Synchronous Replication Timeout

Hi,

I have a replication setup with a master and a single synchronous slave. If the slave dies (or the network goes down) I would like any transaction on the master that requires writing to fail so I can roll it back. At the moment, when I commit it just hangs forever or (if I cancel it using ^C in psql or using kill) it commits locally and not on the synchronous slave. Neither of these options are ok in my use case. I have tried setting statement_timeout but it does not work. So my questions are:

1) Is it possible to rollback transactions that fail to commit after a certain amount of time waiting for the slave?

2) If not, is there any intension of implementing such a feature in the near future?

3) Do any of the answers above change if we are dealing with two-phase commits instead? At the moment it hangs forever on 'prepare transaction', 'commit prepared' and 'rollback prepared' commands.

Thanks,

Tessa