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<?php
/*
* Project: MagpieRSS: a simple RSS integration tool
* File: rss_cache.inc, a simple, rolling(no GC), cache
* for RSS objects, keyed on URL.
* Author: Kellan Elliott-McCrea <kellan@protest.net>
* Version: 0.51
* License: GPL
*
* The lastest version of MagpieRSS can be obtained from:
* http://magpierss.sourceforge.net
*
* For questions, help, comments, discussion, etc., please join the
* Magpie mailing list:
* http://lists.sourceforge.net/lists/listinfo/magpierss-general
*
*/
class RSSCache {
var $BASE_CACHE = './cache'; // where the cache files are stored
var $MAX_AGE = 3600; // when are files stale, default one hour
var $ERROR = ""; // accumulate error messages
function RSSCache ($base='', $age='') {
if ( $base ) {
$this->BASE_CACHE = $base;
}
if ( $age ) {
$this->MAX_AGE = $age;
}
// attempt to make the cache directory
if ( ! @file_exists( $this->BASE_CACHE ) ) {
$status = @mkdir( $this->BASE_CACHE, 0755 );
// if make failed
if ( ! $status ) {
$this->error(
"Cache couldn't make dir '" . $this->BASE_CACHE . "'."
);
}
}
}
/*=======================================================================*\
Function: set
Purpose: add an item to the cache, keyed on url
Input: url from wich the rss file was fetched
Output: true on sucess
\*=======================================================================*/
function set ($url, $rss) {
$this->ERROR = "";
$cache_file = $this->file_name( $url );
$fp = @fopen( $cache_file, 'w' );
if ( ! $fp ) {
$this->error(
"Cache unable to open file for writing: $cache_file"
);
return 0;
}
$data = $this->serialize( $rss );
fwrite( $fp, $data );
fclose( $fp );
return $cache_file;
}
/*=======================================================================*\
Function: get
Purpose: fetch an item from the cache
Input: url from wich the rss file was fetched
Output: cached object on HIT, false on MISS
\*=======================================================================*/
function get ($url) {
$this->ERROR = "";
$cache_file = $this->file_name( $url );
if ( ! @file_exists( $cache_file ) ) {
$this->debug(
"Cache doesn't contain: $url (cache file: $cache_file)"
);
return 0;
}
$fp = @fopen($cache_file, 'r');
if ( ! $fp ) {
$this->error(
"Failed to open cache file for reading: $cache_file"
);
return 0;
}
$data = fread( $fp, filesize($cache_file) );
$rss = $this->unserialize( $data );
return $rss;
}
/*=======================================================================*\
Function: check_cache
Purpose: check a url for membership in the cache
and whether the object is older then MAX_AGE (ie. STALE)
Input: url from wich the rss file was fetched
Output: cached object on HIT, false on MISS
\*=======================================================================*/
function check_cache ( $url ) {
$this->ERROR = "";
$filename = $this->file_name( $url );
if ( @file_exists( $filename ) ) {
// find how long ago the file was added to the cache
// and whether that is longer then MAX_AGE
$mtime = filemtime( $filename );
$age = time() - $mtime;
if ( $this->MAX_AGE > $age ) {
// object exists and is current
return 'HIT';
}
else {
// object exists but is old
return 'STALE';
}
}
else {
// object does not exist
return 'MISS';
}
}
/*=======================================================================*\
Function: serialize
\*=======================================================================*/
function serialize ( $rss ) {
return serialize( $rss );
}
/*=======================================================================*\
Function: unserialize
\*=======================================================================*/
function unserialize ( $data ) {
return unserialize( $data );
}
/*=======================================================================*\
Function: file_name
Purpose: map url to location in cache
Input: url from wich the rss file was fetched
Output: a file name
\*=======================================================================*/
function file_name ($url) {
$filename = md5( $url );
return join( DIRECTORY_SEPARATOR, array( $this->BASE_CACHE, $filename ) );
}
/*=======================================================================*\
Function: error
Purpose: register error
\*=======================================================================*/
function error ($errormsg, $lvl=E_USER_WARNING) {
// append PHP's error message if track_errors enabled
if ( isset($php_errormsg) ) {
$errormsg .= " ($php_errormsg)";
}
$this->ERROR = $errormsg;
if ( MAGPIE_DEBUG ) {
trigger_error( $errormsg, $lvl);
}
else {
error_log( $errormsg, 0);
}
}
function debug ($debugmsg, $lvl=E_USER_NOTICE) {
if ( MAGPIE_DEBUG ) {
$this->error("MagpieRSS [debug] $debugmsg", $lvl);
}
}
}
?>
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