<?php
-
/**
* Class for fetching backlink lists, approximate backlink counts and partitions.
* Instances of this class should typically be fetched with $title->getBacklinkCache().
*
- * Ideally you should only get your backlinks from here when you think there is some
+ * Ideally you should only get your backlinks from here when you think there is some
* advantage in caching them. Otherwise it's just a waste of memory.
*/
class BacklinkCache {
$this->title = $title;
}
+ /**
+ * Serialization handler, diasallows to serialize the database to prevent
+ * failures after this class is deserialized from cache with dead DB connection.
+ */
+ function __sleep() {
+ return array( 'partitionCache', 'fullResultCache', 'title' );
+ }
+
/**
* Clear locally stored data
*/
if ( !isset( $this->db ) ) {
$this->db = wfGetDB( DB_SLAVE );
}
+
return $this->db;
}
/**
* Get the backlinks for a given table. Cached in process memory only.
- * @param string $table
+ * @param $table String
+ * @param $startId Integer or false
+ * @param $endId Integer or false
* @return TitleArray
*/
public function getLinks( $table, $startId = false, $endId = false ) {
wfProfileIn( __METHOD__ );
+ $fromField = $this->getPrefix( $table ) . '_from';
+
if ( $startId || $endId ) {
// Partial range, not cached
- wfDebug( __METHOD__.": from DB (uncacheable range)\n" );
+ wfDebug( __METHOD__ . ": from DB (uncacheable range)\n" );
$conds = $this->getConditions( $table );
+
// Use the from field in the condition rather than the joined page_id,
// because databases are stupid and don't necessarily propagate indexes.
- $fromField = $this->getPrefix( $table ) . '_from';
if ( $startId ) {
$conds[] = "$fromField >= " . intval( $startId );
}
+
if ( $endId ) {
$conds[] = "$fromField <= " . intval( $endId );
}
- $res = $this->getDB()->select(
+
+ $res = $this->getDB()->select(
array( $table, 'page' ),
- array( 'page_namespace', 'page_title', 'page_id'),
+ array( 'page_namespace', 'page_title', 'page_id' ),
$conds,
__METHOD__,
- array('STRAIGHT_JOIN') );
+ array(
+ 'STRAIGHT_JOIN',
+ 'ORDER BY' => $fromField
+ ) );
$ta = TitleArray::newFromResult( $res );
+
wfProfileOut( __METHOD__ );
return $ta;
}
if ( !isset( $this->fullResultCache[$table] ) ) {
- wfDebug( __METHOD__.": from DB\n" );
- $res = $this->getDB()->select(
+ wfDebug( __METHOD__ . ": from DB\n" );
+ $res = $this->getDB()->select(
array( $table, 'page' ),
array( 'page_namespace', 'page_title', 'page_id' ),
$this->getConditions( $table ),
__METHOD__,
- array('STRAIGHT_JOIN') );
+ array(
+ 'STRAIGHT_JOIN',
+ 'ORDER BY' => $fromField,
+ ) );
$this->fullResultCache[$table] = $res;
}
+
$ta = TitleArray::newFromResult( $this->fullResultCache[$table] );
+
wfProfileOut( __METHOD__ );
return $ta;
}
'templatelinks' => 'tl',
'redirect' => 'rd',
);
+
if ( isset( $prefixes[$table] ) ) {
return $prefixes[$table];
} else {
*/
protected function getConditions( $table ) {
$prefix = $this->getPrefix( $table );
+
switch ( $table ) {
case 'pagelinks':
case 'templatelinks':
);
break;
case 'imagelinks':
- $conds = array(
+ $conds = array(
'il_to' => $this->title->getDBkey(),
'page_id=il_from'
);
break;
case 'categorylinks':
- $conds = array(
+ $conds = array(
'cl_to' => $this->title->getDBkey(),
'page_id=cl_from',
);
default:
throw new MWException( "Invalid table \"$table\" in " . __CLASS__ );
}
+
return $conds;
}
if ( isset( $this->fullResultCache[$table] ) ) {
return $this->fullResultCache[$table]->numRows();
}
+
if ( isset( $this->partitionCache[$table] ) ) {
$entry = reset( $this->partitionCache[$table] );
return $entry['numRows'];
}
+
$titleArray = $this->getLinks( $table );
+
return $titleArray->count();
}
* Returns an array giving the start and end of each range. The first batch has
* a start of false, and the last batch has an end of false.
*
- * @param string $table The links table name
- * @param integer $batchSize
- * @return array
+ * @param $table String: the links table name
+ * @param $batchSize Integer
+ * @return Array
*/
public function partition( $table, $batchSize ) {
// Try cache
if ( isset( $this->partitionCache[$table][$batchSize] ) ) {
- wfDebug( __METHOD__.": got from partition cache\n" );
+ wfDebug( __METHOD__ . ": got from partition cache\n" );
return $this->partitionCache[$table][$batchSize]['batches'];
}
+
$this->partitionCache[$table][$batchSize] = false;
$cacheEntry =& $this->partitionCache[$table][$batchSize];
// Try full result cache
if ( isset( $this->fullResultCache[$table] ) ) {
$cacheEntry = $this->partitionResult( $this->fullResultCache[$table], $batchSize );
- wfDebug( __METHOD__.": got from full result cache\n" );
+ wfDebug( __METHOD__ . ": got from full result cache\n" );
+
return $cacheEntry['batches'];
}
+
// Try memcached
global $wgMemc;
- $memcKey = wfMemcKey( 'backlinks', md5( $this->title->getPrefixedDBkey() ),
- $table, $batchSize );
+
+ $memcKey = wfMemcKey(
+ 'backlinks',
+ md5( $this->title->getPrefixedDBkey() ),
+ $table,
+ $batchSize
+ );
+
$memcValue = $wgMemc->get( $memcKey );
+
if ( is_array( $memcValue ) ) {
$cacheEntry = $memcValue;
- wfDebug( __METHOD__.": got from memcached $memcKey\n" );
+ wfDebug( __METHOD__ . ": got from memcached $memcKey\n" );
+
return $cacheEntry['batches'];
}
+
// Fetch from database
$this->getLinks( $table );
$cacheEntry = $this->partitionResult( $this->fullResultCache[$table], $batchSize );
// Save to memcached
$wgMemc->set( $memcKey, $cacheEntry, self::CACHE_EXPIRY );
- wfDebug( __METHOD__.": got from database\n" );
+
+ wfDebug( __METHOD__ . ": got from database\n" );
return $cacheEntry['batches'];
}
- /**
+ /**
* Partition a DB result with backlinks in it into batches
*/
protected function partitionResult( $res, $batchSize ) {
$batches = array();
$numRows = $res->numRows();
$numBatches = ceil( $numRows / $batchSize );
+
for ( $i = 0; $i < $numBatches; $i++ ) {
if ( $i == 0 ) {
$start = false;
$row = $res->fetchObject();
$start = $row->page_id;
}
+
if ( $i == $numBatches - 1 ) {
$end = false;
} else {
$row = $res->fetchObject();
$end = $row->page_id - 1;
}
+
+ # Sanity check order
+ if ( $start && $end && $start > $end ) {
+ throw new MWException( __METHOD__ . ': Internal error: query result out of order' );
+ }
+
$batches[] = array( $start, $end );
}
+
return array( 'numRows' => $numRows, 'batches' => $batches );
}
}
scripts.mit.edu / autoinstallsdev / mediawiki.git / blobdiff