[Haskell] select(2) or poll(2)-like function?
johan.tibell at gmail.com
Mon Apr 18 15:14:46 CEST 2011
On Mon, Apr 18, 2011 at 2:25 PM, Mike Meyer <mwm at mired.org> wrote:
> Only if you also made the TCP/IP connection overhead trivial so you
> could stop with HTTP/1.0 and not deal with HTTP/1.1. Failing that, the
> most natural way to do this is:
> forever do
> accept the next connection
> handle requests from connection in new child
> wait for next events
> if one is a client request, start the response
> if one is a finished response, return it to the client
> if one is something else, something broke, deal with it.
> I.e, an event-driven loop for each incoming connection running in it's
> own process.
I'm not sure if I would call this "event driven", depending what's hiding
behind the sentences above. Here's how I've written servers that deal with
keep-alive, errors, etc.
server sock = forever $ do
clientSock <- accept sock
forkIO $ talk clientSock
talk sock = do
maybeReq <- read sock
case maybeReq of
Nothing -> ... -- error while reading/parsing. Close socket or send
400 Bad Request
Just req -> do
resp <- handler req
send sock resp
when (isKeepAlive req) $ talk sock
The above code is executed efficiently using epoll but the programming model
is one with blocking system calls.
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