Fastest way to check aliveness of connection

Hello,

I want to implement a c3p0 ConnectionTester and now need a fast way to
check for the alivelyness of a Connection. Currently I issue a "select
1" to the database and if I don't get an exception I assume the
connection is still alive.

Is there a faster way? How can I check if the underlying socket is still
alive without doing a JDBC request? This has to work only with
PostgreSQL JDBC, so I can cast to any postgres interface available.

With best regards,
Daniel Migowski