diff --git a/wp-common b/wp-common
index 2749265..d12b345 160000
--- a/wp-common
+++ b/wp-common
@@ -1 +1 @@
-Subproject commit 2749265f11b2c2e9d34cc35aa74aca55b2b1b93b
+Subproject commit d12b345560c77634b25fc8ee7571c19730794c69
diff --git a/wp-ffpc-backend.php b/wp-ffpc-backend.php
index c26a783..9923c33 100644
--- a/wp-ffpc-backend.php
+++ b/wp-ffpc-backend.php
@@ -1,992 +1,973 @@
 <?php
+
+if (!class_exists('WP_FFPC_Backend')) :
+
+include_once ( 'wp-common/plugin_utils.php');
 /**
- * backend driver for WordPress plugin WP-FFPC
  *
- * supported storages:
- *  - APC
- *  - Memcached
- *  - Memcache
+ * @var string	$plugin_constant	Namespace of the plugin
+ * @var mixed	$connection	Backend object storage variable
+ * @var boolean	$alive		Alive flag of backend connection
+ * @var boolean $network	WordPress Network flag
+ * @var array	$options	Configuration settings array
+ * @var array	$status		Backends status storage
+ * @var array	$cookies	Logged in cookies to search for
+ * @var array	$urimap		Map to render key with
+ * @var object	$utilities	Utilities singleton
  *
  */
+class WP_FFPC_Backend {
 
-if (!class_exists('WP_FFPC_Backend')) {
+	const network_key = 'network';
+	const host_separator  = ',';
+	const port_separator  = ':';
 
-	/* get the plugin abstract class*/
-	include_once ( 'wp-common/wp-plugin-utilities.php');
+	private $plugin_constant = 'wp-ffpc';
+	private $connection = NULL;
+	private $alive = false;
+	private $network = false;
+	private $options = array();
+	private $status = array();
+	public $cookies = array();
+	private $urimap = array();
+	private $utilities;
 
+	/**
+	* constructor
+	*
+	* @param mixed $config Configuration options
+	* @param boolean $network WordPress Network indicator flah
+	*
+	*/
+	public function __construct( $config, $network = false ) {
+
+		/* no config, nothing is going to work */
+		if ( empty ( $config ) ) {
+			return false;
+			//die ( __translate__ ( 'WP-FFPC Backend class received empty configuration array, the plugin will not work this way', $this->plugin_constant ) );
+		}
+
+		/* set config */
+		$this->options = $config;
+
+		/* set network flag */
+		$this->network = $network;
+
+		/* these are the list of the cookies to look for when looking for logged in user */
+		$this->cookies = array ( 'comment_author_' , 'wordpressuser_' , 'wp-postpass_', 'wordpress_logged_in_' );
+
+		/* make utilities singleton */
+		$this->utilities = PluginUtils::S();
+
+		/* map the key with the predefined schemes */
+		$ruser = isset ( $_SERVER['REMOTE_USER'] ) ? $_SERVER['REMOTE_USER'] : '';
+		$ruri = isset ( $_SERVER['REQUEST_URI'] ) ? $_SERVER['REQUEST_URI'] : '';
+		$rhost = isset ( $_SERVER['HTTP_HOST'] ) ? $_SERVER['HTTP_HOST'] : '';
+		$scookie = isset ( $_COOKIE['PHPSESSID'] ) ? $_COOKIE['PHPSESSID'] : '';
+
+		$this->urimap = array(
+			'$scheme' => str_replace ( '://', '', $this->utilities->replace_if_ssl ( 'http://' ) ),
+			'$host' => $rhost,
+			'$request_uri' => $ruri,
+			'$remote_user' => $ruser,
+			'$cookie_PHPSESSID' => $scookie,
+		);
+
+		/* split hosts entry to servers */
+		$this->set_servers();
+
+		/* call backend initiator based on cache type */
+		$init = $this->proxy( 'init' );
+
+		/* info level */
+		$this->log (  __translate__('init starting', $this->plugin_constant ));
+		$this->$init();
 
-	/* __ only availabe if we're running from the inside of wordpress, not in advanced-cache.php phase */
-	if ( function_exists ( '__' ) ) {
-		function __translate__ ( $text, $domain ) { return __($text, $domain); }
 	}
-	else {
-		function __translate__ ( $text, $domain ) { return $text; }
+
+	/*********************** PUBLIC / PROXY FUNCTIONS ***********************/
+
+	/**
+	 * build key to make requests with
+	 *
+	 * @param string $prefix prefix to add to prefix
+	 *
+	 */
+	public function key ( &$prefix ) {
+		/* data is string only with content, meta is not used in nginx */
+		$key = $prefix . str_replace ( array_keys( $this->urimap ), $this->urimap, $this->options['key'] );
+		$this->log ( sprintf( __translate__( 'original key configuration: %s', $this->plugin_constant ),  $this->options['key'] ) );
+		$this->log ( sprintf( __translate__( 'setting key to: %s', $this->plugin_constant ),  $key ) );
+		return $key;
+	}
+
+
+	/**
+	 * public get function, transparent proxy to internal function based on backend
+	 *
+	 * @param string $key Cache key to get value for
+	 *
+	 * @return mixed False when entry not found or entry value on success
+	 */
+	public function get ( &$key ) {
+
+		/* look for backend aliveness, exit on inactive backend */
+		if ( ! $this->is_alive() )
+			return false;
+
+		/* log the current action */
+		$this->log ( sprintf( __translate__( 'get %s', $this->plugin_constant ),  $key ) );
+
+		/* proxy to internal function */
+		$internal = $this->proxy( 'get' );
+		$result = $this->$internal( $key );
+
+		if ( $result === false  )
+			$this->log ( sprintf( __translate__( 'failed to get entry: %s', $this->plugin_constant ),  $key ) );
+
+		return $result;
+	}
+
+	/**
+	 * public set function, transparent proxy to internal function based on backend
+	 *
+	 * @param string $key Cache key to set with ( reference only, for speed )
+	 * @param mixed $data Data to set ( reference only, for speed )
+	 *
+	 * @return mixed $result status of set function
+	 */
+	public function set ( &$key, &$data ) {
+
+		/* look for backend aliveness, exit on inactive backend */
+		if ( ! $this->is_alive() )
+			return false;
+
+		/* log the current action */
+		$this->log ( sprintf( __translate__( 'set %s expiration time: %s', $this->plugin_constant ),  $key, $this->options['expire'] ) );
+
+		/* proxy to internal function */
+		$internal = $this->proxy( 'set' );
+		$result = $this->$internal( $key, $data );
+
+		/* check result validity */
+		if ( $result === false )
+			$this->log ( sprintf( __translate__( 'failed to set entry: %s', $this->plugin_constant ),  $key ), LOG_WARNING );
+
+		return $result;
+	}
+
+	/**
+	 * public get function, transparent proxy to internal function based on backend
+	 *
+	 * @param string $post_id	ID of post to invalidate
+	 * @param boolean $force 	Force flush cache
+	 * @param boolean $comment	Clear a single page based on comment trigger
+	 *
+	 */
+	public function clear ( $post_id = false, $force = false ) {
+
+		/* look for backend aliveness, exit on inactive backend */
+		if ( ! $this->is_alive() )
+			return false;
+
+		/* exit if no post_id is specified */
+		if ( empty ( $post_id ) && $force === false ) {
+			$this->log (  __translate__('not clearing unidentified post ', $this->plugin_constant ), LOG_WARNING );
+			return false;
+		}
+
+		/* if invalidation method is set to full, flush cache */
+		if ( ( $this->options['invalidation_method'] === 0 || $force === true ) ) {
+			/* log action */
+			$this->log (  __translate__('flushing cache', $this->plugin_constant ) );
+
+			/* proxy to internal function */
+			$internal = $this->proxy ( 'flush' );
+			$result = $this->$internal();
+
+			if ( $result === false )
+				$this->log (  __translate__('failed to flush cache', $this->plugin_constant ), LOG_WARNING );
+
+			return $result;
+		}
+
+		/* storage for entries to clear */
+		$to_clear = array();
+
+		/* clear taxonomies if settings requires it */
+		if ( $this->options['invalidation_method'] == 2 ) {
+			/* this will only clear the current blog's entries */
+			$this->taxonomy_links( $to_clear );
+		}
+
+		/* if there's a post id pushed, it needs to be invalidated in all cases */
+		if ( !empty ( $post_id ) ) {
+
+			/* need permalink functions */
+			if ( !function_exists('get_permalink') )
+				include_once ( ABSPATH . 'wp-includes/link-template.php' );
+
+			/* get path from permalink */
+			$path = substr ( get_permalink( $post_id ) , 7 );
+
+			/* no path, don't do anything */
+			if ( empty( $path ) ) {
+				$this->log ( sprintf( __translate__( 'unable to determine path from Post Permalink, post ID: %s', $this->plugin_constant ),  $post_id ), LOG_WARNING );
+				return false;
+			}
+
+			if ( isset($_SERVER['HTTPS']) && ( ( strtolower($_SERVER['HTTPS']) == 'on' )  || ( $_SERVER['HTTPS'] == '1' ) ) )
+				$protocol = 'https://';
+			else
+				$protocol = 'http://';
+
+			/* elements to clear
+			   values are keys, faster to process and eliminates duplicates
+			*/
+			$to_clear[ $protocol . $path ] = true;
+		}
+
+		foreach ( $to_clear as $link => $dummy ) {
+			/* clear all feeds as well */
+			$to_clear[ $link. 'feed' ] = true;
+		}
+
+		/* add data & meta prefixes */
+		foreach ( $to_clear as $link => $dummy ) {
+			unset ( $to_clear [ $link ]);
+			$to_clear[ $this->options[ 'prefix_meta' ] . $link ] = true;
+			$to_clear[ $this->options[ 'prefix_data' ] . $link ] = true;
+		}
+
+		/* run clear */
+		$internal = $this->proxy ( 'clear' );
+		$this->$internal ( $to_clear );
+	}
+
+	/**
+	 * clear cache triggered by new comment
+	 *
+	 * @param $comment_id	Comment ID
+	 * @param $comment_object	The whole comment object ?
+	 */
+	public function clear_by_comment ( $comment_id, $comment_object ) {
+		if ( empty( $comment_id ) )
+			return false;
+
+		$comment = get_comment( $comment_id );
+		$post_id = $comment->comment_post_ID;
+		if ( !empty( $post_id ) )
+			$this->clear ( $post_id );
+
+		unset ( $comment );
+		unset ( $post_id );
+	}
+
+	/**
+	 * to collect all permalinks of all taxonomy terms used in invalidation & precache
+	 *
+	 * @param array &$links Passed by reference array that has to be filled up with the links
+	 * @param mixed $site Site ID or false; used in WordPress Network
+	 *
+	 */
+	public function taxonomy_links ( &$links, $site = false ) {
+
+		if ( $site !== false ) {
+			$current_blog = get_current_blog_id();
+			switch_to_blog( $site );
+
+			$url = get_blog_option ( $site, 'siteurl' );
+			if ( substr( $url, -1) !== '/' )
+				$url = $url . '/';
+
+			$links[ $url ] = true;
+		}
+
+		/* we're only interested in public taxonomies */
+		$args = array(
+			'public'   => true,
+		);
+
+		/* get taxonomies as objects */
+		$taxonomies = get_taxonomies( $args, 'objects' );
+
+		if ( !empty( $taxonomies ) ) {
+			foreach ( $taxonomies  as $taxonomy ) {
+				/* reset array, just in case */
+				$terms = array();
+
+				/* get all the terms for this taxonomy, only if not empty */
+				$sargs = array(
+					'hide_empty'    => true,
+					'fields'        => 'all',
+					'hierarchical'  =>false,
+				);
+				$terms = get_terms ( $taxonomy->name , $sargs );
+
+				if ( !empty ( $terms ) ) {
+					foreach ( $terms as $term ) {
+						/* get the permalink for the term */
+						$link = get_term_link ( $term->slug, $taxonomy->name );
+						/* add to container */
+						$links[ $link ] = true;
+						/* remove the taxonomy name from the link, lots of plugins remove this for SEO, it's better to include them than leave them out
+						   in worst case, we cache some 404 as well
+						*/
+						$link = str_replace ( '/'.$taxonomy->rewrite['slug'], '', $link  );
+						/* add to container */
+						$links[ $link ] = true;
+					}
+				}
+			}
+		}
+
+		/* switch back to original site if we navigated away */
+		if ( $site !== false ) {
+			switch_to_blog( $current_blog );
+		}
+
+	}
+
+	/**
+	 * get backend aliveness
+	 *
+	 * @return array Array of configured servers with aliveness value
+	 *
+	 */
+	public function status () {
+
+		/* look for backend aliveness, exit on inactive backend */
+		if ( ! $this->is_alive() )
+			return false;
+
+		$internal = $this->proxy ( 'status' );
+		$this->$internal();
+		return $this->status;
+	}
+
+	/**
+	 * backend proxy function name generator
+	 *
+	 * @return string Name of internal function based on cache_type
+	 *
+	 */
+	private function proxy ( $method ) {
+		return $this->options['cache_type'] . '_' . $method;
+	}
+
+	/**
+	 * function to check backend aliveness
+	 *
+	 * @return boolean true if backend is alive, false if not
+	 *
+	 */
+	private function is_alive() {
+		if ( ! $this->alive ) {
+			$this->log (  __translate__("backend is not active, exiting function ", $this->plugin_constant ) . __FUNCTION__, LOG_WARNING );
+			return false;
+		}
+
+		return true;
+	}
+
+	/**
+	 * split hosts string to backend servers
+	 *
+	 *
+	 */
+	private function set_servers () {
+		/* replace servers array in config according to hosts field */
+		$servers = explode( self::host_separator , $this->options['hosts']);
+
+		$options['servers'] = array();
+
+		foreach ( $servers as $snum => $sstring ) {
+
+			$separator = strpos( $sstring , self::port_separator );
+			$host = substr( $sstring, 0, $separator );
+			$port = substr( $sstring, $separator + 1 );
+			// unix socket failsafe
+			if ( empty ($port) ) $port = 0;
+
+			$this->options['servers'][$sstring] = array (
+				'host' => $host,
+				'port' => $port
+			);
+		}
+
+	}
+
+	/**
+	 * get current array of servers
+	 *
+	 * @return array Server list in current config
+	 *
+	 */
+	public function get_servers () {
+		$r = isset ( $this->options['servers'] ) ? $this->options['servers'] : '';
+		return $r;
+	}
+
+	/**
+	 * log wrapper to include options
+	 *
+	 * @var mixed $message Message to log
+	 * @var int $log_level Log level
+	 */
+	private function log ( $message, $log_level = LOG_WARNING ) {
+		if ( !isset ( $this->options['log'] ) || $this->options['log'] != 1 )
+			return false;
+		else
+			$this->utilities->log ( $this->plugin_constant , $message, $log_level );
+	}
+
+	/*********************** END PUBLIC FUNCTIONS ***********************/
+	/*********************** APC FUNCTIONS ***********************/
+	/**
+	 * init apc backend: test APC availability and set alive status
+	 */
+	private function apc_init () {
+		/* verify apc functions exist, apc extension is loaded */
+		if ( ! function_exists( 'apc_cache_info' ) ) {
+			$this->log (  __translate__('APC extension missing', $this->plugin_constant ) );
+			return false;
+		}
+
+		/* verify apc is working */
+		if ( apc_cache_info("user",true) ) {
+			$this->log (  __translate__('backend OK', $this->plugin_constant ) );
+			$this->alive = true;
+		}
+	}
+
+	/**
+	 * health checker for APC
+	 *
+	 * @return boolean Aliveness status
+	 *
+	 */
+	private function apc_status () {
+		$this->status = true;
+		return $this->alive;
+	}
+
+	/**
+	 * get function for APC backend
+	 *
+	 * @param string $key Key to get values for
+	 *
+	 * @return mixed Fetched data based on key
+	 *
+	*/
+	private function apc_get ( &$key ) {
+		return apc_fetch( $key );
+	}
+
+	/**
+	 * Set function for APC backend
+	 *
+	 * @param string $key Key to set with
+	 * @param mixed $data Data to set
+	 *
+	 * @return boolean APC store outcome
+	 */
+	private function apc_set (  &$key, &$data ) {
+		return apc_store( $key , $data , $this->options['expire'] );
+	}
+
+
+	/**
+	 * Flushes APC user entry storage
+	 *
+	 * @return boolean APC flush outcome status
+	 *
+	*/
+	private function apc_flush ( ) {
+		return apc_clear_cache('user');
+	}
+
+	/**
+	 * Removes entry from APC or flushes APC user entry storage
+	 *
+	 * @param mixed $keys Keys to clear, string or array
+	*/
+	private function apc_clear ( &$keys ) {
+		/* make an array if only one string is present, easier processing */
+		if ( !is_array ( $keys ) )
+			$keys = array ( $keys => true );
+
+		foreach ( $keys as $key => $dummy ) {
+			if ( ! apc_delete ( $key ) ) {
+				$this->log ( sprintf( __translate__( 'Failed to delete APC entry: %s', $this->plugin_constant ),  $key ), LOG_ERR );
+				//throw new Exception ( __translate__('Deleting APC entry failed with key ', $this->plugin_constant ) . $key );
+			}
+			else {
+				$this->log ( sprintf( __translate__( 'APC entry delete: %s', $this->plugin_constant ),  $key ) );
+			}
+		}
+	}
+
+	/*********************** END APC FUNCTIONS ***********************/
+	/*********************** APCu FUNCTIONS ***********************/
+	/**
+	 * init apcu backend: test APCu availability and set alive status
+	 */
+	private function apcu_init () {
+		/* verify apcu functions exist, apcu extension is loaded */
+		if ( ! function_exists( 'apcu_cache_info' ) ) {
+			$this->log (  __translate__('APCu extension missing', $this->plugin_constant ) );
+			return false;
+		}
+
+		/* verify apcu is working */
+		if ( apcu_cache_info("user",true) ) {
+			$this->log (  __translate__('backend OK', $this->plugin_constant ) );
+			$this->alive = true;
+		}
+	}
+
+	/**
+	 * health checker for APC
+	 *
+	 * @return boolean Aliveness status
+	 *
+	 */
+	private function apcu_status () {
+		$this->status = true;
+		return $this->alive;
+	}
+
+	/**
+	 * get function for APC backend
+	 *
+	 * @param string $key Key to get values for
+	 *
+	 * @return mixed Fetched data based on key
+	 *
+	*/
+	private function apcu_get ( &$key ) {
+		return apcu_fetch( $key );
+	}
+
+	/**
+	 * Set function for APC backend
+	 *
+	 * @param string $key Key to set with
+	 * @param mixed $data Data to set
+	 *
+	 * @return boolean APC store outcome
+	 */
+	private function apcu_set (  &$key, &$data ) {
+		return apcu_store( $key , $data , $this->options['expire'] );
+	}
+
+
+	/**
+	 * Flushes APC user entry storage
+	 *
+	 * @return boolean APC flush outcome status
+	 *
+	*/
+	private function apcu_flush ( ) {
+		return apcu_clear_cache();
+	}
+
+	/**
+	 * Removes entry from APC or flushes APC user entry storage
+	 *
+	 * @param mixed $keys Keys to clear, string or array
+	*/
+	private function apcu_clear ( &$keys ) {
+		/* make an array if only one string is present, easier processing */
+		if ( !is_array ( $keys ) )
+			$keys = array ( $keys => true );
+
+		foreach ( $keys as $key => $dummy ) {
+			if ( ! apcu_delete ( $key ) ) {
+				$this->log ( sprintf( __translate__( 'Failed to delete APC entry: %s', $this->plugin_constant ),  $key ), LOG_ERR );
+				//throw new Exception ( __translate__('Deleting APC entry failed with key ', $this->plugin_constant ) . $key );
+			}
+			else {
+				$this->log ( sprintf( __translate__( 'APC entry delete: %s', $this->plugin_constant ),  $key ) );
+			}
+		}
+	}
+
+	/*********************** END APC FUNCTIONS ***********************/
+
+	/*********************** XCACHE FUNCTIONS ***********************/
+	/**
+	 * init apc backend: test APC availability and set alive status
+	 */
+	private function xcache_init () {
+		/* verify apc functions exist, apc extension is loaded */
+		if ( ! function_exists( 'xcache_info' ) ) {
+			$this->log (  __translate__('XCACHE extension missing', $this->plugin_constant ) );
+			return false;
+		}
+
+		/* verify apc is working */
+		$info = xcache_info();
+		if ( !empty( $info )) {
+			$this->log (  __translate__('backend OK', $this->plugin_constant ) );
+			$this->alive = true;
+		}
+	}
+
+	/**
+	 * health checker for Xcache
+	 *
+	 * @return boolean Aliveness status
+	 *
+	 */
+	private function xcache_status () {
+		$this->status = true;
+		return $this->alive;
+	}
+
+	/**
+	 * get function for APC backend
+	 *
+	 * @param string $key Key to get values for
+	 *
+	 * @return mixed Fetched data based on key
+	 *
+	*/
+	private function xcache_get ( &$key ) {
+		if ( xcache_isset ( $key ) )
+			return xcache_get( $key );
+		else
+			return false;
+	}
+
+	/**
+	 * Set function for APC backend
+	 *
+	 * @param string $key Key to set with
+	 * @param mixed $data Data to set
+	 *
+	 * @return boolean APC store outcome
+	 */
+	private function xcache_set (  &$key, &$data ) {
+		return xcache_set( $key , $data , $this->options['expire'] );
+	}
+
+
+	/**
+	 * Flushes APC user entry storage
+	 *
+	 * @return boolean APC flush outcome status
+	 *
+	*/
+	private function xcache_flush ( ) {
+		return xcache_clear_cache(XC_TYPE_VAR);
+	}
+
+	/**
+	 * Removes entry from APC or flushes APC user entry storage
+	 *
+	 * @param mixed $keys Keys to clear, string or array
+	*/
+	private function xcache_clear ( &$keys ) {
+		/* make an array if only one string is present, easier processing */
+		if ( !is_array ( $keys ) )
+			$keys = array ( $keys => true );
+
+		foreach ( $keys as $key => $dummy ) {
+			if ( ! xcache_unset ( $key ) ) {
+				$this->log ( sprintf( __translate__( 'Failed to delete XCACHE entry: %s', $this->plugin_constant ),  $key ), LOG_ERR );
+				//throw new Exception ( __translate__('Deleting APC entry failed with key ', $this->plugin_constant ) . $key );
+			}
+			else {
+				$this->log ( sprintf( __translate__( 'XCACHE entry delete: %s', $this->plugin_constant ),  $key ) );
+			}
+		}
+	}
+
+	/*********************** END XCACHE FUNCTIONS ***********************/
+
+
+	/*********************** MEMCACHED FUNCTIONS ***********************/
+	/**
+	 * init memcached backend
+	 */
+	private function memcached_init () {
+		/* Memcached class does not exist, Memcached extension is not available */
+		if (!class_exists('Memcached')) {
+			$this->log (  __translate__(' Memcached extension missing', $this->plugin_constant ), LOG_ERR );
+			return false;
+		}
+
+		/* check for existing server list, otherwise we cannot add backends */
+		if ( empty ( $this->options['servers'] ) && ! $this->alive ) {
+			$this->log (  __translate__("Memcached servers list is empty, init failed", $this->plugin_constant ), LOG_WARNING );
+			return false;
+		}
+
+		/* check is there's no backend connection yet */
+		if ( $this->connection === NULL ) {
+			/* persistent backend needs an identifier */
+			if ( $this->options['persistent'] == '1' )
+				$this->connection = new Memcached( $this->plugin_constant );
+			else
+				$this->connection = new Memcached();
+
+			/* use binary and not compressed format, good for nginx and still fast */
+			$this->connection->setOption( Memcached::OPT_COMPRESSION , false );
+			$this->connection->setOption( Memcached::OPT_BINARY_PROTOCOL , true );
+
+			if ( version_compare( phpversion( 'memcached' ) , '2.0.0', '>=' ) && ini_get( 'memcached.use_sasl' ) == 1 ) {
+				$this->connection->setSaslAuthData ( $this->options['authuser'], $this->options['authpass']);
+			}
+		}
+
+		/* check if initialization was success or not */
+		if ( $this->connection === NULL ) {
+			$this->log (  __translate__( 'error initializing Memcached PHP extension, exiting', $this->plugin_constant ) );
+			return false;
+		}
+
+		/* check if we already have list of servers, only add server(s) if it's not already connected */
+		$servers_alive = array();
+		if ( !empty ( $this->status ) ) {
+			$servers_alive = $this->connection->getServerList();
+			/* create check array if backend servers are already connected */
+			if ( !empty ( $servers ) ) {
+				foreach ( $servers_alive as $skey => $server ) {
+					$skey =  $server['host'] . ":" . $server['port'];
+					$servers_alive[ $skey ] = true;
+				}
+			}
+		}
+
+		/* adding servers */
+		foreach ( $this->options['servers'] as $server_id => $server ) {
+			/* reset server status to unknown */
+			$this->status[$server_id] = -1;
+
+			/* only add servers that does not exists already  in connection pool */
+			if ( !@array_key_exists($server_id , $servers_alive ) ) {
+				$this->connection->addServer( $server['host'], $server['port'] );
+				$this->log ( sprintf( __translate__( '%s added, persistent mode: %s', $this->plugin_constant ),  $server_id, $this->options['persistent'] ) );
+			}
+		}
+
+		/* backend is now alive */
+		$this->alive = true;
+		$this->memcached_status();
+	}
+
+	/**
+	 * sets current backend alive status for Memcached servers
+	 *
+	 */
+	private function memcached_status () {
+		/* server status will be calculated by getting server stats */
+		$this->log (  __translate__("checking server statuses", $this->plugin_constant ));
+		/* get servers statistic from connection */
+		$report =  $this->connection->getStats();
+
+		foreach ( $report as $server_id => $details ) {
+			/* reset server status to offline */
+			$this->status[$server_id] = 0;
+			/* if server uptime is not empty, it's most probably up & running */
+			if ( !empty($details['uptime']) ) {
+				$this->log ( sprintf( __translate__( '%s server is up & running', $this->plugin_constant ),  $server_id ) );
+				$this->status[$server_id] = 1;
+			}
+		}
+
+	}
+
+	/**
+	 * get function for Memcached backend
+	 *
+	 * @param string $key Key to get values for
+	 *
+	*/
+	private function memcached_get ( &$key ) {
+		return $this->connection->get($key);
+	}
+
+	/**
+	 * Set function for Memcached backend
+	 *
+	 * @param string $key Key to set with
+	 * @param mixed $data Data to set
+	 *
+	 */
+	private function memcached_set ( &$key, &$data ) {
+		$result = $this->connection->set ( $key, $data , $this->options['expire']  );
+
+		/* if storing failed, log the error code */
+		if ( $result === false ) {
+			$code = $this->connection->getResultCode();
+			$this->log ( sprintf( __translate__( 'unable to set entry: %s', $this->plugin_constant ),  $key ) );
+			$this->log ( sprintf( __translate__( 'Memcached error code: %s', $this->plugin_constant ),  $code ) );
+			//throw new Exception ( __translate__('Unable to store Memcached entry ', $this->plugin_constant ) . $key . __translate__( ', error code: ', $this->plugin_constant ) . $code );
+		}
+
+		return $result;
 	}
 
