transient-0.7.0.0: src/Transient/Internals.hs
------------------------------------------------------------------------------
--
-- Module : Transient.Internals
-- Copyright :
-- License : MIT
--
-- Maintainer : agocorona@gmail.com
-- Stability :
-- Portability :
--
-- | See http://github.com/transient-haskell/transient
-- Everything in this module is exported in order to allow extensibility.
-----------------------------------------------------------------------------
{-# LANGUAGE CPP #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE ExistentialQuantification #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE UndecidableInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE ConstraintKinds #-}
--{-# LANGUAGE MonoLocalBinds #-}
module Transient.Internals where
import Control.Applicative
import Control.Monad.State
--import Data.Dynamic
import qualified Data.Map as M
import System.IO.Unsafe
import Unsafe.Coerce
import Control.Exception hiding (try,onException)
import qualified Control.Exception (try)
import Control.Concurrent
-- import GHC.Real
-- import GHC.Conc(unsafeIOToSTM)
-- import Control.Concurrent.STM hiding (retry)
-- import qualified Control.Concurrent.STM as STM (retry)
import Data.Maybe
import Data.List
import Data.IORef
import System.Environment
import System.IO
import System.IO.Error
import Data.String
import qualified Data.ByteString.Char8 as BS
import qualified Data.ByteString.Lazy.Char8 as BSL
import Data.Typeable
import Control.Monad.Fail
import System.Directory
#ifdef DEBUG
import Debug.Trace
import System.Exit
tshow :: Show a => a -> x -> x
tshow= Debug.Trace.traceShow
{-# INLINE (!>) #-}
(!>) :: Show a => b -> a -> b
(!>) x y = trace (show (unsafePerformIO myThreadId, y)) x
infixr 0 !>
#else
tshow :: a -> x -> x
tshow _ y= y
{-# INLINE (!>) #-}
(!>) :: a -> b -> a
(!>) = const
#endif
tr x= return () !> x
type StateIO = StateT EventF IO
newtype TransIO a = Transient { runTrans :: StateIO (Maybe a) }
type SData = ()
type EventId = Int
type TransientIO = TransIO
data LifeCycle = Alive | Parent | Listener | Dead
deriving (Eq, Show)
-- | EventF describes the context of a TransientIO computation:
data EventF = forall a b. EventF
{ event :: Maybe SData
-- ^ Not yet consumed result (event) from the last asynchronous computation
, xcomp :: TransIO a
, fcomp :: [b -> TransIO b]
-- ^ List of continuations
, mfData :: M.Map TypeRep SData
-- ^ State data accessed with get or put operations
, mfSequence :: Int
, threadId :: ThreadId
, freeTh :: Bool
-- ^ When 'True', threads are not killed using kill primitives
, parent :: Maybe EventF
-- ^ The parent of this thread
, children :: MVar [EventF]
-- ^ Forked child threads, used only when 'freeTh' is 'False'
, maxThread :: Maybe (IORef Int)
-- ^ Maximum number of threads that are allowed to be created
, labelth :: IORef (LifeCycle, BS.ByteString)
-- ^ Label the thread with its lifecycle state and a label string
, parseContext :: ParseContext
, execMode :: ExecMode
} deriving Typeable
data ParseContext = ParseContext { more :: TransIO (StreamData BSL.ByteString)
, buffer :: BSL.ByteString
, done :: IORef Bool} deriving Typeable
-- | To define primitives for all the transient monads: TransIO, Cloud and Widget
class MonadState EventF m => TransMonad m
instance MonadState EventF m => TransMonad m
instance MonadState EventF TransIO where
get = Transient $ get >>= return . Just
put x = Transient $ put x >> return (Just ())
state f = Transient $ do
s <- get
let ~(a, s') = f s
put s'
return $ Just a
-- | Run a computation in the underlying state monad. it is a little lighter and
-- performant and it should not contain advanced effects beyond state.
noTrans :: StateIO x -> TransIO x
noTrans x = Transient $ x >>= return . Just
-- | filters away the Nothing responses of the State monad.
