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REVISION SUMMARY QSqlDatabase connection instances are global reference counted objects which can be crated using the QSqlDatabase::addDatabase(...) method and later retrieved with QSqlDatabase::database(connectionname). Connections should only be used from a single thread, and should be cleaned up with QSD::removeDatabase(name), which implicitly closes the connection when the last reference is removed. Currently, the same connection (name) is reused over all threads, and the connection is only removed implicitly by replacing it via addDatabase(). This leads to warnings, i.e.: "QSqlDatabasePrivate::addDatabase: duplicate connection name '...', old connection removed." As one reference is held by the m_db member, the implicit removal triggers another warning: "QSqlDatabasePrivate::removeDatabase: connection '..." is still in use, all queries will cease to work." According to the documentation, "It is highly recommended that you do not keep a copy of the QSqlDatabase around as a member of a class, as this will prevent the instance from being correctly cleaned up on shutdown." There is no need to keep a reference using a member variable, as retrieving an open connection via QSqlDatabase::database(...) is cheap. Create a per-thread DB connection on first use, and remove the connections when the FetchSqlite instance is torn down. Delaying the open is beneficial for the favicon instance, which may be unused when the icon is already cached on disk. See also T9626 <https://phabricator.kde.org/T9626>. TEST PLAN execute a query in krunner 1. Results are as expected 2. The 'QSqlDatabasePrivate::removeDatabase: connection ... is still in use, all queries will cease to work.' warning no longer appears 3. The 'QSqlDatabasePrivate::addDatabase: duplicate connection name ..., old connection removed' warning no longer appears REPOSITORY R120 Plasma Workspace BRANCH master REVISION DETAIL https://phabricator.kde.org/D16409 AFFECTED FILES runners/bookmarks/fetchsqlite.cpp runners/bookmarks/fetchsqlite.h To: bruns, #frameworks Cc: plasma-devel, ragreen, Pitel, ZrenBot, lesliezhai, ali-mohamed, jensreuterberg, abetts, sebas, apol, mart
