includes/parser/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 $memCached Object
  24          */
  25         function __construct( $memCached ) {
  26                 $this->mMemc = $memCached;
  27         }
  28
  29         function getKey( $article, $popts ) {
  30                 global $wgRequest;
  31
  32                 if( $popts instanceof User )    // It used to be getKey( &$article, &$user )
  33                         $popts = ParserOptions::newFromUser( $popts );
  34
  35                 $user = $popts->mUser;
  36                 $printable = ( $popts->getIsPrintable() ) ? '!printable=1' : '';
  37                 $hash = $user->getPageRenderingHash();
  38                 if( !$article->mTitle->quickUserCan( 'edit' ) ) {
  39                         // section edit links are suppressed even if the user has them on
  40                         $edit = '!edit=0';
  41                 } else {
  42                         $edit = '';
  43                 }
  44                 $pageid = $article->getID();
  45                 $renderkey = (int)($wgRequest->getVal('action') == 'render');
  46                 $key = wfMemcKey( 'pcache', 'idhash', "{$pageid}-{$renderkey}!{$hash}{$edit}{$printable}" );
  47                 return $key;
  48         }
  49
  50         function getETag( $article, $popts ) {
  51                 return 'W/"' . $this->getKey($article, $popts) . "--" . $article->mTouched. '"';
  52         }
  53
  54         function getDirty( $article, $popts ) {
  55                 $key = $this->getKey( $article, $popts );
  56                 wfDebug( "Trying parser cache $key\n" );
  57                 $value = $this->mMemc->get( $key );
  58                 return is_object( $value ) ? $value : false;
  59         }
  60
  61         function get( $article, $popts ) {
  62                 global $wgCacheEpoch;
  63                 wfProfileIn( __METHOD__ );
  64
  65                 $value = $this->getDirty( $article, $popts );
  66                 if ( !$value ) {
  67                         wfDebug( "Parser cache miss.\n" );
  68                         wfIncrStats( "pcache_miss_absent" );
  69                         wfProfileOut( __METHOD__ );
  70                         return false;
  71                 }
  72
  73                 wfDebug( "Found.\n" );
  74                 # Invalid if article has changed since the cache was made
  75                 $canCache = $article->checkTouched();
  76                 $cacheTime = $value->getCacheTime();
  77                 $touched = $article->mTouched;
  78                 if ( !$canCache || $value->expired( $touched ) ) {
  79                         if ( !$canCache ) {
  80                                 wfIncrStats( "pcache_miss_invalid" );
  81                                 wfDebug( "Invalid cached redirect, touched $touched, epoch $wgCacheEpoch, cached $cacheTime\n" );
  82                         } else {
  83                                 wfIncrStats( "pcache_miss_expired" );
  84                                 wfDebug( "Key expired, touched $touched, epoch $wgCacheEpoch, cached $cacheTime\n" );
  85                         }
  86                         $value = false;
  87                 } else {
  88                         if ( isset( $value->mTimestamp ) ) {
  89                                 $article->mTimestamp = $value->mTimestamp;
  90                         }
  91                         wfIncrStats( "pcache_hit" );
  92                 }
  93
  94                 wfProfileOut( __METHOD__ );
  95                 return $value;
  96         }
  97
  98         function save( $parserOutput, $article, $popts ){
  99                 $key = $this->getKey( $article, $popts );
 100                 $expire = $parserOutput->getCacheExpiry();
 101
 102                 if( $expire > 0 ) {
 103                         $now = wfTimestampNow();
 104                         $parserOutput->setCacheTime( $now );
 105
 106                         // Save the timestamp so that we don't have to load the revision row on view
 107                         $parserOutput->mTimestamp = $article->getTimestamp();
 108
 109                         $parserOutput->mText .= "\n<!-- Saved in parser cache with key $key and timestamp $now -->\n";
 110                         wfDebug( "Saved in parser cache with key $key and timestamp $now\n" );
 111
 112                         $this->mMemc->set( $key, $parserOutput, $expire );
 113
 114                 } else {
 115                         wfDebug( "Parser output was marked as uncacheable and has not been saved.\n" );
 116                 }
 117         }
 118
 119 }