* @ingroup Database
*/
+use Psr\Log\LoggerInterface;
+use MediaWiki\Logger\LoggerFactory;
+
/**
* An interface for generating database load balancers
* @ingroup Database
abstract class LBFactory {
/** @var ChronologyProtector */
protected $chronProt;
+
/** @var TransactionProfiler */
protected $trxProfiler;
+ /** @var LoggerInterface */
+ protected $logger;
+
/** @var LBFactory */
private static $instance;
$this->chronProt = $this->newChronologyProtector();
$this->trxProfiler = Profiler::instance()->getTransactionProfiler();
+ $this->logger = LoggerFactory::getInstance( 'DBTransaction' );
}
/**
* @param string $fname Caller name
*/
public function commitAll( $fname = __METHOD__ ) {
+ $this->logMultiDbTransaction();
+
$start = microtime( true );
$this->forEachLBCallMethod( 'commitAll', array( $fname ) );
$timeMs = 1000 * ( microtime( true ) - $start );
/**
* Commit changes on all master connections
* @param string $fname Caller name
+ * @param array $options Options map:
+ * - maxWriteDuration: abort if more than this much time was spent in write queries
*/
- public function commitMasterChanges( $fname = __METHOD__ ) {
+ public function commitMasterChanges( $fname = __METHOD__, array $options = array() ) {
+ $limit = isset( $options['maxWriteDuration'] ) ? $options['maxWriteDuration'] : 0;
+
+ $this->logMultiDbTransaction();
+ $this->forEachLB( function ( LoadBalancer $lb ) use ( $limit ) {
+ $lb->forEachOpenConnection( function ( IDatabase $db ) use ( $limit ) {
+ $time = $db->pendingWriteQueryDuration();
+ if ( $limit > 0 && $time > $limit ) {
+ throw new DBTransactionError(
+ $db,
+ wfMessage( 'transaction-duration-limit-exceeded', $time, $limit )->text()
+ );
+ }
+ } );
+ } );
+
$start = microtime( true );
$this->forEachLBCallMethod( 'commitMasterChanges', array( $fname ) );
$timeMs = 1000 * ( microtime( true ) - $start );
$this->forEachLBCallMethod( 'rollbackMasterChanges', array( $fname ) );
}
+ /**
+ * Log query info if multi DB transactions are going to be committed now
+ */
+ private function logMultiDbTransaction() {
+ $callersByDB = array();
+ $this->forEachLB( function ( LoadBalancer $lb ) use ( &$callersByDB ) {
+ $masterName = $lb->getServerName( $lb->getWriterIndex() );
+ $callers = $lb->pendingMasterChangeCallers();
+ if ( $callers ) {
+ $callersByDB[$masterName] = $callers;
+ }
+ } );
+
+ if ( count( $callersByDB ) >= 2 ) {
+ $dbs = implode( ', ', array_keys( $callersByDB ) );
+ $msg = "Multi-DB transaction [{$dbs}]:\n";
+ foreach ( $callersByDB as $db => $callers ) {
+ $msg .= "$db: " . implode( '; ', $callers ) . "\n";
+ }
+ $this->logger->info( $msg );
+ }
+ }
+
/**
* Determine if any master connection has pending changes
* @return bool
return $ret;
}
+ /**
+ * Waits for the slave DBs to catch up to the current master position
+ *
+ * Use this when updating very large numbers of rows, as in maintenance scripts,
+ * to avoid causing too much lag. Of course, this is a no-op if there are no slaves.
+ *
+ * By default this waits on all DB clusters actually used in this request.
+ * This makes sense when lag being waiting on is caused by the code that does this check.
+ * In that case, setting "ifWritesSince" can avoid the overhead of waiting for clusters
+ * that were not changed since the last wait check. To forcefully wait on a specific cluster
+ * for a given wiki, use the 'wiki' parameter. To forcefully wait on an "external" cluster,
+ * use the "cluster" parameter.
+ *
+ * Never call this function after a large DB write that is *still* in a transaction.
+ * It only makes sense to call this after the possible lag inducing changes were committed.
+ *
+ * @param array $opts Optional fields that include:
+ * - wiki : wait on the load balancer DBs that handles the given wiki
+ * - cluster : wait on the given external load balancer DBs
+ * - timeout : Max wait time. Default: ~60 seconds
+ * - ifWritesSince: Only wait if writes were done since this UNIX timestamp
+ * @throws DBReplicationWaitError If a timeout or error occured waiting on a DB cluster
+ * @since 1.27
+ */
+ public function waitForReplication( array $opts = array() ) {
+ $opts += array(
+ 'wiki' => false,
+ 'cluster' => false,
+ 'timeout' => 60,
+ 'ifWritesSince' => null
+ );
+
+ // Figure out which clusters need to be checked
+ /** @var LoadBalancer[] $lbs */
+ $lbs = array();
+ if ( $opts['cluster'] !== false ) {
+ $lbs[] = $this->getExternalLB( $opts['cluster'] );
+ } elseif ( $opts['wiki'] !== false ) {
+ $lbs[] = $this->getMainLB( $opts['wiki'] );
+ } else {
+ $this->forEachLB( function ( LoadBalancer $lb ) use ( &$lbs ) {
+ $lbs[] = $lb;
+ } );
+ if ( !$lbs ) {
+ return; // nothing actually used
+ }
+ }
+
+ // Get all the master positions of applicable DBs right now.
+ // This can be faster since waiting on one cluster reduces the
+ // time needed to wait on the next clusters.
+ $masterPositions = array_fill( 0, count( $lbs ), false );
+ foreach ( $lbs as $i => $lb ) {
+ if ( $lb->getServerCount() <= 1 ) {
+ // Bug 27975 - Don't try to wait for slaves if there are none
+ // Prevents permission error when getting master position
+ continue;
+ } elseif ( $opts['ifWritesSince']
+ && $lb->lastMasterChangeTimestamp() < $opts['ifWritesSince']
+ ) {
+ continue; // no writes since the last wait
+ }
+ $masterPositions[$i] = $lb->getMasterPos();
+ }
+
+ $failed = array();
+ foreach ( $lbs as $i => $lb ) {
+ if ( $masterPositions[$i] ) {
+ // The DBMS may not support getMasterPos() or the whole
+ // load balancer might be fake (e.g. $wgAllDBsAreLocalhost).
+ if ( !$lb->waitForAll( $masterPositions[$i], $opts['timeout'] ) ) {
+ $failed[] = $lb->getServerName( $lb->getWriterIndex() );
+ }
+ }
+ }
+
+ if ( $failed ) {
+ throw new DBReplicationWaitError(
+ "Could not wait for slaves to catch up to " .
+ implode( ', ', $failed )
+ );
+ }
+ }
+
/**
* Disable the ChronologyProtector for all load balancers
*
"This is not allowed." );
}
}
+
+/**
+ * Exception class for replica DB wait timeouts
+ */
+class DBReplicationWaitError extends Exception {
+}
dépôts / lhc / web / wiklou.git / blobdiff