includes/ParserCache.php

   1 <?php
   2 /**
   3  *
   4  * @addtogroup Cache
   5  */
   6
   7 /**
   8  * @todo document
   9  */
  10 class ParserCache {
  11         /**
  12          * Get an instance of this object
  13          */
  14         public static function &singleton() {
  15                 static $instance;
  16                 if ( !isset( $instance ) ) {
  17                         global $parserMemc;
  18                         $instance = new ParserCache( $parserMemc );
  19                 }
  20                 return $instance;
  21         }
  22
  23         /**
  24          * Setup a cache pathway with a given back-end storage mechanism.
  25          * May be a memcached client or a BagOStuff derivative.
  26          *
  27          * @param object $memCached
  28          */
  29         function __construct( &$memCached ) {
  30                 $this->mMemc =& $memCached;
  31         }
  32
  33         function getKey( &$article, &$user ) {
  34                 global $action;
  35                 $hash = $user->getPageRenderingHash();
  36                 if( !$article->mTitle->quickUserCan( 'edit' ) ) {
  37                         // section edit links are suppressed even if the user has them on
  38                         $edit = '!edit=0';
  39                 } else {
  40                         $edit = '';
  41                 }
  42                 $pageid = intval( $article->getID() );
  43                 $renderkey = (int)($action == 'render');
  44                 $key = wfMemcKey( 'pcache', 'idhash', "$pageid-$renderkey!$hash$edit" );
  45                 return $key;
  46         }
  47
  48         function getETag( &$article, &$user ) {
  49                 return 'W/"' . $this->getKey($article, $user) . "--" . $article->mTouched. '"';
  50         }
  51
  52         function get( &$article, &$user ) {
  53                 global $wgCacheEpoch;
  54                 $fname = 'ParserCache::get';
  55                 wfProfileIn( $fname );
  56
  57                 $key = $this->getKey( $article, $user );
  58
  59                 wfDebug( "Trying parser cache $key\n" );
  60                 $value = $this->mMemc->get( $key );
  61                 if ( is_object( $value ) ) {
  62                         wfDebug( "Found.\n" );
  63                         # Delete if article has changed since the cache was made
  64                         $canCache = $article->checkTouched();
  65                         $cacheTime = $value->getCacheTime();
  66                         $touched = $article->mTouched;
  67                         if ( !$canCache || $value->expired( $touched ) ) {
  68                                 if ( !$canCache ) {
  69                                         wfIncrStats( "pcache_miss_invalid" );
  70                                         wfDebug( "Invalid cached redirect, touched $touched, epoch $wgCacheEpoch, cached $cacheTime\n" );
  71                                 } else {
  72                                         wfIncrStats( "pcache_miss_expired" );
  73                                         wfDebug( "Key expired, touched $touched, epoch $wgCacheEpoch, cached $cacheTime\n" );
  74                                 }
  75                                 $this->mMemc->delete( $key );
  76                                 $value = false;
  77                         } else {
  78                                 if ( isset( $value->mTimestamp ) ) {
  79                                         $article->mTimestamp = $value->mTimestamp;
  80                                 }
  81                                 wfIncrStats( "pcache_hit" );
  82                         }
  83                 } else {
  84                         wfDebug( "Parser cache miss.\n" );
  85                         wfIncrStats( "pcache_miss_absent" );
  86                         $value = false;
  87                 }
  88
  89                 wfProfileOut( $fname );
  90                 return $value;
  91         }
  92
  93         function save( $parserOutput, &$article, &$user ){
  94                 global $wgParserCacheExpireTime;
  95                 $key = $this->getKey( $article, $user );
  96
  97                 if( $parserOutput->getCacheTime() != -1 ) {
  98
  99                         $now = wfTimestampNow();
 100                         $parserOutput->setCacheTime( $now );
 101
 102                         // Save the timestamp so that we don't have to load the revision row on view
 103                         $parserOutput->mTimestamp = $article->getTimestamp();
 104
 105                         $parserOutput->mText .= "\n<!-- Saved in parser cache with key $key and timestamp $now -->\n";
 106                         wfDebug( "Saved in parser cache with key $key and timestamp $now\n" );
 107
 108                         if( $parserOutput->containsOldMagic() ){
 109                                 $expire = 3600; # 1 hour
 110                         } else {
 111                                 $expire = $wgParserCacheExpireTime;
 112                         }
 113                         $this->mMemc->set( $key, $parserOutput, $expire );
 114
 115                 } else {
 116                         wfDebug( "Parser output was marked as uncacheable and has not been saved.\n" );
 117                 }
 118
 119         }
 120
 121 }
 122
 123 ?>