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 __construct() {
  33                 $this->mForUpdate = false;
  34                 $this->mPageLinks = array();
  35                 $this->mGoodLinks = array();
  36                 $this->mBadLinks = array();
  37         }
  38
  39         /* private */ function getKey( $title ) {
  40                 return wfMemcKey( 'lc', 'title', $title );
  41         }
  42
  43         /**
  44          * General accessor to get/set whether SELECT FOR UPDATE should be used
  45          */
  46         function forUpdate( $update = NULL ) {
  47                 return wfSetVar( $this->mForUpdate, $update );
  48         }
  49
  50         function getGoodLinkID( $title ) {
  51                 if ( array_key_exists( $title, $this->mGoodLinks ) ) {
  52                         return $this->mGoodLinks[$title];
  53                 } else {
  54                         return 0;
  55                 }
  56         }
  57
  58         function isBadLink( $title ) {
  59                 return array_key_exists( $title, $this->mBadLinks );
  60         }
  61
  62         function addGoodLinkObj( $id, $title ) {
  63                 $dbkey = $title->getPrefixedDbKey();
  64                 $this->mGoodLinks[$dbkey] = $id;
  65                 $this->mPageLinks[$dbkey] = $title;
  66         }
  67
  68         function addBadLinkObj( $title ) {
  69                 $dbkey = $title->getPrefixedDbKey();
  70                 if ( ! $this->isBadLink( $dbkey ) ) {
  71                         $this->mBadLinks[$dbkey] = 1;
  72                         $this->mPageLinks[$dbkey] = $title;
  73                 }
  74         }
  75
  76         function clearBadLink( $title ) {
  77                 unset( $this->mBadLinks[$title] );
  78                 $this->clearLink( $title );
  79         }
  80
  81         function clearLink( $title ) {
  82                 global $wgMemc, $wgLinkCacheMemcached;
  83                 if( $wgLinkCacheMemcached )
  84                         $wgMemc->delete( $this->getKey( $title ) );
  85         }
  86
  87         function getPageLinks() { return $this->mPageLinks; }
  88         function getGoodLinks() { return $this->mGoodLinks; }
  89         function getBadLinks() { return array_keys( $this->mBadLinks ); }
  90
  91         /**
  92          * Add a title to the link cache, return the page_id or zero if non-existent
  93          * @param $title String: title to add
  94          * @return integer
  95          */
  96         function addLink( $title ) {
  97                 $nt = Title::newFromDBkey( $title );
  98                 if( $nt ) {
  99                         return $this->addLinkObj( $nt );
 100                 } else {
 101                         return 0;
 102                 }
 103         }
 104
 105         /**
 106          * Add a title to the link cache, return the page_id or zero if non-existent
 107          * @param $nt Title to add.
 108          * @return integer
 109          */
 110         function addLinkObj( &$nt ) {
 111                 global $wgMemc, $wgLinkCacheMemcached, $wgAntiLockFlags;
 112                 $title = $nt->getPrefixedDBkey();
 113                 if ( $this->isBadLink( $title ) ) { return 0; }
 114                 $id = $this->getGoodLinkID( $title );
 115                 if ( 0 != $id ) { return $id; }
 116
 117                 $fname = 'LinkCache::addLinkObj';
 118                 global $wgProfiling, $wgProfiler;
 119                 if ( $wgProfiling && isset( $wgProfiler ) ) {
 120                         $fname .= ' (' . $wgProfiler->getCurrentSection() . ')';
 121                 }
 122
 123                 wfProfileIn( $fname );
 124
 125                 $ns = $nt->getNamespace();
 126                 $t = $nt->getDBkey();
 127
 128                 if ( '' == $title ) {
 129                         wfProfileOut( $fname );
 130                         return 0;
 131                 }
 132
 133                 $id = NULL;
 134                 if( $wgLinkCacheMemcached )
 135                         $id = $wgMemc->get( $key = $this->getKey( $title ) );
 136                 if( ! is_integer( $id ) ) {
 137                         if ( $this->mForUpdate ) {
 138                                 $db =& wfGetDB( DB_MASTER );
 139                                 if ( !( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) ) {
 140                                         $options = array( 'FOR UPDATE' );
 141                                 } else {
 142                                         $options = array();
 143                                 }
 144                         } else {
 145                                 $db =& wfGetDB( DB_SLAVE );
 146                                 $options = array();
 147                         }
 148
 149                         $id = $db->selectField( 'page', 'page_id',
 150                                         array( 'page_namespace' => $ns, 'page_title' => $t ),
 151                                         $fname, $options );
 152                         if ( !$id ) {
 153                                 $id = 0;
 154                         }
 155                         if( $wgLinkCacheMemcached )
 156                                 $wgMemc->add( $key, $id, 3600*24 );
 157                 }
 158
 159                 if( 0 == $id ) {
 160                         $this->addBadLinkObj( $nt );
 161                 } else {
 162                         $this->addGoodLinkObj( $id, $nt );
 163                 }
 164                 wfProfileOut( $fname );
 165                 return $id;
 166         }
 167
 168         /**
 169          * Clears cache
 170          */
 171         function clear() {
 172                 $this->mPageLinks = array();
 173                 $this->mGoodLinks = array();
 174                 $this->mBadLinks = array();
 175         }
 176 }
 177 ?>