 	/**
 	 *
-	 * @var string	$plugin_constant	Namespace of the plugin
-	 * @var mixed	$connection	Backend object storage variable
-	 * @var boolean	$alive		Alive flag of backend connection
-	 * @var boolean $network	WordPress Network flag
-	 * @var array	$options	Configuration settings array
-	 * @var array	$status		Backends status storage
-	 * @var array	$cookies	Logged in cookies to search for
-	 * @var array	$urimap		Map to render key with
-	 * @var object	$utilities	Utilities singleton
+	 * Flush memcached entries
+	 */
+	private function memcached_flush ( ) {
+		return $this->connection->flush();
+	}
+
+
+	/**
+	 * Removes entry from Memcached or flushes Memcached storage
+	 *
+	 * @param mixed $keys String / array of string of keys to delete entries with
+	*/
+	private function memcached_clear ( &$keys ) {
+
+		/* make an array if only one string is present, easier processing */
+		if ( !is_array ( $keys ) )
+			$keys = array ( $keys => true );
+
+		foreach ( $keys as $key => $dummy ) {
+			$kresult = $this->connection->delete( $key );
+
+			if ( $kresult === false ) {
+				$code = $this->connection->getResultCode();
+				$this->log ( sprintf( __translate__( 'unable to delete entry: %s', $this->plugin_constant ),  $key ) );
+				$this->log ( sprintf( __translate__( 'Memcached error code: %s', $this->plugin_constant ),  $code ) );
+			}
+			else {
+				$this->log ( sprintf( __translate__( 'entry deleted: %s', $this->plugin_constant ),  $key ) );
+			}
+		}
+	}
+	/*********************** END MEMCACHED FUNCTIONS ***********************/
+
+	/*********************** MEMCACHE FUNCTIONS ***********************/
+	/**
+	 * init memcache backend
+	 */
+	private function memcache_init () {
+		/* Memcached class does not exist, Memcache extension is not available */
+		if (!class_exists('Memcache')) {
+			$this->log (  __translate__('PHP Memcache extension missing', $this->plugin_constant ), LOG_ERR );
+			return false;
+		}
+
+		/* check for existing server list, otherwise we cannot add backends */
+		if ( empty ( $this->options['servers'] ) && ! $this->alive ) {
+			$this->log (  __translate__("servers list is empty, init failed", $this->plugin_constant ), LOG_WARNING );
+			return false;
+		}
+
+		/* check is there's no backend connection yet */
+		if ( $this->connection === NULL )
+			$this->connection = new Memcache();
+
+		/* check if initialization was success or not */
+		if ( $this->connection === NULL ) {
+			$this->log (  __translate__( 'error initializing Memcache PHP extension, exiting', $this->plugin_constant ) );
+			return false;
+		}
+
+		/* adding servers */
+		foreach ( $this->options['servers'] as $server_id => $server ) {
+			if ( $this->options['persistent'] == '1' )
+				$conn = 'pconnect';
+			else
+				$conn = 'connect';
+
+				/* in case of unix socket */
+			if ( $server['port'] === 0 )
+				$this->status[$server_id] = $this->connection->$conn ( 'unix:/' . $server['host'] );
+			else
+				$this->status[$server_id] = $this->connection->$conn ( $server['host'] , $server['port'] );
+
+			$this->log ( sprintf( __translate__( '%s added, persistent mode: %s', $this->plugin_constant ),  $server_id, $this->options['persistent'] ) );
+		}
+
+		/* backend is now alive */
+		$this->alive = true;
+		$this->memcache_status();
+	}
+
+	/**
+	 * check current backend alive status for Memcached
 	 *
 	 */
-	class WP_FFPC_Backend {
-
-		const network_key = 'network';
-		const host_separator  = ',';
-		const port_separator  = ':';
-
-		private $plugin_constant = 'wp-ffpc';
-		private $connection = NULL;
-		private $alive = false;
-		private $network = false;
-		private $options = array();
-		private $status = array();
-		public $cookies = array();
-		private $urimap = array();
-		private $utilities;
-
-		/**
-		* constructor
-		*
-		* @param mixed $config Configuration options
-		* @param boolean $network WordPress Network indicator flah
-		*
-		*/
-		public function __construct( $config, $network = false ) {
-
-			/* no config, nothing is going to work */
-			if ( empty ( $config ) ) {
-				return false;
-				//die ( __translate__ ( 'WP-FFPC Backend class received empty configuration array, the plugin will not work this way', $this->plugin_constant ) );
-			}
-
-			/* set config */
-			$this->options = $config;
-
-			/* set network flag */
-			$this->network = $network;
-
-			/* these are the list of the cookies to look for when looking for logged in user */
-			$this->cookies = array ( 'comment_author_' , 'wordpressuser_' , 'wp-postpass_', 'wordpress_logged_in_' );
-
-			/* make utilities singleton */
-			$this->utilities = WP_Plugins_Utilities_v1::Utility();
-
-			/* map the key with the predefined schemes */
-			$ruser = isset ( $_SERVER['REMOTE_USER'] ) ? $_SERVER['REMOTE_USER'] : '';
-			$ruri = isset ( $_SERVER['REQUEST_URI'] ) ? $_SERVER['REQUEST_URI'] : '';
-			$rhost = isset ( $_SERVER['HTTP_HOST'] ) ? $_SERVER['HTTP_HOST'] : '';
-			$scookie = isset ( $_COOKIE['PHPSESSID'] ) ? $_COOKIE['PHPSESSID'] : '';
-
-			$this->urimap = array(
-				'$scheme' => str_replace ( '://', '', $this->utilities->replace_if_ssl ( 'http://' ) ),
-				'$host' => $rhost,
-				'$request_uri' => $ruri,
-				'$remote_user' => $ruser,
-				'$cookie_PHPSESSID' => $scookie,
-			);
-
-			/* split hosts entry to servers */
-			$this->set_servers();
-
-			/* call backend initiator based on cache type */
-			$init = $this->proxy( 'init' );
-
-			/* info level */
-			$this->log (  __translate__('init starting', $this->plugin_constant ));
-			$this->$init();
-
-		}
-
-		/*********************** PUBLIC / PROXY FUNCTIONS ***********************/
-
-		/**
-		 * build key to make requests with
-		 *
-		 * @param string $prefix prefix to add to prefix
-		 *
-		 */
-		public function key ( &$prefix ) {
-			/* data is string only with content, meta is not used in nginx */
-			$key = $prefix . str_replace ( array_keys( $this->urimap ), $this->urimap, $this->options['key'] );
-			$this->log ( sprintf( __translate__( 'original key configuration: %s', $this->plugin_constant ),  $this->options['key'] ) );
-			$this->log ( sprintf( __translate__( 'setting key to: %s', $this->plugin_constant ),  $key ) );
-			return $key;
-		}
-
-
-		/**
-		 * public get function, transparent proxy to internal function based on backend
-		 *
-		 * @param string $key Cache key to get value for
-		 *
-		 * @return mixed False when entry not found or entry value on success
-		 */
-		public function get ( &$key ) {
-
-			/* look for backend aliveness, exit on inactive backend */
-			if ( ! $this->is_alive() )
-				return false;
-
-			/* log the current action */
-			$this->log ( sprintf( __translate__( 'get %s', $this->plugin_constant ),  $key ) );
-
-			/* proxy to internal function */
-			$internal = $this->proxy( 'get' );
-			$result = $this->$internal( $key );
-
-			if ( $result === false  )
-				$this->log ( sprintf( __translate__( 'failed to get entry: %s', $this->plugin_constant ),  $key ) );
-
-			return $result;
-		}
-
-		/**
-		 * public set function, transparent proxy to internal function based on backend
-		 *
-		 * @param string $key Cache key to set with ( reference only, for speed )
-		 * @param mixed $data Data to set ( reference only, for speed )
-		 *
-		 * @return mixed $result status of set function
-		 */
-		public function set ( &$key, &$data ) {
-
-			/* look for backend aliveness, exit on inactive backend */
-			if ( ! $this->is_alive() )
-				return false;
-
-			/* log the current action */
-			$this->log ( sprintf( __translate__( 'set %s expiration time: %s', $this->plugin_constant ),  $key, $this->options['expire'] ) );
-
-			/* proxy to internal function */
-			$internal = $this->proxy( 'set' );
-			$result = $this->$internal( $key, $data );
-
-			/* check result validity */
-			if ( $result === false )
-				$this->log ( sprintf( __translate__( 'failed to set entry: %s', $this->plugin_constant ),  $key ), LOG_WARNING );
-
-			return $result;
-		}
-
-		/**
-		 * public get function, transparent proxy to internal function based on backend
-		 *
-		 * @param string $post_id	ID of post to invalidate
-		 * @param boolean $force 	Force flush cache
-		 * @param boolean $comment	Clear a single page based on comment trigger
-		 *
-		 */
-		public function clear ( $post_id = false, $force = false ) {
-
-			/* look for backend aliveness, exit on inactive backend */
-			if ( ! $this->is_alive() )
-				return false;
-
-			/* exit if no post_id is specified */
-			if ( empty ( $post_id ) && $force === false ) {
-				$this->log (  __translate__('not clearing unidentified post ', $this->plugin_constant ), LOG_WARNING );
-				return false;
-			}
-
-			/* if invalidation method is set to full, flush cache */
-			if ( ( $this->options['invalidation_method'] === 0 || $force === true ) ) {
-				/* log action */
-				$this->log (  __translate__('flushing cache', $this->plugin_constant ) );
-
-				/* proxy to internal function */
-				$internal = $this->proxy ( 'flush' );
-				$result = $this->$internal();
-
-				if ( $result === false )
-					$this->log (  __translate__('failed to flush cache', $this->plugin_constant ), LOG_WARNING );
-
-				return $result;
-			}
-
-			/* storage for entries to clear */
-			$to_clear = array();
-
-			/* clear taxonomies if settings requires it */
-			if ( $this->options['invalidation_method'] == 2 ) {
-				/* this will only clear the current blog's entries */
-				$this->taxonomy_links( $to_clear );
-			}
-
-			/* if there's a post id pushed, it needs to be invalidated in all cases */
-			if ( !empty ( $post_id ) ) {
-
-				/* need permalink functions */
-				if ( !function_exists('get_permalink') )
-					include_once ( ABSPATH . 'wp-includes/link-template.php' );
-
-				/* get path from permalink */
-				$path = substr ( get_permalink( $post_id ) , 7 );
-
-				/* no path, don't do anything */
-				if ( empty( $path ) ) {
-					$this->log ( sprintf( __translate__( 'unable to determine path from Post Permalink, post ID: %s', $this->plugin_constant ),  $post_id ), LOG_WARNING );
-					return false;
-				}
-
-				if ( isset($_SERVER['HTTPS']) && ( ( strtolower($_SERVER['HTTPS']) == 'on' )  || ( $_SERVER['HTTPS'] == '1' ) ) )
-					$protocol = 'https://';
-				else
-					$protocol = 'http://';
-
-				/* elements to clear
-				   values are keys, faster to process and eliminates duplicates
-				*/
-				$to_clear[ $protocol . $path ] = true;
-			}
-
-			foreach ( $to_clear as $link => $dummy ) {
-				/* clear all feeds as well */
-				$to_clear[ $link. 'feed' ] = true;
-			}
-
-			/* add data & meta prefixes */
-			foreach ( $to_clear as $link => $dummy ) {
-				unset ( $to_clear [ $link ]);
-				$to_clear[ $this->options[ 'prefix_meta' ] . $link ] = true;
-				$to_clear[ $this->options[ 'prefix_data' ] . $link ] = true;
-			}
-
-			/* run clear */
-			$internal = $this->proxy ( 'clear' );
-			$this->$internal ( $to_clear );
-		}
-
-		/**
-		 * clear cache triggered by new comment
-		 *
-		 * @param $comment_id	Comment ID
-		 * @param $comment_object	The whole comment object ?
-		 */
-		public function clear_by_comment ( $comment_id, $comment_object ) {
-			if ( empty( $comment_id ) )
-				return false;
-
-			$comment = get_comment( $comment_id );
-			$post_id = $comment->comment_post_ID;
-			if ( !empty( $post_id ) )
-				$this->clear ( $post_id );
-
-			unset ( $comment );
-			unset ( $post_id );
-		}
-
-		/**
-		 * to collect all permalinks of all taxonomy terms used in invalidation & precache
-		 *
-		 * @param array &$links Passed by reference array that has to be filled up with the links
-		 * @param mixed $site Site ID or false; used in WordPress Network
-		 *
-		 */
-		public function taxonomy_links ( &$links, $site = false ) {
-
-			if ( $site !== false ) {
-				$current_blog = get_current_blog_id();
-				switch_to_blog( $site );
-
-				$url = get_blog_option ( $site, 'siteurl' );
-				if ( substr( $url, -1) !== '/' )
-					$url = $url . '/';
-
-				$links[ $url ] = true;
-			}
-
-			/* we're only interested in public taxonomies */
-			$args = array(
-				'public'   => true,
-			);
-
-			/* get taxonomies as objects */
-			$taxonomies = get_taxonomies( $args, 'objects' );
-
-			if ( !empty( $taxonomies ) ) {
-				foreach ( $taxonomies  as $taxonomy ) {
-					/* reset array, just in case */
-					$terms = array();
-
-					/* get all the terms for this taxonomy, only if not empty */
-					$sargs = array(
-						'hide_empty'    => true,
-						'fields'        => 'all',
-						'hierarchical'  =>false,
-					);
-					$terms = get_terms ( $taxonomy->name , $sargs );
-
-					if ( !empty ( $terms ) ) {
-						foreach ( $terms as $term ) {
-							/* get the permalink for the term */
-							$link = get_term_link ( $term->slug, $taxonomy->name );
-							/* add to container */
-							$links[ $link ] = true;
-							/* remove the taxonomy name from the link, lots of plugins remove this for SEO, it's better to include them than leave them out
-							   in worst case, we cache some 404 as well
-							*/
-							$link = str_replace ( '/'.$taxonomy->rewrite['slug'], '', $link  );
-							/* add to container */
-							$links[ $link ] = true;
-						}
-					}
-				}
-			}
-
-			/* switch back to original site if we navigated away */
-			if ( $site !== false ) {
-				switch_to_blog( $current_blog );
-			}
-
-		}
-
-		/**
-		 * get backend aliveness
-		 *
-		 * @return array Array of configured servers with aliveness value
-		 *
-		 */
-		public function status () {
-
-			/* look for backend aliveness, exit on inactive backend */
-			if ( ! $this->is_alive() )
-				return false;
-
-			$internal = $this->proxy ( 'status' );
-			$this->$internal();
-			return $this->status;
-		}
-
-		/**
-		 * backend proxy function name generator
-		 *
-		 * @return string Name of internal function based on cache_type
-		 *
-		 */
-		private function proxy ( $method ) {
-			return $this->options['cache_type'] . '_' . $method;
-		}
-
-		/**
-		 * function to check backend aliveness
-		 *
-		 * @return boolean true if backend is alive, false if not
-		 *
-		 */
-		private function is_alive() {
-			if ( ! $this->alive ) {
-				$this->log (  __translate__("backend is not active, exiting function ", $this->plugin_constant ) . __FUNCTION__, LOG_WARNING );
-				return false;
-			}
-
-			return true;
-		}
-
-		/**
-		 * split hosts string to backend servers
-		 *
-		 *
-		 */
-		private function set_servers () {
-			/* replace servers array in config according to hosts field */
-			$servers = explode( self::host_separator , $this->options['hosts']);
-
-			$options['servers'] = array();
-
-			foreach ( $servers as $snum => $sstring ) {
-
-				$separator = strpos( $sstring , self::port_separator );
-				$host = substr( $sstring, 0, $separator );
-				$port = substr( $sstring, $separator + 1 );
-				// unix socket failsafe
-				if ( empty ($port) ) $port = 0;
-
-				$this->options['servers'][$sstring] = array (
-					'host' => $host,
-					'port' => $port
-				);
-			}
-
-		}
-
-		/**
-		 * get current array of servers
-		 *
-		 * @return array Server list in current config
-		 *
-		 */
-		public function get_servers () {
-			$r = isset ( $this->options['servers'] ) ? $this->options['servers'] : '';
-			return $r;
-		}
-
-		/**
-		 * log wrapper to include options
-		 *
-		 * @var mixed $message Message to log
-		 * @var int $log_level Log level
-		 */
-		private function log ( $message, $log_level = LOG_WARNING ) {
-			if ( !isset ( $this->options['log'] ) || $this->options['log'] != 1 )
-				return false;
+	private function memcache_status () {
+		/* server status will be calculated by getting server stats */
+		$this->log (  __translate__("checking server statuses", $this->plugin_constant ));
+		/* get servers statistic from connection */
+		foreach ( $this->options['servers'] as $server_id => $server ) {
+			if ( $server['port'] === 0 )
+				$this->status[$server_id] = $this->connection->getServerStatus( $server['host'] );
 			else
-				$this->utilities->log ( $this->plugin_constant , $message, $log_level );
-		}
-
-		/*********************** END PUBLIC FUNCTIONS ***********************/
-		/*********************** APC FUNCTIONS ***********************/
-		/**
-		 * init apc backend: test APC availability and set alive status
-		 */
-		private function apc_init () {
-			/* verify apc functions exist, apc extension is loaded */
-			if ( ! function_exists( 'apc_cache_info' ) ) {
-				$this->log (  __translate__('APC extension missing', $this->plugin_constant ) );
-				return false;
-			}
-
-			/* verify apc is working */
-			if ( apc_cache_info("user",true) ) {
-				$this->log (  __translate__('backend OK', $this->plugin_constant ) );
-				$this->alive = true;
-			}
-		}
-
-		/**
-		 * health checker for APC
-		 *
-		 * @return boolean Aliveness status
-		 *
-		 */
-		private function apc_status () {
-			$this->status = true;
-			return $this->alive;
-		}
-
-		/**
-		 * get function for APC backend
-		 *
-		 * @param string $key Key to get values for
-		 *
-		 * @return mixed Fetched data based on key
-		 *
-		*/
-		private function apc_get ( &$key ) {
-			return apc_fetch( $key );
-		}
-
-		/**
-		 * Set function for APC backend
-		 *
-		 * @param string $key Key to set with
-		 * @param mixed $data Data to set
-		 *
-		 * @return boolean APC store outcome
-		 */
-		private function apc_set (  &$key, &$data ) {
-			return apc_store( $key , $data , $this->options['expire'] );
-		}
-
-
-		/**
-		 * Flushes APC user entry storage
-		 *
-		 * @return boolean APC flush outcome status
-		 *
-		*/
-		private function apc_flush ( ) {
-			return apc_clear_cache('user');
-		}
-
-		/**
-		 * Removes entry from APC or flushes APC user entry storage
-		 *
-		 * @param mixed $keys Keys to clear, string or array
-		*/
-		private function apc_clear ( &$keys ) {
-			/* make an array if only one string is present, easier processing */
-			if ( !is_array ( $keys ) )
-				$keys = array ( $keys => true );
-
-			foreach ( $keys as $key => $dummy ) {
-				if ( ! apc_delete ( $key ) ) {
-					$this->log ( sprintf( __translate__( 'Failed to delete APC entry: %s', $this->plugin_constant ),  $key ), LOG_ERR );
-					//throw new Exception ( __translate__('Deleting APC entry failed with key ', $this->plugin_constant ) . $key );
-				}
-				else {
-					$this->log ( sprintf( __translate__( 'APC entry delete: %s', $this->plugin_constant ),  $key ) );
-				}
-			}
-		}
-
-		/*********************** END APC FUNCTIONS ***********************/
-		/*********************** APCu FUNCTIONS ***********************/
-		/**
-		 * init apcu backend: test APCu availability and set alive status
-		 */
-		private function apcu_init () {
-			/* verify apcu functions exist, apcu extension is loaded */
-			if ( ! function_exists( 'apcu_cache_info' ) ) {
-				$this->log (  __translate__('APCu extension missing', $this->plugin_constant ) );
-				return false;
-			}
-
-			/* verify apcu is working */
-			if ( apcu_cache_info("user",true) ) {
-				$this->log (  __translate__('backend OK', $this->plugin_constant ) );
-				$this->alive = true;
-			}
-		}
-
-		/**
-		 * health checker for APC
-		 *
-		 * @return boolean Aliveness status
-		 *
-		 */
-		private function apcu_status () {
-			$this->status = true;
-			return $this->alive;
-		}
-
-		/**
-		 * get function for APC backend
-		 *
-		 * @param string $key Key to get values for
-		 *
-		 * @return mixed Fetched data based on key
-		 *
-		*/
-		private function apcu_get ( &$key ) {
-			return apcu_fetch( $key );
-		}
-
-		/**
-		 * Set function for APC backend
-		 *
-		 * @param string $key Key to set with
-		 * @param mixed $data Data to set
-		 *
-		 * @return boolean APC store outcome
-		 */
-		private function apcu_set (  &$key, &$data ) {
-			return apcu_store( $key , $data , $this->options['expire'] );
-		}
-
-
-		/**
-		 * Flushes APC user entry storage
-		 *
-		 * @return boolean APC flush outcome status
-		 *
-		*/
-		private function apcu_flush ( ) {
-			return apcu_clear_cache();
-		}
-
-		/**
-		 * Removes entry from APC or flushes APC user entry storage
-		 *
-		 * @param mixed $keys Keys to clear, string or array
-		*/
-		private function apcu_clear ( &$keys ) {
-			/* make an array if only one string is present, easier processing */
-			if ( !is_array ( $keys ) )
-				$keys = array ( $keys => true );
-
-			foreach ( $keys as $key => $dummy ) {
-				if ( ! apcu_delete ( $key ) ) {
-					$this->log ( sprintf( __translate__( 'Failed to delete APC entry: %s', $this->plugin_constant ),  $key ), LOG_ERR );
-					//throw new Exception ( __translate__('Deleting APC entry failed with key ', $this->plugin_constant ) . $key );
-				}
-				else {
-					$this->log ( sprintf( __translate__( 'APC entry delete: %s', $this->plugin_constant ),  $key ) );
-				}
-			}
-		}
-
-		/*********************** END APC FUNCTIONS ***********************/
-
-		/*********************** XCACHE FUNCTIONS ***********************/
-		/**
-		 * init apc backend: test APC availability and set alive status
-		 */
-		private function xcache_init () {
-			/* verify apc functions exist, apc extension is loaded */
-			if ( ! function_exists( 'xcache_info' ) ) {
-				$this->log (  __translate__('XCACHE extension missing', $this->plugin_constant ) );
-				return false;
-			}
-
-			/* verify apc is working */
-			$info = xcache_info();
-			if ( !empty( $info )) {
-				$this->log (  __translate__('backend OK', $this->plugin_constant ) );
-				$this->alive = true;
-			}
-		}
-
-		/**
-		 * health checker for Xcache
-		 *
-		 * @return boolean Aliveness status
-		 *
-		 */
-		private function xcache_status () {
-			$this->status = true;
-			return $this->alive;
-		}
-
-		/**
-		 * get function for APC backend
-		 *
-		 * @param string $key Key to get values for
-		 *
-		 * @return mixed Fetched data based on key
-		 *
-		*/
-		private function xcache_get ( &$key ) {
-			if ( xcache_isset ( $key ) )
-				return xcache_get( $key );
-			else
-				return false;
-		}
-
-		/**
-		 * Set function for APC backend
-		 *
-		 * @param string $key Key to set with
-		 * @param mixed $data Data to set
-		 *
-		 * @return boolean APC store outcome
-		 */
-		private function xcache_set (  &$key, &$data ) {
-			return xcache_set( $key , $data , $this->options['expire'] );
-		}
-
-
-		/**
-		 * Flushes APC user entry storage
-		 *
-		 * @return boolean APC flush outcome status
-		 *
-		*/
-		private function xcache_flush ( ) {
-			return xcache_clear_cache(XC_TYPE_VAR);
-		}
-
-		/**
-		 * Removes entry from APC or flushes APC user entry storage
-		 *
-		 * @param mixed $keys Keys to clear, string or array
-		*/
-		private function xcache_clear ( &$keys ) {
-			/* make an array if only one string is present, easier processing */
-			if ( !is_array ( $keys ) )
-				$keys = array ( $keys => true );
-
-			foreach ( $keys as $key => $dummy ) {
-				if ( ! xcache_unset ( $key ) ) {
-					$this->log ( sprintf( __translate__( 'Failed to delete XCACHE entry: %s', $this->plugin_constant ),  $key ), LOG_ERR );
-					//throw new Exception ( __translate__('Deleting APC entry failed with key ', $this->plugin_constant ) . $key );
-				}
-				else {
-					$this->log ( sprintf( __translate__( 'XCACHE entry delete: %s', $this->plugin_constant ),  $key ) );
-				}
-			}
-		}
-
-		/*********************** END XCACHE FUNCTIONS ***********************/
-
-
-		/*********************** MEMCACHED FUNCTIONS ***********************/
-		/**
-		 * init memcached backend
-		 */
-		private function memcached_init () {
-			/* Memcached class does not exist, Memcached extension is not available */
-			if (!class_exists('Memcached')) {
-				$this->log (  __translate__(' Memcached extension missing', $this->plugin_constant ), LOG_ERR );
-				return false;
-			}
-
-			/* check for existing server list, otherwise we cannot add backends */
-			if ( empty ( $this->options['servers'] ) && ! $this->alive ) {
-				$this->log (  __translate__("Memcached servers list is empty, init failed", $this->plugin_constant ), LOG_WARNING );
-				return false;
-			}
-
-			/* check is there's no backend connection yet */
-			if ( $this->connection === NULL ) {
-				/* persistent backend needs an identifier */
-				if ( $this->options['persistent'] == '1' )
-					$this->connection = new Memcached( $this->plugin_constant );
-				else
-					$this->connection = new Memcached();
-
-				/* use binary and not compressed format, good for nginx and still fast */
-				$this->connection->setOption( Memcached::OPT_COMPRESSION , false );
-				$this->connection->setOption( Memcached::OPT_BINARY_PROTOCOL , true );
-
-				if ( version_compare( phpversion( 'memcached' ) , '2.0.0', '>=' ) && ini_get( 'memcached.use_sasl' ) == 1 ) {
-					$this->connection->setSaslAuthData ( $this->options['authuser'], $this->options['authpass']);
-				}
-			}
-
-			/* check if initialization was success or not */
-			if ( $this->connection === NULL ) {
-				$this->log (  __translate__( 'error initializing Memcached PHP extension, exiting', $this->plugin_constant ) );
-				return false;
-			}
-
-			/* check if we already have list of servers, only add server(s) if it's not already connected */
-			$servers_alive = array();
-			if ( !empty ( $this->status ) ) {
-				$servers_alive = $this->connection->getServerList();
-				/* create check array if backend servers are already connected */
-				if ( !empty ( $servers ) ) {
-					foreach ( $servers_alive as $skey => $server ) {
-						$skey =  $server['host'] . ":" . $server['port'];
-						$servers_alive[ $skey ] = true;
-					}
-				}
-			}
-
-			/* adding servers */
-			foreach ( $this->options['servers'] as $server_id => $server ) {
-				/* reset server status to unknown */
-				$this->status[$server_id] = -1;
-
-				/* only add servers that does not exists already  in connection pool */
-				if ( !@array_key_exists($server_id , $servers_alive ) ) {
-					$this->connection->addServer( $server['host'], $server['port'] );
-					$this->log ( sprintf( __translate__( '%s added, persistent mode: %s', $this->plugin_constant ),  $server_id, $this->options['persistent'] ) );
-				}
-			}
-
-			/* backend is now alive */
-			$this->alive = true;
-			$this->memcached_status();
-		}
-
-		/**
-		 * sets current backend alive status for Memcached servers
-		 *
-		 */
-		private function memcached_status () {
-			/* server status will be calculated by getting server stats */
-			$this->log (  __translate__("checking server statuses", $this->plugin_constant ));
-			/* get servers statistic from connection */
-			$report =  $this->connection->getStats();
-
-			foreach ( $report as $server_id => $details ) {
-				/* reset server status to offline */
-				$this->status[$server_id] = 0;
-				/* if server uptime is not empty, it's most probably up & running */
-				if ( !empty($details['uptime']) ) {
-					$this->log ( sprintf( __translate__( '%s server is up & running', $this->plugin_constant ),  $server_id ) );
-					$this->status[$server_id] = 1;
-				}
-			}
-
-		}
-
-		/**
-		 * get function for Memcached backend
-		 *
-		 * @param string $key Key to get values for
-		 *
-		*/
-		private function memcached_get ( &$key ) {
-			return $this->connection->get($key);
-		}
-
-		/**
-		 * Set function for Memcached backend
-		 *
-		 * @param string $key Key to set with
-		 * @param mixed $data Data to set
-		 *
-		 */
-		private function memcached_set ( &$key, &$data ) {
-			$result = $this->connection->set ( $key, $data , $this->options['expire']  );
-
-			/* if storing failed, log the error code */
-			if ( $result === false ) {
-				$code = $this->connection->getResultCode();
-				$this->log ( sprintf( __translate__( 'unable to set entry: %s', $this->plugin_constant ),  $key ) );
-				$this->log ( sprintf( __translate__( 'Memcached error code: %s', $this->plugin_constant ),  $code ) );
-				//throw new Exception ( __translate__('Unable to store Memcached entry ', $this->plugin_constant ) . $key . __translate__( ', error code: ', $this->plugin_constant ) . $code );
-			}
-
-			return $result;
-		}
-
-		/**
-		 *
-		 * Flush memcached entries
-		 */
-		private function memcached_flush ( ) {
-			return $this->connection->flush();
-		}
-
-
-		/**
-		 * Removes entry from Memcached or flushes Memcached storage
-		 *
-		 * @param mixed $keys String / array of string of keys to delete entries with
-		*/
-		private function memcached_clear ( &$keys ) {
-
-			/* make an array if only one string is present, easier processing */
-			if ( !is_array ( $keys ) )
-				$keys = array ( $keys => true );
-
-			foreach ( $keys as $key => $dummy ) {
-				$kresult = $this->connection->delete( $key );
-
-				if ( $kresult === false ) {
-					$code = $this->connection->getResultCode();
-					$this->log ( sprintf( __translate__( 'unable to delete entry: %s', $this->plugin_constant ),  $key ) );
-					$this->log ( sprintf( __translate__( 'Memcached error code: %s', $this->plugin_constant ),  $code ) );
-				}
-				else {
-					$this->log ( sprintf( __translate__( 'entry deleted: %s', $this->plugin_constant ),  $key ) );
-				}
-			}
-		}
-		/*********************** END MEMCACHED FUNCTIONS ***********************/
-
-		/*********************** MEMCACHE FUNCTIONS ***********************/
-		/**
-		 * init memcache backend
-		 */
-		private function memcache_init () {
-			/* Memcached class does not exist, Memcache extension is not available */
-			if (!class_exists('Memcache')) {
-				$this->log (  __translate__('PHP Memcache extension missing', $this->plugin_constant ), LOG_ERR );
-				return false;
-			}
-
-			/* check for existing server list, otherwise we cannot add backends */
-			if ( empty ( $this->options['servers'] ) && ! $this->alive ) {
-				$this->log (  __translate__("servers list is empty, init failed", $this->plugin_constant ), LOG_WARNING );
-				return false;
-			}
-
-			/* check is there's no backend connection yet */
-			if ( $this->connection === NULL )
-				$this->connection = new Memcache();
-
-			/* check if initialization was success or not */
-			if ( $this->connection === NULL ) {
-				$this->log (  __translate__( 'error initializing Memcache PHP extension, exiting', $this->plugin_constant ) );
-				return false;
-			}
-
-			/* adding servers */
-			foreach ( $this->options['servers'] as $server_id => $server ) {
-				if ( $this->options['persistent'] == '1' )
-					$conn = 'pconnect';
-				else
-					$conn = 'connect';
-
-					/* in case of unix socket */
-				if ( $server['port'] === 0 )
-					$this->status[$server_id] = $this->connection->$conn ( 'unix:/' . $server['host'] );
-				else
-					$this->status[$server_id] = $this->connection->$conn ( $server['host'] , $server['port'] );
-
-				$this->log ( sprintf( __translate__( '%s added, persistent mode: %s', $this->plugin_constant ),  $server_id, $this->options['persistent'] ) );
-			}
-
-			/* backend is now alive */
-			$this->alive = true;
-			$this->memcache_status();
-		}
-
-		/**
-		 * check current backend alive status for Memcached
-		 *
-		 */
-		private function memcache_status () {
-			/* server status will be calculated by getting server stats */
-			$this->log (  __translate__("checking server statuses", $this->plugin_constant ));
-			/* get servers statistic from connection */
-			foreach ( $this->options['servers'] as $server_id => $server ) {
 				$this->status[$server_id] = $this->connection->getServerStatus( $server['host'], $server['port'] );
-				if ( $this->status[$server_id] == 0 )
-					$this->log ( sprintf( __translate__( '%s server is down', $this->plugin_constant ),  $server_id ) );
-				else
-					$this->log ( sprintf( __translate__( '%s server is up & running', $this->plugin_constant ),  $server_id ) );
-			}
+			if ( $this->status[$server_id] == 0 )
+				$this->log ( sprintf( __translate__( '%s server is down', $this->plugin_constant ),  $server_id ) );
+			else
+				$this->log ( sprintf( __translate__( '%s server is up & running', $this->plugin_constant ),  $server_id ) );
 		}
-
-		/**
-		 * get function for Memcached backend
-		 *
-		 * @param string $key Key to get values for
-		 *
-		*/
-		private function memcache_get ( &$key ) {
-			return $this->connection->get($key);
-		}
-
-		/**
-		 * Set function for Memcached backend
-		 *
-		 * @param string $key Key to set with
-		 * @param mixed $data Data to set
-		 *
-		 */
-		private function memcache_set ( &$key, &$data ) {
-			$result = $this->connection->set ( $key, $data , 0 , $this->options['expire'] );
-			return $result;
-		}
-
-		/**
-		 *
-		 * Flush memcached entries
-		 */
-		private function memcache_flush ( ) {
-			return $this->connection->flush();
-		}
-
-
-		/**
-		 * Removes entry from Memcached or flushes Memcached storage
-		 *
-		 * @param mixed $keys String / array of string of keys to delete entries with
-		*/
-		private function memcache_clear ( &$keys ) {
-			/* make an array if only one string is present, easier processing */
-			if ( !is_array ( $keys ) )
-				$keys = array ( $keys => true );
-
-			foreach ( $keys as $key => $dummy ) {
-				$kresult = $this->connection->delete( $key );
-
-				if ( $kresult === false ) {
-					$this->log ( sprintf( __translate__( 'unable to delete entry: %s', $this->plugin_constant ),  $key ) );
-				}
-				else {
-					$this->log ( sprintf( __translate__( 'entry deleted: %s', $this->plugin_constant ),  $key ) );
-				}
-			}
-		}
-
-		/*********************** END MEMCACHE FUNCTIONS ***********************/
-
 	}
 
