MDCAdapter.java

/* 
 * Copyright (c) 2004-2007 QOS.ch
 * All rights reserved.
 * 
 * Permission is hereby granted, free  of charge, to any person obtaining
 * a  copy  of this  software  and  associated  documentation files  (the
 * "Software"), to  deal in  the Software without  restriction, including
 * without limitation  the rights to  use, copy, modify,  merge, publish,
 * distribute,  sublicense, and/or sell  copies of  the Software,  and to
 * permit persons to whom the Software  is furnished to do so, subject to
 * the following conditions:
 * 
 * The  above  copyright  notice  and  this permission  notice  shall  be
 * included in all copies or substantial portions of the Software.
 * 
 * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
 * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
 * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package org.slf4j.spi;

import java.util.Map;

/**
 * This interface abstracts the service offered by various MDC
 * implementations.
 * 
 * @author Ceki Gülcü
 * @since 1.4.1
 */
public interface MDCAdapter {

  /**
   * Put a context value (the <code>val</code> parameter) as identified with
   * the <code>key</code> parameter into the current thread's context map. 
   * The <code>key</code> parameter cannot be null. The code>val</code> parameter 
   * can be null only if the underlying implementation supports it.
   * 
   * <p>If the current thread does not have a context map it is created as a side
   * effect of this call.
   */
  public void put(String key, String val);

  /**
   * Get the context identified by the <code>key</code> parameter.
   * The <code>key</code> parameter cannot be null.
   * 
   * @return the string value identified by the <code>key</code> parameter.
   */
  public String get(String key);

  /**
   * Remove the the context identified by the <code>key</code> parameter. 
   * The <code>key</code> parameter cannot be null. 
   * 
   * <p>
   * This method does nothing if there is no previous value 
   * associated with <code>key</code>.
   */
  public void remove(String key);

  /**
   * Clear all entries in the MDC.
   */
  public void clear();

  /**
   * Return a copy of the current thread's context map, with keys and 
   * values of type String. Returned value may be null.
   * 
   * @return A copy of the current thread's context map. May be null.
   * @since 1.5.1
   */
  public Map getCopyOfContextMap();
  
  /**
   * Set the current thread's context map by first clearing any existing 
   * map and then copying the map passed as parameter. The context map 
   * parameter must only contain keys and values of type String.
   * 
   * @param contextMap must contain only keys and values of type String
   * 
   * @since 1.5.1
   */
  public void setContextMap(Map contextMap);
}