includes/LinkCache.php

   1 <?php
   2 /**
   3  * Cache for article titles (prefixed DB keys) and ids linked from one source
   4  *
   5  * @ingroup 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 = 4;
  11
  12         /* private */ var $mGoodLinks, $mBadLinks;
  13         /* private */ var $mForUpdate;
  14
  15         /**
  16          * Get an instance of this class
  17          */
  18         static function &singleton() {
  19                 static $instance;
  20                 if ( !isset( $instance ) ) {
  21                         $instance = new LinkCache;
  22                 }
  23                 return $instance;
  24         }
  25
  26         function __construct() {
  27                 $this->mForUpdate = false;
  28                 $this->mGoodLinks = array();
  29                 $this->mGoodLinkFields = array();
  30                 $this->mBadLinks = array();
  31         }
  32
  33         /**
  34          * General accessor to get/set whether SELECT FOR UPDATE should be used
  35          */
  36         public function forUpdate( $update = null ) {
  37                 return wfSetVar( $this->mForUpdate, $update );
  38         }
  39
  40         public function getGoodLinkID( $title ) {
  41                 if ( array_key_exists( $title, $this->mGoodLinks ) ) {
  42                         return $this->mGoodLinks[$title];
  43                 } else {
  44                         return 0;
  45                 }
  46         }
  47
  48         /**
  49          * Get a field of a title object from cache.
  50          * If this link is not good, it will return NULL.
  51          * @param Title $title
  52          * @param string $field ('length','redirect')
  53          * @return mixed
  54          */
  55         public function getGoodLinkFieldObj( $title, $field ) {
  56                 $dbkey = $title->getPrefixedDbKey();
  57                 if ( array_key_exists( $dbkey, $this->mGoodLinkFields ) ) {
  58                         return $this->mGoodLinkFields[$dbkey][$field];
  59                 } else {
  60                         return null;
  61                 }
  62         }
  63
  64         public function isBadLink( $title ) {
  65                 return array_key_exists( $title, $this->mBadLinks );
  66         }
  67
  68         /**
  69          * Add a link for the title to the link cache
  70          * @param int $id
  71          * @param Title $title
  72          * @param int $len
  73          * @param int $redir
  74          */
  75         public function addGoodLinkObj( $id, $title, $len = -1, $redir = null ) {
  76                 $dbkey = $title->getPrefixedDbKey();
  77                 $this->mGoodLinks[$dbkey] = intval( $id );
  78                 $this->mGoodLinkFields[$dbkey] = array(
  79                         'length' => intval( $len ),
  80                         'redirect' => intval( $redir ) );
  81         }
  82
  83         public function addBadLinkObj( $title ) {
  84                 $dbkey = $title->getPrefixedDbKey();
  85                 if ( !$this->isBadLink( $dbkey ) ) {
  86                         $this->mBadLinks[$dbkey] = 1;
  87                 }
  88         }
  89
  90         public function clearBadLink( $title ) {
  91                 unset( $this->mBadLinks[$title] );
  92         }
  93
  94         public function clearLink( $title ) {
  95                 $dbkey = $title->getPrefixedDbKey();
  96                 if( isset($this->mBadLinks[$dbkey]) ) {
  97                         unset($this->mBadLinks[$dbkey]);
  98                 }
  99                 if( isset($this->mGoodLinks[$dbkey]) ) {
 100                         unset($this->mGoodLinks[$dbkey]);
 101                 }
 102                 if( isset($this->mGoodLinkFields[$dbkey]) ) {
 103                         unset($this->mGoodLinkFields[$dbkey]);
 104                 }
 105         }
 106
 107         public function getGoodLinks() { return $this->mGoodLinks; }
 108         public function getBadLinks() { return array_keys( $this->mBadLinks ); }
 109
 110         /**
 111          * Add a title to the link cache, return the page_id or zero if non-existent
 112          * @param $title String: title to add
 113          * @param $len int, page size
 114          * @param $redir bool, is redirect?
 115          * @return integer
 116          */
 117         public function addLink( $title, $len = -1, $redir = null ) {
 118                 $nt = Title::newFromDBkey( $title );
 119                 if( $nt ) {
 120                         return $this->addLinkObj( $nt, $len, $redir );
 121                 } else {
 122                         return 0;
 123                 }
 124         }
 125
 126         /**
 127          * Add a title to the link cache, return the page_id or zero if non-existent
 128          * @param $nt Title to add.
 129          * @param $len int, page size
 130          * @param $redir bool, is redirect?
 131          * @return integer
 132          */
 133         public function addLinkObj( &$nt, $len = -1, $redirect = null ) {
 134                 global $wgAntiLockFlags, $wgProfiler;
 135                 wfProfileIn( __METHOD__ );
 136
 137                 $key = $nt->getPrefixedDBkey();
 138                 if ( $this->isBadLink( $key ) ) {
 139                         wfProfileOut( __METHOD__ );
 140                         return 0;
 141                 }
 142                 $id = $this->getGoodLinkID( $key );
 143                 if ( $id != 0 ) {
 144                         wfProfileOut( __METHOD__ );
 145                         return $id;
 146                 }
 147
 148                 if ( $key === '' ) {
 149                         wfProfileOut( __METHOD__ );
 150                         return 0;
 151                 }
 152
 153                 # Some fields heavily used for linking...
 154                 if ( $this->mForUpdate ) {
 155                         $db = wfGetDB( DB_MASTER );
 156                         if ( !( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) ) {
 157                                 $options = array( 'FOR UPDATE' );
 158                         } else {
 159                                 $options = array();
 160                         }
 161                 } else {
 162                         $db = wfGetDB( DB_SLAVE );
 163                         $options = array();
 164                 }
 165
 166                 $s = $db->selectRow( 'page',
 167                         array( 'page_id', 'page_len', 'page_is_redirect' ),
 168                         array( 'page_namespace' => $nt->getNamespace(), 'page_title' => $nt->getDBkey() ),
 169                         __METHOD__, $options );
 170                 # Set fields...
 171                 if ( $s !== false ) {
 172                         $id = intval( $s->page_id );
 173                         $len = intval( $s->page_len );
 174                         $redirect = intval( $s->page_is_redirect );
 175                 } else {
 176                         $len = -1;
 177                         $redirect = 0;
 178                 }
 179
 180                 if ( $id == 0 ) {
 181                         $this->addBadLinkObj( $nt );
 182                 } else {
 183                         $this->addGoodLinkObj( $id, $nt, $len, $redirect );
 184                 }
 185                 wfProfileOut( __METHOD__ );
 186                 return $id;
 187         }
 188
 189         /**
 190          * Clears cache
 191          */
 192         public function clear() {
 193                 $this->mGoodLinks = array();
 194                 $this->mGoodLinkFields = array();
 195                 $this->mBadLinks = array();
 196         }
 197 }