cet-is » art

As part of ensuring thread-safe interactions with SQLite databases, a cet::sqlite::ConnectionFactory class has been developed. Although the ConnectionFactory class is not a singleton, a single instance of the class will need to be used in the context of services (e.g. MemoryTracker). To that end, a DatabaseConnection service should be developed so that SQLite database connections can be established via the pattern:

auto c = ServiceHandle<DatabaseConnection>{}->get(dbFilename);

The service is simple to write (and has been done so already), however it is not clear to me if it should be a "system" or an "optional" service. Also, the DatabaseConnection need not be configurable via FHiCL. Should it have an associated ParameterSet that is persisted to a file if (e.g.) MemoryTracker is configured?