On Sun, Feb 14, 2010 at 2:04 PM, Bardur Arantsson <s...@scientician.net>wrote:
> > I've tested this extensively during this weekend and not a single "leaked" > FD so far. > > I think we can safely say that polling an FD for read readiness is > sufficient to properly detect a disconnected client regardless of why/how > the client disconnected. > > The only issue I can see with just dropping the above code directly into > the sendfile library is that it may lead to busy-waiting on EAGAIN *if* the > client is actually trying to send data to the server while it's receiving > the file via sendfile(). If the client sends even a single byte and the > server isn't reading it from the socket, then threadWaitRead will keep > returning immediately since it's level-triggered rather than edge triggered. > Yeah. That could be trouble. > Not sure what the best solution for this would be, API-wise... Maybe > actually have sendfile read the data and supply it to a user-defined > function which could react to the data in some way? (Could supply two > standard functions: "disconnect immediately" and "accumulate all received > data into a bytestring".) > > I think this goes beyond just a sendfile issue -- anyone trying to write non-blocking network code should run into this issue, right ? For now, maybe we should patch sendfile with what we have. But I think we really need to summarize our findings, see if we can generate a test case, and then see what Simon Marlow and company have to say... - jeremy
_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
