rdbms: make connection counting logic in LoadBalancer less stateful

Change-Id: I8428897fa5b6d09e5e3fb84b1adc6e55354eb44c

diff --git a/includes/libs/rdbms/loadbalancer/LoadBalancer.php b/includes/libs/rdbms/loadbalancer/LoadBalancer.php
index 6617ab1..7f12d14 100644 (file)
--- a/includes/libs/rdbms/loadbalancer/LoadBalancer.php
+++ b/includes/libs/rdbms/loadbalancer/LoadBalancer.php
@@ -117,8 +117,8 @@ class LoadBalancer implements ILoadBalancer {
        private $lastError = 'Unknown error';
        /** @var string|bool Reason the LB is read-only or false if not */
        private $readOnlyReason = false;
-       /** @var int Total connections opened */
-       private $connsOpened = 0;
+       /** @var int Total number of new connections ever made with this instance */
+       private $connectionCounter = 0;
        /** @var bool */
        private $disabled = false;
        /** @var bool Whether any connection has been attempted yet */
@@ -199,7 +199,7 @@ class LoadBalancer implements ILoadBalancer {
 
                $this->waitTimeout = $params['waitTimeout'] ?? self::MAX_WAIT_DEFAULT;
 
-               $this->conns = self::newConnsArray();
+               $this->conns = self::newTrackedConnectionsArray();
                $this->waitForPos = false;
                $this->allowLagged = false;
 
@@ -248,7 +248,7 @@ class LoadBalancer implements ILoadBalancer {
                $this->ownerId = $params['ownerId'] ?? null;
        }
 
-       private static function newConnsArray() {
+       private static function newTrackedConnectionsArray() {
                return [
                        // Connection were transaction rounds may be applied
                        self::KEY_LOCAL => [],
@@ -834,8 +834,7 @@ class LoadBalancer implements ILoadBalancer {
                $masterOnly = ( $i === self::DB_MASTER || $i === $this->getWriterIndex() );
 
                // Number of connections made before getting the server index and handle
-               $priorConnectionsMade = $this->connsOpened;
-
+               $priorConnectionsMade = $this->connectionCounter;
                // Choose a server if $i is DB_MASTER/DB_REPLICA (might trigger new connections)
                $serverIndex = $this->getConnectionIndex( $i, $groups, $domain );
                // Get an open connection to that server (might trigger a new connection)
@@ -852,7 +851,7 @@ class LoadBalancer implements ILoadBalancer {
                }
 
                // Profile any new connections caused by this method
-               if ( $this->connsOpened > $priorConnectionsMade ) {
+               if ( $this->connectionCounter > $priorConnectionsMade ) {
                        $host = $conn->getServer();
                        $dbname = $conn->getDBname();
                        $this->trxProfiler->recordConnection( $host, $dbname, $masterOnly );
@@ -1207,12 +1206,6 @@ class LoadBalancer implements ILoadBalancer {
                $masterName = $this->getServerName( $this->getWriterIndex() );
                $server['clusterMasterHost'] = $masterName;
 
-               // Log when many connection are made on requests
-               if ( ++$this->connsOpened >= self::CONN_HELD_WARN_THRESHOLD ) {
-                       $this->perfLogger->warning( __METHOD__ . ": " .
-                               "{$this->connsOpened}+ connections made (master=$masterName)" );
-               }
-
                $server['srvCache'] = $this->srvCache;
                // Set loggers and profilers
                $server['connLogger'] = $this->connLogger;
@@ -1231,6 +1224,15 @@ class LoadBalancer implements ILoadBalancer {
                // Create a live connection object
                try {
                        $db = Database::factory( $server['type'], $server );
+                       // Log when many connection are made on requests
+                       ++$this->connectionCounter;
+                       $currentConnCount = $this->getCurrentConnectionCount();
+                       if ( $currentConnCount >= self::CONN_HELD_WARN_THRESHOLD ) {
+                               $this->perfLogger->warning(
+                                       __METHOD__ . ": {connections}+ connections made (master={masterdb})",
+                                       [ 'connections' => $currentConnCount, 'masterdb' => $masterName ]
+                               );
+                       }
                } catch ( DBConnectionError $e ) {
                        // FIXME: This is probably the ugliest thing I have ever done to
                        // PHP. I'm half-expecting it to segfault, just out of disgust. -- TS
@@ -1377,8 +1379,7 @@ class LoadBalancer implements ILoadBalancer {
                        $conn->close();
                } );
 
-               $this->conns = self::newConnsArray();
-               $this->connsOpened = 0;
+               $this->conns = self::newTrackedConnectionsArray();
        }
 
        public function closeConnection( IDatabase $conn ) {
@@ -1399,7 +1400,6 @@ class LoadBalancer implements ILoadBalancer {
                                        $this->connLogger->debug(
                                                __METHOD__ . ": closing connection to database $i at '$host'." );
                                        unset( $this->conns[$type][$serverIndex][$i] );
-                                       --$this->connsOpened;
                                        break 2;
                                }
                        }
@@ -1926,6 +1926,20 @@ class LoadBalancer implements ILoadBalancer {
                }
        }
 
+       /**
+        * @return int
+        */
+       private function getCurrentConnectionCount() {
+               $count = 0;
+               foreach ( $this->conns as $connsByServer ) {
+                       foreach ( $connsByServer as $serverConns ) {
+                               $count += count( $serverConns );
+                       }
+               }
+
+               return $count;
+       }
+
        public function getMaxLag( $domain = false ) {
                $host = '';
                $maxLag = -1;