*/
abstract protected function mysqlPing();
- /**
- * Returns slave lag.
- *
- * This will do a SHOW SLAVE STATUS
- *
- * @return int
- */
function getLag() {
- if ( $this->lagDetectionMethod === 'pt-heartbeat' ) {
+ if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
return $this->getLagFromPtHeartbeat();
} else {
return $this->getLagFromSlaveStatus();
}
}
+ /**
+ * @return string
+ */
+ protected function getLagDetectionMethod() {
+ return $this->lagDetectionMethod;
+ }
+
/**
* @return bool|int
*/
* @return bool|float
*/
protected function getLagFromPtHeartbeat() {
- $key = wfMemcKey( 'mysql', 'master-server-id', $this->getServer() );
- $masterId = intval( $this->srvCache->get( $key ) );
- if ( !$masterId ) {
- $res = $this->query( 'SHOW SLAVE STATUS', __METHOD__ );
- $row = $res ? $res->fetchObject() : false;
- if ( $row && strval( $row->Master_Server_Id ) !== '' ) {
- $masterId = intval( $row->Master_Server_Id );
- $this->srvCache->set( $key, $masterId, 30 );
- }
+ $masterInfo = $this->getMasterServerInfo();
+ if ( !$masterInfo ) {
+ wfLogDBError(
+ "Unable to query master of {db_server} for server ID",
+ $this->getLogContext( array(
+ 'method' => __METHOD__
+ ) )
+ );
+
+ return false; // could not get master server ID
}
- if ( !$masterId ) {
- return false;
+ list( $time, $nowUnix ) = $this->getHeartbeatData( $masterInfo['serverId'] );
+ if ( $time !== null ) {
+ // @time is in ISO format like "2015-09-25T16:48:10.000510"
+ $dateTime = new DateTime( $time, new DateTimeZone( 'UTC' ) );
+ $timeUnix = (int)$dateTime->format( 'U' ) + $dateTime->format( 'u' ) / 1e6;
+
+ return max( $nowUnix - $timeUnix, 0.0 );
}
+ wfLogDBError(
+ "Unable to find pt-heartbeat row for {db_server}",
+ $this->getLogContext( array(
+ 'method' => __METHOD__
+ ) )
+ );
+
+ return false;
+ }
+
+ protected function getMasterServerInfo() {
+ $cache = $this->srvCache;
+ $key = $cache->makeGlobalKey(
+ 'mysql',
+ 'master-info',
+ // Using one key for all cluster slaves is preferable
+ $this->getLBInfo( 'clusterMasterHost' ) ?: $this->getServer()
+ );
+
+ $that = $this;
+ return $cache->getWithSetCallback(
+ $key,
+ $cache::TTL_INDEFINITE,
+ function () use ( $that, $cache, $key ) {
+ // Get and leave a lock key in place for a short period
+ if ( !$cache->lock( $key, 0, 10 ) ) {
+ return false; // avoid master connection spike slams
+ }
+
+ $conn = $that->getLazyMasterHandle();
+ if ( !$conn ) {
+ return false; // something is misconfigured
+ }
+
+ // Connect to and query the master; catch errors to avoid outages
+ try {
+ $res = $conn->query( 'SELECT @@server_id AS id', __METHOD__ );
+ $row = $res ? $res->fetchObject() : false;
+ $id = $row ? (int)$row->id : 0;
+ } catch ( DBError $e ) {
+ $id = 0;
+ }
+
+ // Cache the ID if it was retrieved
+ return $id ? array( 'serverId' => $id, 'asOf' => time() ) : false;
+ }
+ );
+ }
+
+ /**
+ * @param string $masterId Server ID
+ * @return array (heartbeat `ts` column value or null, UNIX timestamp)
+ * @see https://www.percona.com/doc/percona-toolkit/2.1/pt-heartbeat.html
+ */
+ protected function getHeartbeatData( $masterId ) {
+ // Get the status row for this master; use the oldest for sanity in case the master
+ // has entries listed under different server IDs (which should really not happen).
+ // Note: this would use "MAX(TIMESTAMPDIFF(MICROSECOND,ts,UTC_TIMESTAMP(6)))" but the
+ // percision field is not supported in MySQL <= 5.5.
$res = $this->query(
- "SELECT TIMESTAMPDIFF(MICROSECOND,ts,UTC_TIMESTAMP(6)) AS Lag " .
- "FROM heartbeat.heartbeat WHERE server_id = $masterId"
+ "SELECT ts FROM heartbeat.heartbeat WHERE server_id=" . intval( $masterId )
);
$row = $res ? $res->fetchObject() : false;
- if ( $row ) {
- return max( floatval( $row->Lag ) / 1e6, 0.0 );
- }
- return false;
+ return array( $row ? $row->ts : null, microtime( true ) );
}
public function getApproximateLagStatus() {
- if ( $this->lagDetectionMethod === 'pt-heartbeat' ) {
+ if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
// Disable caching since this is fast enough and we don't wan't
// to be *too* pessimistic by having both the cache TTL and the
// pt-heartbeat interval count as lag in getSessionLagStatus()
return parent::getApproximateLagStatus();
}
- $key = wfGlobalCacheKey( 'mysql-lag', $this->getServer() );
+ $key = $this->srvCache->makeGlobalKey( 'mysql-lag', $this->getServer() );
$approxLag = $this->srvCache->get( $key );
if ( !$approxLag ) {
$approxLag = parent::getApproximateLagStatus();
$res = $this->doQuery( $sql );
$status = false;
- if ( $res && $row = $this->fetchRow( $res ) ) {
- $status = $row[0]; // can be NULL, -1, or 0+ per the MySQL manual
- if ( ctype_digit( $status ) ) { // success
- $this->lastKnownSlavePos = $pos;
+ if ( $res ) {
+ $row = $this->fetchRow( $res );
+ if ( $row ) {
+ $status = $row[0]; // can be NULL, -1, or 0+ per the MySQL manual
+ if ( ctype_digit( $status ) ) { // success
+ $this->lastKnownSlavePos = $pos;
+ }
}
}
* @since 1.20
*/
public function lockIsFree( $lockName, $method ) {
- $lockName = $this->addQuotes( $lockName );
+ $lockName = $this->addQuotes( $this->makeLockName( $lockName ) );
$result = $this->query( "SELECT IS_FREE_LOCK($lockName) AS lockstatus", $method );
$row = $this->fetchObject( $result );
* @return bool
*/
public function lock( $lockName, $method, $timeout = 5 ) {
- $lockName = $this->addQuotes( $lockName );
+ $lockName = $this->addQuotes( $this->makeLockName( $lockName ) );
$result = $this->query( "SELECT GET_LOCK($lockName, $timeout) AS lockstatus", $method );
$row = $this->fetchObject( $result );
* @return bool
*/
public function unlock( $lockName, $method ) {
- $lockName = $this->addQuotes( $lockName );
+ $lockName = $this->addQuotes( $this->makeLockName( $lockName ) );
$result = $this->query( "SELECT RELEASE_LOCK($lockName) as lockstatus", $method );
$row = $this->fetchObject( $result );
return ( $row->lockstatus == 1 );
}
+ private function makeLockName( $lockName ) {
+ // http://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
+ // Newer version enforce a 64 char length limit.
+ return ( strlen( $lockName ) > 64 ) ? sha1( $lockName ) : $lockName;
+ }
+
public function namedLocksEnqueue() {
return true;
}
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