{-# LINE 1 "libraries/base/./System/Event/KQueue.hsc" #-}
{-# LANGUAGE ForeignFunctionInterface, GeneralizedNewtypeDeriving,
{-# LINE 2 "libraries/base/./System/Event/KQueue.hsc" #-}
    NoImplicitPrelude, RecordWildCards #-}

module System.Event.KQueue
    (
      new
    , available
    ) where

import qualified System.Event.Internal as E


{-# LINE 13 "libraries/base/./System/Event/KQueue.hsc" #-}

{-# LINE 23 "libraries/base/./System/Event/KQueue.hsc" #-}

import Control.Concurrent.MVar (MVar, newMVar, swapMVar, withMVar)
import Control.Monad (when, unless)
import Data.Bits (Bits(..))
import Data.Word (Word16, Word32)
import Foreign.C.Error (throwErrnoIfMinus1)
import Foreign.C.Types (CInt, CLong, CTime)
import Foreign.Marshal.Alloc (alloca)
import Foreign.Ptr (Ptr, nullPtr)
import Foreign.Storable (Storable(..))
import GHC.Base
import GHC.Enum (toEnum)
import GHC.Err (undefined)
import GHC.Num (Num(..))
import GHC.Real (ceiling, floor, fromIntegral)
import GHC.Show (Show(show))
import System.Event.Internal (Timeout(..))
import System.Posix.Internals (c_close)
import System.Posix.Types (Fd(..))
import qualified System.Event.Array as A


{-# LINE 49 "libraries/base/./System/Event/KQueue.hsc" #-}
import Foreign.C.Types (CIntPtr, CUIntPtr)

{-# LINE 51 "libraries/base/./System/Event/KQueue.hsc" #-}


{-# LINE 53 "libraries/base/./System/Event/KQueue.hsc" #-}

{-# LINE 54 "libraries/base/./System/Event/KQueue.hsc" #-}

{-# LINE 55 "libraries/base/./System/Event/KQueue.hsc" #-}

-- Handle brokenness on some BSD variants, notably OS X up to at least
-- 10.6.  If NOTE_EOF isn't available, we have no way to receive a
-- notification from the kernel when we reach EOF on a plain file.

{-# LINE 62 "libraries/base/./System/Event/KQueue.hsc" #-}

available :: Bool
available = True
{-# INLINE available #-}

------------------------------------------------------------------------
-- Exported interface

data EventQueue = EventQueue {
      eqFd       :: {-# UNPACK #-} !QueueFd
    , eqChanges  :: {-# UNPACK #-} !(MVar (A.Array Event))
    , eqEvents   :: {-# UNPACK #-} !(A.Array Event)
    }

new :: IO E.Backend
new = do
  qfd <- kqueue
  changesArr <- A.empty
  changes <- newMVar changesArr 
  events <- A.new 64
  let !be = E.backend poll modifyFd delete (EventQueue qfd changes events)
  return be

delete :: EventQueue -> IO ()
delete q = do
  _ <- c_close . fromQueueFd . eqFd $ q
  return ()

modifyFd :: EventQueue -> Fd -> E.Event -> E.Event -> IO ()
modifyFd q fd oevt nevt = withMVar (eqChanges q) $ \ch -> do
  let addChange filt flag = A.snoc ch $ event fd filt flag noteEOF
  when (oevt `E.eventIs` E.evtRead)  $ addChange filterRead flagDelete
  when (oevt `E.eventIs` E.evtWrite) $ addChange filterWrite flagDelete
  when (nevt `E.eventIs` E.evtRead)  $ addChange filterRead flagAdd
  when (nevt `E.eventIs` E.evtWrite) $ addChange filterWrite flagAdd

poll :: EventQueue
     -> Timeout
     -> (Fd -> E.Event -> IO ())
     -> IO ()
poll EventQueue{..} tout f = do
    changesArr <- A.empty
    changes <- swapMVar eqChanges changesArr
    changesLen <- A.length changes
    len <- A.length eqEvents
    when (changesLen > len) $ A.ensureCapacity eqEvents (2 * changesLen)
    n <- A.useAsPtr changes $ \changesPtr chLen ->
           A.unsafeLoad eqEvents $ \evPtr evCap ->
             withTimeSpec (fromTimeout tout) $
               kevent eqFd changesPtr chLen evPtr evCap

    unless (n == 0) $ do
        cap <- A.capacity eqEvents
        when (n == cap) $ A.ensureCapacity eqEvents (2 * cap)
        A.forM_ eqEvents $ \e -> f (fromIntegral (ident e)) (toEvent (filter e))

