newWith :: Bool -> Backend -> IO EventManager
newWith oneShot be = do
  iofds <- fmap (listArray (0, callbackArraySize-1)) $
           replicateM callbackArraySize (newMVar =<< IT.new 8)
  ctrl <- newControl False
  state <- newIORef Created
  us <- newSource
  _ <- mkWeakIORef state $ do
               st <- atomicModifyIORef' state $ \s -> (Finished, s)
               when (st /= Finished) $ do
                 I.delete be
                 closeControl ctrl
  lockVar <- newMVar ()
  let mgr = EventManager { emBackend = be
                         , emFds = iofds
                         , emState = state
                         , emUniqueSource = us
                         , emControl = ctrl
                         , emOneShot = oneShot
                         , emLock = lockVar
                         }
  registerControlFd mgr (controlReadFd ctrl) evtRead
  registerControlFd mgr (wakeupReadFd ctrl) evtRead
  return mgr
  where
    replicateM n x = sequence (replicate n x)
newWith :: Bool -> Backend -> IO EventManager
newWith oneShot be = do
  iofds <- fmap (listArray (0, callbackArraySize-1)) $
           replicateM callbackArraySize (newMVar =<< IT.new 8)
  ctrl <- newControl False
  state <- newIORef Created
  us <- newSource
  _ <- mkWeakIORef state $ do
               st <- atomicModifyIORef' state $ \s -> (Finished, s)
               when (st /= Finished) $ do
                 I.delete be
                 closeControl ctrl
  lockVar <- newMVar ()
  let mgr = EventManager { emBackend = be
                         , emFds = iofds
                         , emState = state
                         , emUniqueSource = us
                         , emControl = ctrl
                         , emOneShot = oneShot
                         , emLock = lockVar
                         }
  registerControlFd mgr (controlReadFd ctrl) evtRead
  registerControlFd mgr (wakeupReadFd ctrl) evtRead
  return mgr
  where
    replicateM n x = sequence (replicate n x)
newWith oneShot be = do
  iofds <- fmap (listArray (0, callbackArraySize-1)) $
           replicateM callbackArraySize (newMVar =<< IT.new 8)
  ctrl <- newControl False
  state <- newIORef Created
  us <- newSource
  _ <- mkWeakIORef state $ do
               st <- atomicModifyIORef' state $ \s -> (Finished, s)
               when (st /= Finished) $ do
                 I.delete be
                 closeControl ctrl
  lockVar <- newMVar ()
  let mgr = EventManager { emBackend = be
                         , emFds = iofds
                         , emState = state
                         , emUniqueSource = us
                         , emControl = ctrl
                         , emOneShot = oneShot
                         , emLock = lockVar
                         }
  registerControlFd mgr (controlReadFd ctrl) evtRead
  registerControlFd mgr (wakeupReadFd ctrl) evtRead
  return mgr
  where
    replicateM n x = sequence (replicate n x)