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.core.selector;
018    
019    import java.net.URI;
020    import java.util.ArrayList;
021    import java.util.Collections;
022    import java.util.List;
023    import java.util.Map;
024    import java.util.concurrent.ConcurrentHashMap;
025    import java.util.concurrent.ConcurrentMap;
026    import javax.naming.NamingException;
027    
028    import org.apache.logging.log4j.core.LoggerContext;
029    import org.apache.logging.log4j.core.impl.ContextAnchor;
030    import org.apache.logging.log4j.core.net.JndiManager;
031    import org.apache.logging.log4j.core.util.Constants;
032    import org.apache.logging.log4j.status.StatusLogger;
033    
034    /**
035     * This class can be used to define a custom logger repository. It makes use of the fact that in J2EE environments, each
036     * web-application is guaranteed to have its own JNDI context relative to the <code>java:comp/env</code> context. In
037     * EJBs, each enterprise bean (albeit not each application) has its own context relative to the
038     * <code>java:comp/env</code> context. An <code>env-entry</code> in a deployment descriptor provides the information to
039     * the JNDI context. Once the <code>env-entry</code> is set, a repository selector can query the JNDI application
040     * context to look up the value of the entry. The logging context of the web-application will depend on the value the
041     * env-entry. The JNDI context which is looked up by this class is <code>java:comp/env/log4j/context-name</code>.
042     *
043     * <p>
044     * Here is an example of an <code>env-entry</code>:
045     * </p>
046     * <blockquote>
047     * 
048     * <pre>
049     * &lt;env-entry&gt;
050     *   &lt;description&gt;JNDI logging context name for this app&lt;/description&gt;
051     *   &lt;env-entry-name&gt;log4j/context-name&lt;/env-entry-name&gt;
052     *   &lt;env-entry-value&gt;aDistinctiveLoggingContextName&lt;/env-entry-value&gt;
053     *   &lt;env-entry-type&gt;java.lang.String&lt;/env-entry-type&gt;
054     * &lt;/env-entry&gt;
055     * </pre>
056     * 
057     * </blockquote>
058     *
059     * <p>
060     * <em>If multiple applications use the same logging context name, then they
061     * will share the same logging context.</em>
062     * </p>
063     *
064     * <p>
065     * You can also specify the URL for this context's configuration resource. This repository selector
066     * (ContextJNDISelector) will use this resource to automatically configure the log4j repository.
067     * </p>
068     ** <blockquote>
069     * 
070     * <pre>
071     * &lt;env-entry&gt;
072     *   &lt;description&gt;URL for configuring log4j context&lt;/description&gt;
073     *   &lt;env-entry-name&gt;log4j/configuration-resource&lt;/env-entry-name&gt;
074     *   &lt;env-entry-value&gt;urlOfConfigurationResource&lt;/env-entry-value&gt;
075     *   &lt;env-entry-type&gt;java.lang.String&lt;/env-entry-type&gt;
076     * &lt;/env-entry&gt;
077     * </pre>
078     * 
079     * </blockquote>
080     *
081     * <p>
082     * It usually good practice for configuration resources of distinct applications to have distinct names. However, if
083     * this is not possible Naming
084     * </p>
085     */
086    public class JndiContextSelector implements NamedContextSelector {
087    
088        private static final LoggerContext CONTEXT = new LoggerContext("Default");
089    
090        private static final ConcurrentMap<String, LoggerContext> CONTEXT_MAP =
091            new ConcurrentHashMap<String, LoggerContext>();
092    
093        private static final StatusLogger LOGGER = StatusLogger.getLogger();
094    
095        @Override
096        public LoggerContext getContext(final String fqcn, final ClassLoader loader, final boolean currentContext) {
097            return getContext(fqcn, loader, currentContext, null);
098        }
099    
100        @Override
101        public LoggerContext getContext(final String fqcn, final ClassLoader loader, final boolean currentContext,
102                                        final URI configLocation) {
103    
104            final LoggerContext lc = ContextAnchor.THREAD_CONTEXT.get();
105            if (lc != null) {
106                return lc;
107            }
108    
109            String loggingContextName = null;
110    
111            final JndiManager jndiManager = JndiManager.getDefaultManager();
112            try {
113                loggingContextName = jndiManager.lookup(Constants.JNDI_CONTEXT_NAME);
114            } catch (final NamingException ne) {
115                LOGGER.error("Unable to lookup {}", Constants.JNDI_CONTEXT_NAME, ne);
116            } finally {
117                jndiManager.release();
118            }
119    
120            return loggingContextName == null ? CONTEXT : locateContext(loggingContextName, null, configLocation);
121        }
122    
123        @Override
124        public LoggerContext locateContext(final String name, final Object externalContext, final URI configLocation) {
125            if (name == null) {
126                LOGGER.error("A context name is required to locate a LoggerContext");
127                return null;
128            }
129            if (!CONTEXT_MAP.containsKey(name)) {
130                final LoggerContext ctx = new LoggerContext(name, externalContext, configLocation);
131                CONTEXT_MAP.putIfAbsent(name, ctx);
132            }
133            return CONTEXT_MAP.get(name);
134        }
135    
136        @Override
137        public void removeContext(final LoggerContext context) {
138    
139            for (final Map.Entry<String, LoggerContext> entry : CONTEXT_MAP.entrySet()) {
140                if (entry.getValue().equals(context)) {
141                    CONTEXT_MAP.remove(entry.getKey());
142                }
143            }
144        }
145    
146        @Override
147        public LoggerContext removeContext(final String name) {
148            return CONTEXT_MAP.remove(name);
149        }
150    
151        @Override
152        public List<LoggerContext> getLoggerContexts() {
153            final List<LoggerContext> list = new ArrayList<LoggerContext>(CONTEXT_MAP.values());
154            return Collections.unmodifiableList(list);
155        }
156    
157    }