Postgres CopyManager with c3p0 connection pool

  def writeBuffersToDb(files: Seq[File]) = {
    println(s"Writing buffers $files")
    def diff(ts: Long) = (System.currentTimeMillis() - ts) / 1000
    // parallel works suspiciously slow under windows,
    // however it is expected to be faster
    // http://dba.stackexchange.com/questions/20723/postgresql-two-concurrent-copy-from
    DB localTx { implicit session: DBSession =>
      // dropIndexes()
      files.foreach { case file =>
        val ts = System.currentTimeMillis()
        println(s"Processing $file")
        Using.using(new FileInputStream(file)) { stream ⇒
          val field = session.connection.getClass.getDeclaredField("this$0")
          field.setAccessible(true)
          val ds = field.get(session.connection).asInstanceOf[PoolingDataSource]
          ds.setAccessToUnderlyingConnectionAllowed(true)
          val conn = session.connection.asInstanceOf[DelegatingConnection].getInnermostDelegate
          val copyManager = new CopyManager(conn.asInstanceOf[BaseConnection])
          // val reader = new FileReader(file)
          //"COPY timeseriesentry(ts, val, componentgroup_id) FROM STDIN",
          copyManager.copyIn("COPY observation(ts, vl, parameter_id) FROM STDIN;", stream)
        }
        println(s"Done $file in ${diff(ts)} seconds")
      }
      println(s"Recreating index...")
      val ts = System.currentTimeMillis()
      // createIndexes()
      println(s"Done index in ${diff(ts)} seconds")
    }
  }