logf(time.Now().Format(time.RFC3339Nano)+": "+format, args...)
	}
}

// markReused marks this connection as having been successfully used for a
// request and response.
func (pc *persistConn) markReused() {
	pc.mu.Lock()
	pc.reused = true
	pc.mu.Unlock()
}

// close closes the underlying TCP connection and closes