rdbms: make schema/prefix handling more consistent in LoadBalancer

Move "tablePrefix" logic to LoadBalancer::reallyOpenConnection and
make it more consistent for local vs foreign connections. The prefix
for local connections is now set even if $domain does not provide a
database.

Also set the schema even if $domain does not provide a database.

Typically a database domain is either fully specified or comes from
DatabaseDomain::newUnspecified(), but there's no reason not to use
at least the schema/prefix of otherwise unspecified domains. The only
other sensible option would be some sort of exception.

Change-Id: Ib52f4b69e429810e3c5eac92a48aecf7b22e86e6

diff --git a/includes/libs/rdbms/loadbalancer/LoadBalancer.php b/includes/libs/rdbms/loadbalancer/LoadBalancer.php
index fbc3be9..00b4130 100644 (file)
--- a/includes/libs/rdbms/loadbalancer/LoadBalancer.php
+++ b/includes/libs/rdbms/loadbalancer/LoadBalancer.php
@@ -938,10 +938,6 @@ class LoadBalancer implements ILoadBalancer {
                        $server = $this->servers[$i];
                        $server['serverIndex'] = $i;
                        $server['autoCommitOnly'] = $autoCommit;
-                       if ( $this->localDomain->getDatabase() !== null ) {
-                               // Use the local domain table prefix if the local domain is specified
-                               $server['tablePrefix'] = $this->localDomain->getTablePrefix();
-                       }
                        $conn = $this->reallyOpenConnection( $server, $this->localDomain );
                        $host = $this->getServerName( $i );
                        if ( $conn->isOpen() ) {
@@ -1037,7 +1033,6 @@ class LoadBalancer implements ILoadBalancer {
                                $this->errorConnection = $conn;
                                $conn = false;
                        } else {
-                               $conn->tablePrefix( $prefix ); // as specified
                                // Note that if $domain is an empty string, getDomainID() might not match it
                                $this->conns[$connInUseKey][$i][$conn->getDomainID()] = $conn;
                                $this->connLogger->debug( __METHOD__ . ": opened new connection for $i/$domain" );
@@ -1081,20 +1076,20 @@ class LoadBalancer implements ILoadBalancer {
         * Returns a Database object whether or not the connection was successful.
         *
         * @param array $server
-        * @param DatabaseDomain $domainOverride Use an unspecified domain to not select any database
+        * @param DatabaseDomain $domain Domain the connection is for, possibly unspecified
         * @return Database
         * @throws DBAccessError
         * @throws InvalidArgumentException
         */
-       protected function reallyOpenConnection( array $server, DatabaseDomain $domainOverride ) {
+       protected function reallyOpenConnection( array $server, DatabaseDomain $domain ) {
                if ( $this->disabled ) {
                        throw new DBAccessError();
                }
 
-               // Handle $domainOverride being a specified or an unspecified domain
-               if ( $domainOverride->getDatabase() === null ) {
-                       // Normally, an RDBMS requires a DB name specified on connection and the $server
-                       // configuration array is assumed to already specify an appropriate DB name.
+               if ( $domain->getDatabase() === null ) {
+                       // The database domain does not specify a DB name and some database systems require a
+                       // valid DB specified on connection. The $server configuration array contains a default
+                       // DB name to use for connections in such cases.
                        if ( $server['type'] === 'mysql' ) {
                                // For MySQL, DATABASE and SCHEMA are synonyms, connections need not specify a DB,
                                // and the DB name in $server might not exist due to legacy reasons (the default
@@ -1102,10 +1097,16 @@ class LoadBalancer implements ILoadBalancer {
                                $server['dbname'] = null;
                        }
                } else {
-                       $server['dbname'] = $domainOverride->getDatabase();
-                       $server['schema'] = $domainOverride->getSchema();
+                       $server['dbname'] = $domain->getDatabase();
+               }
+
+               if ( $domain->getSchema() !== null ) {
+                       $server['schema'] = $domain->getSchema();
                }
 
+               // It is always possible to connect with any prefix, even the empty string
+               $server['tablePrefix'] = $domain->getTablePrefix();
+
                // Let the handle know what the cluster master is (e.g. "db1052")
                $masterName = $this->getServerName( $this->getWriterIndex() );
                $server['clusterMasterHost'] = $masterName;