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 */
017package org.apache.logging.log4j.jul;
018
019import java.util.Collections;
020import java.util.Enumeration;
021import java.util.HashSet;
022import java.util.Set;
023import java.util.logging.Logger;
024
025import org.apache.logging.log4j.LoggingException;
026import org.apache.logging.log4j.status.StatusLogger;
027import org.apache.logging.log4j.util.LoaderUtil;
028import org.apache.logging.log4j.util.PropertiesUtil;
029
030/**
031 * Log4j implementation of {@link java.util.logging.LogManager}. Note that the system property
032 * {@code java.util.logging.manager} must be set to {@code org.apache.logging.log4j.jul.LogManager} in order to use
033 * this adaptor. This LogManager requires the {@code log4j-api} library to be available. If {@code log4j-core} is
034 * also available, then more features of {@link java.util.logging.Logger} are supported.
035 *
036 * <p>To override the default {@link AbstractLoggerAdapter} that is used, specify the Log4j property
037 * {@code log4j.jul.LoggerAdapter} and set it to the fully qualified class name of a custom
038 * implementation. All implementations must have a default constructor.</p>
039 *
040 * @since 2.1
041 */
042public class LogManager extends java.util.logging.LogManager {
043
044    private static final org.apache.logging.log4j.Logger LOGGER = StatusLogger.getLogger();
045    private final AbstractLoggerAdapter loggerAdapter;
046    // Contains the set of logger names that are actively being requested using getLogger.
047    private final ThreadLocal<Set<String>> recursive = ThreadLocal.withInitial(HashSet::new);
048
049    public LogManager() {
050        AbstractLoggerAdapter adapter = null;
051        final String overrideAdaptorClassName =
052            PropertiesUtil.getProperties().getStringProperty(Constants.LOGGER_ADAPTOR_PROPERTY);
053        if (overrideAdaptorClassName != null) {
054            try {
055                LOGGER.info("Trying to use LoggerAdaptor [{}] specified by Log4j property.", overrideAdaptorClassName);
056                adapter = LoaderUtil.newCheckedInstanceOf(overrideAdaptorClassName, AbstractLoggerAdapter.class);
057            } catch (final Exception e) {
058                LOGGER.error("Specified LoggerAdapter [{}] is incompatible.", overrideAdaptorClassName, e);
059            }
060        }
061        if (adapter == null) {
062            // default adapter
063            String adapterClassName;
064            try {
065                // find out if log4j-core is available
066                LoaderUtil.loadClass(Constants.CORE_LOGGER_CLASS_NAME);
067                adapterClassName = Constants.CORE_LOGGER_ADAPTER_CLASS_NAME;
068            } catch (final ClassNotFoundException ignored) {
069                adapterClassName = Constants.API_LOGGER_ADAPTER_CLASS_NAME;
070            }
071            LOGGER.debug("Attempting to use {}", adapterClassName);
072            try {
073                adapter = LoaderUtil.newCheckedInstanceOf(adapterClassName, AbstractLoggerAdapter.class);
074            } catch (final Exception e) {
075                throw LOGGER.throwing(new LoggingException(e));
076            }
077        }
078        loggerAdapter = adapter;
079        LOGGER.info("Registered Log4j as the java.util.logging.LogManager.");
080    }
081
082    @Override
083    public boolean addLogger(final Logger logger) {
084        // in order to prevent non-bridged loggers from being registered, we always return false to indicate that
085        // the named logger should be obtained through getLogger(name)
086        return false;
087    }
088
089    @Override
090    public Logger getLogger(final String name) {
091        LOGGER.trace("Call to LogManager.getLogger({})", name);
092        Set<String> activeRequests = recursive.get();
093        if (activeRequests.add(name)) {
094            try {
095                return loggerAdapter.getLogger(name);
096            } finally {
097                activeRequests.remove(name);
098            }
099        }
100        LOGGER.warn("Recursive call to getLogger for {} ignored.", name);
101        return new NoOpLogger(name);
102    }
103
104    @Override
105    public Enumeration<String> getLoggerNames() {
106        return Collections.enumeration(loggerAdapter.getLoggersInContext(loggerAdapter.getContext()).keySet());
107    }
108
109}