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|
{-# LANGUAGE TypeApplications #-}
module Network.HTTP.Server.Mini (
run,
module Network.HTTP.Server.Mini.Types,
) where
import Control.Concurrent
import Control.Concurrent.STM
import Control.Exception
import Control.Monad
import Data.List.NonEmpty qualified as NE
import Network.Socket
import Network.Socket.ByteString
import Network.HTTP.Server.Mini.Parser
import Network.HTTP.Server.Mini.Printer
import Network.HTTP.Server.Mini.Types
-- | The request handler will run in a forkIO thread.
run :: Settings -> (Request -> IO Response) -> IO ()
run settings handler = do
let hints = defaultHints { addrFlags = [AI_NUMERICHOST, AI_NUMERICSERV, AI_PASSIVE]
, addrSocketType = Stream }
addrs <- getAddrInfo @NE.NonEmpty (Just hints) Nothing (Just (show (setPort settings)))
semaphore <- newTVarIO (setMaxParallelRequests settings)
finishVar <- newEmptyMVar
threads <- forM addrs $ \addr ->
forkIO $
bracket
(openSocket addr)
(\sock -> close sock `finally` putMVar finishVar ())
(\sock -> do
setSocketOption sock ReusePort 1
bind sock (addrAddress addr)
listen sock (setListenQueue settings)
acceptLoop sock semaphore)
takeMVar finishVar
forM_ threads killThread
where
-- Put the forever _outside_ the mask_ to unmask briefly between iterations
-- (when it's safe because we have nothing ongoing).
acceptLoop sock semaphore = forever $ mask_ $ do
-- Because we're masked, if atomically exits with an async exception, it
-- was while blocking so the transaction failed, so nothing happened, so
-- no cleanup necessary.
atomically $ do
n <- readTVar semaphore
when (n == 0) retry
writeTVar semaphore $! n - 1
let increment = atomically (modifyTVar' semaphore (+1))
(conn, _peer) <- accept sock `onException` increment
let cleanup = close conn `finally` increment
onException
(do allowInterrupt -- we're masked but we just blocked (in `accept` in FFI), so let exceptions through
-- Now either the forkIO succeeds (and the responsibility for
-- closing and incrementing is passed to the thread) or it fails
-- (and we retain both responsibilities).
void $ forkIO $
handleConnection settings conn handler `finally` cleanup)
cleanup
-- | Will not close the connection, instead will just return, expecting the
-- caller to close the connection then.
handleConnection :: Settings -> Socket -> (Request -> IO Response) -> IO ()
handleConnection settings conn handler =
readRequest (setMaxRequestSize settings) (recv conn) >>= \case
Nothing -> return ()
Just req -> do
resp <- handler req
sendResponse conn resp
|
