includes/LinkCache.php

   1 <?php
   2 /**
   3  * Cache for article titles (prefixed DB keys) and ids linked from one source
   4  * @package MediaWiki
   5  * @subpackage Cache
   6  */
   7
   8 /**
   9  * @package MediaWiki
  10  * @subpackage Cache
  11  */
  12 class LinkCache {
  13         // Increment $mClassVer whenever old serialized versions of this class
  14         // becomes incompatible with the new version.
  15         /* private */ var $mClassVer = 3;
  16
  17         /* private */ var $mPageLinks;
  18         /* private */ var $mGoodLinks, $mBadLinks;
  19         /* private */ var $mForUpdate;
  20
  21         /**
  22          * Get an instance of this class
  23          */
  24         static function &singleton() {
  25                 static $instance;
  26                 if ( !isset( $instance ) ) {
  27                         $instance = new LinkCache;
  28                 }
  29                 return $instance;
  30         }
  31
  32         function LinkCache() {
  33                 $this->mForUpdate = false;
  34                 $this->mPageLinks = array();
  35                 $this->mGoodLinks = array();
  36                 $this->mBadLinks = array();
  37         }
  38
  39         /* private */ function getKey( $title ) {
  40                 global $wgDBname;
  41                 return $wgDBname.':lc:title:'.$title;
  42         }
  43
  44         /**
  45          * General accessor to get/set whether SELECT FOR UPDATE should be used
  46          */
  47         function forUpdate( $update = NULL ) {
  48                 return wfSetVar( $this->mForUpdate, $update );
  49         }
  50
  51         function getGoodLinkID( $title ) {
  52                 if ( array_key_exists( $title, $this->mGoodLinks ) ) {
  53                         return $this->mGoodLinks[$title];
  54                 } else {
  55                         return 0;
  56                 }
  57         }
  58
  59         function isBadLink( $title ) {
  60                 return array_key_exists( $title, $this->mBadLinks );
  61         }
  62
  63         function addGoodLinkObj( $id, $title ) {
  64                 $dbkey = $title->getPrefixedDbKey();
  65                 $this->mGoodLinks[$dbkey] = $id;
  66                 $this->mPageLinks[$dbkey] = $title;
  67         }
  68
  69         function addBadLinkObj( $title ) {
  70                 $dbkey = $title->getPrefixedDbKey();
  71                 if ( ! $this->isBadLink( $dbkey ) ) {
  72                         $this->mBadLinks[$dbkey] = 1;
  73                         $this->mPageLinks[$dbkey] = $title;
  74                 }
  75         }
  76
  77         function clearBadLink( $title ) {
  78                 unset( $this->mBadLinks[$title] );
  79                 $this->clearLink( $title );
  80         }
  81
  82         function clearLink( $title ) {
  83                 global $wgMemc, $wgLinkCacheMemcached;
  84                 if( $wgLinkCacheMemcached )
  85                         $wgMemc->delete( $this->getKey( $title ) );
  86         }
  87
  88         function getPageLinks() { return $this->mPageLinks; }
  89         function getGoodLinks() { return $this->mGoodLinks; }
  90         function getBadLinks() { return array_keys( $this->mBadLinks ); }
  91
  92         /**
  93          * Add a title to the link cache, return the page_id or zero if non-existent
  94          * @param $title String: title to add
  95          * @return integer
  96          */
  97         function addLink( $title ) {
  98                 $nt = Title::newFromDBkey( $title );
  99                 if( $nt ) {
 100                         return $this->addLinkObj( $nt );
 101                 } else {
 102                         return 0;
 103                 }
 104         }
 105
 106         /**
 107          * Add a title to the link cache, return the page_id or zero if non-existent
 108          * @param $nt Title to add.
 109          * @return integer
 110          */
 111         function addLinkObj( &$nt ) {
 112                 global $wgMemc, $wgLinkCacheMemcached, $wgAntiLockFlags;
 113                 $title = $nt->getPrefixedDBkey();
 114                 if ( $this->isBadLink( $title ) ) { return 0; }
 115                 $id = $this->getGoodLinkID( $title );
 116                 if ( 0 != $id ) { return $id; }
 117
 118                 $fname = 'LinkCache::addLinkObj';
 119                 global $wgProfiling, $wgProfiler;
 120                 if ( $wgProfiling && isset( $wgProfiler ) ) {
 121                         $fname .= ' (' . $wgProfiler->getCurrentSection() . ')';
 122                 }
 123
 124                 wfProfileIn( $fname );
 125
 126                 $ns = $nt->getNamespace();
 127                 $t = $nt->getDBkey();
 128
 129                 if ( '' == $title ) {
 130                         wfProfileOut( $fname );
 131                         return 0;
 132                 }
 133
 134                 $id = NULL;
 135                 if( $wgLinkCacheMemcached )
 136                         $id = $wgMemc->get( $key = $this->getKey( $title ) );
 137                 if( ! is_integer( $id ) ) {
 138                         if ( $this->mForUpdate ) {
 139                                 $db =& wfGetDB( DB_MASTER );
 140                                 if ( !( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) ) {
 141                                         $options = array( 'FOR UPDATE' );
 142                                 } else {
 143                                         $options = array();
 144                                 }
 145                         } else {
 146                                 $db =& wfGetDB( DB_SLAVE );
 147                                 $options = array();
 148                         }
 149
 150                         $id = $db->selectField( 'page', 'page_id',
 151                                         array( 'page_namespace' => $ns, 'page_title' => $t ),
 152                                         $fname, $options );
 153                         if ( !$id ) {
 154                                 $id = 0;
 155                         }
 156                         if( $wgLinkCacheMemcached )
 157                                 $wgMemc->add( $key, $id, 3600*24 );
 158                 }
 159
 160                 if( 0 == $id ) {
 161                         $this->addBadLinkObj( $nt );
 162                 } else {
 163                         $this->addGoodLinkObj( $id, $nt );
 164                 }
 165                 wfProfileOut( $fname );
 166                 return $id;
 167         }
 168
 169         /**
 170          * Clears cache
 171          */
 172         function clear() {
 173                 $this->mPageLinks = array();
 174                 $this->mGoodLinks = array();
 175                 $this->mBadLinks = array();
 176         }
 177 }
 178 ?>