Issue with transaction handling

[davydkov]

I faced with the problem that when transaction is failed the connection becomes absolutely useless and further requests lead to exceptions.

After looking at the documentation of postgrsql-async@mauricio I realized that scalikejdbc-async handles transaction in its own way, while driver already provides such functionality.
Also @mauricio recommends:

You should not reuse a database connection that has rolled back a transaction, just close it and create a new connection to continue using it.

So I suggest:

• use transaction's handling via driver
• remove code related to the old version of driver

Well, at least these changes work for me and my project

[mauricio]

👍 that.

Documentation for the network protocol for both databases say that reusing connections that failed for any reason or were rolled back is not advisable.

[seratch]

Thanks.

I just tried your change but some unit tests with PostgreSQL occasionally fail. My work around code in AsyncDBSession.scala seems to be still needed.

Changes on AsyncDB.scala look reasonable. If you don't mind, please revert changes on AsyncDBSession.scala.

[davydkov]

@seratch I reverted changes of AsyncDBSession