practice for configuration resources of distinct applications to have distinct names. However, if
 * this is not possible Naming
 * 
 */
public class JndiContextSelector implements NamedContextSelector {

    private static final LoggerContext CONTEXT = new LoggerContext("Default");

    private static final ConcurrentMap CONTEXT_MAP =
        new ConcurrentHashMap<>();

    private static final StatusLogger LOGGER = StatusLogger.getLogger();

    @Override
    public LoggerContext getContext(final String fqcn, final ClassLoader loader, final boolean currentContext) {
        return getContext(fqcn, loader, currentContext, null);
    }

    @Override
    public LoggerContext getContext(final String fqcn, final ClassLoader loader, final boolean currentContext,
                                    final URI configLocation) {

        final LoggerContext lc = ContextAnchor.THREAD_CONTEXT.get();
        if (lc != null) {
            return lc;
        }

        String loggingContextName = null;

        final JndiManager jndiManager = JndiManager.getDefaultManager();
        try {
            loggingContextName = jndiManager.lookup(Constants.JNDI_CONTEXT_NAME);
        } catch (final NamingException ne) {
            LOGGER.error("Unable to lookup {}", Constants.JNDI_CONTEXT_NAME, ne);
        } finally {
            jndiManager.release();
        }

        return loggingContextName == null ? CONTEXT : locateContext(loggingContextName, null, configLocation);
    }

    @Override
    public LoggerContext locateContext(final String name, final Object externalContext, final URI configLocation) {
        if (name == null) {
            LOGGER.error("A context name is required to locate a LoggerContext");
            return null;
        }
        if (!CONTEXT_MAP.containsKey(name)) {
            final LoggerContext ctx = new LoggerContext(name, externalContext, configLocation);
            CONTEXT_MAP.putIfAbsent(name, ctx);
        }
        return CONTEXT_MAP.get(name);
    }

    @Override
    public void removeContext(final LoggerContext context) {

        for (final Map.Entry entry : CONTEXT_MAP.entrySet()) {
            if (entry.getValue().equals(context)) {
                CONTEXT_MAP.remove(entry.getKey());
            }
        }
    }

    @Override
    public LoggerContext removeContext(final String name) {
        return CONTEXT_MAP.remove(name);
    }

    @Override
    public List getLoggerContexts() {
        final List list = new ArrayList<>(CONTEXT_MAP.values());
        return Collections.unmodifiableList(list);
    }

}