includes/LinkBatch.php

   1 <?php
   2
   3 /**
   4  * Class representing a list of titles
   5  * The execute() method checks them all for existence and adds them to a LinkCache object
   6  *
   7  * @ingroup Cache
   8  */
   9 class LinkBatch {
  10         /**
  11          * 2-d array, first index namespace, second index dbkey, value arbitrary
  12          */
  13         var $data = array();
  14
  15         function __construct( $arr = array() ) {
  16                 foreach( $arr as $item ) {
  17                         $this->addObj( $item );
  18                 }
  19         }
  20
  21         public function addObj( $title ) {
  22                 if ( is_object( $title ) ) {
  23                         $this->add( $title->getNamespace(), $title->getDBkey() );
  24                 } else {
  25                         wfDebug( "Warning: LinkBatch::addObj got invalid title object\n" );
  26                 }
  27         }
  28
  29         public function add( $ns, $dbkey ) {
  30                 if ( $ns < 0 ) {
  31                         return;
  32                 }
  33                 if ( !array_key_exists( $ns, $this->data ) ) {
  34                         $this->data[$ns] = array();
  35                 }
  36
  37                 $this->data[$ns][str_replace( ' ', '_', $dbkey )] = 1;
  38         }
  39
  40         /**
  41          * Set the link list to a given 2-d array
  42          * First key is the namespace, second is the DB key, value arbitrary
  43          */
  44         public function setArray( $array ) {
  45                 $this->data = $array;
  46         }
  47
  48         /**
  49          * Returns true if no pages have been added, false otherwise.
  50          */
  51         public function isEmpty() {
  52                 return ($this->getSize() == 0);
  53         }
  54
  55         /**
  56          * Returns the size of the batch.
  57          */
  58         public function getSize() {
  59                 return count( $this->data );
  60         }
  61
  62         /**
  63          * Do the query and add the results to the LinkCache object
  64          * Return an array mapping PDBK to ID
  65          */
  66          public function execute() {
  67                 $linkCache = LinkCache::singleton();
  68                 return $this->executeInto( $linkCache );
  69          }
  70
  71         /**
  72          * Do the query and add the results to a given LinkCache object
  73          * Return an array mapping PDBK to ID
  74          */
  75         protected function executeInto( &$cache ) {
  76                 wfProfileIn( __METHOD__ );
  77                 $res = $this->doQuery();
  78                 $ids = $this->addResultToCache( $cache, $res );
  79                 wfProfileOut( __METHOD__ );
  80                 return $ids;
  81         }
  82
  83         /**
  84          * Add a ResultWrapper containing IDs and titles to a LinkCache object.
  85          * As normal, titles will go into the static Title cache field.
  86          * This function *also* stores extra fields of the title used for link
  87          * parsing to avoid extra DB queries.
  88          */
  89         public function addResultToCache( $cache, $res ) {
  90                 if ( !$res ) {
  91                         return array();
  92                 }
  93
  94                 // For each returned entry, add it to the list of good links, and remove it from $remaining
  95
  96                 $ids = array();
  97                 $remaining = $this->data;
  98                 while ( $row = $res->fetchObject() ) {
  99                         $title = Title::makeTitle( $row->page_namespace, $row->page_title );
 100                         $cache->addGoodLinkObj( $row->page_id, $title, $row->page_len, $row->page_is_redirect );
 101                         $ids[$title->getPrefixedDBkey()] = $row->page_id;
 102                         unset( $remaining[$row->page_namespace][$row->page_title] );
 103                 }
 104
 105                 // The remaining links in $data are bad links, register them as such
 106                 foreach ( $remaining as $ns => $dbkeys ) {
 107                         foreach ( $dbkeys as $dbkey => $unused ) {
 108                                 $title = Title::makeTitle( $ns, $dbkey );
 109                                 $cache->addBadLinkObj( $title );
 110                                 $ids[$title->getPrefixedDBkey()] = 0;
 111                         }
 112                 }
 113                 return $ids;
 114         }
 115
 116         /**
 117          * Perform the existence test query, return a ResultWrapper with page_id fields
 118          */
 119         public function doQuery() {
 120                 if ( $this->isEmpty() ) {
 121                         return false;
 122                 }
 123                 wfProfileIn( __METHOD__ );
 124
 125                 // Construct query
 126                 // This is very similar to Parser::replaceLinkHolders
 127                 $dbr = wfGetDB( DB_SLAVE );
 128                 $page = $dbr->tableName( 'page' );
 129                 $set = $this->constructSet( 'page', $dbr );
 130                 if ( $set === false ) {
 131                         wfProfileOut( __METHOD__ );
 132                         return false;
 133                 }
 134                 $sql = "SELECT page_id, page_namespace, page_title, page_len, page_is_redirect FROM $page WHERE $set";
 135
 136                 // Do query
 137                 $res = $dbr->query( $sql, __METHOD__ );
 138                 wfProfileOut( __METHOD__ );
 139                 return $res;
 140         }
 141
 142         /**
 143          * Construct a WHERE clause which will match all the given titles.
 144          *
 145          * @param $prefix String: the appropriate table's field name prefix ('page', 'pl', etc)
 146          * @param $db DatabaseBase object to use
 147          * @return String
 148          */
 149         public function constructSet( $prefix, &$db ) {
 150                 $first = true;
 151                 $firstTitle = true;
 152                 $sql = '';
 153                 foreach ( $this->data as $ns => $dbkeys ) {
 154                         if ( !count( $dbkeys ) ) {
 155                                 continue;
 156                         }
 157
 158                         if ( $first ) {
 159                                 $first = false;
 160                         } else {
 161                                 $sql .= ' OR ';
 162                         }
 163
 164                         if (count($dbkeys)==1) { // avoid multiple-reference syntax if simple equality can be used
 165                                 $singleKey = array_keys($dbkeys);
 166                                 $sql .= "({$prefix}_namespace=$ns AND {$prefix}_title=".
 167                                         $db->addQuotes($singleKey[0]).
 168                                         ")";
 169                         } else {
 170                                 $sql .= "({$prefix}_namespace=$ns AND {$prefix}_title IN (";
 171
 172                                 $firstTitle = true;
 173                                 foreach( $dbkeys as $dbkey => $unused ) {
 174                                         if ( $firstTitle ) {
 175                                                 $firstTitle = false;
 176                                         } else {
 177                                                 $sql .= ',';
 178                                         }
 179                                         $sql .= $db->addQuotes( $dbkey );
 180                                 }
 181                                 $sql .= '))';
 182                         }
 183                 }
 184                 if ( $first && $firstTitle ) {
 185                         # No titles added
 186                         return false;
 187                 } else {
 188                         return $sql;
 189                 }
 190         }
 191 }