+	/**
+	 * get function for Memcached backend
+	 *
+	 * @param string $key Key to get values for
+	 *
+	*/
+	private function memcache_get ( &$key ) {
+		return $this->connection->get($key);
+	}
+
+	/**
+	 * Set function for Memcached backend
+	 *
+	 * @param string $key Key to set with
+	 * @param mixed $data Data to set
+	 *
+	 */
+	private function memcache_set ( &$key, &$data ) {
+		$result = $this->connection->set ( $key, $data , 0 , $this->options['expire'] );
+		return $result;
+	}
+
+	/**
+	 *
+	 * Flush memcached entries
+	 */
+	private function memcache_flush ( ) {
+		return $this->connection->flush();
+	}
+
+
+	/**
+	 * Removes entry from Memcached or flushes Memcached storage
+	 *
+	 * @param mixed $keys String / array of string of keys to delete entries with
+	*/
+	private function memcache_clear ( &$keys ) {
+		/* make an array if only one string is present, easier processing */
+		if ( !is_array ( $keys ) )
+			$keys = array ( $keys => true );
+
+		foreach ( $keys as $key => $dummy ) {
+			$kresult = $this->connection->delete( $key );
+
+			if ( $kresult === false ) {
+				$this->log ( sprintf( __translate__( 'unable to delete entry: %s', $this->plugin_constant ),  $key ) );
+			}
+			else {
+				$this->log ( sprintf( __translate__( 'entry deleted: %s', $this->plugin_constant ),  $key ) );
+			}
+		}
+	}
+
+	/*********************** END MEMCACHE FUNCTIONS ***********************/
+
 }
 
