includes/cache/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 $mClassVer = 4;
  11
  12         private $mGoodLinks, $mBadLinks;
  13         private $mForUpdate;
  14
  15         /**
  16          * Get an instance of this class
  17          *
  18          * @return LinkCache
  19          */
  20         static function &singleton() {
  21                 static $instance;
  22                 if ( !isset( $instance ) ) {
  23                         $instance = new LinkCache;
  24                 }
  25                 return $instance;
  26         }
  27
  28         function __construct() {
  29                 $this->mForUpdate = false;
  30                 $this->mGoodLinks = array();
  31                 $this->mGoodLinkFields = array();
  32                 $this->mBadLinks = array();
  33         }
  34
  35         /**
  36          * General accessor to get/set whether SELECT FOR UPDATE should be used
  37          */
  38         public function forUpdate( $update = null ) {
  39                 return wfSetVar( $this->mForUpdate, $update );
  40         }
  41
  42         public function getGoodLinkID( $title ) {
  43                 if ( array_key_exists( $title, $this->mGoodLinks ) ) {
  44                         return $this->mGoodLinks[$title];
  45                 } else {
  46                         return 0;
  47                 }
  48         }
  49
  50         /**
  51          * Get a field of a title object from cache.
  52          * If this link is not good, it will return NULL.
  53          * @param $title Title
  54          * @param $field String: ('length','redirect','revision')
  55          * @return mixed
  56          */
  57         public function getGoodLinkFieldObj( $title, $field ) {
  58                 $dbkey = $title->getPrefixedDbKey();
  59                 if ( array_key_exists( $dbkey, $this->mGoodLinkFields ) ) {
  60                         return $this->mGoodLinkFields[$dbkey][$field];
  61                 } else {
  62                         return null;
  63                 }
  64         }
  65
  66         public function isBadLink( $title ) {
  67                 return array_key_exists( $title, $this->mBadLinks );
  68         }
  69
  70         /**
  71          * Add a link for the title to the link cache
  72          *
  73          * @param $id Integer: page's ID
  74          * @param $title Title object
  75          * @param $len Integer: text's length
  76          * @param $redir Integer: whether the page is a redirect
  77          * @param $revision Integer: latest revision's ID
  78          */
  79         public function addGoodLinkObj( $id, $title, $len = -1, $redir = null, $revision = false ) {
  80                 $dbkey = $title->getPrefixedDbKey();
  81                 $this->mGoodLinks[$dbkey] = intval( $id );
  82                 $this->mGoodLinkFields[$dbkey] = array(
  83                         'length' => intval( $len ),
  84                         'redirect' => intval( $redir ),
  85                         'revision' => intval( $revision ) );
  86         }
  87
  88         public function addBadLinkObj( $title ) {
  89                 $dbkey = $title->getPrefixedDbKey();
  90                 if ( !$this->isBadLink( $dbkey ) ) {
  91                         $this->mBadLinks[$dbkey] = 1;
  92                 }
  93         }
  94
  95         public function clearBadLink( $title ) {
  96                 unset( $this->mBadLinks[$title] );
  97         }
  98
  99         public function clearLink( $title ) {
 100                 $dbkey = $title->getPrefixedDbKey();
 101                 if( isset($this->mBadLinks[$dbkey]) ) {
 102                         unset($this->mBadLinks[$dbkey]);
 103                 }
 104                 if( isset($this->mGoodLinks[$dbkey]) ) {
 105                         unset($this->mGoodLinks[$dbkey]);
 106                 }
 107                 if( isset($this->mGoodLinkFields[$dbkey]) ) {
 108                         unset($this->mGoodLinkFields[$dbkey]);
 109                 }
 110         }
 111
 112         public function getGoodLinks() { return $this->mGoodLinks; }
 113         public function getBadLinks() { return array_keys( $this->mBadLinks ); }
 114
 115         /**
 116          * Add a title to the link cache, return the page_id or zero if non-existent
 117          *
 118          * @param $title String: title to add
 119          * @return Integer
 120          */
 121         public function addLink( $title ) {
 122                 $nt = Title::newFromDBkey( $title );
 123                 if( $nt ) {
 124                         return $this->addLinkObj( $nt );
 125                 } else {
 126                         return 0;
 127                 }
 128         }
 129
 130         /**
 131          * Add a title to the link cache, return the page_id or zero if non-existent
 132          *
 133          * @param $nt Title object to add
 134          * @return Integer
 135          */
 136         public function addLinkObj( $nt ) {
 137                 global $wgAntiLockFlags;
 138                 wfProfileIn( __METHOD__ );
 139
 140                 $key = $nt->getPrefixedDBkey();
 141                 if ( $this->isBadLink( $key ) || $nt->isExternal() ) {
 142                         wfProfileOut( __METHOD__ );
 143                         return 0;
 144                 }
 145                 $id = $this->getGoodLinkID( $key );
 146                 if ( $id != 0 ) {
 147                         wfProfileOut( __METHOD__ );
 148                         return $id;
 149                 }
 150
 151                 if ( $key === '' ) {
 152                         wfProfileOut( __METHOD__ );
 153                         return 0;
 154                 }
 155
 156                 # Some fields heavily used for linking...
 157                 if ( $this->mForUpdate ) {
 158                         $db = wfGetDB( DB_MASTER );
 159                         if ( !( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) ) {
 160                                 $options = array( 'FOR UPDATE' );
 161                         } else {
 162                                 $options = array();
 163                         }
 164                 } else {
 165                         $db = wfGetDB( DB_SLAVE );
 166                         $options = array();
 167                 }
 168
 169                 $s = $db->selectRow( 'page',
 170                         array( 'page_id', 'page_len', 'page_is_redirect', 'page_latest' ),
 171                         array( 'page_namespace' => $nt->getNamespace(), 'page_title' => $nt->getDBkey() ),
 172                         __METHOD__, $options );
 173                 # Set fields...
 174                 if ( $s !== false ) {
 175                         $id = intval( $s->page_id );
 176                         $len = intval( $s->page_len );
 177                         $redirect = intval( $s->page_is_redirect );
 178                         $revision = intval( $s->page_latest );
 179                 } else {
 180                         $id = 0;
 181                         $len = -1;
 182                         $redirect = 0;
 183                         $revision = 0;
 184                 }
 185
 186                 if ( $id == 0 ) {
 187                         $this->addBadLinkObj( $nt );
 188                 } else {
 189                         $this->addGoodLinkObj( $id, $nt, $len, $redirect, $revision );
 190                 }
 191                 wfProfileOut( __METHOD__ );
 192                 return $id;
 193         }
 194
 195         /**
 196          * Clears cache
 197          */
 198         public function clear() {
 199                 $this->mGoodLinks = array();
 200                 $this->mGoodLinkFields = array();
 201                 $this->mBadLinks = array();
 202         }
 203 }