Version: 0.2
Type: Class
Category: HTML
License: GNU General Public License
Description: Persistently cache whole pages identified by their md5 hash.
<?
/*
* $Header: /var/cvs/formcache/formcache.php,v 1.6 2001/04/26 16:44:24 mfischer Exp $
*
* Class : formcache
* Version : 0.2
* Author : [email protected]
* http://josefine.ben.tuwien.ac.at/~mfischer/
*
* Description : Class which handles cached form submission
*
* Exaomple :
* If someone just submitted the form and its in the cache,
* serve the user the cached result :
*
* $fc = new formcache( 'myform', '/tmp/php/');
*
* if( $fc->exists( array_merge( $HTTP_POST_VARS, $HTTP_GET_VARS)))
* echo join( '', $fc->serve());
* else
* doGetResult(); // that's up to you
*
*
* Somewhere in 'doGetResult()' you then write the output to the cache :
*
* $fc->cache( $output);
*/
// That's up to the end-developer, really
// error_reporting( E_ALL ^ E_NOTICE);
/*
Change this to a default setting which makes sense to your enviroment
FORMCACHE_NAMESPACE - Is part of the name of the cachefile to easier distingiush cached files from different forms
FORMCACHE_CACHDIR - The directory where everything gets writte to and served from
Make sure Apache/PHP has the proper rights to write and read files from there
If the directory does not exist the class tries to create it automatically
*/
define( 'FORMCACHE_NAMESPACE', 'formcache');
define( 'FORMCACHE_CACHEDIR', '/tmp/');
/**
* Provides detection if a FORM was submitted a second time a feed
* feed brwoser with resulting page from cache
* @access public
* @author Markus Fischer <[email protected]>
* @link http://josefine.ben.tuwien.ac.at Homepage of the author
* @copyright Netway AG
*/
class formcache {
/**
* Namespace declaration
* @var string
* @access private
*/
var $namespace;
/**
* Directory name where to store/retrieve cached files
* @var string
* @access private
*/
var $cachedir;
/**
* Cache filename
* @var string
* @access private
*/
var $cachefile;
/**
* Wheter use compression or not when writing to the cache. Defaults to false.
* @var boolean
* @access public
*/
var $compress;
/**
* Contains last error message
* @var string
* @access public
*/
var $err;
/**
* Constructor
*
* Instances a new formcheck object.
*
* @param string The Namespace the cache lives under
* @param string Optional directory for reading/writing cached files. Defaults to FORMCACHE_CACHDIR
* @param boolean Whether use gzip compression (TRUE) or not (FALSE)
*/
function formcache( $namespace = FORMCACHE_NAMESPACE, $cachedir = FORMCACHE_CACHDIR, $compress = false) {
$this->namespace = $namespace;
if( empty( $this->namespace))
$this->namespace = FORMCACHE_NAMESPACE;
$this->cachedir = $cachedir;
if( empty( $this->cachedir))
$this->cachedir = FORMCACHE_CACHEDIR;
else
if( $this->cachedir[ strlen( $this->cachedir) - 1] != '/')
$this->cachedir .= '/';
if( ! @is_dir( $this->cachedir)) {
$dirs = split( '/', $this->cachedir);
$createdir = '';
foreach( $dirs as $dir) { $createdir .= '/' . $dir; @mkdir( $createdir, 0775);}
}
$this->cachefile = '';
if( $compress)
$this->compress = true;
else
$this->compress = false;
}
/**
* Elicit the disambiguatity for cache-hits by means of the form elements
*
* @param array Form elements
* @return boolean True if uniqie identifier (cachefile) has been generated; False if not (ie. $form was empty or not an array)
* @access public
*/
function formdata( $form) {
$param = array();
if( empty( $form) || ( ! gettype( $form) == 'array'))
return $this->error( 'Form elements array is empty or not of type 'array'');
// Different browsers return form elements in different orders => fix this!
ksort( $form, SORT_STRING);
foreach( $form as $key => $value)
$param[] = urlencode( $key) . '=' . urlencode( $value);
$this->cachefile = $this->cachedir . $this->namespace . '-' . md5( join( '&', $param)) . '.cache';
return true;
}
/**
* Check wether a cached file exists or not
*
* @param array A optional hash containing all form elements for determining the disambiguatity.
* Use this if you haven't called $this-set() before
*
* @return boolean True if a cached file exists; False if not (or there was no cachefile previously generated)
*
* @acces public
*/
function exists( $form = '') {
$this->formdata( $form);
if( empty( $this->cachefile))
return $this->error( 'Cachefile is empty; initialize first with method formadata()');
if( file_exists( $this->cachefile))
return true;
else
return $this->error( 'Cachefile does not exist');
}
/**
* Serve file from cache
*
* @param array A optional hash containing all form elements for determining the disambiguatity.
* Use this if you haven't called $this-set() before
*
* @return mixed Array containing the cached file, line by line. False on failure
*
* @access public
*/
function serve( $form = '') {
$this->formdata( $form);
if( empty( $this->cachefile))
return $this->error( 'Cachefile is empty; initialize first with method formadata()');
if( $this->exists())
return @gzfile( $this->cachefile);
else
return false;
}
/**
* Caches the data
*
* Note that this function overwrites without warning; use exists() before inserting
*
* @param array Data to cache
*
* @return boolean True on successful cache insertion; False if something has gone wrong
*
* @access public
*/
function cache( $data, $form = '') {
if( empty( $data) || ( gettype( $data) != 'array'))
return $this->error( 'Data is empty or not an array');
if( ! empty( $form))
$this->formdata( $form);
if( empty( $this->cachefile))
return $this->error( 'Cachefile is empty; initialize first with method formdata()');
if( ( $fp = fopen( $this->cachefile, 'wb'))) {
if( $this->compress) {
$compressed = gzencode( join( '', $data));
if( strlen( $compressed) != fwrite( $fp, $compressed, strlen( $compressed))) {
fclose( $fp);
return $this->error( 'Compressed data only partially written; low on disk space ?');
}
} else
foreach( $data as $line)
if( strlen( $line) != fwrite( $fp, $line, strlen( $line))) {
fclose( $fp);
return $this->error( 'Data only partially written; low on disk space ?');
}
if( fclose( $fp))
return true;
else
$this->error( 'Can't close file handle');
} else
return $this->error( 'Can't open cache file for writing');
}
/**
* Stores error message
*
* This method is just for convinience. all it does it stores the parameter in a member variable $this->errmsg and always returns false
*
* @param string Optional error message string
* @return boolean Always returns false
* @access private
*/
function error( $message = '') {
$this->err[] = $message;
return false;
}
}
?>