-?>
+endif; ?>
diff --git a/wp-ffpc-class.php b/wp-ffpc-class.php
index 7d71713..3961d77 100644
--- a/wp-ffpc-class.php
+++ b/wp-ffpc-class.php
@@ -1,1202 +1,1183 @@
 <?php
-/**
- * main class for WordPress plugin WP-FFPC
- *
- * supported storages:
- *  - APC
- *  - Memcached
- *  - Memcache
- *
- */
 
-if ( ! class_exists( 'WP_FFPC' ) ) {
-	/* get the plugin abstract class*/
-	include_once ( 'wp-common/wp-plugin-abstract.php' );
-	/* get the common functions class*/
-	include_once ( 'wp-ffpc-backend.php' );
+if ( ! class_exists( 'WP_FFPC' ) ) :
+
+/* get the plugin abstract class*/
+include_once ( 'wp-common/plugin_abstract.php' );
+/* get the common functions class*/
+include_once ( 'wp-ffpc-backend.php' );
+
+/**
+ * main wp-ffpc class
+ *
+ * @var string $acache_worker	advanced cache "worker" file, bundled with the plugin
+ * @var string $acache	WordPress advanced-cache.php file location
+ * @var string $nginx_sample	nginx sample config file, bundled with the plugin
+ * @var string $acache_backend	backend driver file, bundled with the plugin
+ * @var string $button_flush	flush button identifier
+ * @var string $button_precache	precache button identifier
+ * @var string $global_option	global options identifier
+ * @var string $precache_logfile	Precache log file location
+ * @var string $precache_phpfile	Precache PHP worker location
+ * @var array $shell_possibilities	List of possible precache worker callers
+ [TODO] finish list of vars
+ */
+class WP_FFPC extends PluginAbstract {
+	const host_separator  = ',';
+	const port_separator  = ':';
+	const donation_id_key = 'hosted_button_id=';
+	const global_config_var = '$wp_ffpc_config';
+	const key_save = 'saved';
+	const key_delete = 'deleted';
+	const key_flush = 'flushed';
+	const slug_flush = '&flushed=true';
+	const key_precache = 'precached';
+	const slug_precache = '&precached=true';
+	const key_precache_disabled = 'precache_disabled';
+	const slug_precache_disabled = '&precache_disabled=true';
+	const precache_log = 'wp-ffpc-precache-log';
+	const precache_timestamp = 'wp-ffpc-precache-timestamp';
+	const precache_php = 'wp-ffpc-precache.php';
+	const precache_id = 'wp-ffpc-precache-task';
+	private $precache_message = '';
+	private $precache_logfile = '';
+	private $precache_phpfile = '';
+	private $global_option = '';
+	private $global_config_key = '';
+	private $global_config = array();
+	private $global_saved = false;
+	private $acache_worker = '';
+	private $acache = '';
+	private $nginx_sample = '';
+	private $acache_backend = '';
+	private $button_flush;
+	private $button_precache;
+	private $select_cache_type = array ();
+	private $select_invalidation_method = array ();
+	private $select_schedules = array();
+	private $valid_cache_type = array ();
+	private $list_uri_vars = array();
+	private $shell_function = false;
+	private $shell_possibilities = array ();
+	private $backend = NULL;
+	private $scheduled = false;
+	private $errors = array();
 
 	/**
-	 * main wp-ffpc class
-	 *
-	 * @var string $acache_worker	advanced cache "worker" file, bundled with the plugin
-	 * @var string $acache	WordPress advanced-cache.php file location
-	 * @var string $nginx_sample	nginx sample config file, bundled with the plugin
-	 * @var string $acache_backend	backend driver file, bundled with the plugin
-	 * @var string $button_flush	flush button identifier
-	 * @var string $button_precache	precache button identifier
-	 * @var string $global_option	global options identifier
-	 * @var string $precache_logfile	Precache log file location
-	 * @var string $precache_phpfile	Precache PHP worker location
-	 * @var array $shell_possibilities	List of possible precache worker callers
-	 [TODO] finish list of vars
+	 * init hook function runs before admin panel hook, themeing and options read
 	 */
-	class WP_FFPC extends WP_Plugins_Abstract_v3 {
-		const host_separator  = ',';
-		const port_separator  = ':';
-		const donation_id_key = 'hosted_button_id=';
-		const global_config_var = '$wp_ffpc_config';
-		const key_save = 'saved';
-		const key_delete = 'deleted';
-		const key_flush = 'flushed';
-		const slug_flush = '&flushed=true';
-		const key_precache = 'precached';
-		const slug_precache = '&precached=true';
-		const key_precache_disabled = 'precache_disabled';
-		const slug_precache_disabled = '&precache_disabled=true';
-		const precache_log = 'wp-ffpc-precache-log';
-		const precache_timestamp = 'wp-ffpc-precache-timestamp';
-		const precache_php = 'wp-ffpc-precache.php';
-		const precache_id = 'wp-ffpc-precache-task';
-		private $precache_message = '';
-		private $precache_logfile = '';
-		private $precache_phpfile = '';
-		private $global_option = '';
-		private $global_config_key = '';
-		private $global_config = array();
-		private $global_saved = false;
-		private $acache_worker = '';
-		private $acache = '';
-		private $nginx_sample = '';
-		private $acache_backend = '';
-		private $button_flush;
-		private $button_precache;
-		private $select_cache_type = array ();
-		private $select_invalidation_method = array ();
-		private $select_schedules = array();
-		private $valid_cache_type = array ();
-		private $list_uri_vars = array();
-		private $shell_function = false;
-		private $shell_possibilities = array ();
-		private $backend = NULL;
-		private $scheduled = false;
-		private $errors = array();
+	public function plugin_pre_init() {
+		/* advanced cache "worker" file */
+		$this->acache_worker = $this->plugin_dir . $this->plugin_constant . '-acache.php';
+		/* WordPress advanced-cache.php file location */
+		$this->acache = WP_CONTENT_DIR . '/advanced-cache.php';
+		/* nginx sample config file */
+		$this->nginx_sample = $this->plugin_dir . $this->plugin_constant . '-nginx-sample.conf';
+		/* backend driver file */
+		$this->acache_backend = $this->plugin_dir . $this->plugin_constant . '-backend.php';
+		/* flush button identifier */
+		$this->button_flush = $this->plugin_constant . '-flush';
+		/* precache button identifier */
+		$this->button_precache = $this->plugin_constant . '-precache';
+		/* global options identifier */
+		$this->global_option = $this->plugin_constant . '-global';
+		/* precache log */
+		$this->precache_logfile = sys_get_temp_dir() . '/' . self::precache_log;
+		/* this is the precacher php worker file */
+		$this->precache_phpfile = sys_get_temp_dir() . '/' . self::precache_php;
+		/* search for a system function */
+		$this->shell_possibilities = array ( 'shell_exec', 'exec', 'system', 'passthru' );
+		/* get disabled functions list */
+		$disabled_functions = array_map('trim', explode(',', ini_get('disable_functions') ) );
 
-		/**
-		 * init hook function runs before admin panel hook, themeing and options read
-		 */
-		public function plugin_init() {
-			/* advanced cache "worker" file */
-			$this->acache_worker = $this->plugin_dir . $this->plugin_constant . '-acache.php';
-			/* WordPress advanced-cache.php file location */
-			$this->acache = WP_CONTENT_DIR . '/advanced-cache.php';
-			/* nginx sample config file */
-			$this->nginx_sample = $this->plugin_dir . $this->plugin_constant . '-nginx-sample.conf';
-			/* backend driver file */
-			$this->acache_backend = $this->plugin_dir . $this->plugin_constant . '-backend.php';
-			/* flush button identifier */
-			$this->button_flush = $this->plugin_constant . '-flush';
-			/* precache button identifier */
-			$this->button_precache = $this->plugin_constant . '-precache';
-			/* global options identifier */
-			$this->global_option = $this->plugin_constant . '-global';
-			/* precache log */
-			$this->precache_logfile = sys_get_temp_dir() . '/' . self::precache_log;
-			/* this is the precacher php worker file */
-			$this->precache_phpfile = sys_get_temp_dir() . '/' . self::precache_php;
-			/* search for a system function */
-			$this->shell_possibilities = array ( 'shell_exec', 'exec', 'system', 'passthru' );
-			/* get disabled functions list */
-			$disabled_functions = array_map('trim', explode(',', ini_get('disable_functions') ) );
-
-			foreach ( $this->shell_possibilities as $possible ) {
-				if ( function_exists ($possible) && ! ( ini_get('safe_mode') || in_array( $possible, $disabled_functions ) ) ) {
-					/* set shell function */
-					$this->shell_function = $possible;
-					break;
-				}
-			}
-
-			/* set global config key; here, because it's needed for migration */
-			if ( $this->network )
-				$this->global_config_key = 'network';
-			else
-				$this->global_config_key = $_SERVER['HTTP_HOST'];
-
-			/* cache type possible values array */
-			$this->select_cache_type = array (
-				'apc' => __( 'APC' , $this->plugin_constant ),
-				'apcu' => __( 'APCu' , $this->plugin_constant ),
-				'xcache' => __( 'XCache' , $this->plugin_constant ),
-				'memcache' => __( 'PHP Memcache' , $this->plugin_constant ),
-				'memcached' => __( 'PHP Memcached' , $this->plugin_constant ),
-			);
-			/* check for required functions / classes for the cache types */
-			$this->valid_cache_type = array (
-				'apc' => function_exists( 'apc_cache_info' ) ? true : false,
-				'apcu' => function_exists( 'apcu_cache_info' ) ? true : false,
-				'xcache' => function_exists( 'xcache_info' ) ? true : false,
-				'memcache' => class_exists ( 'Memcache') ? true : false,
-				'memcached' => class_exists ( 'Memcached') ? true : false,
-			);
-
-			/* invalidation method possible values array */
-			$this->select_invalidation_method = array (
-				0 => __( 'flush cache' , $this->plugin_constant ),
-				1 => __( 'only modified post' , $this->plugin_constant ),
-				2 => __( 'modified post and all taxonomies' , $this->plugin_constant ),
-			);
-
-			/* map of possible key masks */
-			$this->list_uri_vars = array (
-				'$scheme' => __('The HTTP scheme (i.e. http, https).', $this->plugin_constant ),
-				'$host' => __('Host in the header of request or name of the server processing the request if the Host header is not available.', $this->plugin_constant ),
-				'$request_uri' => __('The *original* request URI as received from the client including the args', $this->plugin_constant ),
-				'$remote_user' => __('Name of user, authenticated by the Auth Basic Module', $this->plugin_constant ),
-				'$cookie_PHPSESSID' => __('PHP Session Cookie ID, if set ( empty if not )', $this->plugin_constant ),
-				//'$cookie_COOKnginy IE' => __('Value of COOKIE', $this->plugin_constant ),
-				//'$http_HEADER' => __('Value of HTTP request header HEADER ( lowercase, dashes converted to underscore )', $this->plugin_constant ),
-				//'$query_string' => __('Full request URI after rewrites', $this->plugin_constant ),
-				//'' => __('', $this->plugin_constant ),
-			);
-
-			/* get current wp_cron schedules */
-			$wp_schedules = wp_get_schedules();
-			/* add 'null' to switch off timed precache */
-			$schedules['null'] = __( 'do not use timed precache' );
-			foreach ( $wp_schedules as $interval=>$details ) {
-				$schedules[ $interval ] = $details['display'];
-			}
-			$this->select_schedules = $schedules;
-
-		}
-
-		/**
-		 * additional init, steps that needs the plugin options
-		 *
-		 */
-		public function plugin_setup () {
-
-			/* initiate backend */
-			$this->backend = new WP_FFPC_Backend ( $this->options, $this->network );
-
-			/* get all available post types */
-			$post_types = get_post_types( );
-
-			/* cache invalidation hooks */
-			foreach ( $post_types as $post_type ) {
-				add_action( 'new_to_publish_' .$post_type , array( &$this->backend , 'clear' ), 0 );
-				add_action( 'draft_to_publish' .$post_type , array( &$this->backend , 'clear' ), 0 );
-				add_action( 'pending_to_publish' .$post_type , array( &$this->backend , 'clear' ), 0 );
-				add_action( 'private_to_publish' .$post_type , array( &$this->backend , 'clear' ), 0 );
-				add_action( 'publish_' . $post_type , array( &$this->backend , 'clear' ), 0 );
-			}
-
-			/* comments invalidation hooks */
-			if ( $this->options['comments_invalidate'] ) {
-				add_action( 'comment_post', array( &$this->backend , 'clear' ), 0 );
-				add_action( 'edit_comment', array( &$this->backend , 'clear' ), 0 );
-				add_action( 'trashed_comment', array( &$this->backend , 'clear' ), 0 );
-				add_action( 'pingback_post', array( &$this->backend , 'clear' ), 0 );
-				add_action( 'trackback_post', array( &$this->backend , 'clear' ), 0 );
-				add_action( 'wp_insert_comment', array( &$this->backend , 'clear' ), 0 );
-				add_action( '', array( &$this->backend , 'clear' ), 0 );
-			}
-
-			/* invalidation on some other ocasions as well */
-			add_action( 'switch_theme', array( &$this->backend , 'clear' ), 0 );
-			add_action( 'deleted_post', array( &$this->backend , 'clear' ), 0 );
-			add_action( 'edit_post', array( &$this->backend , 'clear' ), 0 );
-
-			/* add filter for catching canonical redirects */
-			if ( WP_CACHE )
-				add_filter('redirect_canonical', 'wp_ffpc_redirect_callback', 10, 2);
-
-			/* clean up schedule if needed */
-			if ( !isset( $this->options['precache_schedule'] ) || $this->options['precache_schedule'] == 'null' ) {
-				$this->log ( sprintf ( __( 'clearing scheduled hook %s', $this->plugin_constant ), self::precache_id ) );
-			}
-
-			/* add precache coldrun action */
-			add_action( self::precache_id , array( &$this, 'precache_coldrun' ) );
-
-			$settings_link = ' &raquo; <a href="' . $this->settings_link . '">' . __( 'WP-FFPC Settings', $this->plugin_constant ) . '</a>';
-			/* check for errors */
-			if ( ! WP_CACHE )
-				$this->errors['no_wp_cache'] = __("WP_CACHE is disabled, plugin will not work that way. Please add define `( 'WP_CACHE', true );` in wp-config.php", $this->plugin_constant ) . $settings_link;
-
-			if ( ! $this->global_saved )
-				$this->errors['no_global_saved'] = __("Plugin settings are not yet saved for the site, please save settings!", $this->plugin_constant) . $settings_link;
-
-			if ( ! file_exists ( $this->acache ) )
-				$this->errors['no_acache_saved'] = __("Advanced cache file is yet to be generated, please save settings!", $this->plugin_constant). $settings_link;
-
-			if ( file_exists ( $this->acache ) && ! is_writable ( $this->acache ) )
-				$this->errors['no_acache_write'] = __("Advanced cache file is not writeable!<br />Please change the permissions on the file: ", $this->plugin_constant) . $this->acache;
-
-			foreach ( $this->valid_cache_type as $backend => $status ) {
-				if ( $this->options['cache_type'] == $backend && ! $status ) {
-					$this->errors['no_backend'] = sprintf ( __('%s cache backend activated but no PHP %s extension was found.<br />Please either use different backend or activate the module!', $this->plugin_constant), $backend, $backend );
-				}
-			}
-
-			/* get the current runtime configuration for memcache in PHP because Memcache in binary mode is really problematic */
-			if ( extension_loaded ( 'memcache' )  ) {
-				$memcache_settings = ini_get_all( 'memcache' );
-				if ( !empty ( $memcache_settings ) && $this->options['cache_type'] == 'memcache' )
-				{
-					$memcache_protocol = strtolower($memcache_settings['memcache.protocol']['local_value']);
-					if ( $memcache_protocol == 'binary' ) {
-						$this->errors['binary_memcache'] = __('WARNING: Memcache extension is configured to use binary mode. This is very buggy and the plugin will most probably not work correctly. <br />Please consider to change either to ASCII mode or to Memcached extension.', $this->plugin_constant );
-					}
-				}
-			}
-
-			/* display errors globally */
-			if ( $this->network )
-				add_action( 'network_admin_notices', array( &$this, 'display_errors') );
-			else
-				add_action( 'admin_notices', array( &$this, 'display_errors') );
-		}
-
-		/**
-		 * activation hook function, to be extended
-		 */
-		public function plugin_activate() {
-			/* we leave this empty to avoid not detecting WP network correctly */
-		}
-
-		/**
-		 * deactivation hook function, to be extended
-		 */
-		public function plugin_deactivate () {
-			/* remove current site config from global config */
-			$this->update_global_config( true );
-		}
-
-		/**
-		 * uninstall hook function, to be extended
-		 */
-		public function plugin_uninstall( $delete_options = true ) {
-			/* delete advanced-cache.php file */
-			unlink ( $this->acache );
-
-			/* delete site settings */
-			if ( $delete_options ) {
-				$this->plugin_options_delete ();
+		foreach ( $this->shell_possibilities as $possible ) {
+			if ( function_exists ($possible) && ! ( ini_get('safe_mode') || in_array( $possible, $disabled_functions ) ) ) {
+				/* set shell function */
+				$this->shell_function = $possible;
+				break;
 			}
 		}
 
-		/**
-		 * extending admin init
-		 *
-		 */
-		public function plugin_hook_admin_init () {
-			/* save parameter updates, if there are any */
-			if ( isset( $_POST[ $this->button_flush ] ) ) {
+		/* set global config key; here, because it's needed for migration */
+		if ( $this->network )
+			$this->global_config_key = 'network';
+		else
+			$this->global_config_key = $_SERVER['HTTP_HOST'];
 
-				/* remove precache log entry */
-				$this->_delete_option( self::precache_log  );
-				/* remove precache timestamp entry */
-				$this->_delete_option( self::precache_timestamp );
+		/* cache type possible values array */
+		$this->select_cache_type = array (
+			'apc' => __( 'APC' , $this->plugin_constant ),
+			'apcu' => __( 'APCu' , $this->plugin_constant ),
+			'xcache' => __( 'XCache' , $this->plugin_constant ),
+			'memcache' => __( 'PHP Memcache' , $this->plugin_constant ),
+			'memcached' => __( 'PHP Memcached' , $this->plugin_constant ),
+		);
+		/* check for required functions / classes for the cache types */
+		$this->valid_cache_type = array (
+			'apc' => function_exists( 'apc_cache_info' ) ? true : false,
+			'apcu' => function_exists( 'apcu_cache_info' ) ? true : false,
+			'xcache' => function_exists( 'xcache_info' ) ? true : false,
+			'memcache' => class_exists ( 'Memcache') ? true : false,
+			'memcached' => class_exists ( 'Memcached') ? true : false,
+		);
 
-				/* remove precache logfile */
-				if ( @file_exists ( $this->precache_logfile ) ) {
-					unlink ( $this->precache_logfile );
-				}
+		/* invalidation method possible values array */
+		$this->select_invalidation_method = array (
+			0 => __( 'flush cache' , $this->plugin_constant ),
+			1 => __( 'only modified post' , $this->plugin_constant ),
+			2 => __( 'modified post and all taxonomies' , $this->plugin_constant ),
+		);
 
