includes/ParserCache.php

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