Merge "Migrate remaining usages of Title::userCan() to PermissionManager"

[lhc/web/wiklou.git] / includes / libs / rdbms / loadbalancer / LoadBalancer.php

diff --git a/includes/libs/rdbms/loadbalancer/LoadBalancer.php b/includes/libs/rdbms/loadbalancer/LoadBalancer.php
index 3fd0189..ffb7a34 100644 (file)
--- a/includes/libs/rdbms/loadbalancer/LoadBalancer.php
+++ b/includes/libs/rdbms/loadbalancer/LoadBalancer.php
@@ -105,6 +105,8 @@ class LoadBalancer implements ILoadBalancer {
        private $errorConnection;
        /** @var int The generic (not query grouped) replica DB index */
        private $genericReadIndex = -1;
+       /** @var int[] The group replica DB indexes keyed by group */
+       private $readIndexByGroup = [];
        /** @var bool|DBMasterPos False if not set */
        private $waitForPos;
        /** @var bool Whether the generic reader fell back to a lagged replica DB */
@@ -398,9 +400,12 @@ class LoadBalancer implements ILoadBalancer {
                if ( count( $this->servers ) == 1 ) {
                        // Skip the load balancing if there's only one server
                        return $this->getWriterIndex();
-               } elseif ( $group === false && $this->genericReadIndex >= 0 ) {
-                       // A generic reader index was already selected and "waitForPos" was handled
-                       return $this->genericReadIndex;
+               }
+
+               $index = $this->getExistingReaderIndex( $group );
+               if ( $index >= 0 ) {
+                       // A reader index was already selected and "waitForPos" was handled
+                       return $index;
                }
 
                if ( $group !== false ) {
@@ -435,11 +440,11 @@ class LoadBalancer implements ILoadBalancer {
                        $laggedReplicaMode = true;
                }
 
-               if ( $this->genericReadIndex < 0 && $this->genericLoads[$i] > 0 && $group === false ) {
-                       // Cache the generic (ungrouped) reader index for future DB_REPLICA handles
-                       $this->genericReadIndex = $i;
-                       // Record if the generic reader index is in "lagged replica DB" mode
-                       $this->laggedReplicaMode = ( $laggedReplicaMode || $this->laggedReplicaMode );
+               // Cache the reader index for future DB_REPLICA handles
+               $this->setExistingReaderIndex( $group, $i );
+               // Record whether the generic reader index is in "lagged replica DB" mode
+               if ( $group === false && $laggedReplicaMode ) {
+                       $this->laggedReplicaMode = true;
                }
 
                $serverName = $this->getServerName( $i );
@@ -448,6 +453,40 @@ class LoadBalancer implements ILoadBalancer {
                return $i;
        }
 
+       /**
+        * Get the server index chosen by the load balancer for use with the given query group
+        *
+        * @param string|bool $group Query group; use false for the generic group
+        * @return int Server index or -1 if none was chosen
+        */
+       protected function getExistingReaderIndex( $group ) {
+               if ( $group === false ) {
+                       $index = $this->genericReadIndex;
+               } else {
+                       $index = $this->readIndexByGroup[$group] ?? -1;
+               }
+
+               return $index;
+       }
+
+       /**
+        * Set the server index chosen by the load balancer for use with the given query group
+        *
+        * @param string|bool $group Query group; use false for the generic group
+        * @param int $index The index of a specific server
+        */
+       private function setExistingReaderIndex( $group, $index ) {
+               if ( $index < 0 ) {
+                       throw new UnexpectedValueException( "Cannot set a negative read server index" );
+               }
+
+               if ( $group === false ) {
+                       $this->genericReadIndex = $index;
+               } else {
+                       $this->readIndexByGroup[$group] = $index;
+               }
+       }
+
        /**
         * @param array $loads List of server weights
         * @param string|bool $domain