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 $mPageLinks;
  13         /* private */ var $mGoodLinks, $mBadLinks;
  14         /* private */ var $mForUpdate;
  15
  16         /**
  17          * Get an instance of this class
  18          */
  19         static function &singleton() {
  20                 static $instance;
  21                 if ( !isset( $instance ) ) {
  22                         $instance = new LinkCache;
  23                 }
  24                 return $instance;
  25         }
  26
  27         function __construct() {
  28                 $this->mForUpdate = false;
  29                 $this->mPageLinks = array();
  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 string $field ('length','redirect')
  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          * @param int $id
  73          * @param Title $title
  74          * @param int $len
  75          * @param int $redir
  76          */
  77         public function addGoodLinkObj( $id, $title, $len = -1, $redir = NULL ) {
  78                 $dbkey = $title->getPrefixedDbKey();
  79                 $this->mGoodLinks[$dbkey] = $id;
  80                 $this->mGoodLinkFields[$dbkey] = array( 'length' => $len, 'redirect' => $redir );
  81                 $this->mPageLinks[$dbkey] = $title;
  82         }
  83
  84         public function addBadLinkObj( $title ) {
  85                 $dbkey = $title->getPrefixedDbKey();
  86                 if ( ! $this->isBadLink( $dbkey ) ) {
  87                         $this->mBadLinks[$dbkey] = 1;
  88                         $this->mPageLinks[$dbkey] = $title;
  89                 }
  90         }
  91
  92         public function clearBadLink( $title ) {
  93                 unset( $this->mBadLinks[$title] );
  94         }
  95
  96         /* obsolete, for old $wgLinkCacheMemcached stuff */
  97         public function clearLink( $title ) {}
  98
  99         public function getPageLinks() { return $this->mPageLinks; }
 100         public function getGoodLinks() { return $this->mGoodLinks; }
 101         public function getBadLinks() { return array_keys( $this->mBadLinks ); }
 102
 103         /**
 104          * Add a title to the link cache, return the page_id or zero if non-existent
 105          * @param $title String: title to add
 106          * @param $len int, page size
 107          * @param $redir bool, is redirect?
 108          * @return integer
 109          */
 110         public function addLink( $title, $len = -1, $redir = NULL ) {
 111                 $nt = Title::newFromDBkey( $title );
 112                 if( $nt ) {
 113                         return $this->addLinkObj( $nt, $len, $redir );
 114                 } else {
 115                         return 0;
 116                 }
 117         }
 118
 119         /**
 120          * Add a title to the link cache, return the page_id or zero if non-existent
 121          * @param $nt Title to add.
 122          * @param $len int, page size
 123          * @param $redir bool, is redirect?
 124          * @return integer
 125          */
 126         public function addLinkObj( &$nt, $len = -1, $redirect = NULL ) {
 127                 global $wgAntiLockFlags, $wgProfiler;
 128
 129                 $title = $nt->getPrefixedDBkey();
 130                 if ( $this->isBadLink( $title ) ) { return 0; }
 131                 $id = $this->getGoodLinkID( $title );
 132                 if ( 0 != $id ) { return $id; }
 133
 134                 $fname = 'LinkCache::addLinkObj';
 135                 if ( isset( $wgProfiler ) ) {
 136                         $fname .= ' (' . $wgProfiler->getCurrentSection() . ')';
 137                 }
 138
 139                 wfProfileIn( $fname );
 140
 141                 $ns = $nt->getNamespace();
 142                 $t = $nt->getDBkey();
 143
 144                 if ( '' == $title ) {
 145                         wfProfileOut( $fname );
 146                         return 0;
 147                 }
 148
 149                 # Some fields heavily used for linking...
 150                 if ( $this->mForUpdate ) {
 151                         $db = wfGetDB( DB_MASTER );
 152                         if ( !( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) ) {
 153                                 $options = array( 'FOR UPDATE' );
 154                         } else {
 155                                 $options = array();
 156                         }
 157                 } else {
 158                         $db = wfGetDB( DB_SLAVE );
 159                         $options = array();
 160                 }
 161
 162                 $s = $db->selectRow( 'page',
 163                         array( 'page_id', 'page_len', 'page_is_redirect' ),
 164                         array( 'page_namespace' => $ns, 'page_title' => $t ),
 165                         $fname, $options );
 166                 # Set fields...
 167                 $id = $s ? $s->page_id : 0;
 168                 $len = $s ? $s->page_len : -1;
 169                 $redirect = $s ? $s->page_is_redirect : 0;
 170
 171                 if( 0 == $id ) {
 172                         $this->addBadLinkObj( $nt );
 173                 } else {
 174                         $this->addGoodLinkObj( $id, $nt, $len, $redirect );
 175                 }
 176                 wfProfileOut( $fname );
 177                 return $id;
 178         }
 179
 180         /**
 181          * Clears cache
 182          */
 183         public function clear() {
 184                 $this->mPageLinks = array();
 185                 $this->mGoodLinks = array();
 186                 $this->mGoodLinkFields = array();
 187                 $this->mBadLinks = array();
 188         }
 189 }