includes/ParserCache.php

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