lib/magpierss/rss_cache.inc

   1 <?php
   2 /*
   3  * Project:     MagpieRSS: a simple RSS integration tool
   4  * File:        rss_cache.inc, a simple, rolling(no GC), cache
   5  *              for RSS objects, keyed on URL.
   6  * Author:      Kellan Elliott-McCrea <kellan@protest.net>
   7  * Version:     0.51
   8  * License:     GPL
   9  *
  10  * The lastest version of MagpieRSS can be obtained from:
  11  * http://magpierss.sourceforge.net
  12  *
  13  * For questions, help, comments, discussion, etc., please join the
  14  * Magpie mailing list:
  15  * http://lists.sourceforge.net/lists/listinfo/magpierss-general
  16  *
  17  */
  18
  19 class RSSCache {
  20     var $BASE_CACHE = './cache';    // where the cache files are stored
  21     var $MAX_AGE    = 3600;         // when are files stale, default one hour
  22     var $ERROR      = "";           // accumulate error messages
  23
  24     function RSSCache ($base='', $age='') {
  25         if ( $base ) {
  26             $this->BASE_CACHE = $base;
  27         }
  28         if ( $age ) {
  29             $this->MAX_AGE = $age;
  30         }
  31
  32         // attempt to make the cache directory
  33         if ( ! file_exists( $this->BASE_CACHE ) ) {
  34             $status = @mkdir( $this->BASE_CACHE, 0755 );
  35
  36             // if make failed
  37             if ( ! $status ) {
  38                 $this->error(
  39                     "Cache couldn't make dir '" . $this->BASE_CACHE . "'."
  40                 );
  41             }
  42         }
  43     }
  44
  45 /*=======================================================================*\
  46     Function:   set
  47     Purpose:    add an item to the cache, keyed on url
  48     Input:      url from wich the rss file was fetched
  49     Output:     true on sucess
  50 \*=======================================================================*/
  51     function set ($url, $rss) {
  52         $this->ERROR = "";
  53         $cache_file = $this->file_name( $url );
  54         $fp = @fopen( $cache_file, 'w' );
  55
  56         if ( ! $fp ) {
  57             $this->error(
  58                 "Cache unable to open file for writing: $cache_file"
  59             );
  60             return 0;
  61         }
  62
  63
  64         $data = $this->serialize( $rss );
  65         fwrite( $fp, $data );
  66         fclose( $fp );
  67
  68         return $cache_file;
  69     }
  70
  71 /*=======================================================================*\
  72     Function:   get
  73     Purpose:    fetch an item from the cache
  74     Input:      url from wich the rss file was fetched
  75     Output:     cached object on HIT, false on MISS
  76 \*=======================================================================*/
  77     function get ($url) {
  78         $this->ERROR = "";
  79         $cache_file = $this->file_name( $url );
  80
  81         if ( ! file_exists( $cache_file ) ) {
  82             $this->debug(
  83                 "Cache doesn't contain: $url (cache file: $cache_file)"
  84             );
  85             return 0;
  86         }
  87
  88         $fp = @fopen($cache_file, 'r');
  89         if ( ! $fp ) {
  90             $this->error(
  91                 "Failed to open cache file for reading: $cache_file"
  92             );
  93             return 0;
  94         }
  95
  96         if ($filesize = filesize($cache_file) ) {
  97                 $data = fread( $fp, filesize($cache_file) );
  98                 $rss = $this->unserialize( $data );
  99
 100                 return $rss;
 101         }
 102
 103         return 0;
 104     }
 105
 106 /*=======================================================================*\
 107     Function:   check_cache
 108     Purpose:    check a url for membership in the cache
 109                 and whether the object is older then MAX_AGE (ie. STALE)
 110     Input:      url from wich the rss file was fetched
 111     Output:     cached object on HIT, false on MISS
 112 \*=======================================================================*/
 113     function check_cache ( $url ) {
 114         $this->ERROR = "";
 115         $filename = $this->file_name( $url );
 116
 117         if ( file_exists( $filename ) ) {
 118             // find how long ago the file was added to the cache
 119             // and whether that is longer then MAX_AGE
 120             $mtime = filemtime( $filename );
 121             $age = time() - $mtime;
 122             if ( $this->MAX_AGE > $age ) {
 123                 // object exists and is current
 124                 return 'HIT';
 125             }
 126             else {
 127                 // object exists but is old
 128                 return 'STALE';
 129             }
 130         }
 131         else {
 132             // object does not exist
 133             return 'MISS';
 134         }
 135     }
 136
 137         function cache_age( $cache_key ) {
 138                 $filename = $this->file_name( $url );
 139                 if ( file_exists( $filename ) ) {
 140                         $mtime = filemtime( $filename );
 141             $age = time() - $mtime;
 142                         return $age;
 143                 }
 144                 else {
 145                         return -1;
 146                 }
 147         }
 148
 149 /*=======================================================================*\
 150     Function:   serialize
 151 \*=======================================================================*/
 152     function serialize ( $rss ) {
 153         return serialize( $rss );
 154     }
 155
 156 /*=======================================================================*\
 157     Function:   unserialize
 158 \*=======================================================================*/
 159     function unserialize ( $data ) {
 160         return unserialize( $data );
 161     }
 162
 163 /*=======================================================================*\
 164     Function:   file_name
 165     Purpose:    map url to location in cache
 166     Input:      url from wich the rss file was fetched
 167     Output:     a file name
 168 \*=======================================================================*/
 169     function file_name ($url) {
 170         $filename = md5( $url );
 171         return join( DIRECTORY_SEPARATOR, array( $this->BASE_CACHE, $filename ) );
 172     }
 173
 174 /*=======================================================================*\
 175     Function:   error
 176     Purpose:    register error
 177 \*=======================================================================*/
 178     function error ($errormsg, $lvl=E_USER_WARNING) {
 179         // append PHP's error message if track_errors enabled
 180         if ( isset($php_errormsg) ) {
 181             $errormsg .= " ($php_errormsg)";
 182         }
 183         $this->ERROR = $errormsg;
 184         if ( MAGPIE_DEBUG ) {
 185             trigger_error( $errormsg, $lvl);
 186         }
 187         else {
 188             error_log( $errormsg, 0);
 189         }
 190     }
 191
 192     function debug ($debugmsg, $lvl=E_USER_NOTICE) {
 193         if ( MAGPIE_DEBUG ) {
 194             $this->error("MagpieRSS [debug] $debugmsg", $lvl);
 195         }
 196     }
 197
 198 }
 199
 200 ?>