/** @var float Moving average ratio (e.g. 0.1 for 10% weight to new weight) */
private $movingAveRatio;
+ /** @var int Amount of replication lag in seconds before warnings are logged */
+ private $lagWarnThreshold;
- const VERSION = 1; // cache key version
+ /** @var int cache key version */
+ const VERSION = 1;
+ /** @var int Default 'max lag' in seconds when unspecified */
+ const LAG_WARN_THRESHOLD = 10;
+ /**
+ * @param ILoadBalancer $lb
+ * @param BagOStuff $srvCache
+ * @param WANObjectCache $wCache
+ * @param array $options
+ * - movingAveRatio: moving average constant for server weight updates based on lag
+ * - lagWarnThreshold: how many seconds of lag trigger warnings
+ */
public function __construct(
ILoadBalancer $lb, BagOStuff $srvCache, WANObjectCache $wCache, array $options = []
) {
$this->movingAveRatio = isset( $options['movingAveRatio'] )
? $options['movingAveRatio']
: 0.1;
+ $this->lagWarnThreshold = isset( $options['lagWarnThreshold'] )
+ ? $options['lagWarnThreshold']
+ : self::LAG_WARN_THRESHOLD;
}
public function setLogger( LoggerInterface $logger ) {
$this->replLogger = $logger;
}
- public function scaleLoads( array &$weightByServer, $domain ) {
+ final public function scaleLoads( array &$weightByServer, $domain ) {
$serverIndexes = array_keys( $weightByServer );
$states = $this->getServerStates( $serverIndexes, $domain );
- $coefficientsByServer = $states['weightScales'];
+ $newScalesByServer = $states['weightScales'];
foreach ( $weightByServer as $i => $weight ) {
- if ( isset( $coefficientsByServer[$i] ) ) {
- $weightByServer[$i] = $weight * $coefficientsByServer[$i];
+ if ( isset( $newScalesByServer[$i] ) ) {
+ $weightByServer[$i] = $weight * $newScalesByServer[$i];
} else { // server recently added to config?
$host = $this->parent->getServerName( $i );
$this->replLogger->error( __METHOD__ . ": host $host not in cache" );
}
}
- public function getLagTimes( array $serverIndexes, $domain ) {
- $states = $this->getServerStates( $serverIndexes, $domain );
-
- return $states['lagTimes'];
+ final public function getLagTimes( array $serverIndexes, $domain ) {
+ return $this->getServerStates( $serverIndexes, $domain )['lagTimes'];
}
protected function getServerStates( array $serverIndexes, $domain ) {
// Scale from 10% to 100% of nominal weight
$weightScales[$i] = max( $newWeight, 0.10 );
+ $host = $this->parent->getServerName( $i );
+
if ( !$conn ) {
$lagTimes[$i] = false;
- $host = $this->parent->getServerName( $i );
$this->replLogger->error(
__METHOD__ . ": host {db_server} is unreachable",
[ 'db_server' => $host ]
} else {
$lagTimes[$i] = $conn->getLag();
if ( $lagTimes[$i] === false ) {
- $host = $this->parent->getServerName( $i );
$this->replLogger->error(
__METHOD__ . ": host {db_server} is not replicating?",
[ 'db_server' => $host ]
);
+ } elseif ( $lagTimes[$i] > $this->lagWarnThreshold ) {
+ $this->replLogger->error(
+ "Server {host} has {lag} seconds of lag (>= {maxlag})",
+ [
+ 'host' => $host,
+ 'lag' => $lagTimes[$i],
+ 'maxlag' => $this->lagWarnThreshold
+ ]
+ );
}
}