-				/* remove precache PHP worker */
-				if ( @file_exists ( $this->precache_phpfile ) ) {
-					unlink ( $this->precache_phpfile );
-				}
+		/* map of possible key masks */
+		$this->list_uri_vars = array (
+			'$scheme' => __('The HTTP scheme (i.e. http, https).', $this->plugin_constant ),
+			'$host' => __('Host in the header of request or name of the server processing the request if the Host header is not available.', $this->plugin_constant ),
+			'$request_uri' => __('The *original* request URI as received from the client including the args', $this->plugin_constant ),
+			'$remote_user' => __('Name of user, authenticated by the Auth Basic Module', $this->plugin_constant ),
+			'$cookie_PHPSESSID' => __('PHP Session Cookie ID, if set ( empty if not )', $this->plugin_constant ),
+			//'$cookie_COOKnginy IE' => __('Value of COOKIE', $this->plugin_constant ),
+			//'$http_HEADER' => __('Value of HTTP request header HEADER ( lowercase, dashes converted to underscore )', $this->plugin_constant ),
+			//'$query_string' => __('Full request URI after rewrites', $this->plugin_constant ),
+			//'' => __('', $this->plugin_constant ),
+		);
 
-				/* flush backend */
-				$this->backend->clear( false, true );
-				$this->status = 3;
-				header( "Location: ". $this->settings_link . self::slug_flush );
+		/* get current wp_cron schedules */
+		$wp_schedules = wp_get_schedules();
+		/* add 'null' to switch off timed precache */
+		$schedules['null'] = __( 'do not use timed precache' );
+		foreach ( $wp_schedules as $interval=>$details ) {
+			$schedules[ $interval ] = $details['display'];
+		}
+		$this->select_schedules = $schedules;
+
+	}
+
+	/**
+	 * additional init, steps that needs the plugin options
+	 *
+	 */
+	public function plugin_post_init () {
+
+		/* initiate backend */
+		$this->backend = new WP_FFPC_Backend ( $this->options, $this->network );
+
+		/* get all available post types */
+		$post_types = get_post_types( );
+
+		/* cache invalidation hooks */
+		foreach ( $post_types as $post_type ) {
+			add_action( 'new_to_publish_' .$post_type , array( &$this->backend , 'clear' ), 0 );
+			add_action( 'draft_to_publish' .$post_type , array( &$this->backend , 'clear' ), 0 );
+			add_action( 'pending_to_publish' .$post_type , array( &$this->backend , 'clear' ), 0 );
+			add_action( 'private_to_publish' .$post_type , array( &$this->backend , 'clear' ), 0 );
+			add_action( 'publish_' . $post_type , array( &$this->backend , 'clear' ), 0 );
+		}
+
+		/* comments invalidation hooks */
+		if ( $this->options['comments_invalidate'] ) {
+			add_action( 'comment_post', array( &$this->backend , 'clear' ), 0 );
+			add_action( 'edit_comment', array( &$this->backend , 'clear' ), 0 );
+			add_action( 'trashed_comment', array( &$this->backend , 'clear' ), 0 );
+			add_action( 'pingback_post', array( &$this->backend , 'clear' ), 0 );
+			add_action( 'trackback_post', array( &$this->backend , 'clear' ), 0 );
+			add_action( 'wp_insert_comment', array( &$this->backend , 'clear' ), 0 );
+			add_action( '', array( &$this->backend , 'clear' ), 0 );
+		}
+
+		/* invalidation on some other ocasions as well */
+		add_action( 'switch_theme', array( &$this->backend , 'clear' ), 0 );
+		add_action( 'deleted_post', array( &$this->backend , 'clear' ), 0 );
+		add_action( 'edit_post', array( &$this->backend , 'clear' ), 0 );
+
+		/* add filter for catching canonical redirects */
+		if ( WP_CACHE )
+			add_filter('redirect_canonical', 'wp_ffpc_redirect_callback', 10, 2);
+
+		/* clean up schedule if needed */
+		if ( !isset( $this->options['precache_schedule'] ) || $this->options['precache_schedule'] == 'null' ) {
+			$this->log ( sprintf ( __( 'clearing scheduled hook %s', $this->plugin_constant ), self::precache_id ) );
+		}
+
+		/* add precache coldrun action */
+		add_action( self::precache_id , array( &$this, 'precache_coldrun' ) );
+
+		$settings_link = ' &raquo; <a href="' . $this->settings_link . '">' . __( 'WP-FFPC Settings', $this->plugin_constant ) . '</a>';
+		/* check for errors */
+		if ( ! WP_CACHE )
+			$this->errors['no_wp_cache'] = __("WP_CACHE is disabled, plugin will not work that way. Please add define `( 'WP_CACHE', true );` in wp-config.php", $this->plugin_constant ) . $settings_link;
+
+		if ( ! $this->global_saved )
+			$this->errors['no_global_saved'] = __("Plugin settings are not yet saved for the site, please save settings!", $this->plugin_constant) . $settings_link;
+
+		if ( ! file_exists ( $this->acache ) )
+			$this->errors['no_acache_saved'] = __("Advanced cache file is yet to be generated, please save settings!", $this->plugin_constant). $settings_link;
+
+		if ( file_exists ( $this->acache ) && ! is_writable ( $this->acache ) )
+			$this->errors['no_acache_write'] = __("Advanced cache file is not writeable!<br />Please change the permissions on the file: ", $this->plugin_constant) . $this->acache;
+
+		foreach ( $this->valid_cache_type as $backend => $status ) {
+			if ( $this->options['cache_type'] == $backend && ! $status ) {
+				$this->errors['no_backend'] = sprintf ( __('%s cache backend activated but no PHP %s extension was found.<br />Please either use different backend or activate the module!', $this->plugin_constant), $backend, $backend );
 			}
+		}
 
-			/* save parameter updates, if there are any */
-			if ( isset( $_POST[ $this->button_precache ] ) ) {
-
-				/* is no shell function is possible, fail */
-				if ( $this->shell_function == false ) {
-					$this->status = 5;
-					header( "Location: ". $this->settings_link . self::slug_precache_disabled );
-				}
-				/* otherwise start full precache */
-				else {
-					$this->precache_message = $this->precache_coldrun();
-					$this->status = 4;
-					header( "Location: ". $this->settings_link . self::slug_precache );
+		/* get the current runtime configuration for memcache in PHP because Memcache in binary mode is really problematic */
+		if ( extension_loaded ( 'memcache' )  ) {
+			$memcache_settings = ini_get_all( 'memcache' );
+			if ( !empty ( $memcache_settings ) && $this->options['cache_type'] == 'memcache' )
+			{
+				$memcache_protocol = strtolower($memcache_settings['memcache.protocol']['local_value']);
+				if ( $memcache_protocol == 'binary' ) {
+					$this->errors['binary_memcache'] = __('WARNING: Memcache extension is configured to use binary mode. This is very buggy and the plugin will most probably not work correctly. <br />Please consider to change either to ASCII mode or to Memcached extension.', $this->plugin_constant );
 				}
 			}
 		}
 
-		/**
-		 * admin help panel
-		 */
-		public function plugin_admin_help($contextual_help, $screen_id ) {
+		foreach ( $this->errors as $e => $msg ) {
+			$this->utils->alert ( $msg, 'error', $this->network );
+		}
+	}
 
-			/* add our page only if the screenid is correct */
-			if ( strpos( $screen_id, $this->plugin_settings_page ) ) {
-				$contextual_help = __('<p>Please visit <a href="http://wordpress.org/support/plugin/wp-ffpc">the official support forum of the plugin</a> for help.</p>', $this->plugin_constant );
+	/**
+	 * activation hook function, to be extended
+	 */
+	public function plugin_activate() {
+		/* we leave this empty to avoid not detecting WP network correctly */
+	}
 
-				/* [TODO] give detailed information on errors & troubleshooting
-				get_current_screen()->add_help_tab( array(
-						'id'		=> $this->plugin_constant . '-issues',
-						'title'		=> __( 'Troubleshooting' ),
-						'content'	=> __( '<p>List of errors, possible reasons and solutions</p><dl>
-							<dt>E#</dt><dd></dd>
-						</ol>' )
-				) );
-				*/
+	/**
+	 * deactivation hook function, to be extended
+	 */
+	public function plugin_deactivate () {
+		/* remove current site config from global config */
+		$this->update_global_config( true );
+	}
 
+	/**
+	 * uninstall hook function, to be extended
+	 */
+	public function plugin_uninstall( $delete_options = true ) {
+		/* delete advanced-cache.php file */
+		unlink ( $this->acache );
+
+		/* delete site settings */
+		if ( $delete_options ) {
+			$this->plugin_options_delete ();
+		}
+	}
+
+	/**
+	 * extending admin init
+	 *
+	 */
+	public function plugin_extend_admin_init () {
+		/* save parameter updates, if there are any */
+		if ( isset( $_POST[ $this->button_flush ] ) ) {
+
+			/* remove precache log entry */
+			$this->_delete_option( self::precache_log  );
+			/* remove precache timestamp entry */
+			$this->_delete_option( self::precache_timestamp );
+
+			/* remove precache logfile */
+			if ( @file_exists ( $this->precache_logfile ) ) {
+				unlink ( $this->precache_logfile );
 			}
 
-			return $contextual_help;
-		}
-
-		/**
-		 * admin panel, the admin page displayed for plugin settings
-		 */
-		public function plugin_admin_panel() {
-			/**
-			 * security, if somehow we're running without WordPress security functions
-			 */
-			if( ! function_exists( 'current_user_can' ) || ! current_user_can( 'manage_options' ) ){
-				die( );
-			}
-			?>
-
-			<div class="wrap">
-
-			<script>
-				jQuery(document).ready(function($) {
-					jQuery( "#<?php echo $this->plugin_constant ?>-settings" ).tabs();
-					jQuery( "#<?php echo $this->plugin_constant ?>-commands" ).tabs();
-				});
-			</script>
-
-			<?php
-
-			/* display donation form */
-			$this->plugin_donation_form();
-
-			/**
-			 * if options were saved, display saved message
-			 */
-			if (isset($_GET[ self::key_save ]) && $_GET[ self::key_save ]=='true' || $this->status == 1) { ?>
-				<div class='updated settings-error'><p><strong><?php _e( 'Settings saved.' , $this->plugin_constant ) ?></strong></p></div>
-			<?php }
-
-			/**
-			 * if options were delete, display delete message
-			 */
-			if (isset($_GET[ self::key_delete ]) && $_GET[ self::key_delete ]=='true' || $this->status == 2) { ?>
-				<div class='error'><p><strong><?php _e( 'Plugin options deleted.' , $this->plugin_constant ) ?></strong></p></div>
-			<?php }
-
-			/**
-			 * if options were saved
-			 */
-			if (isset($_GET[ self::key_flush ]) && $_GET[ self::key_flush ]=='true' || $this->status == 3) { ?>
-				<div class='updated settings-error'><p><strong><?php _e( "Cache flushed." , $this->plugin_constant ); ?></strong></p></div>
-			<?php }
-
-			/**
-			 * if options were saved, display saved message
-			 */
-			if ( ( isset($_GET[ self::key_precache ]) && $_GET[ self::key_precache ]=='true' ) || $this->status == 4) { ?>
-			<div class='updated settings-error'><p><strong><?php _e( 'Precache process was started, it is now running in the background, please be patient, it may take a very long time to finish.' , $this->plugin_constant ) ?></strong></p></div>
-			<?php }
-
-			/**
-			 * the admin panel itself
-			 */
-			?>
-
-			<h2><?php echo $this->plugin_name ; _e( ' settings', $this->plugin_constant ) ; ?></h2>
-
-			<div class="updated">
-				<p><strong><?php _e ( 'Driver: ' , $this->plugin_constant); echo $this->options['cache_type']; ?></strong></p>
-				<?php
-				/* only display backend status if memcache-like extension is running */
-				if ( strstr ( $this->options['cache_type'], 'memcache') ) {
-					?><p><?php
-					_e( '<strong>Backend status:</strong><br />', $this->plugin_constant );
-
-					/* we need to go through all servers */
-					$servers = $this->backend->status();
-					foreach ( $servers as $server_string => $status ) {
-						echo $server_string ." => ";
-
-						if ( $status == 0 )
-							_e ( '<span class="error-msg">down</span><br />', $this->plugin_constant );
-						elseif ( ( $this->options['cache_type'] == 'memcache' && $status > 0 )  || $status == 1 )
-							_e ( '<span class="ok-msg">up & running</span><br />', $this->plugin_constant );
-						else
-							_e ( '<span class="error-msg">unknown, please try re-saving settings!</span><br />', $this->plugin_constant );
-					}
-
-					?></p><?php
-				} ?>
-			</div>
-			<form method="post" action="#" id="<?php echo $this->plugin_constant ?>-settings" class="plugin-admin">
-
-				<ul class="tabs">
-					<li><a href="#<?php echo $this->plugin_constant ?>-type" class="wp-switch-editor"><?php _e( 'Cache type', $this->plugin_constant ); ?></a></li>
-					<li><a href="#<?php echo $this->plugin_constant ?>-debug" class="wp-switch-editor"><?php _e( 'Debug & in-depth', $this->plugin_constant ); ?></a></li>
-					<li><a href="#<?php echo $this->plugin_constant ?>-exceptions" class="wp-switch-editor"><?php _e( 'Cache exceptions', $this->plugin_constant ); ?></a></li>
-					<li><a href="#<?php echo $this->plugin_constant ?>-memcached" class="wp-switch-editor"><?php _e( 'Memcache(d)', $this->plugin_constant ); ?></a></li>
-					<li><a href="#<?php echo $this->plugin_constant ?>-nginx" class="wp-switch-editor"><?php _e( 'nginx', $this->plugin_constant ); ?></a></li>
-					<li><a href="#<?php echo $this->plugin_constant ?>-precache" class="wp-switch-editor"><?php _e( 'Precache & precache log', $this->plugin_constant ); ?></a></li>
-				</ul>
-
-				<fieldset id="<?php echo $this->plugin_constant ?>-type">
-				<legend><?php _e( 'Set cache type', $this->plugin_constant ); ?></legend>
-				<dl>
-					<dt>
-						<label for="cache_type"><?php _e('Select backend', $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<select name="cache_type" id="cache_type">
-							<?php $this->print_select_options ( $this->select_cache_type , $this->options['cache_type'], $this->valid_cache_type ) ?>
-						</select>
-						<span class="description"><?php _e('Select backend storage driver', $this->plugin_constant); ?></span>
-					</dd>
-
-					<dt>
-						<label for="expire"><?php _e('Expiration time (seconds)', $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="number" name="expire" id="expire" value="<?php echo $this->options['expire']; ?>" />
-						<span class="description"><?php _e('Sets validity time of entry in seconds', $this->plugin_constant); ?></span>
-					</dd>
-
-					<dt>
-						<label for="charset"><?php _e('Charset', $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="text" name="charset" id="charset" value="<?php echo $this->options['charset']; ?>" />
-						<span class="description"><?php _e('Charset of HTML and XML (pages and feeds) data.', $this->plugin_constant); ?></span>
-					</dd>
-
-					<dt>
-						<label for="invalidation_method"><?php _e('Cache invalidation method', $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<select name="invalidation_method" id="invalidation_method">
-							<?php $this->print_select_options ( $this->select_invalidation_method , $this->options['invalidation_method'] ) ?>
-						</select>
-						<span class="description"><?php _e('Select cache invalidation method. <ol><li><em>flush cache</em> - clears everything in storage, <strong>including values set by other applications</strong></li><li><em>only modified post</em> - clear only the modified posts entry, everything else remains in cache</li><li><em>modified post and all taxonomies</em> - removes all taxonomy term cache ( categories, tags, home, etc ) and the modified post as well</li></ol>', $this->plugin_constant); ?></span>
-					</dd>
-
-					<dt>
-						<label for="comments_invalidate"><?php _e('Invalidate on comment actions', $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="checkbox" name="comments_invalidate" id="comments_invalidate" value="1" <?php checked($this->options['comments_invalidate'],true); ?> />
-						<span class="description"><?php _e('Trigger cache invalidation when a comments is posted, edited, trashed. ', $this->plugin_constant); ?></span>
-					</dd>
-
-					<dt>
-						<label for="prefix_data"><?php _e('Data prefix', $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="text" name="prefix_data" id="prefix_data" value="<?php echo $this->options['prefix_data']; ?>" />
-						<span class="description"><?php _e('Prefix for HTML content keys, can be used in nginx.<br /><strong>WARNING</strong>: changing this will result the previous cache to becomes invalid!<br />If you are caching with nginx, you should update your nginx configuration and reload nginx after changing this value.', $this->plugin_constant); ?></span>
-					</dd>
-
-					<dt>
-						<label for="prefix_meta"><?php _e('Meta prefix', $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="text" name="prefix_meta" id="prefix_meta" value="<?php echo $this->options['prefix_meta']; ?>" />
-						<span class="description"><?php _e('Prefix for meta content keys, used only with PHP processing.<br /><strong>WARNING</strong>: changing this will result the previous cache to becomes invalid!', $this->plugin_constant); ?></span>
-					</dd>
-
-					<dt>
-						<label for="key"><?php _e('Key scheme', $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="text" name="key" id="key" value="<?php echo $this->options['key']; ?>" />
-						<span class="description"><?php _e('Key layout; <strong>use the guide below to change it</strong>.<br /><strong>WARNING</strong>: changing this will result the previous cache to becomes invalid!<br />If you are caching with nginx, you should update your nginx configuration and reload nginx after changing this value.', $this->plugin_constant); ?><?php ?></span>
-						<dl class="description"><?php
-						foreach ( $this->list_uri_vars as $uri => $desc ) {
-							echo '<dt>'. $uri .'</dt><dd>'. $desc .'</dd>';
-						}
-						?></dl>
-					</dd>
-
-				</dl>
-				</fieldset>
-
-				<fieldset id="<?php echo $this->plugin_constant ?>-debug">
-				<legend><?php _e( 'Debug & in-depth settings', $this->plugin_constant ); ?></legend>
-				<dl>
-					<dt>
-						<label for="log"><?php _e("Enable logging", $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="checkbox" name="log" id="log" value="1" <?php checked($this->options['log'],true); ?> />
-						<span class="description"><?php _e('Enables log messages; if <a href="http://codex.wordpress.org/WP_DEBUG">WP_DEBUG</a> is enabled, notices and info level is displayed as well, otherwie only ERRORS are logged.', $this->plugin_constant); ?></span>
-					</dd>
-
-					<dt>
-						<label for="response_header"><?php _e("Add X-Cache-Engine header", $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="checkbox" name="response_header" id="response_header" value="1" <?php checked($this->options['response_header'],true); ?> />
-						<span class="description"><?php _e('Add X-Cache-Engine HTTP header to HTTP responses.', $this->plugin_constant); ?></span>
-					</dd>
-
-					<dt>
-						<label for="generate_time"><?php _e("Add HTML debug comment", $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="checkbox" name="generate_time" id="generate_time" value="1" <?php checked($this->options['generate_time'],true); ?> />
-						<span class="description"><?php _e('Adds comment string including plugin name, cache engine and page generation time to every generated entry before closing <body> tag.', $this->plugin_constant); ?></span>
-					</dd>
-
-				</dl>
-				</fieldset>
-
-				<fieldset id="<?php echo $this->plugin_constant ?>-exceptions">
-				<legend><?php _e( 'Set cache additions/excepions', $this->plugin_constant ); ?></legend>
-				<dl>
-					<dt>
-						<label for="cache_loggedin"><?php _e('Enable cache for logged in users', $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="checkbox" name="cache_loggedin" id="cache_loggedin" value="1" <?php checked($this->options['cache_loggedin'],true); ?> />
-						<span class="description"><?php _e('Cache pages even if user is logged in.', $this->plugin_constant); ?></span>
-					</dd>
-
-					<dt>
-						<label for="nocache_home"><?php _e("Don't cache home", $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="checkbox" name="nocache_home" id="nocache_home" value="1" <?php checked($this->options['nocache_home'],true); ?> />
-						<span class="description"><?php _e('Exclude home page from caching', $this->plugin_constant); ?></span>
-
-					</dd>
-
-					<dt>
-						<label for="nocache_feed"><?php _e("Don't cache feeds", $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="checkbox" name="nocache_feed" id="nocache_feed" value="1" <?php checked($this->options['nocache_feed'],true); ?> />
-						<span class="description"><?php _e('Exclude feeds from caching.', $this->plugin_constant); ?></span>
-					</dd>
-
-					<dt>
-						<label for="nocache_archive"><?php _e("Don't cache archives", $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="checkbox" name="nocache_archive" id="nocache_archive" value="1" <?php checked($this->options['nocache_archive'],true); ?> />
-						<span class="description"><?php _e('Exclude archives from caching.', $this->plugin_constant); ?></span>
-					</dd>
-
-					<dt>
-						<label for="nocache_single"><?php _e("Don't cache posts (and single-type entries)", $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="checkbox" name="nocache_single" id="nocache_single" value="1" <?php checked($this->options['nocache_single'],true); ?> />
-						<span class="description"><?php _e('Exclude singles from caching.', $this->plugin_constant); ?></span>
-					</dd>
-
-					<dt>
-						<label for="nocache_page"><?php _e("Don't cache pages", $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="checkbox" name="nocache_page" id="nocache_page" value="1" <?php checked($this->options['nocache_page'],true); ?> />
-						<span class="description"><?php _e('Exclude pages from caching.', $this->plugin_constant); ?></span>
-					</dd>
-
-					<dt>
-						<label for="nocache_cookies"><?php _e("Don't cache cookies", $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="text" name="nocache_cookies" id="nocache_cookies" value="<?php if(isset( $this->options['nocache_cookies'] ) ) echo $this->options['nocache_cookies']; ?>" />
-						<span class="description"><?php _e('Exclude cookies names starting with this from caching. Separate multiple cookies names with commas.<br />If you are caching with nginx, you should update your nginx configuration and reload nginx after changing this value.', $this->plugin_constant); ?></span>
-					</dd>
-				</dl>
-				</fieldset>
-
-				<fieldset id="<?php echo $this->plugin_constant ?>-memcached">
-				<legend><?php _e('Settings for memcached backend', $this->plugin_constant); ?></legend>
-				<dl>
-					<dt>
-						<label for="hosts"><?php _e('Hosts', $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="text" name="hosts" id="hosts" value="<?php echo $this->options['hosts']; ?>" />
-						<span class="description">
-						<?php _e('List of memcached backends, with the following syntax: <br />- in case of TCP based connections, list the servers as host1:port1,host2:port2,... . Do not add trailing , and always separate host and port with : .<br />- in2.0.0b1 case using unix sockets with the Memcache driver: unix:// ', $this->plugin_constant); ?></span>
-					</dd>
-					<dt>
-						<label for="persistent"><?php _e('Persistent memcache connections', $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="checkbox" name="persistent" id="persistent" value="1" <?php checked($this->options['persistent'],true); ?> />
-						<span class="description"><?php _e('Make all memcache(d) connections persistent. Be careful with this setting, always test the outcome.', $this->plugin_constant); ?></span>
-					</dd>
-
-					<?php
-					if ( strstr ( $this->options['cache_type'], 'memcached') && extension_loaded ( 'memcached' ) && version_compare( phpversion( 'memcached' ) , '2.0.0', '>=' ) ) { ?>
-					<?php
-						if ( ! ini_get('memcached.use_sasl') && ( !empty( $this->options['authuser'] ) || !empty( $this->options['authpass'] ) ) ) { ?>
-							<div class="error"><p><strong><?php _e( 'WARNING: you\'ve entered username and/or password for memcached authentication ( or your browser\'s autocomplete did ) which will not work unless you enable memcached sasl in the PHP settings: add `memcached.use_sasl=1` to php.ini' , $this->plugin_constant ) ?></strong></p></div>
-					<?php } ?>
-					<dt>
-						<label for="authuser"><?php _e('Authentication: username', $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="text" name="authuser" id="authuser" value="<?php echo $this->options['authuser']; ?>" />
-						<span class="description">
-						<?php _e('Username for authentication with memcached backends', $this->plugin_constant); ?></span>
-					</dd>
-
-					<dt>
-						<label for="authpass"><?php _e('Authentication: password', $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<input type="password" name="authpass" id="authpass" value="<?php echo $this->options['authpass']; ?>" />
-						<span class="description">
-						<?php _e('Password for authentication with memcached backends - WARNING, the password will be stored plain-text since it needs to be used!', $this->plugin_constant); ?></span>
-					</dd>
-					<?php } ?>
-				</dl>
-				</fieldset>
-
-				<fieldset id="<?php echo $this->plugin_constant ?>-nginx">
-				<legend><?php _e('Sample config for nginx to utilize the data entries', $this->plugin_constant); ?></legend>
-				<pre><?php echo $this->nginx_example(); ?></pre>
-				</fieldset>
-
-				<fieldset id="<?php echo $this->plugin_constant ?>-precache">
-				<legend><?php _e('Precache settings & log from previous pre-cache generation', $this->plugin_constant); ?></legend>
-
-					<dt>
-						<label for="precache_schedule"><?php _e('Precache schedule', $this->plugin_constant); ?></label>
-					</dt>
-					<dd>
-						<select name="precache_schedule" id="precache_schedule">
-							<?php $this->print_select_options ( $this->select_schedules, $this->options['precache_schedule'] ) ?>
-						</select>
-						<span class="description"><?php _e('Schedule autorun for precache with WP-Cron', $this->plugin_constant); ?></span>
-					</dd>
-
-					<?php
-
-					$gentime = $this->_get_option( self::precache_timestamp );
-					$log = $this->_get_option( self::precache_log );
-
-					if ( @file_exists ( $this->precache_logfile ) ) {
-						$logtime = filemtime ( $this->precache_logfile );
-
-						/* update precache log in DB if needed */
-						if ( $logtime > $gentime ) {
-							$log = file ( $this->precache_logfile );
-							$this->_update_option( self::precache_log , $log );
-							$this->_update_option( self::precache_timestamp , $logtime );
-						}
-
-					}
-
-					if ( empty ( $log ) ) {
-						_e('No precache log was found!', $this->plugin_constant);
-					}
-					else { ?>
-						<p><strong><?php _e( 'Time of run: ') ?><?php echo date('r', $gentime ); ?></strong></p>
-						<div  style="overflow: auto; max-height: 20em;"><table style="width:100%; border: 1px solid #ccc;">
-							<thead><tr>
-									<?php $head = explode( "	", array_shift( $log ));
-									foreach ( $head as $column ) { ?>
-										<th><?php echo $column; ?></th>
-									<?php } ?>
-							</tr></thead>
-							<?php
-							foreach ( $log as $line ) { ?>
-								<tr>
-									<?php $line = explode ( "	", $line );
-									foreach ( $line as $column ) { ?>
-										<td><?php echo $column; ?></td>
-									<?php } ?>
-								</tr>
-							<?php } ?>
-					</table></div>
-				<?php } ?>
-				</fieldset>
-
-				<p class="clear">
-					<input class="button-primary" type="submit" name="<?php echo $this->button_save ?>" id="<?php echo $this->button_save ?>" value="<?php _e('Save Changes', $this->plugin_constant ) ?>" />
-				</p>
-
-			</form>
-
-			<form method="post" action="#" id="<?php echo $this->plugin_constant ?>-commands" class="plugin-admin" style="padding-top:2em;">
-
-				<ul class="tabs">
-					<li><a href="#<?php echo $this->plugin_constant ?>-precache" class="wp-switch-editor"><?php _e( 'Precache', $this->plugin_constant ); ?></a></li>
-					<li><a href="#<?php echo $this->plugin_constant ?>-flush" class="wp-switch-editor"><?php _e( 'Empty cache', $this->plugin_constant ); ?></a></li>
-					<li><a href="#<?php echo $this->plugin_constant ?>-reset" class="wp-switch-editor"><?php _e( 'Reset settings', $this->plugin_constant ); ?></a></li>
-				</ul>
-
-				<fieldset id="<?php echo $this->plugin_constant ?>-precache">
-				<legend><?php _e( 'Precache', $this->plugin_constant ); ?></legend>
-				<dl>
-					<dt>
-						<?php if ( ( isset( $_GET[ self::key_precache_disabled ] ) && $_GET[ self::key_precache_disabled ] =='true' ) || $this->status == 5 || $this->shell_function == false ) { ?>
-							<strong><?php _e( "Precache functionality is disabled due to unavailable system call function. <br />Since precaching may take a very long time, it's done through a background CLI process in order not to run out of max execution time of PHP. Please enable one of the following functions if you whish to use precaching: " , $this->plugin_constant ) ?><?php echo join( ',' , $this->shell_possibilities ); ?></strong>
-						<?php }
-						else { ?>
-							<input class="button-secondary" type="submit" name="<?php echo $this->button_precache ?>" id="<?php echo $this->button_precache ?>" value="<?php _e('Pre-cache', $this->plugin_constant ) ?>" />
-						<?php } ?>
-					</dt>
-					<dd>
-						<span class="description"><?php _e('Start a background process that visits all permalinks of all blogs it can found thus forces WordPress to generate cached version of all the pages.<br />The plugin tries to visit links of taxonomy terms without the taxonomy name as well. This may generate 404 hits, please be prepared for these in your logfiles if you plan to pre-cache.', $this->plugin_constant); ?></span>
-					</dd>
-				</dl>
-				</fieldset>
-				<fieldset id="<?php echo $this->plugin_constant ?>-flush">
-				<legend><?php _e( 'Precache', $this->plugin_constant ); ?></legend>
-				<dl>
-					<dt>
-						<input class="button-warning" type="submit" name="<?php echo $this->button_flush ?>" id="<?php echo $this->button_flush ?>" value="<?php _e('Clear cache', $this->plugin_constant ) ?>" />
-					</dt>
-					<dd>
-						<span class="description"><?php _e ( "Clear all entries in the storage, including the ones that were set by other processes.", $this->plugin_constant ); ?> </span>
-					</dd>
-				</dl>
-				</fieldset>
-				<fieldset id="<?php echo $this->plugin_constant ?>-reset">
-				<legend><?php _e( 'Precache', $this->plugin_constant ); ?></legend>
-				<dl>
-					<dt>
-						<input class="button-warning" type="submit" name="<?php echo $this->button_delete ?>" id="<?php echo $this->button_delete ?>" value="<?php _e('Reset options', $this->plugin_constant ) ?>" />
-					</dt>
-					<dd>
-						<span class="description"><?php _e ( "Reset settings to defaults.", $this->plugin_constant ); ?> </span>
-					</dd>
-				</dl>
-				</fieldset>
-			</form>
-			</div>
-			<?php
-		}
-
-		/**
-		 * extending options_save
-		 *
-		 */
-		public function plugin_hook_options_save( $activating ) {
-
-			/* schedule cron if posted */
-			$schedule = wp_get_schedule( self::precache_id );
-			if ( $this->options['precache_schedule'] != 'null' ) {
-				/* clear all other schedules before adding a new in order to replace */
-				wp_clear_scheduled_hook ( self::precache_id );
-				$this->log ( __( 'Scheduling WP-CRON event', $this->plugin_constant ) );
-				$this->scheduled = wp_schedule_event( time(), $this->options['precache_schedule'] , self::precache_id );
-			}
-			elseif ( ( !isset($this->options['precache_schedule']) || $this->options['precache_schedule'] == 'null' ) && !empty( $schedule ) ) {
-				$this->log ( __('Clearing WP-CRON scheduled hook ' , $this->plugin_constant ) );
-				wp_clear_scheduled_hook ( self::precache_id );
+			/* remove precache PHP worker */
+			if ( @file_exists ( $this->precache_phpfile ) ) {
+				unlink ( $this->precache_phpfile );
 			}
 
