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.spi;
018
019import java.util.Map;
020import java.util.WeakHashMap;
021import java.util.concurrent.ConcurrentHashMap;
022import java.util.concurrent.ConcurrentMap;
023
024import org.apache.logging.log4j.LogManager;
025import org.apache.logging.log4j.util.LoaderUtil;
026
027/**
028 * Provides an abstract base class to use for implementing LoggerAdapter.
029 * @param <L> the Logger class to adapt
030 * @since 2.1
031 */
032public abstract class AbstractLoggerAdapter<L> implements LoggerAdapter<L> {
033
034    /**
035     * A map to store loggers for their given LoggerContexts.
036     */
037    protected final Map<LoggerContext, ConcurrentMap<String, L>> registry =
038        new WeakHashMap<LoggerContext, ConcurrentMap<String, L>>();
039
040    @Override
041    public L getLogger(final String name) {
042        final LoggerContext context = getContext();
043        final ConcurrentMap<String, L> loggers = getLoggersInContext(context);
044        if (loggers.containsKey(name)) {
045            return loggers.get(name);
046        }
047        loggers.putIfAbsent(name, newLogger(name, context));
048        return loggers.get(name);
049    }
050
051    /**
052     * Gets or creates the ConcurrentMap of named loggers for a given LoggerContext.
053     *
054     * @param context the LoggerContext to get loggers for
055     * @return the map of loggers for the given LoggerContext
056     */
057    public ConcurrentMap<String, L> getLoggersInContext(final LoggerContext context) {
058        synchronized (registry) {
059            ConcurrentMap<String, L> loggers = registry.get(context);
060            if (loggers == null) {
061                loggers = new ConcurrentHashMap<String, L>();
062                registry.put(context, loggers);
063            }
064            return loggers;
065        }
066    }
067
068    /**
069     * Creates a new named logger for a given {@link LoggerContext}.
070     *
071     * @param name    the name of the logger to create
072     * @param context the LoggerContext this logger will be associated with
073     * @return the new named logger
074     */
075    protected abstract L newLogger(final String name, final LoggerContext context);
076
077    /**
078     * Gets the {@link LoggerContext} that should be used to look up or create loggers. This is similar in spirit to
079     * the {@code ContextSelector} class in {@code log4j-core}. However, implementations can rely on their own
080     * framework's separation of contexts instead (or simply use a singleton).
081     *
082     * @return the LoggerContext to be used for lookup and creation purposes
083     * @see org.apache.logging.log4j.LogManager#getContext(ClassLoader, boolean)
084     * @see org.apache.logging.log4j.LogManager#getContext(String, boolean)
085     */
086    protected abstract LoggerContext getContext();
087
088    /**
089     * Gets the {@link LoggerContext} associated with the given caller class.
090     *
091     * @param callerClass the caller class
092     * @return the LoggerContext for the calling class
093     */
094    protected LoggerContext getContext(final Class<?> callerClass) {
095        ClassLoader cl = null;
096        if (callerClass != null) {
097            cl = callerClass.getClassLoader();
098        }
099        if (cl == null) {
100            cl = LoaderUtil.getThreadContextClassLoader();
101        }
102        return LogManager.getContext(cl, false);
103    }
104
105    @Override
106    public void close() {
107        registry.clear();
108    }
109}