-- in principle the state monad should return a single response, but, for performance reasons,
-- it can run inside elements of transient monad (using `runTrans`) which may produce
-- many results
liftTrans :: StateIO (Maybe b) -> TransIO b
liftTrans mx= do
r <- noTrans mx
case r of
Nothing -> empty
Just x -> return x
emptyEventF :: ThreadId -> IORef (LifeCycle, BS.ByteString) -> MVar [EventF] -> EventF
emptyEventF th label childs =
EventF { event = mempty
, xcomp = empty
, fcomp = []
, mfData = mempty
, mfSequence = 0
, threadId = th
, freeTh = False
, parent = Nothing
, children = childs
, maxThread = Nothing
, labelth = label
, parseContext = ParseContext (return SDone) mempty undefined
, execMode = Serial}
-- | Run a transient computation with a default initial state
runTransient :: TransIO a -> IO (Maybe a, EventF)
runTransient t = do
th <- myThreadId
label <- newIORef $ (Alive, BS.pack "top")
childs <- newMVar []
runStateT (runTrans t) $ emptyEventF th label childs
-- | Run a transient computation with a given initial state
runTransState :: EventF -> TransIO x -> IO (Maybe x, EventF)
runTransState st x = runStateT (runTrans x) st
emptyIfNothing :: Maybe a -> TransIO a
emptyIfNothing = Transient . return
-- | Get the continuation context: closure, continuation, state, child threads etc
getCont :: TransIO EventF
getCont = Transient $ Just <$> get
-- | Run the closure and the continuation using the state data of the calling thread
runCont :: EventF -> StateIO (Maybe a)
runCont EventF { xcomp = x, fcomp = fs } = runTrans $ do
r <- unsafeCoerce x
compose fs r
-- | Run the closure and the continuation using its own state data.
runCont' :: EventF -> IO (Maybe a, EventF)
runCont' cont = runStateT (runCont cont) cont
-- | Warning: Radically untyped stuff. handle with care
getContinuations :: StateIO [a -> TransIO b]
getContinuations = do
EventF { fcomp = fs } <- get
return $ unsafeCoerce fs
{-
runCont cont = do
mr <- runClosure cont
case mr of
Nothing -> return Nothing
Just r -> runContinuation cont r
-}
-- | Compose a list of continuations.
{-# INLINE compose #-}
compose :: [a -> TransIO a] -> (a -> TransIO b)
compose [] = const empty
compose (f:fs) = \x -> f x >>= compose fs
-- | Run the closure (the 'x' in 'x >>= f') of the current bind operation.
runClosure :: EventF -> StateIO (Maybe a)
runClosure EventF { xcomp = x } = unsafeCoerce (runTrans x)
-- | Run the continuation (the 'f' in 'x >>= f') of the current bind operation with the current state.
runContinuation :: EventF -> a -> StateIO (Maybe b)
runContinuation EventF { fcomp = fs } =
runTrans . (unsafeCoerce $ compose $ fs)
-- | Save a closure and a continuation ('x' and 'f' in 'x >>= f').
setContinuation :: TransIO a -> (a -> TransIO b) -> [c -> TransIO c] -> StateIO ()
setContinuation b c fs = do
modify $ \EventF{..} -> EventF { xcomp = b
, fcomp = unsafeCoerce c : fs
, .. }
-- | Save a closure and continuation, run the closure, restore the old continuation.
-- | NOTE: The old closure is discarded.
withContinuation :: b -> TransIO a -> TransIO a
withContinuation c mx = do
EventF { fcomp = fs, .. } <- get
put $ EventF { xcomp = mx
, fcomp = unsafeCoerce c : fs
, .. }
r <- mx
restoreStack fs
return r
-- | Restore the continuations to the provided ones.
-- | NOTE: Events are also cleared out.
restoreStack :: TransMonad m => [a -> TransIO a] -> m ()
restoreStack fs = modify $ \EventF {..} -> EventF { event = Nothing, fcomp = fs, .. }
-- | Run a chain of continuations.