-			/* flush the cache when news options are saved, not needed on activation */
-			if ( !$activating )
-				$this->backend->clear();
-
-			/* create the to-be-included configuration for advanced-cache.php */
-			$this->update_global_config();
-
-			/* create advanced cache file, needed only once or on activation, because there could be lefover advanced-cache.php from different plugins */
-			if (  !$activating )
-				$this->deploy_advanced_cache();
-
+			/* flush backend */
+			$this->backend->clear( false, true );
+			$this->status = 3;
+			header( "Location: ". $this->settings_link . self::slug_flush );
 		}
 
-		/**
-		 * read hook; needs to be implemented
-		 */
-		public function plugin_hook_options_read( &$options ) {
-			/* read the global options, network compatibility */
-			$this->global_config = get_site_option( $this->global_option );
-
-			/* check if current site present in global config */
-			if ( !empty ( $this->global_config[ $this->global_config_key ] ) )
-				$this->global_saved = true;
-
-			$this->global_config[ $this->global_config_key ] = $options;
-		}
-
-		/**
-		 * options delete hook; needs to be implemented
-		 */
-		public function plugin_hook_options_delete(  ) {
-			delete_site_option ( $this->global_option );
-		}
-
-		/**
-		 * need to do migrations from previous versions of the plugin
-		 *
-		 */
-		public function plugin_hook_options_migrate( &$options ) {
-			$migrated = false;
-
-			if ( version_compare ( $options['version'] , $this->plugin_version , '<' ) ) {
-				/* cleanup possible leftover files from previous versions */
-				$check = array ( 'advanced-cache.php', 'nginx-sample.conf', 'wp-ffpc.admin.css', 'wp-ffpc-common.php' );
-				foreach ( $check as $fname ) {
-					$fname = $this->plugin_dir . $fname;
-					if ( file_exists ( $fname ) )
-						unlink ( $fname );
-				}
-
-				/* look for previous config leftovers */
-				$try = get_site_option( $this->plugin_constant );
-				/* network option key changed, remove & migrate the leftovers if there's any */
-				if ( !empty ( $try ) && $this->network ) {
-					/* clean it up, we don't use it anymore */
-					delete_site_option ( $this->plugin_constant );
-
-					if ( empty ( $options ) && array_key_exists ( $this->global_config_key, $try ) ) {
-						$options = $try [ $this->global_config_key ];
-						$migrated = true;
-					}
-					elseif ( empty ( $options ) && array_key_exists ( 'host', $try ) ) {
-						$options = $try;
-						$migrated = true;
-					}
-				 }
-
-				/* updating from version <= 0.4.x */
-				if ( !empty ( $options['host'] ) ) {
-					$options['hosts'] = $options['host'] . ':' . $options['port'];
-					$migrated = true;
-				}
-				/* migrating from version 0.6.x */
-				elseif ( is_array ( $options ) && array_key_exists ( $this->global_config_key , $options ) ) {
-					$options = $options[ $this->global_config_key ];
-					$migrated = true;
-				}
-				/* migrating from something, drop previous config */
-				else {
-					$options = array();
-				}
-
-				if ( $migrated ) {
-					/* renamed options */
-					if ( isset ( $options['syslog'] ) )
-						$options['log'] = $options['syslog'];
-					if ( isset ( $options['debug'] ) )
-					$options['response_header'] = $options['debug'];
-				}
+		/* save parameter updates, if there are any */
+		if ( isset( $_POST[ $this->button_precache ] ) ) {
 
+			/* is no shell function is possible, fail */
+			if ( $this->shell_function == false ) {
+				$this->status = 5;
+				header( "Location: ". $this->settings_link . self::slug_precache_disabled );
 			}
-		}
-
-		/**
-		 * advanced-cache.php creator function
-		 *
-		 */
-		private function deploy_advanced_cache( ) {
-
-			/* in case advanced-cache.php was already there, remove it */
-			if ( @file_exists( $this->acache ))
-				unlink ($this->acache);
-
-			/* is deletion was unsuccessful, die, we have no rights to do that, fail */
-			if ( @file_exists( $this->acache ))
-				return false;
-
-			/* if no active site left no need for advanced cache :( */
-			if ( empty ( $this->global_config ) )
-				return false;
-
-			/* add the required includes and generate the needed code */
-			$string[] = "<?php";
-			$string[] = self::global_config_var . ' = ' . var_export ( $this->global_config, true ) . ';' ;
-			//$string[] = "include_once ('" . $this->acache_backend . "');";
-			$string[] = "include_once ('" . $this->acache_worker . "');";
-			$string[] = "?>";
-
-			/* write the file and start caching from this point */
-			return file_put_contents( $this->acache, join( "\n" , $string ) );
-		}
-
-		/**
-		 * function to generate working example from the nginx sample file
-		 *
-		 * @return string nginx config file
-		 *
-		 */
-		private function nginx_example () {
-			/* read the sample file */
-			$nginx = file_get_contents ( $this->nginx_sample );
-
-			/* replace the data prefix with the configured one */
-			$to_replace = array ( 'DATAPREFIX' , 'SERVERROOT', 'SERVERLOG' );
-			$replace_with = array ( $this->options['prefix_data'] . $this->options['key'] , ABSPATH, $_SERVER['SERVER_NAME'] );
-			$nginx = str_replace ( $to_replace , $replace_with , $nginx );
-
-			/* set upstream servers from configured servers, best to get from the actual backend */
-			$servers = $this->backend->get_servers();
-			$nginx_servers = '';
-			if ( is_array ( $servers )) {
-				foreach ( array_keys( $servers ) as $server ) {
-					$nginx_servers .= "		server ". $server .";\n";
-				}
-			}
+			/* otherwise start full precache */
 			else {
-				$nginx_servers .= "		server ". $servers .";\n";
+				$this->precache_message = $this->precache_coldrun();
+				$this->status = 4;
+				header( "Location: ". $this->settings_link . self::slug_precache );
 			}
-			$nginx = str_replace ( 'MEMCACHED_SERVERS' , $nginx_servers , $nginx );
-
-			$loggedincookies = join('|', $this->backend->cookies );
-			/* this part is not used when the cache is turned on for logged in users */
-			$loggedin = '
-				if ($http_cookie ~* "'. $loggedincookies .'" ) {
-					set $memcached_request 0;
-				}';
-
-			/* add logged in cache, if valid */
-			if ( ! $this->options['cache_loggedin'])
-				$nginx = str_replace ( 'LOGGEDIN_EXCEPTION' , $loggedin , $nginx );
-			else
-				$nginx = str_replace ( 'LOGGEDIN_EXCEPTION' , '' , $nginx );
-
-			/* nginx can skip caching for visitors with certain cookies specified in the options */
-			if( $this->options['nocache_cookies'] ) {
-				$cookies = str_replace( ",","|", $this->options['nocache_cookies'] );
-				$cookies = str_replace( " ","", $cookies );
-				$cookie_exception = '# avoid cache for cookies specified
-				if ($http_cookie ~* ' . $cookies . ' ) {
-					set $memcached_request 0;
-				}';
-				$nginx = str_replace ( 'COOKIES_EXCEPTION' , $cookie_exception , $nginx );
-			} else {
-				$nginx = str_replace ( 'COOKIES_EXCEPTION' , '' , $nginx );
-			}
-
-			/* add custom response header if specified in the options */
-			if( $this->options['response_header'] ){
-				$response_header =  'add_header X-Cache-Engine "WP-FFPC with ' . $this->options['cache_type'] .' via nginx";';
-				$nginx = str_replace ( 'RESPONSE_HEADER' , $response_header , $nginx );
-			} else{
-				$nginx = str_replace ( 'RESPONSE_HEADER' , '' , $nginx );
-			}
-
-			return $nginx;
 		}
+	}
 
-		/**
-		 * function to update global configuration
-		 *
-		 * @param boolean $remove_site Bool to remove or add current config to global
-		 *
-		 */
-		private function update_global_config ( $remove_site = false ) {
+	/**
+	 * admin help panel
+	 */
+	public function plugin_admin_help($contextual_help, $screen_id ) {
 
-			/* remove or add current config to global config */
-			if ( $remove_site ) {
-				unset ( $this->global_config[ $this->global_config_key ] );
-			}
-			else {
-				$this->global_config[ $this->global_config_key ] = $this->options;
-			}
+		/* add our page only if the screenid is correct */
+		if ( strpos( $screen_id, $this->plugin_settings_page ) ) {
+			$contextual_help = __('<p>Please visit <a href="http://wordpress.org/support/plugin/wp-ffpc">the official support forum of the plugin</a> for help.</p>', $this->plugin_constant );
 
-			/* deploy advanced-cache.php */
-			$this->deploy_advanced_cache ();
-
-			/* save options to database */
-			update_site_option( $this->global_option , $this->global_config );
-		}
-
-
-		/**
-		 * generate cache entry for every available permalink, might be very-very slow,
-		 * therefore it starts a background process
-		 *
-		 */
-		private function precache ( &$links ) {
-
-			/* double check if we do have any links to pre-cache */
-			if ( !empty ( $links ) && !$this->precache_running() )  {
-
-				$out = '<?php
-					$links = ' . var_export ( $links , true ) . ';
-
-					echo "permalink\tgeneration time (s)\tsize ( kbyte )\n";
-					foreach ( $links as $permalink => $dummy ) {
-						$starttime = explode ( " ", microtime() );
-						$starttime = $starttime[1] + $starttime[0];
-
-							$page = file_get_contents( $permalink );
-							$size = round ( ( strlen ( $page ) / 1024 ), 2 );
-
-						$endtime = explode ( " ", microtime() );
-						$endtime = round( ( $endtime[1] + $endtime[0] ) - $starttime, 2 );
-
-						echo $permalink . "\t" .  $endtime . "\t" . $size . "\n";
-						unset ( $page, $size, $starttime, $endtime );
-						sleep( 1 );
-					}
-					unlink ( "'. $this->precache_phpfile .'" );
-				?>';
-
-				file_put_contents ( $this->precache_phpfile, $out  );
-				/* call the precache worker file in the background */
-				$shellfunction = $this->shell_function;
-				$shellfunction( 'php '. $this->precache_phpfile .' >'. $this->precache_logfile .' 2>&1 &' );
-			}
-
-		}
-
-		/**
-		 * check is precache is still ongoing
-		 *
-		 */
-		private function precache_running () {
-			$return = false;
-
-			/* if the precache file exists, it did not finish running as it should delete itself on finish */
-			if ( file_exists ( $this->precache_phpfile )) {
-				$return = true;
-			}
-			/*
-			 [TODO] cross-platform process check; this is *nix only
-			else {
-				$shellfunction = $this->shell_function;
-				$running = $shellfunction( "ps aux | grep \"". $this->precache_phpfile ."\" | grep -v grep | awk '{print $2}'" );
-				if ( is_int( $running ) && $running != 0 ) {
-					$return = true;
-				}
-			}
+			/* [TODO] give detailed information on errors & troubleshooting
+			get_current_screen()->add_help_tab( array(
+					'id'		=> $this->plugin_constant . '-issues',
+					'title'		=> __( 'Troubleshooting' ),
+					'content'	=> __( '<p>List of errors, possible reasons and solutions</p><dl>
+						<dt>E#</dt><dd></dd>
+					</ol>' )
+			) );
 			*/
 
