Exceptions in recursive functions Haskell
Question
I have the following code for a simple web server in Haskell.
module Main where
import Control.Exception
import Control.Monad
import qualified Data.ByteString as B
import qualified Data.ByteString.Char8
import Data.Char
import Network.Socket
import Network.Socket.ByteString (recv, sendAll)
import System.Mem (performGC)
packStr = B.pack . map (fromIntegral . ord)
msg :: String
msg =
"HTTP/1.1 200 OK\n"
++ "Content-Type: text/html\n\n"
++ "<html><body><a href=#>download</a></body></html>\n"
manageConnections sock =
forever
( do
(conn, addr) <- accept sock
putStrLn $ "Connection from" ++ show addr ++ "\n"
r <- recv conn 1024
B.putStr r
sendAll conn $ packStr msg
seq id close conn -- for force close the socket the socket
)
main :: IO ()
main = do
putStrLn "Starting"
sock <- socket AF_INET Stream 0
setSocketOption sock ReuseAddr 1
bind sock (SockAddrInet 1337 $ tupleToHostAddress (127, 0, 0, 1))
listen sock 4
manageConnections sock
As you can see the function manageConnections is where the main thread spends most of the time. My question is how do I handle user interrupts in the manageConnections function ?. What I mean is, if I press Ctrl-C the program would not close the "conn" socket and it would exit. I want to catch the user interrupt and close the socket properly.
1 answers
solution1
1 2022-07-09 13:49:19
if I press Ctrl-C the program would not close the "conn" socket
All file descriptors (including sockets) are closed by the OS when the program finishes its execution.
I want to catch the user interrupt
You might want to try System.Posix.Signals.installHandler .
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