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          * @return bool
  39          */
  40         public function forUpdate( $update = null ) {
  41                 return wfSetVar( $this->mForUpdate, $update );
  42         }
  43
  44         /**
  45          * @param $title
  46          * @return array|int
  47          */
  48         public 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         /**
  57          * Get a field of a title object from cache.
  58          * If this link is not good, it will return NULL.
  59          * @param $title Title
  60          * @param $field String: ('length','redirect','revision')
  61          * @return mixed
  62          */
  63         public function getGoodLinkFieldObj( $title, $field ) {
  64                 $dbkey = $title->getPrefixedDbKey();
  65                 if ( array_key_exists( $dbkey, $this->mGoodLinkFields ) ) {
  66                         return $this->mGoodLinkFields[$dbkey][$field];
  67                 } else {
  68                         return null;
  69                 }
  70         }
  71
  72         /**
  73          * @param $title
  74          * @return bool
  75          */
  76         public function isBadLink( $title ) {
  77                 return array_key_exists( $title, $this->mBadLinks );
  78         }
  79
  80         /**
  81          * Add a link for the title to the link cache
  82          *
  83          * @param $id Integer: page's ID
  84          * @param $title Title object
  85          * @param $len Integer: text's length
  86          * @param $redir Integer: whether the page is a redirect
  87          * @param $revision Integer: latest revision's ID
  88          */
  89         public function addGoodLinkObj( $id, $title, $len = -1, $redir = null, $revision = false ) {
  90                 $dbkey = $title->getPrefixedDbKey();
  91                 $this->mGoodLinks[$dbkey] = intval( $id );
  92                 $this->mGoodLinkFields[$dbkey] = array(
  93                         'length' => intval( $len ),
  94                         'redirect' => intval( $redir ),
  95                         'revision' => intval( $revision ) );
  96         }
  97
  98         /**
  99          * @param $title Title
 100          */
 101         public function addBadLinkObj( $title ) {
 102                 $dbkey = $title->getPrefixedDbKey();
 103                 if ( !$this->isBadLink( $dbkey ) ) {
 104                         $this->mBadLinks[$dbkey] = 1;
 105                 }
 106         }
 107
 108         public function clearBadLink( $title ) {
 109                 unset( $this->mBadLinks[$title] );
 110         }
 111
 112         /**
 113          * @param $title Title
 114          */
 115         public function clearLink( $title ) {
 116                 $dbkey = $title->getPrefixedDbKey();
 117                 if( isset($this->mBadLinks[$dbkey]) ) {
 118                         unset($this->mBadLinks[$dbkey]);
 119                 }
 120                 if( isset($this->mGoodLinks[$dbkey]) ) {
 121                         unset($this->mGoodLinks[$dbkey]);
 122                 }
 123                 if( isset($this->mGoodLinkFields[$dbkey]) ) {
 124                         unset($this->mGoodLinkFields[$dbkey]);
 125                 }
 126         }
 127
 128         public function getGoodLinks() { return $this->mGoodLinks; }
 129         public function getBadLinks() { return array_keys( $this->mBadLinks ); }
 130
 131         /**
 132          * Add a title to the link cache, return the page_id or zero if non-existent
 133          *
 134          * @param $title String: title to add
 135          * @return Integer
 136          */
 137         public function addLink( $title ) {
 138                 $nt = Title::newFromDBkey( $title );
 139                 if( $nt ) {
 140                         return $this->addLinkObj( $nt );
 141                 } else {
 142                         return 0;
 143                 }
 144         }
 145
 146         /**
 147          * Add a title to the link cache, return the page_id or zero if non-existent
 148          *
 149          * @param $nt Title object to add
 150          * @return Integer
 151          */
 152         public function addLinkObj( $nt ) {
 153                 global $wgAntiLockFlags;
 154                 wfProfileIn( __METHOD__ );
 155
 156                 $key = $nt->getPrefixedDBkey();
 157                 if ( $this->isBadLink( $key ) || $nt->isExternal() ) {
 158                         wfProfileOut( __METHOD__ );
 159                         return 0;
 160                 }
 161                 $id = $this->getGoodLinkID( $key );
 162                 if ( $id != 0 ) {
 163                         wfProfileOut( __METHOD__ );
 164                         return $id;
 165                 }
 166
 167                 if ( $key === '' ) {
 168                         wfProfileOut( __METHOD__ );
 169                         return 0;
 170                 }
 171
 172                 # Some fields heavily used for linking...
 173                 if ( $this->mForUpdate ) {
 174                         $db = wfGetDB( DB_MASTER );
 175                         if ( !( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) ) {
 176                                 $options = array( 'FOR UPDATE' );
 177                         } else {
 178                                 $options = array();
 179                         }
 180                 } else {
 181                         $db = wfGetDB( DB_SLAVE );
 182                         $options = array();
 183                 }
 184
 185                 $s = $db->selectRow( 'page',
 186                         array( 'page_id', 'page_len', 'page_is_redirect', 'page_latest' ),
 187                         array( 'page_namespace' => $nt->getNamespace(), 'page_title' => $nt->getDBkey() ),
 188                         __METHOD__, $options );
 189                 # Set fields...
 190                 if ( $s !== false ) {
 191                         $id = intval( $s->page_id );
 192                         $len = intval( $s->page_len );
 193                         $redirect = intval( $s->page_is_redirect );
 194                         $revision = intval( $s->page_latest );
 195                 } else {
 196                         $id = 0;
 197                         $len = -1;
 198                         $redirect = 0;
 199                         $revision = 0;
 200                 }
 201
 202                 if ( $id == 0 ) {
 203                         $this->addBadLinkObj( $nt );
 204                 } else {
 205                         $this->addGoodLinkObj( $id, $nt, $len, $redirect, $revision );
 206                 }
 207                 wfProfileOut( __METHOD__ );
 208                 return $id;
 209         }
 210
 211         /**
 212          * Clears cache
 213          */
 214         public function clear() {
 215                 $this->mGoodLinks = array();
 216                 $this->mGoodLinkFields = array();
 217                 $this->mBadLinks = array();
 218         }
 219 }