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k0001 / network-simple

Haskell library abstracting common network sockets usage patterns.
BSD 3-Clause "New" or "Revised" License
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Server does not output to console. #24

Closed PiotrJustyna closed 8 years ago

PiotrJustyna commented 8 years ago

First of all, thank you for putting the library together - super useful!

I've been playing with the server code for a while now and for some reason, it doesn't always print to the console when I would expect it to. Sample code:

module Main where

import Network.Simple.TCP

main :: IO ()
main = serve (Host "127.0.0.1") "4242" $ \(connectionSocket, remoteAddr) -> do
  putStrLn $ "TCP connection established from " ++ show remoteAddr

The server is running just fine, I can connect both from telnet and from a client written in Network.Simple.TCP. Same happens with the examples, e.g. https://github.com/k0001/network-simple/blob/master/examples/echo-tcp.hs. Am I missing something?

Environment: Windows 10, Stack

k0001 commented 8 years ago

Piotr,

I suspect the issue you are having is not related to network-simple, but to how stdout buffering is configured for your application. See https://hackage.haskell.org/package/base-4.9.0.0/docs/System-IO.html#g:12

Try enabling line buffering explicitly and see if that improves things.

On Sep 11, 2016 2:24 PM, "Piotr Justyna" notifications@github.com wrote:

First of all, thank you for putting the library together - super useful!

I've been playing with the server code for a while now and for some reason, it doesn't always print to the console when I would expect it to. Sample code:

module Main where import Network.Simple.TCP main :: IO () main = serve (Host "127.0.0.1") "4242" $ (connectionSocket, remoteAddr) -> do putStrLn $ "TCP connection established from " ++ show remoteAddr

The server is running just fine, I can connect both from telnet and from a client written in Network.Simple.TCP. Same happens with the examples, e.g. https://github.com/k0001/network-simple/blob/master/ examples/echo-tcp.hs. Am I missing something?

Environment: Windows 10, Stack

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PiotrJustyna commented 8 years ago

Thanks. Let me try that and I'll update the issue with me findings.

PiotrJustyna commented 8 years ago

Thank you, that was it :smile:

If anybody else gets stuck on this issue, here's a sample piece of code checking and then setting the desired buffering type:

module Main where

import Network.Simple.TCP
import System.IO

main :: IO ()
main = do
  bufferingModeBefore <- hGetBuffering stdout
  putStrLn $ "Current buffering mode: " ++ (show bufferingModeBefore)
  hSetBuffering stdout NoBuffering
  bufferingModeAfter <- hGetBuffering stdout
  putStrLn $ "Current buffering mode: " ++ (show bufferingModeAfter)
  serve (Host "127.0.0.1") "4242" $ \(connectionSocket, remoteAddr) -> do
    putStrLn $ "TCP connection established from " ++ show remoteAddr

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