-			return $return;
 		}
 
+		return $contextual_help;
+	}
+
+	/**
+	 * admin panel, the admin page displayed for plugin settings
+	 */
+	public function plugin_admin_panel() {
 		/**
-		 * run full-site precache
+		 * security, if somehow we're running without WordPress security functions
 		 */
-		public function precache_coldrun () {
+		if( ! function_exists( 'current_user_can' ) || ! current_user_can( 'manage_options' ) ){
+			die( );
+		}
+		?>
 
-			/* container for links to precache, well be accessed by reference */
-			$links = array();
+		<div class="wrap">
 
-			/* when plugin is  network wide active, we need to pre-cache for all link of all blogs */
-			if ( $this->network ) {
-				/* list all blogs */
-				global $wpdb;
-				$blog_list = $wpdb->get_results( $wpdb->prepare( "SELECT * FROM wp_blogs ORDER BY blog_id", '' ) );
+		<script>
+			jQuery(document).ready(function($) {
+				jQuery( "#<?php echo $this->plugin_constant ?>-settings" ).tabs();
+				jQuery( "#<?php echo $this->plugin_constant ?>-commands" ).tabs();
+			});
+		</script>
 
-				foreach ($blog_list as $blog) {
-					if ( $blog->archived != 1 && $blog->spam != 1 && $blog->deleted != 1) {
-						/* get permalinks for this blog */
-						$this->precache_list_permalinks ( $links, $blog->blog_id );
+		<?php
+
+		/* display donation form */
+		$this->plugin_donation_form();
+
+		/**
+		 * if options were saved, display saved message
+		 */
+		if (isset($_GET[ self::key_save ]) && $_GET[ self::key_save ]=='true' || $this->status == 1) { ?>
+			<div class='updated settings-error'><p><strong><?php _e( 'Settings saved.' , $this->plugin_constant ) ?></strong></p></div>
+		<?php }
+
+		/**
+		 * if options were delete, display delete message
+		 */
+		if (isset($_GET[ self::key_delete ]) && $_GET[ self::key_delete ]=='true' || $this->status == 2) { ?>
+			<div class='error'><p><strong><?php _e( 'Plugin options deleted.' , $this->plugin_constant ) ?></strong></p></div>
+		<?php }
+
+		/**
+		 * if options were saved
+		 */
+		if (isset($_GET[ self::key_flush ]) && $_GET[ self::key_flush ]=='true' || $this->status == 3) { ?>
+			<div class='updated settings-error'><p><strong><?php _e( "Cache flushed." , $this->plugin_constant ); ?></strong></p></div>
+		<?php }
+
+		/**
+		 * if options were saved, display saved message
+		 */
+		if ( ( isset($_GET[ self::key_precache ]) && $_GET[ self::key_precache ]=='true' ) || $this->status == 4) { ?>
+		<div class='updated settings-error'><p><strong><?php _e( 'Precache process was started, it is now running in the background, please be patient, it may take a very long time to finish.' , $this->plugin_constant ) ?></strong></p></div>
+		<?php }
+
+		/**
+		 * the admin panel itself
+		 */
+		?>
+
+		<h2><?php echo $this->plugin_name ; _e( ' settings', $this->plugin_constant ) ; ?></h2>
+
+		<div class="updated">
+			<p><strong><?php _e ( 'Driver: ' , $this->plugin_constant); echo $this->options['cache_type']; ?></strong></p>
+			<?php
+			/* only display backend status if memcache-like extension is running */
+			if ( strstr ( $this->options['cache_type'], 'memcache') ) {
+				?><p><?php
+				_e( '<strong>Backend status:</strong><br />', $this->plugin_constant );
+
+				/* we need to go through all servers */
+				$servers = $this->backend->status();
+				foreach ( $servers as $server_string => $status ) {
+					echo $server_string ." => ";
+
+					if ( $status == 0 )
+						_e ( '<span class="error-msg">down</span><br />', $this->plugin_constant );
+					elseif ( ( $this->options['cache_type'] == 'memcache' && $status > 0 )  || $status == 1 )
+						_e ( '<span class="ok-msg">up & running</span><br />', $this->plugin_constant );
+					else
+						_e ( '<span class="error-msg">unknown, please try re-saving settings!</span><br />', $this->plugin_constant );
+				}
+
+				?></p><?php
+			} ?>
+		</div>
+		<form autocomplete="off" method="post" action="#" id="<?php echo $this->plugin_constant ?>-settings" class="plugin-admin">
+
+			<ul class="tabs">
+				<li><a href="#<?php echo $this->plugin_constant ?>-type" class="wp-switch-editor"><?php _e( 'Cache type', $this->plugin_constant ); ?></a></li>
+				<li><a href="#<?php echo $this->plugin_constant ?>-debug" class="wp-switch-editor"><?php _e( 'Debug & in-depth', $this->plugin_constant ); ?></a></li>
+				<li><a href="#<?php echo $this->plugin_constant ?>-exceptions" class="wp-switch-editor"><?php _e( 'Cache exceptions', $this->plugin_constant ); ?></a></li>
+				<li><a href="#<?php echo $this->plugin_constant ?>-memcached" class="wp-switch-editor"><?php _e( 'Memcache(d)', $this->plugin_constant ); ?></a></li>
+				<li><a href="#<?php echo $this->plugin_constant ?>-nginx" class="wp-switch-editor"><?php _e( 'nginx', $this->plugin_constant ); ?></a></li>
+				<li><a href="#<?php echo $this->plugin_constant ?>-precache" class="wp-switch-editor"><?php _e( 'Precache & precache log', $this->plugin_constant ); ?></a></li>
+			</ul>
+
+			<fieldset id="<?php echo $this->plugin_constant ?>-type">
+			<legend><?php _e( 'Set cache type', $this->plugin_constant ); ?></legend>
+			<dl>
+				<dt>
+					<label for="cache_type"><?php _e('Select backend', $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<select name="cache_type" id="cache_type">
+						<?php $this->print_select_options ( $this->select_cache_type , $this->options['cache_type'], $this->valid_cache_type ) ?>
+					</select>
+					<span class="description"><?php _e('Select backend storage driver', $this->plugin_constant); ?></span>
+				</dd>
+
+				<dt>
+					<label for="expire"><?php _e('Expiration time (seconds)', $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="number" name="expire" id="expire" value="<?php echo $this->options['expire']; ?>" />
+					<span class="description"><?php _e('Sets validity time of entry in seconds', $this->plugin_constant); ?></span>
+				</dd>
+
+				<dt>
+					<label for="charset"><?php _e('Charset', $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="text" name="charset" id="charset" value="<?php echo $this->options['charset']; ?>" />
+					<span class="description"><?php _e('Charset of HTML and XML (pages and feeds) data.', $this->plugin_constant); ?></span>
+				</dd>
+
+				<dt>
+					<label for="invalidation_method"><?php _e('Cache invalidation method', $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<select name="invalidation_method" id="invalidation_method">
+						<?php $this->print_select_options ( $this->select_invalidation_method , $this->options['invalidation_method'] ) ?>
+					</select>
+					<span class="description"><?php _e('Select cache invalidation method. <ol><li><em>flush cache</em> - clears everything in storage, <strong>including values set by other applications</strong></li><li><em>only modified post</em> - clear only the modified posts entry, everything else remains in cache</li><li><em>modified post and all taxonomies</em> - removes all taxonomy term cache ( categories, tags, home, etc ) and the modified post as well</li></ol>', $this->plugin_constant); ?></span>
+				</dd>
+
+				<dt>
+					<label for="comments_invalidate"><?php _e('Invalidate on comment actions', $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="checkbox" name="comments_invalidate" id="comments_invalidate" value="1" <?php checked($this->options['comments_invalidate'],true); ?> />
+					<span class="description"><?php _e('Trigger cache invalidation when a comments is posted, edited, trashed. ', $this->plugin_constant); ?></span>
+				</dd>
+
+				<dt>
+					<label for="prefix_data"><?php _e('Data prefix', $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="text" name="prefix_data" id="prefix_data" value="<?php echo $this->options['prefix_data']; ?>" />
+					<span class="description"><?php _e('Prefix for HTML content keys, can be used in nginx.<br /><strong>WARNING</strong>: changing this will result the previous cache to becomes invalid!<br />If you are caching with nginx, you should update your nginx configuration and reload nginx after changing this value.', $this->plugin_constant); ?></span>
+				</dd>
+
+				<dt>
+					<label for="prefix_meta"><?php _e('Meta prefix', $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="text" name="prefix_meta" id="prefix_meta" value="<?php echo $this->options['prefix_meta']; ?>" />
+					<span class="description"><?php _e('Prefix for meta content keys, used only with PHP processing.<br /><strong>WARNING</strong>: changing this will result the previous cache to becomes invalid!', $this->plugin_constant); ?></span>
+				</dd>
+
+				<dt>
+					<label for="key"><?php _e('Key scheme', $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="text" name="key" id="key" value="<?php echo $this->options['key']; ?>" />
+					<span class="description"><?php _e('Key layout; <strong>use the guide below to change it</strong>.<br /><strong>WARNING</strong>: changing this will result the previous cache to becomes invalid!<br />If you are caching with nginx, you should update your nginx configuration and reload nginx after changing this value.', $this->plugin_constant); ?><?php ?></span>
+					<dl class="description"><?php
+					foreach ( $this->list_uri_vars as $uri => $desc ) {
+						echo '<dt>'. $uri .'</dt><dd>'. $desc .'</dd>';
 					}
-				}
-			}
-			else {
-				/* no network, better */
-				$this->precache_list_permalinks ( $links, false );
-			}
+					?></dl>
+				</dd>
 
-			/* double check if we do have any links to pre-cache */
-			if ( !empty ( $links ) )  {
-				$this->precache ( $links );
-			}
+			</dl>
+			</fieldset>
+
+			<fieldset id="<?php echo $this->plugin_constant ?>-debug">
+			<legend><?php _e( 'Debug & in-depth settings', $this->plugin_constant ); ?></legend>
+			<dl>
+				<dt>
+					<label for="log"><?php _e("Enable logging", $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="checkbox" name="log" id="log" value="1" <?php checked($this->options['log'],true); ?> />
+					<span class="description"><?php _e('Enables log messages; if <a href="http://codex.wordpress.org/WP_DEBUG">WP_DEBUG</a> is enabled, notices and info level is displayed as well, otherwie only ERRORS are logged.', $this->plugin_constant); ?></span>
+				</dd>
+
+				<dt>
+					<label for="response_header"><?php _e("Add X-Cache-Engine header", $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="checkbox" name="response_header" id="response_header" value="1" <?php checked($this->options['response_header'],true); ?> />
+					<span class="description"><?php _e('Add X-Cache-Engine HTTP header to HTTP responses.', $this->plugin_constant); ?></span>
+				</dd>
+
+				<dt>
+					<label for="generate_time"><?php _e("Add HTML debug comment", $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="checkbox" name="generate_time" id="generate_time" value="1" <?php checked($this->options['generate_time'],true); ?> />
+					<span class="description"><?php _e('Adds comment string including plugin name, cache engine and page generation time to every generated entry before closing <body> tag.', $this->plugin_constant); ?></span>
+				</dd>
+
+			</dl>
+			</fieldset>
+
+			<fieldset id="<?php echo $this->plugin_constant ?>-exceptions">
+			<legend><?php _e( 'Set cache additions/excepions', $this->plugin_constant ); ?></legend>
+			<dl>
+				<dt>
+					<label for="cache_loggedin"><?php _e('Enable cache for logged in users', $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="checkbox" name="cache_loggedin" id="cache_loggedin" value="1" <?php checked($this->options['cache_loggedin'],true); ?> />
+					<span class="description"><?php _e('Cache pages even if user is logged in.', $this->plugin_constant); ?></span>
+				</dd>
+
+				<dt>
+					<label for="nocache_home"><?php _e("Don't cache home", $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="checkbox" name="nocache_home" id="nocache_home" value="1" <?php checked($this->options['nocache_home'],true); ?> />
+					<span class="description"><?php _e('Exclude home page from caching', $this->plugin_constant); ?></span>
+
+				</dd>
+
+				<dt>
+					<label for="nocache_feed"><?php _e("Don't cache feeds", $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="checkbox" name="nocache_feed" id="nocache_feed" value="1" <?php checked($this->options['nocache_feed'],true); ?> />
+					<span class="description"><?php _e('Exclude feeds from caching.', $this->plugin_constant); ?></span>
+				</dd>
+
+				<dt>
+					<label for="nocache_archive"><?php _e("Don't cache archives", $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="checkbox" name="nocache_archive" id="nocache_archive" value="1" <?php checked($this->options['nocache_archive'],true); ?> />
+					<span class="description"><?php _e('Exclude archives from caching.', $this->plugin_constant); ?></span>
+				</dd>
+
+				<dt>
+					<label for="nocache_single"><?php _e("Don't cache posts (and single-type entries)", $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="checkbox" name="nocache_single" id="nocache_single" value="1" <?php checked($this->options['nocache_single'],true); ?> />
+					<span class="description"><?php _e('Exclude singles from caching.', $this->plugin_constant); ?></span>
+				</dd>
+
+				<dt>
+					<label for="nocache_page"><?php _e("Don't cache pages", $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="checkbox" name="nocache_page" id="nocache_page" value="1" <?php checked($this->options['nocache_page'],true); ?> />
+					<span class="description"><?php _e('Exclude pages from caching.', $this->plugin_constant); ?></span>
+				</dd>
+
+				<dt>
+					<label for="nocache_cookies"><?php _e("Don't cache cookies", $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="text" name="nocache_cookies" id="nocache_cookies" value="<?php if(isset( $this->options['nocache_cookies'] ) ) echo $this->options['nocache_cookies']; ?>" />
+					<span class="description"><?php _e('Exclude cookies names starting with this from caching. Separate multiple cookies names with commas.<br />If you are caching with nginx, you should update your nginx configuration and reload nginx after changing this value.', $this->plugin_constant); ?></span>
+				</dd>
+			</dl>
+			</fieldset>
+
+			<fieldset id="<?php echo $this->plugin_constant ?>-memcached">
+			<legend><?php _e('Settings for memcached backend', $this->plugin_constant); ?></legend>
+			<dl>
+				<dt>
+					<label for="hosts"><?php _e('Hosts', $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="text" name="hosts" id="hosts" value="<?php echo $this->options['hosts']; ?>" />
+					<span class="description">
+					<?php _e('List of memcached backends, with the following syntax: <br />- in case of TCP based connections, list the servers as host1:port1,host2:port2,... . Do not add trailing , and always separate host and port with : .<br />- in2.0.0b1 case using unix sockets with the Memcache driver: unix:// ', $this->plugin_constant); ?></span>
+				</dd>
+				<dt>
+					<label for="persistent"><?php _e('Persistent memcache connections', $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="checkbox" name="persistent" id="persistent" value="1" <?php checked($this->options['persistent'],true); ?> />
+					<span class="description"><?php _e('Make all memcache(d) connections persistent. Be careful with this setting, always test the outcome.', $this->plugin_constant); ?></span>
+				</dd>
+
+				<?php
+				if ( strstr ( $this->options['cache_type'], 'memcached') && extension_loaded ( 'memcached' ) && version_compare( phpversion( 'memcached' ) , '2.0.0', '>=' ) ) { ?>
+				<?php
+					if ( ! ini_get('memcached.use_sasl') && ( !empty( $this->options['authuser'] ) || !empty( $this->options['authpass'] ) ) ) { ?>
+						<div class="error"><p><strong><?php _e( 'WARNING: you\'ve entered username and/or password for memcached authentication ( or your browser\'s autocomplete did ) which will not work unless you enable memcached sasl in the PHP settings: add `memcached.use_sasl=1` to php.ini' , $this->plugin_constant ) ?></strong></p></div>
+				<?php } ?>
+				<dt>
+					<label for="authuser"><?php _e('Authentication: username', $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="text" autocomplete="off" name="authuser" id="authuser" value="<?php echo $this->options['authuser']; ?>" />
+					<span class="description">
+					<?php _e('Username for authentication with memcached backends', $this->plugin_constant); ?></span>
+				</dd>
+
+				<dt>
+					<label for="authpass"><?php _e('Authentication: password', $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<input type="password" autocomplete="off" name="authpass" id="authpass" value="<?php echo $this->options['authpass']; ?>" />
+					<span class="description">
+					<?php _e('Password for authentication with memcached backends - WARNING, the password will be stored plain-text since it needs to be used!', $this->plugin_constant); ?></span>
+				</dd>
+				<?php } ?>
+			</dl>
+			</fieldset>
+
+			<fieldset id="<?php echo $this->plugin_constant ?>-nginx">
+			<legend><?php _e('Sample config for nginx to utilize the data entries', $this->plugin_constant); ?></legend>
+			<pre><?php echo $this->nginx_example(); ?></pre>
+			</fieldset>
+
+			<fieldset id="<?php echo $this->plugin_constant ?>-precache">
+			<legend><?php _e('Precache settings & log from previous pre-cache generation', $this->plugin_constant); ?></legend>
+
+				<dt>
+					<label for="precache_schedule"><?php _e('Precache schedule', $this->plugin_constant); ?></label>
+				</dt>
+				<dd>
+					<select name="precache_schedule" id="precache_schedule">
+						<?php $this->print_select_options ( $this->select_schedules, $this->options['precache_schedule'] ) ?>
+					</select>
+					<span class="description"><?php _e('Schedule autorun for precache with WP-Cron', $this->plugin_constant); ?></span>
+				</dd>
+
+				<?php
+
+				$gentime = $this->utils->_get_option( self::precache_timestamp, $this->network );
+				$log = $this->utils->_get_option( self::precache_log, $this->network );
+
+				if ( @file_exists ( $this->precache_logfile ) ) {
+					$logtime = filemtime ( $this->precache_logfile );
+
+					/* update precache log in DB if needed */
+					if ( $logtime > $gentime ) {
+						$log = file ( $this->precache_logfile );
+						$this->utils->_update_option( self::precache_log , $log, $this->network );
+						$this->utils->_update_option( self::precache_timestamp , $logtime, $this->network );
+					}
+
+				}
+
+				if ( empty ( $log ) ) {
+					_e('No precache log was found!', $this->plugin_constant);
+				}
+				else { ?>
+					<p><strong><?php _e( 'Time of run: ') ?><?php echo date('r', $gentime ); ?></strong></p>
+					<div  style="overflow: auto; max-height: 20em;"><table style="width:100%; border: 1px solid #ccc;">
+						<thead><tr>
+								<?php $head = explode( "	", array_shift( $log ));
+								foreach ( $head as $column ) { ?>
+									<th><?php echo $column; ?></th>
+								<?php } ?>
+						</tr></thead>
+						<?php
+						foreach ( $log as $line ) { ?>
+							<tr>
+								<?php $line = explode ( "	", $line );
+								foreach ( $line as $column ) { ?>
+									<td><?php echo $column; ?></td>
+								<?php } ?>
+							</tr>
+						<?php } ?>
+				</table></div>
+			<?php } ?>
+			</fieldset>
+
+			<p class="clear">
+				<input class="button-primary" type="submit" name="<?php echo $this->button_save ?>" id="<?php echo $this->button_save ?>" value="<?php _e('Save Changes', $this->plugin_constant ) ?>" />
+			</p>
+
+		</form>
+
+		<form method="post" action="#" id="<?php echo $this->plugin_constant ?>-commands" class="plugin-admin" style="padding-top:2em;">
+
+			<ul class="tabs">
+				<li><a href="#<?php echo $this->plugin_constant ?>-precache" class="wp-switch-editor"><?php _e( 'Precache', $this->plugin_constant ); ?></a></li>
+				<li><a href="#<?php echo $this->plugin_constant ?>-flush" class="wp-switch-editor"><?php _e( 'Empty cache', $this->plugin_constant ); ?></a></li>
+				<li><a href="#<?php echo $this->plugin_constant ?>-reset" class="wp-switch-editor"><?php _e( 'Reset settings', $this->plugin_constant ); ?></a></li>
+			</ul>
+
+			<fieldset id="<?php echo $this->plugin_constant ?>-precache">
+			<legend><?php _e( 'Precache', $this->plugin_constant ); ?></legend>
+			<dl>
+				<dt>
+					<?php if ( ( isset( $_GET[ self::key_precache_disabled ] ) && $_GET[ self::key_precache_disabled ] =='true' ) || $this->status == 5 || $this->shell_function == false ) { ?>
+						<strong><?php _e( "Precache functionality is disabled due to unavailable system call function. <br />Since precaching may take a very long time, it's done through a background CLI process in order not to run out of max execution time of PHP. Please enable one of the following functions if you whish to use precaching: " , $this->plugin_constant ) ?><?php echo join( ',' , $this->shell_possibilities ); ?></strong>
+					<?php }
+					else { ?>
+						<input class="button-secondary" type="submit" name="<?php echo $this->button_precache ?>" id="<?php echo $this->button_precache ?>" value="<?php _e('Pre-cache', $this->plugin_constant ) ?>" />
+					<?php } ?>
+				</dt>
+				<dd>
+					<span class="description"><?php _e('Start a background process that visits all permalinks of all blogs it can found thus forces WordPress to generate cached version of all the pages.<br />The plugin tries to visit links of taxonomy terms without the taxonomy name as well. This may generate 404 hits, please be prepared for these in your logfiles if you plan to pre-cache.', $this->plugin_constant); ?></span>
+				</dd>
+			</dl>
+			</fieldset>
+			<fieldset id="<?php echo $this->plugin_constant ?>-flush">
+			<legend><?php _e( 'Precache', $this->plugin_constant ); ?></legend>
+			<dl>
+				<dt>
+					<input class="button-warning" type="submit" name="<?php echo $this->button_flush ?>" id="<?php echo $this->button_flush ?>" value="<?php _e('Clear cache', $this->plugin_constant ) ?>" />
+				</dt>
+				<dd>
+					<span class="description"><?php _e ( "Clear all entries in the storage, including the ones that were set by other processes.", $this->plugin_constant ); ?> </span>
+				</dd>
+			</dl>
+			</fieldset>
+			<fieldset id="<?php echo $this->plugin_constant ?>-reset">
+			<legend><?php _e( 'Precache', $this->plugin_constant ); ?></legend>
+			<dl>
+				<dt>
+					<input class="button-warning" type="submit" name="<?php echo $this->button_delete ?>" id="<?php echo $this->button_delete ?>" value="<?php _e('Reset options', $this->plugin_constant ) ?>" />
+				</dt>
+				<dd>
+					<span class="description"><?php _e ( "Reset settings to defaults.", $this->plugin_constant ); ?> </span>
+				</dd>
+			</dl>
+			</fieldset>
+		</form>
+		</div>
+		<?php
+	}
+
+	/**
+	 * extending options_save
+	 *
+	 */
+	public function plugin_extend_options_save( $activating ) {
+
+		/* schedule cron if posted */
+		$schedule = wp_get_schedule( self::precache_id );
+		if ( $this->options['precache_schedule'] != 'null' ) {
+			/* clear all other schedules before adding a new in order to replace */
+			wp_clear_scheduled_hook ( self::precache_id );
+			$this->log ( __( 'Scheduling WP-CRON event', $this->plugin_constant ) );
+			$this->scheduled = wp_schedule_event( time(), $this->options['precache_schedule'] , self::precache_id );
+		}
+		elseif ( ( !isset($this->options['precache_schedule']) || $this->options['precache_schedule'] == 'null' ) && !empty( $schedule ) ) {
+			$this->log ( __('Clearing WP-CRON scheduled hook ' , $this->plugin_constant ) );
+			wp_clear_scheduled_hook ( self::precache_id );
 		}
 
