includes/LinkCache.php

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