includes/parser/ParserCache.php

   1 <?php
   2 /**
   3  * @ingroup Cache Parser
   4  * @todo document
   5  */
   6 class ParserCache {
   7         private $mMemc;
   8
   9         /**
  10          * Get an instance of this object
  11          */
  12         public static function singleton() {
  13                 static $instance;
  14                 if ( !isset( $instance ) ) {
  15                         global $parserMemc;
  16                         $instance = new ParserCache( $parserMemc );
  17                 }
  18                 return $instance;
  19         }
  20
  21         /**
  22          * Setup a cache pathway with a given back-end storage mechanism.
  23          * May be a memcached client or a BagOStuff derivative.
  24          *
  25          * @param $memCached Object
  26          */
  27         function __construct( $memCached ) {
  28                 if ( !$memCached ) {
  29                         global $parserMemc;
  30                         $parserMemc = $memCached = wfGetParserCacheStorage();
  31                 }
  32                 $this->mMemc = $memCached;
  33         }
  34
  35         function getKey( $article, $popts ) {
  36                 global $wgRequest;
  37
  38                 if( $popts instanceof User )    // It used to be getKey( &$article, &$user )
  39                         $popts = ParserOptions::newFromUser( $popts );
  40
  41                 $user = $popts->mUser;
  42                 $printable = ( $popts->getIsPrintable() ) ? '!printable=1' : '';
  43                 $hash = $user->getPageRenderingHash();
  44                 if( !$article->mTitle->quickUserCan( 'edit' ) ) {
  45                         // section edit links are suppressed even if the user has them on
  46                         $edit = '!edit=0';
  47                 } else {
  48                         $edit = '';
  49                 }
  50                 $pageid = $article->getID();
  51                 $renderkey = (int)($wgRequest->getVal('action') == 'render');
  52                 $key = wfMemcKey( 'pcache', 'idhash', "{$pageid}-{$renderkey}!{$hash}{$edit}{$printable}" );
  53                 return $key;
  54         }
  55
  56         function getETag( $article, $popts ) {
  57                 return 'W/"' . $this->getKey($article, $popts) . "--" . $article->mTouched. '"';
  58         }
  59
  60         function getDirty( $article, $popts ) {
  61                 $key = $this->getKey( $article, $popts );
  62                 wfDebug( "Trying parser cache $key\n" );
  63                 $value = $this->mMemc->get( $key );
  64                 return is_object( $value ) ? $value : false;
  65         }
  66
  67         function get( $article, $popts ) {
  68                 global $wgCacheEpoch;
  69                 wfProfileIn( __METHOD__ );
  70
  71                 $value = $this->getDirty( $article, $popts );
  72                 if ( !$value ) {
  73                         wfDebug( "Parser cache miss.\n" );
  74                         wfIncrStats( "pcache_miss_absent" );
  75                         wfProfileOut( __METHOD__ );
  76                         return false;
  77                 }
  78
  79                 wfDebug( "Found.\n" );
  80                 # Invalid if article has changed since the cache was made
  81                 $canCache = $article->checkTouched();
  82                 $cacheTime = $value->getCacheTime();
  83                 $touched = $article->mTouched;
  84                 if ( !$canCache || $value->expired( $touched ) ) {
  85                         if ( !$canCache ) {
  86                                 wfIncrStats( "pcache_miss_invalid" );
  87                                 wfDebug( "Invalid cached redirect, touched $touched, epoch $wgCacheEpoch, cached $cacheTime\n" );
  88                         } else {
  89                                 wfIncrStats( "pcache_miss_expired" );
  90                                 wfDebug( "Key expired, touched $touched, epoch $wgCacheEpoch, cached $cacheTime\n" );
  91                         }
  92                         $value = false;
  93                 } else {
  94                         if ( isset( $value->mTimestamp ) ) {
  95                                 $article->mTimestamp = $value->mTimestamp;
  96                         }
  97                         wfIncrStats( "pcache_hit" );
  98                 }
  99
 100                 wfProfileOut( __METHOD__ );
 101                 return $value;
 102         }
 103
 104         function save( $parserOutput, $article, $popts ){
 105                 $key = $this->getKey( $article, $popts );
 106                 $expire = $parserOutput->getCacheExpiry();
 107
 108                 if( $expire > 0 ) {
 109                         $now = wfTimestampNow();
 110                         $parserOutput->setCacheTime( $now );
 111
 112                         // Save the timestamp so that we don't have to load the revision row on view
 113                         $parserOutput->mTimestamp = $article->getTimestamp();
 114
 115                         $parserOutput->mText .= "\n<!-- Saved in parser cache with key $key and timestamp $now -->\n";
 116                         wfDebug( "Saved in parser cache with key $key and timestamp $now\n" );
 117
 118                         $this->mMemc->set( $key, $parserOutput, $expire );
 119
 120                 } else {
 121                         wfDebug( "Parser output was marked as uncacheable and has not been saved.\n" );
 122                 }
 123         }
 124
 125 }