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 $field String: ('length','redirect','revision')
  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          *
  71          * @param $id Integer: page's ID
  72          * @param $title Title object
  73          * @param $len Integer: text's length
  74          * @param $redir Integer: whether the page is a redirect
  75          * @param $revision Integer: latest revision's ID
  76          */
  77         public function addGoodLinkObj( $id, $title, $len = -1, $redir = null, $revision = false ) {
  78                 $dbkey = $title->getPrefixedDbKey();
  79                 $this->mGoodLinks[$dbkey] = intval( $id );
  80                 $this->mGoodLinkFields[$dbkey] = array(
  81                         'length' => intval( $len ),
  82                         'redirect' => intval( $redir ),
  83                         'revision' => intval( $revision ) );
  84         }
  85
  86         public function addBadLinkObj( $title ) {
  87                 $dbkey = $title->getPrefixedDbKey();
  88                 if ( !$this->isBadLink( $dbkey ) ) {
  89                         $this->mBadLinks[$dbkey] = 1;
  90                 }
  91         }
  92
  93         public function clearBadLink( $title ) {
  94                 unset( $this->mBadLinks[$title] );
  95         }
  96
  97         public function clearLink( $title ) {
  98                 $dbkey = $title->getPrefixedDbKey();
  99                 if( isset($this->mBadLinks[$dbkey]) ) {
 100                         unset($this->mBadLinks[$dbkey]);
 101                 }
 102                 if( isset($this->mGoodLinks[$dbkey]) ) {
 103                         unset($this->mGoodLinks[$dbkey]);
 104                 }
 105                 if( isset($this->mGoodLinkFields[$dbkey]) ) {
 106                         unset($this->mGoodLinkFields[$dbkey]);
 107                 }
 108         }
 109
 110         public function getGoodLinks() { return $this->mGoodLinks; }
 111         public function getBadLinks() { return array_keys( $this->mBadLinks ); }
 112
 113         /**
 114          * Add a title to the link cache, return the page_id or zero if non-existent
 115          *
 116          * @param $title String: title to add
 117          * @return Integer
 118          */
 119         public function addLink( $title ) {
 120                 $nt = Title::newFromDBkey( $title );
 121                 if( $nt ) {
 122                         return $this->addLinkObj( $nt );
 123                 } else {
 124                         return 0;
 125                 }
 126         }
 127
 128         /**
 129          * Add a title to the link cache, return the page_id or zero if non-existent
 130          *
 131          * @param $nt Title object to add
 132          * @return Integer
 133          */
 134         public function addLinkObj( $nt ) {
 135                 global $wgAntiLockFlags;
 136                 wfProfileIn( __METHOD__ );
 137
 138                 $key = $nt->getPrefixedDBkey();
 139                 if ( $this->isBadLink( $key ) || $nt->isExternal() ) {
 140                         wfProfileOut( __METHOD__ );
 141                         return 0;
 142                 }
 143                 $id = $this->getGoodLinkID( $key );
 144                 if ( $id != 0 ) {
 145                         wfProfileOut( __METHOD__ );
 146                         return $id;
 147                 }
 148
 149                 if ( $key === '' ) {
 150                         wfProfileOut( __METHOD__ );
 151                         return 0;
 152                 }
 153
 154                 # Some fields heavily used for linking...
 155                 if ( $this->mForUpdate ) {
 156                         $db = wfGetDB( DB_MASTER );
 157                         if ( !( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) ) {
 158                                 $options = array( 'FOR UPDATE' );
 159                         } else {
 160                                 $options = array();
 161                         }
 162                 } else {
 163                         $db = wfGetDB( DB_SLAVE );
 164                         $options = array();
 165                 }
 166
 167                 $s = $db->selectRow( 'page',
 168                         array( 'page_id', 'page_len', 'page_is_redirect', 'page_latest' ),
 169                         array( 'page_namespace' => $nt->getNamespace(), 'page_title' => $nt->getDBkey() ),
 170                         __METHOD__, $options );
 171                 # Set fields...
 172                 if ( $s !== false ) {
 173                         $id = intval( $s->page_id );
 174                         $len = intval( $s->page_len );
 175                         $redirect = intval( $s->page_is_redirect );
 176                         $revision = intval( $s->page_latest );
 177                 } else {
 178                         $id = 0;
 179                         $len = -1;
 180                         $redirect = 0;
 181                         $revision = 0;
 182                 }
 183
 184                 if ( $id == 0 ) {
 185                         $this->addBadLinkObj( $nt );
 186                 } else {
 187                         $this->addGoodLinkObj( $id, $nt, $len, $redirect, $revision );
 188                 }
 189                 wfProfileOut( __METHOD__ );
 190                 return $id;
 191         }
 192
 193         /**
 194          * Clears cache
 195          */
 196         public function clear() {
 197                 $this->mGoodLinks = array();
 198                 $this->mGoodLinkFields = array();
 199                 $this->mBadLinks = array();
 200         }
 201 }