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 = array();
  13         private $mGoodLinkFields = array();
  14         private $mBadLinks = array();
  15         private $mForUpdate = false;
  16
  17         /**
  18          * Get an instance of this class
  19          *
  20          * @return LinkCache
  21          */
  22         static function &singleton() {
  23                 static $instance;
  24                 if ( !isset( $instance ) ) {
  25                         $instance = new LinkCache;
  26                 }
  27                 return $instance;
  28         }
  29
  30         /**
  31          * General accessor to get/set whether SELECT FOR UPDATE should be used
  32          *
  33          * @return bool
  34          */
  35         public function forUpdate( $update = null ) {
  36                 return wfSetVar( $this->mForUpdate, $update );
  37         }
  38
  39         /**
  40          * @param $title
  41          * @return array|int
  42          */
  43         public function getGoodLinkID( $title ) {
  44                 if ( array_key_exists( $title, $this->mGoodLinks ) ) {
  45                         return $this->mGoodLinks[$title];
  46                 } else {
  47                         return 0;
  48                 }
  49         }
  50
  51         /**
  52          * Get a field of a title object from cache.
  53          * If this link is not good, it will return NULL.
  54          * @param $title Title
  55          * @param $field String: ('length','redirect','revision')
  56          * @return mixed
  57          */
  58         public function getGoodLinkFieldObj( $title, $field ) {
  59                 $dbkey = $title->getPrefixedDbKey();
  60                 if ( array_key_exists( $dbkey, $this->mGoodLinkFields ) ) {
  61                         return $this->mGoodLinkFields[$dbkey][$field];
  62                 } else {
  63                         return null;
  64                 }
  65         }
  66
  67         /**
  68          * @param $title
  69          * @return bool
  70          */
  71         public function isBadLink( $title ) {
  72                 return array_key_exists( $title, $this->mBadLinks );
  73         }
  74
  75         /**
  76          * Add a link for the title to the link cache
  77          *
  78          * @param $id Integer: page's ID
  79          * @param $title Title object
  80          * @param $len Integer: text's length
  81          * @param $redir Integer: whether the page is a redirect
  82          * @param $revision Integer: latest revision's ID
  83          */
  84         public function addGoodLinkObj( $id, $title, $len = -1, $redir = null, $revision = false ) {
  85                 $dbkey = $title->getPrefixedDbKey();
  86                 $this->mGoodLinks[$dbkey] = intval( $id );
  87                 $this->mGoodLinkFields[$dbkey] = array(
  88                         'length' => intval( $len ),
  89                         'redirect' => intval( $redir ),
  90                         'revision' => intval( $revision ) );
  91         }
  92
  93         /**
  94          * Same as above with better interface.
  95          * @since 1.19
  96          * @param $title Title
  97          * @param $row object which has the fields page_id, page_is_redirect,
  98          *  page_latest
  99          */
 100         public function addGoodLinkObjFromRow( $title, $row ) {
 101                 $dbkey = $title->getPrefixedDbKey();
 102                 $this->mGoodLinks[$dbkey] = intval( $row->page_id );
 103                 $this->mGoodLinkFields[$dbkey] = array(
 104                         'length' => intval( $row->page_len ),
 105                         'redirect' => intval( $row->page_is_redirect ),
 106                         'revision' => intval( $row->page_latest ),
 107                 );
 108         }
 109
 110         /**
 111          * @param $title Title
 112          */
 113         public function addBadLinkObj( $title ) {
 114                 $dbkey = $title->getPrefixedDbKey();
 115                 if ( !$this->isBadLink( $dbkey ) ) {
 116                         $this->mBadLinks[$dbkey] = 1;
 117                 }
 118         }
 119
 120         public function clearBadLink( $title ) {
 121                 unset( $this->mBadLinks[$title] );
 122         }
 123
 124         /**
 125          * @param $title Title
 126          */
 127         public function clearLink( $title ) {
 128                 $dbkey = $title->getPrefixedDbKey();
 129                 unset( $this->mBadLinks[$dbkey] );
 130                 unset( $this->mGoodLinks[$dbkey] );
 131                 unset( $this->mGoodLinkFields[$dbkey] );
 132         }
 133
 134         public function getGoodLinks() { return $this->mGoodLinks; }
 135         public function getBadLinks() { return array_keys( $this->mBadLinks ); }
 136
 137         /**
 138          * Add a title to the link cache, return the page_id or zero if non-existent
 139          *
 140          * @param $title String: title to add
 141          * @return Integer
 142          */
 143         public function addLink( $title ) {
 144                 $nt = Title::newFromDBkey( $title );
 145                 if( $nt ) {
 146                         return $this->addLinkObj( $nt );
 147                 } else {
 148                         return 0;
 149                 }
 150         }
 151
 152         /**
 153          * Add a title to the link cache, return the page_id or zero if non-existent
 154          *
 155          * @param $nt Title object to add
 156          * @return Integer
 157          */
 158         public function addLinkObj( $nt ) {
 159                 global $wgAntiLockFlags;
 160                 wfProfileIn( __METHOD__ );
 161
 162                 $key = $nt->getPrefixedDBkey();
 163                 if ( $this->isBadLink( $key ) || $nt->isExternal() ) {
 164                         wfProfileOut( __METHOD__ );
 165                         return 0;
 166                 }
 167                 $id = $this->getGoodLinkID( $key );
 168                 if ( $id != 0 ) {
 169                         wfProfileOut( __METHOD__ );
 170                         return $id;
 171                 }
 172
 173                 if ( $key === '' ) {
 174                         wfProfileOut( __METHOD__ );
 175                         return 0;
 176                 }
 177
 178                 # Some fields heavily used for linking...
 179                 if ( $this->mForUpdate ) {
 180                         $db = wfGetDB( DB_MASTER );
 181                         if ( !( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) ) {
 182                                 $options = array( 'FOR UPDATE' );
 183                         } else {
 184                                 $options = array();
 185                         }
 186                 } else {
 187                         $db = wfGetDB( DB_SLAVE );
 188                         $options = array();
 189                 }
 190
 191                 $s = $db->selectRow( 'page',
 192                         array( 'page_id', 'page_len', 'page_is_redirect', 'page_latest' ),
 193                         array( 'page_namespace' => $nt->getNamespace(), 'page_title' => $nt->getDBkey() ),
 194                         __METHOD__, $options );
 195                 # Set fields...
 196                 if ( $s !== false ) {
 197                         $this->addGoodLinkObjFromRow( $nt, $s );
 198                         $id = intval( $s->page_id );
 199                 } else {
 200                         $this->addBadLinkObj( $nt );
 201                         $id = 0;
 202                 }
 203
 204                 wfProfileOut( __METHOD__ );
 205                 return $id;
 206         }
 207
 208         /**
 209          * Clears cache
 210          */
 211         public function clear() {
 212                 $this->mGoodLinks = array();
 213                 $this->mGoodLinkFields = array();
 214                 $this->mBadLinks = array();
 215         }
 216 }