001/**
002 * Copyright (c) 2004-2011 QOS.ch
003 * All rights reserved.
004 *
005 * Permission is hereby granted, free  of charge, to any person obtaining
006 * a  copy  of this  software  and  associated  documentation files  (the
007 * "Software"), to  deal in  the Software without  restriction, including
008 * without limitation  the rights to  use, copy, modify,  merge, publish,
009 * distribute,  sublicense, and/or sell  copies of  the Software,  and to
010 * permit persons to whom the Software  is furnished to do so, subject to
011 * the following conditions:
012 *
013 * The  above  copyright  notice  and  this permission  notice  shall  be
014 * included in all copies or substantial portions of the Software.
015 *
016 * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
017 * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
018 * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
019 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
020 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
021 * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
022 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
023 *
024 */
025package org.slf4j.reload4j;
026
027import java.util.concurrent.ConcurrentHashMap;
028import java.util.concurrent.ConcurrentMap;
029
030import org.apache.log4j.LogManager;
031import org.slf4j.ILoggerFactory;
032import org.slf4j.Logger;
033import org.slf4j.helpers.Reporter;
034import org.slf4j.helpers.Util;
035
036/**
037 * Log4jLoggerFactory is an implementation of {@link ILoggerFactory} returning
038 * the appropriate named {@link Reload4jLoggerAdapter} instance.
039 * 
040 * @author Ceki Gülcü
041 */
042public class Reload4jLoggerFactory implements ILoggerFactory {
043
044    private static final String LOG4J_DELEGATION_LOOP_URL = "http://www.slf4j.org/codes.html#log4jDelegationLoop";
045
046    // check for delegation loops
047    static {
048        try {
049            Class.forName("org.apache.log4j.Log4jLoggerFactory");
050            String part1 = "Detected both log4j-over-slf4j.jar AND bound slf4j-log4j12.jar on the class path, preempting StackOverflowError. ";
051            String part2 = "See also " + LOG4J_DELEGATION_LOOP_URL + " for more details.";
052
053            Reporter.error(part1);
054            Reporter.error(part2);
055            throw new IllegalStateException(part1 + part2);
056        } catch (ClassNotFoundException e) {
057            // this is the good case
058        }
059    }
060
061    // key: name (String), value: a Log4jLoggerAdapter;
062    ConcurrentMap<String, Logger> loggerMap;
063
064    public Reload4jLoggerFactory() {
065        loggerMap = new ConcurrentHashMap<>();
066        // force log4j to initialize
067        org.apache.log4j.LogManager.getRootLogger();
068    }
069
070    /*
071     * (non-Javadoc)
072     * 
073     * @see org.slf4j.ILoggerFactory#getLogger(java.lang.String)
074     */
075    public Logger getLogger(String name) {
076        Logger slf4jLogger = loggerMap.get(name);
077        if (slf4jLogger != null) {
078            return slf4jLogger;
079        } else {
080            org.apache.log4j.Logger log4jLogger;
081            if (name.equalsIgnoreCase(Logger.ROOT_LOGGER_NAME))
082                log4jLogger = LogManager.getRootLogger();
083            else
084                log4jLogger = LogManager.getLogger(name);
085
086            Logger newInstance = new Reload4jLoggerAdapter(log4jLogger);
087            Logger oldInstance = loggerMap.putIfAbsent(name, newInstance);
088            return oldInstance == null ? newInstance : oldInstance;
089        }
090    }
091}