------------------------------------------------------------------------
-- FFI binding

newtype QueueFd = QueueFd {
      fromQueueFd :: CInt
    } deriving (Eq, Show)


{-# LINE 167 "libraries/base/./System/Event/KQueue.hsc" #-}
data Event = KEvent {
      ident  :: {-# UNPACK #-} !CUIntPtr
    , filter :: {-# UNPACK #-} !Filter
    , flags  :: {-# UNPACK #-} !Flag
    , fflags :: {-# UNPACK #-} !FFlag
    , data_  :: {-# UNPACK #-} !CIntPtr
    , udata  :: {-# UNPACK #-} !(Ptr ())
    } deriving Show

event :: Fd -> Filter -> Flag -> FFlag -> Event
event fd filt flag fflag = KEvent (fromIntegral fd) filt flag fflag 0 nullPtr

instance Storable Event where
    sizeOf _ = (20)
{-# LINE 181 "libraries/base/./System/Event/KQueue.hsc" #-}
    alignment _ = alignment (undefined :: CInt)

    peek ptr = do
        ident'  <- (\hsc_ptr -> peekByteOff hsc_ptr 0) ptr
{-# LINE 185 "libraries/base/./System/Event/KQueue.hsc" #-}
        filter' <- (\hsc_ptr -> peekByteOff hsc_ptr 4) ptr
{-# LINE 186 "libraries/base/./System/Event/KQueue.hsc" #-}
        flags'  <- (\hsc_ptr -> peekByteOff hsc_ptr 6) ptr
{-# LINE 187 "libraries/base/./System/Event/KQueue.hsc" #-}
        fflags' <- (\hsc_ptr -> peekByteOff hsc_ptr 8) ptr
{-# LINE 188 "libraries/base/./System/Event/KQueue.hsc" #-}
        data'   <- (\hsc_ptr -> peekByteOff hsc_ptr 12) ptr
{-# LINE 189 "libraries/base/./System/Event/KQueue.hsc" #-}
        udata'  <- (\hsc_ptr -> peekByteOff hsc_ptr 16) ptr
{-# LINE 190 "libraries/base/./System/Event/KQueue.hsc" #-}
        let !ev = KEvent ident' (Filter filter') (Flag flags') fflags' data'
                         udata'
        return ev

    poke ptr ev = do
        (\hsc_ptr -> pokeByteOff hsc_ptr 0) ptr (ident ev)
{-# LINE 196 "libraries/base/./System/Event/KQueue.hsc" #-}
        (\hsc_ptr -> pokeByteOff hsc_ptr 4) ptr (filter ev)
{-# LINE 197 "libraries/base/./System/Event/KQueue.hsc" #-}
        (\hsc_ptr -> pokeByteOff hsc_ptr 6) ptr (flags ev)
{-# LINE 198 "libraries/base/./System/Event/KQueue.hsc" #-}
        (\hsc_ptr -> pokeByteOff hsc_ptr 8) ptr (fflags ev)
{-# LINE 199 "libraries/base/./System/Event/KQueue.hsc" #-}
        (\hsc_ptr -> pokeByteOff hsc_ptr 12) ptr (data_ ev)
{-# LINE 200 "libraries/base/./System/Event/KQueue.hsc" #-}
        (\hsc_ptr -> pokeByteOff hsc_ptr 16) ptr (udata ev)
{-# LINE 201 "libraries/base/./System/Event/KQueue.hsc" #-}

{-# LINE 202 "libraries/base/./System/Event/KQueue.hsc" #-}

newtype FFlag = FFlag Word32
    deriving (Eq, Show, Storable)

noteEOF  :: FFlag
noteEOF  = FFlag 0

{-# LINE 209 "libraries/base/./System/Event/KQueue.hsc" #-}

newtype Flag = Flag Word16
    deriving (Eq, Show, Storable)

flagAdd      :: Flag
flagAdd      = Flag 1
flagDelete   :: Flag
flagDelete   = Flag 2

