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September 2, 2021 00:56
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Haskell livestream - Subprocess management
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{-# LANGUAGE ApplicativeDo #-} | |
{-# LANGUAGE OverloadedStrings #-} | |
module Main where | |
import Control.Concurrent.Async (Concurrently(..)) | |
import Data.Foldable (traverse_) | |
import Data.List.NonEmpty (NonEmpty(..)) | |
import Data.Text (Text) | |
import Foreign.C | |
import GHC.IO.Exception (IOErrorType(..), IOException(..)) | |
import System.Process (CreateProcess(..), StdStream(..)) | |
import System.IO (Handle) | |
import qualified Control.Concurrent.Async as Async | |
import qualified Control.Exception as Exception | |
import qualified Control.Monad as Monad | |
import qualified Data.List.NonEmpty as NonEmpty | |
import qualified Data.Text as Text | |
import qualified Data.Text.IO as Text.IO | |
import qualified System.Environment as Environment | |
import qualified System.Exit as Exit | |
import qualified System.IO as IO | |
import qualified System.Process as Process | |
display :: Text -> Handle -> Text -> IO () | |
display prefix handle string = do | |
Text.IO.hPutStrLn handle (prefix <> " " <> string) | |
displayLines :: Text -> Handle -> Text -> IO () | |
displayLines prefix handle string = do | |
traverse_ (display prefix handle) (Text.lines string) | |
ignoreSigPipe :: IO () -> IO () | |
ignoreSigPipe = Exception.handle handler | |
where | |
handler IOError{ ioe_type = ResourceVanished, ioe_errno = Just ioe } | |
| Errno ioe == ePIPE = return () | |
handler exception = Exception.throwIO exception | |
main :: IO () | |
main = do -- ignoreSigPipe $ do | |
args <- Environment.getArgs | |
case args of | |
[] -> mempty | |
command : arguments -> do | |
let process = (Process.proc command arguments) | |
{ std_out = CreatePipe | |
, std_err = CreatePipe | |
} | |
Process.withCreateProcess process | |
$ \_ (Just subStdout) (Just subStderr) processHandle -> do | |
let process prefix inHandle outHandle = loop "" | |
where | |
loop remainder = do | |
let p = display prefix outHandle | |
chunk <- Text.IO.hGetChunk inHandle | |
if Text.null chunk then | |
Monad.when (not (Text.null remainder)) $ do | |
p remainder | |
else do | |
case Text.lines (remainder <> chunk) of | |
[] -> loop "" | |
l : ls -> do | |
let n :: NonEmpty Text | |
n = l :| ls | |
traverse_ p (NonEmpty.init n) | |
loop (NonEmpty.last n) | |
let thread0 = process "[+]" subStdout IO.stdout | |
let thread1 = process "[!]" subStderr IO.stderr | |
let thread2 = do | |
exitCode <- Process.waitForProcess processHandle | |
Exit.exitWith exitCode | |
runConcurrently $ do | |
_ <- Concurrently thread0 | |
_ <- Concurrently thread1 | |
exitCode <- Concurrently thread2 | |
return exitCode |
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