    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.log4j;
    018
    019    import java.util.HashMap;
    020    import java.util.Hashtable;
    021    import java.util.Map;
    022
    023    import org.apache.logging.log4j.ThreadContext;
    024
    025    /**
    026     * This class behaves just like Log4j's MDC would - and so can cause issues with the redeployment of web
    027     * applications if the Objects stored in the threads Map cannot be garbage collected.
    028     */
    029    public final class MDC {
    030
    031
    032        private static ThreadLocal<Map<String, Object>> localMap =
    033            new InheritableThreadLocal<Map<String, Object>>() {
    034                @Override
    035                protected Map<String, Object> initialValue() {
    036                    return new HashMap<String, Object>();
    037                }
    038
    039                @Override
    040                protected Map<String, Object> childValue(final Map<String, Object> parentValue) {
    041                    return parentValue == null ? new HashMap<String, Object>() : new HashMap<String, Object>(parentValue);
    042                }
    043            };
    044
    045        private MDC() {
    046        }
    047
    048
    049        public static void put(final String key, final String value) {
    050            localMap.get().put(key, value);
    051            ThreadContext.put(key, value);
    052        }
    053
    054
    055        public static void put(final String key, final Object value) {
    056            localMap.get().put(key, value);
    057            ThreadContext.put(key, value.toString());
    058        }
    059
    060        public static Object get(final String key) {
    061            return localMap.get().get(key);
    062        }
    063
    064        public static void remove(final String key) {
    065            localMap.get().remove(key);
    066            ThreadContext.remove(key);
    067        }
    068
    069        public static void clear() {
    070            localMap.get().clear();
    071            ThreadContext.clearMap();
    072        }
    073
    074        public static Hashtable<String, Object> getContext() {
    075            return new Hashtable<String, Object>(localMap.get());
    076        }
    077    }