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.
*
* Example:
*
* {@example ../../examples/php/mdc.php 19}
*
* With the properties file:
*
* {@example ../../examples/resources/mdc.properties 18}
*
* Will result in the following (notice the username "knut" in the output):
*
*
* 2009-09-13 18:48:28 DEBUG root knut: Testing MDC in src/examples/php/mdc.php at 23
*
*
* @version $Revision$
* @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.
*
* Special key identifiers can be used to map values in the global $_SERVER
* and $_ENV vars. To access them, use 'server.' or 'env.' followed by the
* desired var name as the key.
*
* @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) {
if(!empty($key)) {
if(strpos($key, 'server.') === 0) {
$varName = substr($key, 7);
return isset($_SERVER[$varName]) ? $_SERVER[$varName] : '';
} else if(strpos($key, 'env.') === 0) {
$varName = substr($key, 4);
$value = getenv($varName);
return ($value !== false) ? $value : '';
} else {
return isset(self::$map[$key]) ? self::$map[$key] : '';
}
}
return '';
}
/**
* Returns the contex map as an array.
* @return array The MDC context map.
*/
public static function getMap() {
return self::$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();
}
}