
On Fri, Apr 29, 2011 at 12:00 AM, Don Stewart
I'm very interested in what the best way to get incremental event data from a running GHC process would be.
Looking at the code, we flush the event buffer fairly regularly, but the event parser is currently strict.
So we'd need a lazy (or incremental) parser, that'll return a list of successful event parses, then block. I suspect this mode would be supported.
*My evil plan is to write a little monitoring web app that just attaches to the event stream and renders it in a useful "heartbeat" format* , but I need incremental parsing.
A less general solution might be to have the program itself start a little web server on some port and use the API I proposed to serve JSON data with the aggregate statistics you care about. Example: main = do eventData <- newIORef server <- serveOn 8080 $ \ _req -> readIORef eventData >>= sendResponse eventData registerEventListener $ \ ev -> updateEventData eventData ev runNormalProgram You can wrap the creation of the webserver in a little helper function an make any program "monitorable" simply by doing main = withMonitoring runApp withMonitoring would take care of starting/stopping the webserver and processing events. Just a thought. Johan