    001/**
    002 * Copyright (c) 2004-2011 QOS.ch
    003 * All rights reserved.
    004 *
    005 * Permission is hereby granted, free  of charge, to any person obtaining
    006 * a  copy  of this  software  and  associated  documentation files  (the
    007 * "Software"), to  deal in  the Software without  restriction, including
    008 * without limitation  the rights to  use, copy, modify,  merge, publish,
    009 * distribute,  sublicense, and/or sell  copies of  the Software,  and to
    010 * permit persons to whom the Software  is furnished to do so, subject to
    011 * the following conditions:
    012 *
    013 * The  above  copyright  notice  and  this permission  notice  shall  be
    014 * included in all copies or substantial portions of the Software.
    015 *
    016 * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
    017 * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
    018 * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
    019 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
    020 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    021 * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
    022 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    023 *
    024 */
    025package org.slf4j.helpers;
    026
    027import org.slf4j.spi.MDCAdapter;
    028
    029import java.util.*;
    030import java.util.Map;
    031
    032/**
    033 * Basic MDC implementation, which can be used with logging systems that lack
    034 * out-of-the-box MDC support.
    035 *
    036 * This code was initially inspired by  logback's LogbackMDCAdapter. However,
    037 * LogbackMDCAdapter has evolved and is now considerably more sophisticated.
    038 *
    039 * @author Ceki Gulcu
    040 * @author Maarten Bosteels
    041 * @author Lukasz Cwik
    042 *
    043 * @since 1.5.0
    044 */
    045public class BasicMDCAdapter implements MDCAdapter {
    046
    047    private InheritableThreadLocal<Map<String, String>> inheritableThreadLocal = new InheritableThreadLocal<Map<String, String>>() {
    048        @Override
    049        protected Map<String, String> childValue(Map<String, String> parentValue) {
    050            if (parentValue == null) {
    051                return null;
    052            }
    053            return new HashMap<String, String>(parentValue);
    054        }
    055    };
    056
    057    /**
    058     * Put a context value (the <code>val</code> parameter) as identified with
    059     * the <code>key</code> parameter into the current thread's context map.
    060     * Note that contrary to log4j, the <code>val</code> parameter can be null.
    061     *
    062     * <p>
    063     * If the current thread does not have a context map it is created as a side
    064     * effect of this call.
    065     *
    066     * @throws IllegalArgumentException
    067     *                 in case the "key" parameter is null
    068     */
    069    public void put(String key, String val) {
    070        if (key == null) {
    071            throw new IllegalArgumentException("key cannot be null");
    072        }
    073        Map<String, String> map = inheritableThreadLocal.get();
    074        if (map == null) {
    075            map = new HashMap<String, String>();
    076            inheritableThreadLocal.set(map);
    077        }
    078        map.put(key, val);
    079    }
    080
    081    /**
    082     * Get the context identified by the <code>key</code> parameter.
    083     */
    084    public String get(String key) {
    085        Map<String, String> map = inheritableThreadLocal.get();
    086        if ((map != null) && (key != null)) {
    087            return map.get(key);
    088        } else {
    089            return null;
    090        }
    091    }
    092
    093    /**
    094     * Remove the the context identified by the <code>key</code> parameter.
    095     */
    096    public void remove(String key) {
    097        Map<String, String> map = inheritableThreadLocal.get();
    098        if (map != null) {
    099            map.remove(key);
    100        }
    101    }
    102
    103    /**
    104     * Clear all entries in the MDC.
    105     */
    106    public void clear() {
    107        Map<String, String> map = inheritableThreadLocal.get();
    108        if (map != null) {
    109            map.clear();
    110            inheritableThreadLocal.remove();
    111        }
    112    }
    113
    114    /**
    115     * Returns the keys in the MDC as a {@link Set} of {@link String}s The
    116     * returned value can be null.
    117     *
    118     * @return the keys in the MDC
    119     */
    120    public Set<String> getKeys() {
    121        Map<String, String> map = inheritableThreadLocal.get();
    122        if (map != null) {
    123            return map.keySet();
    124        } else {
    125            return null;
    126        }
    127    }
    128
    129    /**
    130     * Return a copy of the current thread's context map.
    131     * Returned value may be null.
    132     *
    133     */
    134    public Map<String, String> getCopyOfContextMap() {
    135        Map<String, String> oldMap = inheritableThreadLocal.get();
    136        if (oldMap != null) {
    137            return new HashMap<String, String>(oldMap);
    138        } else {
    139            return null;
    140        }
    141    }
    142
    143    public void setContextMap(Map<String, String> contextMap) {
    144        inheritableThreadLocal.set(new HashMap<String, String>(contextMap));
    145    }
    146}