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<?php
/**
* Class representing a list of titles
* The execute() method checks them all for existence and adds them to a LinkCache object
*
* @ingroup Cache
*/
class LinkBatch {
/**
* 2-d array, first index namespace, second index dbkey, value arbitrary
*/
var $data = array();
function __construct( $arr = array() ) {
foreach( $arr as $item ) {
$this->addObj( $item );
}
}
public function addObj( $title ) {
if ( is_object( $title ) ) {
$this->add( $title->getNamespace(), $title->getDBkey() );
} else {
wfDebug( "Warning: LinkBatch::addObj got invalid title object\n" );
}
}
public function add( $ns, $dbkey ) {
if ( $ns < 0 ) {
return;
}
if ( !array_key_exists( $ns, $this->data ) ) {
$this->data[$ns] = array();
}
$this->data[$ns][str_replace( ' ', '_', $dbkey )] = 1;
}
/**
* Set the link list to a given 2-d array
* First key is the namespace, second is the DB key, value arbitrary
*/
public function setArray( $array ) {
$this->data = $array;
}
/**
* Returns true if no pages have been added, false otherwise.
*/
public function isEmpty() {
return ($this->getSize() == 0);
}
/**
* Returns the size of the batch.
*/
public function getSize() {
return count( $this->data );
}
/**
* Do the query and add the results to the LinkCache object
* Return an array mapping PDBK to ID
*/
public function execute() {
$linkCache = LinkCache::singleton();
return $this->executeInto( $linkCache );
}
/**
* Do the query and add the results to a given LinkCache object
* Return an array mapping PDBK to ID
*/
protected function executeInto( &$cache ) {
wfProfileIn( __METHOD__ );
$res = $this->doQuery();
$ids = $this->addResultToCache( $cache, $res );
wfProfileOut( __METHOD__ );
return $ids;
}
/**
* Add a ResultWrapper containing IDs and titles to a LinkCache object.
* As normal, titles will go into the static Title cache field.
* This function *also* stores extra fields of the title used for link
* parsing to avoid extra DB queries.
*/
public function addResultToCache( $cache, $res ) {
if ( !$res ) {
return array();
}
// For each returned entry, add it to the list of good links, and remove it from $remaining
$ids = array();
$remaining = $this->data;
while ( $row = $res->fetchObject() ) {
$title = Title::makeTitle( $row->page_namespace, $row->page_title );
$cache->addGoodLinkObj( $row->page_id, $title, $row->page_len, $row->page_is_redirect );
$ids[$title->getPrefixedDBkey()] = $row->page_id;
unset( $remaining[$row->page_namespace][$row->page_title] );
}
// The remaining links in $data are bad links, register them as such
foreach ( $remaining as $ns => $dbkeys ) {
foreach ( $dbkeys as $dbkey => $unused ) {
$title = Title::makeTitle( $ns, $dbkey );
$cache->addBadLinkObj( $title );
$ids[$title->getPrefixedDBkey()] = 0;
}
}
return $ids;
}
/**
* Perform the existence test query, return a ResultWrapper with page_id fields
*/
public function doQuery() {
if ( $this->isEmpty() ) {
return false;
}
wfProfileIn( __METHOD__ );
// Construct query
// This is very similar to Parser::replaceLinkHolders
$dbr = wfGetDB( DB_SLAVE );
$page = $dbr->tableName( 'page' );
$set = $this->constructSet( 'page', $dbr );
if ( $set === false ) {
wfProfileOut( __METHOD__ );
return false;
}
$sql = "SELECT page_id, page_namespace, page_title, page_len, page_is_redirect FROM $page WHERE $set";
// Do query
$res = $dbr->query( $sql, __METHOD__ );
wfProfileOut( __METHOD__ );
return $res;
}
/**
* Construct a WHERE clause which will match all the given titles.
*
* @param string $prefix the appropriate table's field name prefix ('page', 'pl', etc)
* @return string
* @public
*/
public function constructSet( $prefix, &$db ) {
$first = true;
$firstTitle = true;
$sql = '';
foreach ( $this->data as $ns => $dbkeys ) {
if ( !count( $dbkeys ) ) {
continue;
}
if ( $first ) {
$first = false;
} else {
$sql .= ' OR ';
}
if (count($dbkeys)==1) { // avoid multiple-reference syntax if simple equality can be used
$singleKey = array_keys($dbkeys);
$sql .= "({$prefix}_namespace=$ns AND {$prefix}_title=".
$db->addQuotes($singleKey[0]).
")";
} else {
$sql .= "({$prefix}_namespace=$ns AND {$prefix}_title IN (";
$firstTitle = true;
foreach( $dbkeys as $dbkey => $unused ) {
if ( $firstTitle ) {
$firstTitle = false;
} else {
$sql .= ',';
}
$sql .= $db->addQuotes( $dbkey );
}
$sql .= '))';
}
}
if ( $first && $firstTitle ) {
# No titles added
return false;
} else {
return $sql;
}
}
}