    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
    021    /**
    022     * Service provider interface to implement custom MDC behavior for {@link org.apache.logging.log4j.ThreadContext}.
    023     */
    024    public interface ThreadContextMap {
    025        /**
    026         * Put a context value (the <code>o</code> parameter) as identified
    027         * with the <code>key</code> parameter into the current thread's
    028         * context map.
    029         *
    030         * <p>If the current thread does not have a context map it is
    031         * created as a side effect.</p>
    032         * @param key The key name.
    033         * @param value The key value.
    034         */
    035        void put(final String key, final String value);
    036
    037        /**
    038         * Get the context identified by the <code>key</code> parameter.
    039         *
    040         * <p>This method has no side effects.</p>
    041         * @param key The key to locate.
    042         * @return The value associated with the key or null.
    043         */
    044        String get(final String key);
    045
    046        /**
    047         * Remove the the context identified by the <code>key</code>
    048         * parameter.
    049         * @param key The key to remove.
    050         */
    051        void remove(final String key);
    052
    053        /**
    054         * Clear the context.
    055         */
    056        void clear();
    057
    058        /**
    059         * Determine if the key is in the context.
    060         * @param key The key to locate.
    061         * @return True if the key is in the context, false otherwise.
    062         */
    063        boolean containsKey(final String key);
    064
    065        /**
    066         * Get a non-{@code null} mutable copy of current thread's context Map.
    067         * @return a mutable copy of the context.
    068         */
    069        Map<String, String> getCopy();
    070
    071        /**
    072         * Return an immutable view on the context Map or {@code null} if the context map is empty.
    073         * @return an immutable context Map or {@code null}.
    074         */
    075        Map<String, String> getImmutableMapOrNull();
    076
    077        /**
    078         * Returns true if the Map is empty.
    079         * @return true if the Map is empty, false otherwise.
    080         */
    081        boolean isEmpty();
    082    }