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          * Same as above with better interface.
 100          * @since 1.19
 101          * @param $title Title
 102          * @param $row object which has the fields page_id, page_is_redirect,
 103          *  page_latest
 104          */
 105         public function addGoodLinkObjFromRow( $title, $row ) {
 106                 $dbkey = $title->getPrefixedDbKey();
 107                 $this->mGoodLinks[$dbkey] = intval( $row->page_id );
 108                 $this->mGoodLinkFields[$dbkey] = array(
 109                         'length' => intval( $row->page_len ),
 110                         'redirect' => intval( $row->page_is_redirect ),
 111                         'revision' => intval( $row->page_latest ),
 112                 );
 113         }
 114
 115         /**
 116          * @param $title Title
 117          */
 118         public function addBadLinkObj( $title ) {
 119                 $dbkey = $title->getPrefixedDbKey();
 120                 if ( !$this->isBadLink( $dbkey ) ) {
 121                         $this->mBadLinks[$dbkey] = 1;
 122                 }
 123         }
 124
 125         public function clearBadLink( $title ) {
 126                 unset( $this->mBadLinks[$title] );
 127         }
 128
 129         /**
 130          * @param $title Title
 131          */
 132         public function clearLink( $title ) {
 133                 $dbkey = $title->getPrefixedDbKey();
 134                 unset( $this->mBadLinks[$dbkey] );
 135                 unset( $this->mGoodLinks[$dbkey] );
 136                 unset( $this->mGoodLinkFields[$dbkey] );
 137         }
 138
 139         public function getGoodLinks() { return $this->mGoodLinks; }
 140         public function getBadLinks() { return array_keys( $this->mBadLinks ); }
 141
 142         /**
 143          * Add a title to the link cache, return the page_id or zero if non-existent
 144          *
 145          * @param $title String: title to add
 146          * @return Integer
 147          */
 148         public function addLink( $title ) {
 149                 $nt = Title::newFromDBkey( $title );
 150                 if( $nt ) {
 151                         return $this->addLinkObj( $nt );
 152                 } else {
 153                         return 0;
 154                 }
 155         }
 156
 157         /**
 158          * Add a title to the link cache, return the page_id or zero if non-existent
 159          *
 160          * @param $nt Title object to add
 161          * @return Integer
 162          */
 163         public function addLinkObj( $nt ) {
 164                 global $wgAntiLockFlags;
 165                 wfProfileIn( __METHOD__ );
 166
 167                 $key = $nt->getPrefixedDBkey();
 168                 if ( $this->isBadLink( $key ) || $nt->isExternal() ) {
 169                         wfProfileOut( __METHOD__ );
 170                         return 0;
 171                 }
 172                 $id = $this->getGoodLinkID( $key );
 173                 if ( $id != 0 ) {
 174                         wfProfileOut( __METHOD__ );
 175                         return $id;
 176                 }
 177
 178                 if ( $key === '' ) {
 179                         wfProfileOut( __METHOD__ );
 180                         return 0;
 181                 }
 182
 183                 # Some fields heavily used for linking...
 184                 if ( $this->mForUpdate ) {
 185                         $db = wfGetDB( DB_MASTER );
 186                         if ( !( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) ) {
 187                                 $options = array( 'FOR UPDATE' );
 188                         } else {
 189                                 $options = array();
 190                         }
 191                 } else {
 192                         $db = wfGetDB( DB_SLAVE );
 193                         $options = array();
 194                 }
 195
 196                 $s = $db->selectRow( 'page',
 197                         array( 'page_id', 'page_len', 'page_is_redirect', 'page_latest' ),
 198                         array( 'page_namespace' => $nt->getNamespace(), 'page_title' => $nt->getDBkey() ),
 199                         __METHOD__, $options );
 200                 # Set fields...
 201                 if ( $s !== false ) {
 202                         $this->addGoodLinkObjFromRow( $nt, $s );
 203                         $id = intval( $s->page_id );
 204                 } else {
 205                         $this->addBadLinkObj( $nt );
 206                         $id = 0;
 207                 }
 208
 209                 wfProfileOut( __METHOD__ );
 210                 return $id;
 211         }
 212
 213         /**
 214          * Clears cache
 215          */
 216         public function clear() {
 217                 $this->mGoodLinks = array();
 218                 $this->mGoodLinkFields = array();
 219                 $this->mBadLinks = array();
 220         }
 221 }