/demo/scalr_newui/app/src/Lib/IO/Logging/log4php/src/main/php/LoggerNDC.php

<?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

 */



/**

 * @ignore 

 */

if (!defined('LOG4PHP_DIR')) define('LOG4PHP_DIR', dirname(__FILE__)); 

 

/**

 */

require_once(LOG4PHP_DIR . '/LoggerLog.php');



define('LOGGER_NDC_HT_SIZE', 7);



/**

 * This is the global repository of NDC stack

 */

$GLOBALS['log4php.LoggerNDC.ht'] = array();



/**

 * This is the max depth of NDC stack

 */

$GLOBALS['log4php.LoggerNDC.maxDepth'] = LOGGER_NDC_HT_SIZE;





/**

 * The NDC class implements <i>nested diagnostic contexts</i> as

 * defined by Neil Harrison in the article "Patterns for Logging

 * Diagnostic Messages" part of the book "<i>Pattern Languages of

 * Program Design 3</i>" edited by Martin et al.

 *

 * <p>A Nested Diagnostic Context, or NDC in short, is an instrument

 * to distinguish interleaved log output from different sources. Log

 * output is typically interleaved when a server handles multiple

 * clients near-simultaneously.

 *

 * <p>Interleaved log output can still be meaningful if each log entry

 * from different contexts had a distinctive stamp. This is where NDCs

 * come into play.

 *

 * <p><i><b>Note that NDCs are managed on a per thread

 * basis</b></i>. NDC operations such as {@link push()}, {@link pop()}, 

 * {@link clear()}, {@link getDepth()} and {@link setMaxDepth()}

 * affect the NDC of the <i>current</i> thread only. NDCs of other

 * threads remain unaffected.

 *

 * <p>For example, a servlet can build a per client request NDC

 * consisting the clients host name and other information contained in

 * the the request. <i>Cookies</i> are another source of distinctive

 * information. To build an NDC one uses the {@link push()}

 * operation.</p>

 * 

 * Simply put,

 *

 * - Contexts can be nested.

 * - When entering a context, call 

 *   <code>LoggerNDC::push()</code>

 *   As a side effect, if there is no nested diagnostic context for the

 *   current thread, this method will create it.

 * - When leaving a context, call 

 *   <code>LoggerNDC::pop()</code>

 * - <b>When exiting a thread make sure to call {@link remove()}</b>

 *   

 * <p>There is no penalty for forgetting to match each

 * <code>push</code> operation with a corresponding <code>pop</code>,

 * except the obvious mismatch between the real application context

 * and the context set in the NDC.</p>

 *

 * <p>If configured to do so, {@link LoggerPatternLayout} and {@link LoggerLayoutTTCC} 

 * instances automatically retrieve the nested diagnostic

 * context for the current thread without any user intervention.

 * Hence, even if a servlet is serving multiple clients

 * simultaneously, the logs emanating from the same code (belonging to

 * the same category) can still be distinguished because each client

 * request will have a different NDC tag.</p>

 *

 *  

 * @author  Marco Vassura

 * @version $Revision: 635069 $

 * @package log4php 

 * @since 0.3

 */

class LoggerNDC {



    /**

     * Clear any nested diagnostic information if any. This method is

     * useful in cases where the same thread can be potentially used

     * over and over in different unrelated contexts.

     *

     * <p>This method is equivalent to calling the {@link setMaxDepth()}

     * method with a zero <var>maxDepth</var> argument.

     *

     * @static  

     */

    public static function clear()

    {

        LoggerLog::debug("LoggerNDC::clear()");

        

        $GLOBALS['log4php.LoggerNDC.ht'] = array();

    }



    /**

     * Never use this method directly, use the {@link LoggerLoggingEvent::getNDC()} method instead.

     * @static

     * @return array

     */

    public static function get()

    {

        LoggerLog::debug("LoggerNDC::get()");

    

        return $GLOBALS['log4php.LoggerNDC.ht'];

    }

  

    /**

     * Get the current nesting depth of this diagnostic context.

     *

     * @see setMaxDepth()

     * @return integer

     * @static

     */

    public static function getDepth()

    {

        LoggerLog::debug("LoggerNDC::getDepth()");

    

        return sizeof($GLOBALS['log4php.LoggerNDC.ht']);      

    }



    /**

     * Clients should call this method before leaving a diagnostic

     * context.

     *

     * <p>The returned value is the value that was pushed last. If no

     * context is available, then the empty string "" is returned.</p>

     *

     * @return string The innermost diagnostic context.

     * @static

     */

    public static function pop()

    {

        LoggerLog::debug("LoggerNDC::pop()");

    

        if (sizeof($GLOBALS['log4php.LoggerNDC.ht']) > 0) {

            return array_pop($GLOBALS['log4php.LoggerNDC.ht']);

        } else {

            return '';

        }

    }



    /**

     * Looks at the last diagnostic context at the top of this NDC

     * without removing it.

     *

     * <p>The returned value is the value that was pushed last. If no

     * context is available, then the empty string "" is returned.</p>

     * @return string The innermost diagnostic context.

     * @static

     */

    public static function peek()

    {

        LoggerLog::debug("LoggerNDC::peek()");

    

        if (sizeof($GLOBALS['log4php.LoggerNDC.ht']) > 0) {

            return end($GLOBALS['log4php.LoggerNDC.ht']);

        } else {

            return '';

        }

    }

  

    /**

     * Push new diagnostic context information for the current thread.

     *

     * <p>The contents of the <var>message</var> parameter is

     * determined solely by the client.

     *  

     * @param string $message The new diagnostic context information.

     * @static  

     */

    public static function push($message)

    {

        LoggerLog::debug("LoggerNDC::push()");

    

        array_push($GLOBALS['log4php.LoggerNDC.ht'], (string)$message);

    }



    /**

     * Remove the diagnostic context for this thread.

     * @static

     */

    public static function remove()

    {

        LoggerLog::debug("LoggerNDC::remove()");

    

        LoggerNDC::clear();

    }



    /**

     * Set maximum depth of this diagnostic context. If the current

     * depth is smaller or equal to <var>maxDepth</var>, then no

     * action is taken.

     *

     * <p>This method is a convenient alternative to multiple 

     * {@link pop()} calls. Moreover, it is often the case that at 

     * the end of complex call sequences, the depth of the NDC is

     * unpredictable. The {@link setMaxDepth()} method circumvents

     * this problem.

     *

     * @param integer $maxDepth

     * @see getDepth()

     * @static

     */

    public static function setMaxDepth($maxDepth)

    {

        LoggerLog::debug("LoggerNDC::setMaxDepth() maxDepth='$maxDepth'");

    

        $maxDepth = (int)$maxDepth;

        if ($maxDepth <= LOGGER_NDC_HT_SIZE) {

            if (LoggerNDC::getDepth() > $maxDepth) {

                $GLOBALS['log4php.LoggerNDC.ht'] = array_slice($GLOBALS['log4php.LoggerNDC.ht'], $maxDepth);

            }

            $GLOBALS['log4php.LoggerNDC.maxDepth'] = $maxDepth;            

        }

    }

  

}