[mssql] Don't share connections between threads

Starting with Qt 5.11, sharing the same connection between threads is not allowed. Use a dedicated connection for each thread requiring access to the database, using the thread address as connection name. https://bugreports.qt.io/browse/QTBUG-68486 indicates that this change is by design and that sharing connections between threads was always unsafe. Fixes broken mssql provider on Qt 5.11, and possibly who know what issues on earlier Qt. Ported from mumble-voip/mumble@a3814e33
qgis · Oct 2, 2018 · 3b8a2d9 · 3b8a2d9
1 parent 57f77d0
commit 3b8a2d9
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/src/providers/mssql/qgsmssqlprovider.cpp b/src/providers/mssql/qgsmssqlprovider.cpp
@@ -233,6 +233,12 @@ QSqlDatabase QgsMssqlProvider::GetDatabase( const QString &service, const QStrin
   else
     connectionName = service;
 
+  // Starting with Qt 5.11, sharing the same connection between threads is not allowed.
+  // We use a dedicated connection for each thread requiring access to the database,
+  // using the thread address as connection name.
+  const QString threadAddress = QStringLiteral( ":0x%1" ).arg( reinterpret_cast< quintptr >( QThread::currentThreadId() ), 16 );
+  connectionName += threadAddress;
+
   if ( !QSqlDatabase::contains( connectionName ) )
   {
     db = QSqlDatabase::addDatabase( QStringLiteral( "QODBC" ), connectionName );