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;
020
021/**
022 * Service provider interface to implement custom MDC behavior for {@link org.apache.logging.log4j.ThreadContext}.
023 */
024public 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}