@Override
    public void heartbeat() throws IOException {
        isOpen();
        int ret = WDT.ping(fd);
        if(ret<0) {
            throw new IOException("Heartbeat error. File " + filename + " got " + ret + " back.");
        }
    }
@ Override public void heartbeat ( ) throws IOException { isOpen ( ) ; int ret = WDT . ping ( fd ) ; if ( ret < 0 ) { throw new IOException ( "Heartbeat error. File " + filename + " got " + ret + " back." ) ; } }
Ping a watchdog.

@throws IOException