includes/LinkCache.php

   1 <?php
   2 /**
   3  * Cache for article titles (prefixed DB keys) and ids linked from one source
   4  *
   5  * @addtogroup Cache
   6  */
   7 class LinkCache {
   8         // Increment $mClassVer whenever old serialized versions of this class
   9         // becomes incompatible with the new version.
  10         /* private */ var $mClassVer = 3;
  11
  12         /* private */ var $mPageLinks;
  13         /* private */ var $mGoodLinks, $mBadLinks;
  14         /* private */ var $mForUpdate;
  15
  16         /**
  17          * Get an instance of this class
  18          */
  19         static function &singleton() {
  20                 static $instance;
  21                 if ( !isset( $instance ) ) {
  22                         $instance = new LinkCache;
  23                 }
  24                 return $instance;
  25         }
  26
  27         function __construct() {
  28                 $this->mForUpdate = false;
  29                 $this->mPageLinks = array();
  30                 $this->mGoodLinks = array();
  31                 $this->mBadLinks = array();
  32         }
  33
  34         /* private */ function getKey( $title ) {
  35                 return wfMemcKey( 'lc', 'title', $title );
  36         }
  37
  38         /**
  39          * General accessor to get/set whether SELECT FOR UPDATE should be used
  40          */
  41         function forUpdate( $update = NULL ) {
  42                 return wfSetVar( $this->mForUpdate, $update );
  43         }
  44
  45         function getGoodLinkID( $title ) {
  46                 if ( array_key_exists( $title, $this->mGoodLinks ) ) {
  47                         return $this->mGoodLinks[$title];
  48                 } else {
  49                         return 0;
  50                 }
  51         }
  52
  53         function isBadLink( $title ) {
  54                 return array_key_exists( $title, $this->mBadLinks );
  55         }
  56
  57         function addGoodLinkObj( $id, $title ) {
  58                 $dbkey = $title->getPrefixedDbKey();
  59                 $this->mGoodLinks[$dbkey] = $id;
  60                 $this->mPageLinks[$dbkey] = $title;
  61         }
  62
  63         function addBadLinkObj( $title ) {
  64                 $dbkey = $title->getPrefixedDbKey();
  65                 if ( ! $this->isBadLink( $dbkey ) ) {
  66                         $this->mBadLinks[$dbkey] = 1;
  67                         $this->mPageLinks[$dbkey] = $title;
  68                 }
  69         }
  70
  71         function clearBadLink( $title ) {
  72                 unset( $this->mBadLinks[$title] );
  73                 $this->clearLink( $title );
  74         }
  75
  76         function clearLink( $title ) {
  77                 global $wgMemc, $wgLinkCacheMemcached;
  78                 if( $wgLinkCacheMemcached )
  79                         $wgMemc->delete( $this->getKey( $title ) );
  80         }
  81
  82         function getPageLinks() { return $this->mPageLinks; }
  83         function getGoodLinks() { return $this->mGoodLinks; }
  84         function getBadLinks() { return array_keys( $this->mBadLinks ); }
  85
  86         /**
  87          * Add a title to the link cache, return the page_id or zero if non-existent
  88          * @param $title String: title to add
  89          * @return integer
  90          */
  91         function addLink( $title ) {
  92                 $nt = Title::newFromDBkey( $title );
  93                 if( $nt ) {
  94                         return $this->addLinkObj( $nt );
  95                 } else {
  96                         return 0;
  97                 }
  98         }
  99
 100         /**
 101          * Add a title to the link cache, return the page_id or zero if non-existent
 102          * @param $nt Title to add.
 103          * @return integer
 104          */
 105         function addLinkObj( &$nt ) {
 106                 global $wgMemc, $wgLinkCacheMemcached, $wgAntiLockFlags;
 107                 $title = $nt->getPrefixedDBkey();
 108                 if ( $this->isBadLink( $title ) ) { return 0; }
 109                 $id = $this->getGoodLinkID( $title );
 110                 if ( 0 != $id ) { return $id; }
 111
 112                 $fname = 'LinkCache::addLinkObj';
 113                 global $wgProfiling, $wgProfiler;
 114                 if ( $wgProfiling && isset( $wgProfiler ) ) {
 115                         $fname .= ' (' . $wgProfiler->getCurrentSection() . ')';
 116                 }
 117
 118                 wfProfileIn( $fname );
 119
 120                 $ns = $nt->getNamespace();
 121                 $t = $nt->getDBkey();
 122
 123                 if ( '' == $title ) {
 124                         wfProfileOut( $fname );
 125                         return 0;
 126                 }
 127
 128                 $id = NULL;
 129                 if( $wgLinkCacheMemcached )
 130                         $id = $wgMemc->get( $key = $this->getKey( $title ) );
 131                 if( ! is_integer( $id ) ) {
 132                         if ( $this->mForUpdate ) {
 133                                 $db = wfGetDB( DB_MASTER );
 134                                 if ( !( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) ) {
 135                                         $options = array( 'FOR UPDATE' );
 136                                 } else {
 137                                         $options = array();
 138                                 }
 139                         } else {
 140                                 $db = wfGetDB( DB_SLAVE );
 141                                 $options = array();
 142                         }
 143
 144                         $id = $db->selectField( 'page', 'page_id',
 145                                         array( 'page_namespace' => $ns, 'page_title' => $t ),
 146                                         $fname, $options );
 147                         if ( !$id ) {
 148                                 $id = 0;
 149                         }
 150                         if( $wgLinkCacheMemcached )
 151                                 $wgMemc->add( $key, $id, 3600*24 );
 152                 }
 153
 154                 if( 0 == $id ) {
 155                         $this->addBadLinkObj( $nt );
 156                 } else {
 157                         $this->addGoodLinkObj( $id, $nt );
 158                 }
 159                 wfProfileOut( $fname );
 160                 return $id;
 161         }
 162
 163         /**
 164          * Clears cache
 165          */
 166         function clear() {
 167                 $this->mPageLinks = array();
 168                 $this->mGoodLinks = array();
 169                 $this->mBadLinks = array();
 170         }
 171 }
 172