The PG::Connection#transaction helper should be provided for em-synchrony version.
The pure EventMachine version can not support the way in which transaction method works. There is no easy controllable point of failure and success in the callback event system.
Any news on this ? Transaction support would be great for using with @fl00r's em-pg-sequel gem.
Currently in progress. Before the 0.3 release, you might want to check pg_compliant_synchrony branch. It contains some api changes along with transaction support and dedicated connection pool.
It's ready but due to the autoreconnect bug since pg >= 0.15.0 need to postpone it until it's resolved.
Sequel DB.transaction are now supported in em-pg-sequel. It has nothing to do with the helper in this topic.