H2 connection manager for Lift app

H2 DBVendor

H2 has it's own connection pool manager that H2 claims [1] is faster than using
DriverManager.getConnection(). Here's how to configure it for use in a Lift app.

/**
* H2 db connection manager
*/
object H2DBVendor extends ConnectionManager {

  // create the connection pool
  private val cp = org.h2.jdbcx.JdbcConnectionPool.create(
    Props.get("db.url") openOr "jdbc:h2:data/test",
    Props.get("db.user") openOr "",
    Props.get("db.password") openOr ""
  )

  // set max connections
  cp.setMaxConnections(10) // default = 10

  // set max time to wait for an available connection
  cp.setLoginTimeout(60) // default = 60 seconds

  // get a new connection
  def newConnection(name: ConnectionIdentifier): Box[Connection] = {
    try {
      Full(cp.getConnection)
    }
    catch {
      case e: Exception => e.printStackTrace; Empty
    }
  }

  def releaseConnection(conn: Connection) {
    conn.close // this puts the connection back into the pool
  }

  def shutdown() {
    cp.dispose // dispose of the connection pool
  }
}

Then in Boot.boot, add:

DB.defineConnectionManager(DefaultConnectionIdentifier, H2DBVendor)
LiftRules.unloadHooks.append(H2DBVendor.shutdown) // optional

The last line will close the connection pool when the servlet context is 
destroyed. Helpful if you need the db shutdown when the JVM is still running.

[1] http://h2database.com/html/tutorial.html#connection_pool