public Interface UnifiedConnectionTester

Having expanded the once-simple ConnectionTester interface to support both user-specified queries and return of root cause Exceptions (via an out-param), this interface has grown unnecessarily complex.

If you wish to implement a custom Connection tester, here is the simple way to do it

1. Extend com.mchange.v2.c3p0.AbstractConnectionTester
2. Override only the two abstract methods
   • public int activeCheckConnection(Connection c, String preferredTestQuery, Throwable[] rootCauseOutParamHolder)
   • public int statusOnException(Connection c, Throwable t, String preferredTestQuery, Throwable[] rootCauseOutParamHolder)
3. Take care to ensure that your methods are defined to allow preferredTestQuery and rootCauseOutParamHolder to be null.

Parameter rootCauseOutParamHolder is an optional parameter, which if supplied, will be a Throwable array whose size it at least one. If a Connection test fails because of some Exception, the Connection tester may set this Exception as the zero-th element of the array to provide information about why and how the test failed.