{-# LINE 217 "libraries/base/./System/Event/KQueue.hsc" #-}

newtype Filter = Filter Word16
    deriving (Bits, Eq, Num, Show, Storable)

filterRead    :: Filter
filterRead    = Filter (-1)
filterWrite   :: Filter
filterWrite   = Filter (-2)

{-# LINE 225 "libraries/base/./System/Event/KQueue.hsc" #-}

data TimeSpec = TimeSpec {
      tv_sec  :: {-# UNPACK #-} !CTime
    , tv_nsec :: {-# UNPACK #-} !CLong
    }

instance Storable TimeSpec where
    sizeOf _ = (8)
{-# LINE 233 "libraries/base/./System/Event/KQueue.hsc" #-}
    alignment _ = alignment (undefined :: CInt)

    peek ptr = do
        tv_sec'  <- (\hsc_ptr -> peekByteOff hsc_ptr 0) ptr
{-# LINE 237 "libraries/base/./System/Event/KQueue.hsc" #-}
        tv_nsec' <- (\hsc_ptr -> peekByteOff hsc_ptr 4) ptr
{-# LINE 238 "libraries/base/./System/Event/KQueue.hsc" #-}
        let !ts = TimeSpec tv_sec' tv_nsec'
        return ts

    poke ptr ts = do
        (\hsc_ptr -> pokeByteOff hsc_ptr 0) ptr (tv_sec ts)
{-# LINE 243 "libraries/base/./System/Event/KQueue.hsc" #-}
        (\hsc_ptr -> pokeByteOff hsc_ptr 4) ptr (tv_nsec ts)
{-# LINE 244 "libraries/base/./System/Event/KQueue.hsc" #-}

kqueue :: IO QueueFd
kqueue = QueueFd `fmap` throwErrnoIfMinus1 "kqueue" c_kqueue

-- TODO: We cannot retry on EINTR as the timeout would be wrong.
-- Perhaps we should just return without calling any callbacks.
kevent :: QueueFd -> Ptr Event -> Int -> Ptr Event -> Int -> Ptr TimeSpec
       -> IO Int
kevent k chs chlen evs evlen ts
    = fmap fromIntegral $ E.throwErrnoIfMinus1NoRetry "kevent" $

{-# LINE 257 "libraries/base/./System/Event/KQueue.hsc" #-}
      c_kevent k chs (fromIntegral chlen) evs (fromIntegral evlen) ts

{-# LINE 259 "libraries/base/./System/Event/KQueue.hsc" #-}

withTimeSpec :: TimeSpec -> (Ptr TimeSpec -> IO a) -> IO a
withTimeSpec ts f =
    if tv_sec ts < 0 then
        f nullPtr
      else
        alloca $ \ptr -> poke ptr ts >> f ptr

fromTimeout :: Timeout -> TimeSpec
fromTimeout Forever     = TimeSpec (-1) (-1)
fromTimeout (Timeout s) = TimeSpec (toEnum sec) (toEnum nanosec)
  where
    sec :: Int
    sec     = floor s

    nanosec :: Int
    nanosec = ceiling $ (s - fromIntegral sec) * 1000000000

toEvent :: Filter -> E.Event
toEvent (Filter f)
    | f == (-1) = E.evtRead
{-# LINE 280 "libraries/base/./System/Event/KQueue.hsc" #-}
    | f == (-2) = E.evtWrite
{-# LINE 281 "libraries/base/./System/Event/KQueue.hsc" #-}
    | otherwise = error $ "toEvent: unknown filter " ++ show f

foreign import ccall unsafe "kqueue"
    c_kqueue :: IO CInt


{-# LINE 291 "libraries/base/./System/Event/KQueue.hsc" #-}
foreign import ccall safe "kevent"
    c_kevent :: QueueFd -> Ptr Event -> CInt -> Ptr Event -> CInt
             -> Ptr TimeSpec -> IO CInt

{-# LINE 297 "libraries/base/./System/Event/KQueue.hsc" #-}


{-# LINE 299 "libraries/base/./System/Event/KQueue.hsc" #-}