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import Control.Concurrent
import Control.Monad
import Foreign.C
import GHC.Clock
import GHC.IO.Device
import GHC.IO.Handle.FD
import System.IO
import System.Posix.IO
import System.Posix.Types
import System.Timeout
main :: IO ()
main = do
socketHandle <- makeTestSocketHandle
let nanoSecondsPerSecond = 1000 * 1000 * 1000
let milliSecondsPerSecond = 1000
let timeToSpend = 1
let timeToSpendNano = timeToSpend * nanoSecondsPerSecond
let timeToSpendMilli = timeToSpend * milliSecondsPerSecond
start <- getMonotonicTimeNSec
b <- hWaitForInput socketHandle timeToSpendMilli
end <- getMonotonicTimeNSec
let timeSpentNano = fromIntegral $ end - start
let delta = timeSpentNano - timeToSpendNano
-- We can never wait for a shorter amount of time than specified
putStrLn $ "delta >= 0: " ++ show (delta >= 0)
foreign import ccall unsafe "socket" c_socket ::
CInt -> CInt -> CInt -> IO CInt
makeTestSocketHandle :: IO Handle
makeTestSocketHandle = do
sockNum <-
c_socket
1 -- PF_LOCAL
2 -- SOCK_DGRAM
0
let fd = fromIntegral sockNum :: Fd
h <-
fdToHandle'
(fromIntegral fd)
(Just GHC.IO.Device.Stream)
True
"testsocket"
ReadMode
True
hSetBuffering h NoBuffering
pure h
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