rdbms: tweak var names in LoadMonitor::scaleLoads()/getLagTimes()

[lhc/web/wiklou.git] / includes / libs / rdbms / loadmonitor / LoadMonitor.php

diff --git a/includes/libs/rdbms/loadmonitor/LoadMonitor.php b/includes/libs/rdbms/loadmonitor/LoadMonitor.php
index 8292c03..50c878d 100644 (file)
--- a/includes/libs/rdbms/loadmonitor/LoadMonitor.php
+++ b/includes/libs/rdbms/loadmonitor/LoadMonitor.php
@@ -45,9 +45,22 @@ class LoadMonitor implements ILoadMonitor {
 
        /** @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 = []
        ) {
@@ -59,19 +72,22 @@ class LoadMonitor implements ILoadMonitor {
                $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" );
@@ -79,10 +95,8 @@ class LoadMonitor implements ILoadMonitor {
                }
        }
 
-       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 ) {
@@ -159,9 +173,10 @@ class LoadMonitor implements ILoadMonitor {
                        // 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 ]
@@ -174,11 +189,19 @@ class LoadMonitor implements ILoadMonitor {
                        } 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
+                                               ]
+                                       );
                                }
                        }