Use HTTP method as hint for the locking mode of sqlite

Bug: T93097
Change-Id: I4aa44345e2f9e252c1a351f252bdcb9e15f180a5

diff --git a/includes/db/MWLBFactory.php b/includes/db/MWLBFactory.php
index 416993c..bbb3d2f 100644 (file)
--- a/includes/db/MWLBFactory.php
+++ b/includes/db/MWLBFactory.php
@@ -82,13 +82,22 @@ abstract class MWLBFactory {
                // for Database classes in the relevant Installer subclass.
                // Such as MysqlInstaller::openConnection and PostgresInstaller::openConnectionWithParams.
                if ( $lbConf['class'] === Wikimedia\Rdbms\LBFactorySimple::class ) {
+                       $httpMethod = $_SERVER['REQUEST_METHOD'] ?? null;
+                       // T93097: hint for how file-based databases (e.g. sqlite) should go about locking.
+                       // See https://www.sqlite.org/lang_transaction.html
+                       // See https://www.sqlite.org/lockingv3.html#shared_lock
+                       $isReadRequest = in_array( $httpMethod, [ 'GET', 'HEAD', 'OPTIONS', 'TRACE' ] );
+
                        if ( isset( $lbConf['servers'] ) ) {
                                // Server array is already explicitly configured; leave alone
                        } elseif ( is_array( $mainConfig->get( 'DBservers' ) ) ) {
                                $lbConf['servers'] = [];
                                foreach ( $mainConfig->get( 'DBservers' ) as $i => $server ) {
                                        if ( $server['type'] === 'sqlite' ) {
-                                               $server += [ 'dbDirectory' => $mainConfig->get( 'SQLiteDataDir' ) ];
+                                               $server += [
+                                                       'dbDirectory' => $mainConfig->get( 'SQLiteDataDir' ),
+                                                       'trxMode' => $isReadRequest ? 'DEFERRED' : 'IMMEDIATE'
+                                               ];
                                        } elseif ( $server['type'] === 'postgres' ) {
                                                $server += [
                                                        'port' => $mainConfig->get( 'DBport' ),
@@ -129,6 +138,7 @@ abstract class MWLBFactory {
                                        'load' => 1,
                                        'flags' => $flags,
                                        'sqlMode' => $mainConfig->get( 'SQLMode' ),
+                                       'trxMode' => $isReadRequest ? 'DEFERRED' : 'IMMEDIATE'
                                ];
                                if ( in_array( $server['type'], $typesWithSchema, true ) ) {
                                        $server += [ 'schema' => $mainConfig->get( 'DBmwschema' ) ];