[syslog-ng] Monitoring syslog-ng logserver

Greetings all, I have a question about monitoring syslog-ng itself. In the event that the log server stops listening or stops processing for messages for whatever reason is there a way to alert on hosts that messages are being queued/buffered? In a situation recently the log server syslog-ng process was running but not accepting log messages from remote hosts for some reason. As a result they all pilled up at the sources until the clients rolled over. It would be helpful to have an alert that it is happening but I can't find anything on monitoring the buffers. Thanks much, PM