-		/**
-		 * gets all post-like entry permalinks for a site, returns values in passed-by-reference array
-		 *
-		 */
-		private function precache_list_permalinks ( &$links, $site = false ) {
-			/* $post will be populated when running throught the posts */
-			global $post;
-			include_once ( ABSPATH . "wp-load.php" );
+		/* flush the cache when news options are saved, not needed on activation */
+		if ( !$activating )
+			$this->backend->clear();
 
-			/* if a site id was provided, save current blog and change to the other site */
-			if ( $site !== false ) {
-				$current_blog = get_current_blog_id();
-				switch_to_blog( $site );
+		/* create the to-be-included configuration for advanced-cache.php */
+		$this->update_global_config();
 
-				$url = $this->_site_url( $site );
-				//$url = get_blog_option ( $site, 'siteurl' );
-				if ( substr( $url, -1) !== '/' )
-					$url = $url . '/';
+		/* create advanced cache file, needed only once or on activation, because there could be lefover advanced-cache.php from different plugins */
+		if (  !$activating )
+			$this->deploy_advanced_cache();
 
-				$links[ $url ] = true;
+	}
+
+	/**
+	 * read hook; needs to be implemented
+	 */
+	public function plugin_extend_options_read( &$options ) {
+		/* read the global options, network compatibility */
+		$this->global_config = get_site_option( $this->global_option );
+
+		/* check if current site present in global config */
+		if ( !empty ( $this->global_config[ $this->global_config_key ] ) )
+			$this->global_saved = true;
+
+		$this->global_config[ $this->global_config_key ] = $options;
+	}
+
+	/**
+	 * options delete hook; needs to be implemented
+	 */
+	public function plugin_extend_options_delete(  ) {
+		delete_site_option ( $this->global_option );
+	}
+
+	/**
+	 * need to do migrations from previous versions of the plugin
+	 *
+	 */
+	public function plugin_options_migrate( &$options ) {
+		$migrated = false;
+
+		if ( version_compare ( $options['version'] , $this->plugin_version , '<' ) ) {
+			/* cleanup possible leftover files from previous versions */
+			$check = array ( 'advanced-cache.php', 'nginx-sample.conf', 'wp-ffpc.admin.css', 'wp-ffpc-common.php' );
+			foreach ( $check as $fname ) {
+				$fname = $this->plugin_dir . $fname;
+				if ( file_exists ( $fname ) )
+					unlink ( $fname );
 			}
 
-			/* get all published posts */
-			$args = array (
-				'post_type' => 'any',
-				'posts_per_page' => -1,
-				'post_status' => 'publish',
-			);
-			$posts = new WP_Query( $args );
+			/* look for previous config leftovers */
+			$try = get_site_option( $this->plugin_constant );
+			/* network option key changed, remove & migrate the leftovers if there's any */
+			if ( !empty ( $try ) && $this->network ) {
+				/* clean it up, we don't use it anymore */
+				delete_site_option ( $this->plugin_constant );
 
-			/* get all the posts, one by one  */
-			while ( $posts->have_posts() ) {
-				$posts->the_post();
-
-				/* get the permalink for currently selected post */
-				switch ($post->post_type) {
-					case 'revision':
-					case 'nav_menu_item':
-						break;
-					case 'page':
-						$permalink = get_page_link( $post->ID );
-						break;
-					case 'post':
-						$permalink = get_permalink( $post->ID );
-						break;
-					case 'attachment':
-						$permalink = get_attachment_link( $post->ID );
-						break;
-					default:
-						$permalink = get_post_permalink( $post->ID );
-					break;
+				if ( empty ( $options ) && array_key_exists ( $this->global_config_key, $try ) ) {
+					$options = $try [ $this->global_config_key ];
+					$migrated = true;
 				}
-
-				/* in case the bloglinks are relative links add the base url, site specific */
-				$baseurl = empty( $url ) ? $this->_site_url() : $url;
-				if ( !strstr( $permalink, $baseurl ) ) {
-					$permalink = $baseurl . $permalink;
+				elseif ( empty ( $options ) && array_key_exists ( 'host', $try ) ) {
+					$options = $try;
+					$migrated = true;
 				}
+			 }
 
-				/* collect permalinks */
-				$links[ $permalink ] = true;
-
+			/* updating from version <= 0.4.x */
+			if ( !empty ( $options['host'] ) ) {
+				$options['hosts'] = $options['host'] . ':' . $options['port'];
+				$migrated = true;
+			}
+			/* migrating from version 0.6.x */
+			elseif ( is_array ( $options ) && array_key_exists ( $this->global_config_key , $options ) ) {
+				$options = $options[ $this->global_config_key ];
+				$migrated = true;
+			}
+			/* migrating from something, drop previous config */
+			else {
+				$options = array();
 			}
 
-			$this->backend->taxonomy_links ( $links );
+			if ( $migrated ) {
+				/* renamed options */
+				if ( isset ( $options['syslog'] ) )
+					$options['log'] = $options['syslog'];
+				if ( isset ( $options['debug'] ) )
+				$options['response_header'] = $options['debug'];
+			}
 
-			/* just in case, reset $post */
-			wp_reset_postdata();
+		}
+	}
 
-			/* switch back to original site if we navigated away */
-			if ( $site !== false ) {
-				switch_to_blog( $current_blog );
+	/**
+	 * advanced-cache.php creator function
+	 *
+	 */
+	private function deploy_advanced_cache( ) {
+
+		/* in case advanced-cache.php was already there, remove it */
+		if ( @file_exists( $this->acache ))
+			unlink ($this->acache);
+
+		/* is deletion was unsuccessful, die, we have no rights to do that, fail */
+		if ( @file_exists( $this->acache ))
+			return false;
+
+		/* if no active site left no need for advanced cache :( */
+		if ( empty ( $this->global_config ) )
+			return false;
+
+		/* add the required includes and generate the needed code */
+		$string[] = "<?php";
+		$string[] = self::global_config_var . ' = ' . var_export ( $this->global_config, true ) . ';' ;
+		//$string[] = "include_once ('" . $this->acache_backend . "');";
+		$string[] = "include_once ('" . $this->acache_worker . "');";
+		$string[] = "?>";
+
+		/* write the file and start caching from this point */
+		return file_put_contents( $this->acache, join( "\n" , $string ) );
+	}
+
+	/**
+	 * function to generate working example from the nginx sample file
+	 *
+	 * @return string nginx config file
+	 *
+	 */
+	private function nginx_example () {
+		/* read the sample file */
+		$nginx = file_get_contents ( $this->nginx_sample );
+
+		/* replace the data prefix with the configured one */
+		$to_replace = array ( 'DATAPREFIX' , 'SERVERROOT', 'SERVERLOG' );
+		$replace_with = array ( $this->options['prefix_data'] . $this->options['key'] , ABSPATH, $_SERVER['SERVER_NAME'] );
+		$nginx = str_replace ( $to_replace , $replace_with , $nginx );
+
+		/* set upstream servers from configured servers, best to get from the actual backend */
+		$servers = $this->backend->get_servers();
+		$nginx_servers = '';
+		if ( is_array ( $servers )) {
+			foreach ( array_keys( $servers ) as $server ) {
+				$nginx_servers .= "		server ". $server .";\n";
 			}
 		}
+		else {
+			$nginx_servers .= "		server ". $servers .";\n";
+		}
+		$nginx = str_replace ( 'MEMCACHED_SERVERS' , $nginx_servers , $nginx );
 
-		/**
-		 * print errors, called by global errors hook
-		 *
-		 */
-		public function display_errors ( ) {
-			if ( empty ( $this->errors )) {
-				$r = false;
-			}
-			else {
-				$r = '<div class="error"><strong>'. __('WP-FFPC found errors, please correct them!', $this->plugin_constant ) .'</strong><ol>';
-				foreach ( $this->errors as $eid => $message ) {
-					$r .= '<li>' . $message . '</li>';
+		$loggedincookies = join('|', $this->backend->cookies );
+		/* this part is not used when the cache is turned on for logged in users */
+		$loggedin = '
+			if ($http_cookie ~* "'. $loggedincookies .'" ) {
+				set $memcached_request 0;
+			}';
+
+		/* add logged in cache, if valid */
+		if ( ! $this->options['cache_loggedin'])
+			$nginx = str_replace ( 'LOGGEDIN_EXCEPTION' , $loggedin , $nginx );
+		else
+			$nginx = str_replace ( 'LOGGEDIN_EXCEPTION' , '' , $nginx );
+
+		/* nginx can skip caching for visitors with certain cookies specified in the options */
+		if( $this->options['nocache_cookies'] ) {
+			$cookies = str_replace( ",","|", $this->options['nocache_cookies'] );
+			$cookies = str_replace( " ","", $cookies );
+			$cookie_exception = '# avoid cache for cookies specified
+			if ($http_cookie ~* ' . $cookies . ' ) {
+				set $memcached_request 0;
+			}';
+			$nginx = str_replace ( 'COOKIES_EXCEPTION' , $cookie_exception , $nginx );
+		} else {
+			$nginx = str_replace ( 'COOKIES_EXCEPTION' , '' , $nginx );
+		}
+
+		/* add custom response header if specified in the options */
+		if( $this->options['response_header'] ){
+			$response_header =  'add_header X-Cache-Engine "WP-FFPC with ' . $this->options['cache_type'] .' via nginx";';
+			$nginx = str_replace ( 'RESPONSE_HEADER' , $response_header , $nginx );
+		} else{
+			$nginx = str_replace ( 'RESPONSE_HEADER' , '' , $nginx );
+		}
+
+		return $nginx;
+	}
+
+	/**
+	 * function to update global configuration
+	 *
+	 * @param boolean $remove_site Bool to remove or add current config to global
+	 *
+	 */
+	private function update_global_config ( $remove_site = false ) {
+
+		/* remove or add current config to global config */
+		if ( $remove_site ) {
+			unset ( $this->global_config[ $this->global_config_key ] );
+		}
+		else {
+			$this->global_config[ $this->global_config_key ] = $this->options;
+		}
+
+		/* deploy advanced-cache.php */
+		$this->deploy_advanced_cache ();
+
+		/* save options to database */
+		update_site_option( $this->global_option , $this->global_config );
+	}
+
+
+	/**
+	 * generate cache entry for every available permalink, might be very-very slow,
+	 * therefore it starts a background process
+	 *
+	 */
+	private function precache ( &$links ) {
+
+		/* double check if we do have any links to pre-cache */
+		if ( !empty ( $links ) && !$this->precache_running() )  {
+
+			$out = '<?php
+				$links = ' . var_export ( $links , true ) . ';
+
+				echo "permalink\tgeneration time (s)\tsize ( kbyte )\n";
+				foreach ( $links as $permalink => $dummy ) {
+					$starttime = explode ( " ", microtime() );
+					$starttime = $starttime[1] + $starttime[0];
+
+						$page = file_get_contents( $permalink );
+						$size = round ( ( strlen ( $page ) / 1024 ), 2 );
+
+					$endtime = explode ( " ", microtime() );
+					$endtime = round( ( $endtime[1] + $endtime[0] ) - $starttime, 2 );
+
+					echo $permalink . "\t" .  $endtime . "\t" . $size . "\n";
+					unset ( $page, $size, $starttime, $endtime );
+					sleep( 1 );
 				}
-				$r.= '</ol></div>';
-			}
+				unlink ( "'. $this->precache_phpfile .'" );
+			?>';
 
-			echo $r;
+			file_put_contents ( $this->precache_phpfile, $out  );
+			/* call the precache worker file in the background */
+			$shellfunction = $this->shell_function;
+			$shellfunction( 'php '. $this->precache_phpfile .' >'. $this->precache_logfile .' 2>&1 &' );
 		}
 
 	}
+
+	/**
+	 * check is precache is still ongoing
+	 *
+	 */
+	private function precache_running () {
+		$return = false;
+
+		/* if the precache file exists, it did not finish running as it should delete itself on finish */
+		if ( file_exists ( $this->precache_phpfile )) {
+			$return = true;
+		}
+		/*
+		 [TODO] cross-platform process check; this is *nix only
+		else {
+			$shellfunction = $this->shell_function;
+			$running = $shellfunction( "ps aux | grep \"". $this->precache_phpfile ."\" | grep -v grep | awk '{print $2}'" );
+			if ( is_int( $running ) && $running != 0 ) {
+				$return = true;
+			}
+		}
+		*/
+
+		return $return;
+	}
+
+	/**
+	 * run full-site precache
+	 */
+	public function precache_coldrun () {
+
+		/* container for links to precache, well be accessed by reference */
+		$links = array();
+
+		/* when plugin is  network wide active, we need to pre-cache for all link of all blogs */
+		if ( $this->network ) {
+			/* list all blogs */
+			global $wpdb;
+			$blog_list = $wpdb->get_results( $wpdb->prepare( "SELECT * FROM wp_blogs ORDER BY blog_id", '' ) );
+
+			foreach ($blog_list as $blog) {
+				if ( $blog->archived != 1 && $blog->spam != 1 && $blog->deleted != 1) {
+					/* get permalinks for this blog */
+					$this->precache_list_permalinks ( $links, $blog->blog_id );
+				}
+			}
+		}
+		else {
+			/* no network, better */
+			$this->precache_list_permalinks ( $links, false );
+		}
+
+		/* double check if we do have any links to pre-cache */
+		if ( !empty ( $links ) )  {
+			$this->precache ( $links );
+		}
+	}
+
+	/**
+	 * gets all post-like entry permalinks for a site, returns values in passed-by-reference array
+	 *
+	 */
+	private function precache_list_permalinks ( &$links, $site = false ) {
+		/* $post will be populated when running throught the posts */
+		global $post;
+		include_once ( ABSPATH . "wp-load.php" );
+
+		/* if a site id was provided, save current blog and change to the other site */
+		if ( $site !== false ) {
+			$current_blog = get_current_blog_id();
+			switch_to_blog( $site );
+
+			$url = $this->_site_url( $site );
+			//$url = get_blog_option ( $site, 'siteurl' );
+			if ( substr( $url, -1) !== '/' )
+				$url = $url . '/';
+
+			$links[ $url ] = true;
+		}
+
+		/* get all published posts */
+		$args = array (
+			'post_type' => 'any',
+			'posts_per_page' => -1,
+			'post_status' => 'publish',
+		);
+		$posts = new WP_Query( $args );
+
+		/* get all the posts, one by one  */
+		while ( $posts->have_posts() ) {
+			$posts->the_post();
+
+			/* get the permalink for currently selected post */
+			switch ($post->post_type) {
+				case 'revision':
+				case 'nav_menu_item':
+					break;
+				case 'page':
+					$permalink = get_page_link( $post->ID );
+					break;
+				case 'post':
+					$permalink = get_permalink( $post->ID );
+					break;
+				case 'attachment':
+					$permalink = get_attachment_link( $post->ID );
+					break;
+				default:
+					$permalink = get_post_permalink( $post->ID );
+				break;
+			}
+
+			/* in case the bloglinks are relative links add the base url, site specific */
+			$baseurl = empty( $url ) ? $this->_site_url() : $url;
+			if ( !strstr( $permalink, $baseurl ) ) {
+				$permalink = $baseurl . $permalink;
+			}
+
+			/* collect permalinks */
+			$links[ $permalink ] = true;
+
+		}
+
+		$this->backend->taxonomy_links ( $links );
+
+		/* just in case, reset $post */
+		wp_reset_postdata();
+
+		/* switch back to original site if we navigated away */
+		if ( $site !== false ) {
+			switch_to_blog( $current_blog );
+		}
+	}
+
+	/**
+	 * log wrapper to include options
+	 *
+	 */
+	public function log ( $message, $log_level = LOG_WARNING ) {
+		if ( !isset ( $this->options['log'] ) || $this->options['log'] != 1 )
+			return false;
+		else
+			$this->utils->log ( $this->plugin_constant, $message, $log_level );
+	}
+
 }
 
-?>
+endif;
diff --git a/wp-ffpc.php b/wp-ffpc.php
index ef1da94..975ccf8 100644
--- a/wp-ffpc.php
+++ b/wp-ffpc.php
@@ -53,6 +53,6 @@ $wp_ffpc_defaults = array (
 	'comments_invalidate' => true,
 );
 
-$wp_ffpc = new WP_FFPC ( 'wp-ffpc', '1.6.0', 'WP-FFPC', $wp_ffpc_defaults, 'https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=XU3DG7LLA76WC' );
+$wp_ffpc = new WP_FFPC ( 'wp-ffpc', '1.6.0', 'WP-FFPC', $wp_ffpc_defaults, 'PeterMolnar_WordPressPlugins_wp-ffpc_HU' , 'WP-FFPC' , 'FA3NT7XDVHPWU' );
 
 ?>