includes/LinkCache.php

   1 <?php
   2 /**
   3  * Cache for article titles (prefixed DB keys) and ids linked from one source
   4  *
   5  * @addtogroup 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                 $this->clearLink( $title );
  95         }
  96
  97         /* obsolete, for old $wgLinkCacheMemcached stuff */
  98         public function clearLink( $title ) {}
  99
 100         public function getPageLinks() { return $this->mPageLinks; }
 101         public function getGoodLinks() { return $this->mGoodLinks; }
 102         public function getBadLinks() { return array_keys( $this->mBadLinks ); }
 103
 104         /**
 105          * Add a title to the link cache, return the page_id or zero if non-existent
 106          * @param $title String: title to add
 107          * @param $len int, page size
 108          * @param $redir bool, is redirect?
 109          * @return integer
 110          */
 111         public function addLink( $title, $len = -1, $redir = NULL ) {
 112                 $nt = Title::newFromDBkey( $title );
 113                 if( $nt ) {
 114                         return $this->addLinkObj( $nt, $len, $redir );
 115                 } else {
 116                         return 0;
 117                 }
 118         }
 119
 120         /**
 121          * Add a title to the link cache, return the page_id or zero if non-existent
 122          * @param $nt Title to add.
 123          * @param $len int, page size
 124          * @param $redir bool, is redirect?
 125          * @return integer
 126          */
 127         public function addLinkObj( &$nt, $len = -1, $redirect = NULL ) {
 128                 global $wgAntiLockFlags;
 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                 global $wgProfiler;
 136                 if ( isset( $wgProfiler ) ) {
 137                         $fname .= ' (' . $wgProfiler->getCurrentSection() . ')';
 138                 }
 139
 140                 wfProfileIn( $fname );
 141
 142                 $ns = $nt->getNamespace();
 143                 $t = $nt->getDBkey();
 144
 145                 if ( '' == $title ) {
 146                         wfProfileOut( $fname );
 147                         return 0;
 148                 }
 149                 # Some fields heavily used for linking...
 150                 $id = NULL;
 151
 152                 if( !is_integer( $id ) ) {
 153                         if ( $this->mForUpdate ) {
 154                                 $db = wfGetDB( DB_MASTER );
 155                                 if ( !( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) ) {
 156                                         $options = array( 'FOR UPDATE' );
 157                                 } else {
 158                                         $options = array();
 159                                 }
 160                         } else {
 161                                 $db = wfGetDB( DB_SLAVE );
 162                                 $options = array();
 163                         }
 164
 165                         $s = $db->selectRow( 'page',
 166                                 array( 'page_id', 'page_len', 'page_is_redirect' ),
 167                                 array( 'page_namespace' => $ns, 'page_title' => $t ),
 168                                 $fname, $options );
 169                         # Set fields...
 170                         $id = $s ? $s->page_id : 0;
 171                         $len = $s ? $s->page_len : -1;
 172                         $redirect = $s ? $s->page_is_redirect : 0;
 173                 }
 174
 175                 if( 0 == $id ) {
 176                         $this->addBadLinkObj( $nt );
 177                 } else {
 178                         $this->addGoodLinkObj( $id, $nt, $len, $redirect );
 179                 }
 180                 wfProfileOut( $fname );
 181                 return $id;
 182         }
 183
 184         /**
 185          * Clears cache
 186          */
 187         public function clear() {
 188                 $this->mPageLinks = array();
 189                 $this->mGoodLinks = array();
 190                 $this->mGoodLinkFields = array();
 191                 $this->mBadLinks = array();
 192         }
 193 }