<?php
  /**
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements. See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License. You may obtain a copy of the License at
   *
   *	   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   *
   * @package log4php
   */
  
  /**
   * The LoggerMDC class provides _mapped diagnostic contexts_.
   * 
   * A Mapped Diagnostic Context, or MDC in short, is an instrument for 
   * distinguishing interleaved log output from different sources. Log output 
   * is typically interleaved when a server handles multiple clients 
   * near-simultaneously.
   * 
   * This class is similar to the {@link LoggerNDC} class except that 
   * it is based on a map instead of a stack.
   * 
   * @version $Revision: 1343630 $
   * @since 0.3
   * @package log4php
   */
  class LoggerMDC {
  	
  	/** Holds the context map. */
  	private static $map = array();
  		
  	/**
  	 * Stores a context value as identified with the key parameter into the 
  	 * context map.
  	 *
  	 * @param string $key the key
  	 * @param string $value the value
  	 */
  	public static function put($key, $value) {
  		self::$map[$key] = $value;
  	}
    
  	/**
  	 * Returns the context value identified by the key parameter.
  	 *
  	 * @param string $key The key.
  	 * @return string The context or an empty string if no context found
  	 * 	for given key.
  	 */
  	public static function get($key) {
  		return isset(self::$map[$key]) ? self::$map[$key] : '';
  	}
  
  	/**
  	 * Returns the contex map as an array.
  	 * @return array The MDC context map.
  	 */
  	public static function getMap() {
  		return self::$map;
  	}
  
  	/**
  	 * Removes the the context identified by the key parameter. 
  	 *
  	 * Only affects user mappings, not $_ENV or $_SERVER.
  	 *
  	 * @param string $key The key to be removed.
  	 */
  	public static function remove($key) {
  		unset(self::$map[$key]);
  	}
  	
  	/**
  	 * Clears the mapped diagnostic context.
  	 */
  	public static function clear() {
  		self::$map = array();
  	}
  }