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.spi;
018
019 import java.util.Map;
020 import java.util.WeakHashMap;
021 import java.util.concurrent.ConcurrentHashMap;
022 import java.util.concurrent.ConcurrentMap;
023
024 import org.apache.logging.log4j.LogManager;
025 import 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 */
032 public 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 }