-- WARNING: It is up to the programmer to assure that each continuation typechecks
-- with the next, and that the parameter type match the input of the first
-- continuation.
-- NOTE: Normally this makes sense to stop the current flow with `stop` after the
-- invocation.
runContinuations :: [a -> TransIO b] -> c -> TransIO d
runContinuations fs x = compose (unsafeCoerce fs) x
-- Instances for Transient Monad
instance Functor TransIO where
fmap f mx = do
x <- mx
return $ f x
instance Applicative TransIO where
pure a = Transient . return $ Just a
mf <*> mx = do -- do f <- mf; x <- mx ; return $ f x
r1 <- liftIO $ newIORef Nothing
r2 <- liftIO $ newIORef Nothing
fparallel r1 r2 <|> xparallel r1 r2
where
fparallel r1 r2= do
f <- mf
liftIO $ (writeIORef r1 $ Just f)
mr <- liftIO (readIORef r2)
case mr of
Nothing -> empty
Just x -> return $ f x
xparallel r1 r2 = do
mr <- liftIO (readIORef r1)
case mr of
Nothing -> do
p <- gets execMode
if p== Serial then empty else do
x <- mx
liftIO $ (writeIORef r2 $ Just x)
mr <- liftIO (readIORef r1)
case mr of
Nothing -> empty
Just f -> return $ f x
Just f -> do
x <- mx
liftIO $ (writeIORef r2 $ Just x)
return $ f x
data ExecMode = Remote | Parallel | Serial
deriving (Typeable, Eq, Show)
-- | stop the current computation and does not execute any alternative computation
fullStop :: TransIO stop
fullStop= do modify $ \s ->s{execMode= Remote} ; stop
instance Monad TransIO where
return = pure
x >>= f = Transient $ do
setEventCont x f
mk <- runTrans x
resetEventCont mk
case mk of
Just k -> runTrans (f k)
Nothing -> return Nothing
instance MonadIO TransIO where
liftIO x = Transient $ liftIO x >>= return . Just
instance Monoid a => Monoid (TransIO a) where
mempty = return mempty
#if MIN_VERSION_base(4,11,0)
mappend = (<>)
instance (Monoid a) => Semigroup (TransIO a) where
(<>)= mappendt
#else
mappend= mappendt
#endif
mappendt x y = mappend <$> x <*> y
instance Alternative TransIO where
empty = Transient $ return Nothing
(<|>) = mplus
instance MonadPlus TransIO where
mzero = empty
mplus x y = Transient $ do
mx <- runTrans x
was <- gets execMode -- getData `onNothing` return Serial
if was == Remote
then return Nothing
else case mx of
Nothing -> runTrans y
justx -> return justx
instance MonadFail TransIO where
fail _ = mzero
readWithErr :: (Typeable a, Read a) => Int -> String -> IO [(a, String)]
readWithErr n line =
(v `seq` return [(v, left)])
`catch` (\(_ :: SomeException) ->
throw $ ParseError $ "read error trying to read type: \"" ++ show (typeOf v)
++ "\" in: " ++ " <" ++ show line ++ "> ")
where (v, left):_ = readsPrec n line
newtype ParseError= ParseError String
instance Show ParseError where
show (ParseError s)= "ParseError " ++ s
instance Exception ParseError
read' s= case readsPrec' 0 s of
[(x,"")] -> x
_ -> throw $ ParseError $ "reading " ++ s
readsPrec' n = unsafePerformIO . readWithErr n
-- | A synonym of 'empty' that can be used in a monadic expression. It stops
-- the computation, which allows the next computation in an 'Alternative'
-- ('<|>') composition to run.
stop :: Alternative m => m stopped
stop = empty
instance (Num a,Eq a,Fractional a) =>Fractional (TransIO a)where
mf / mg = (/) <$> mf <*> mg
fromRational r = return $ fromRational r
instance (Num a, Eq a) => Num (TransIO a) where
fromInteger = return . fromInteger
mf + mg = (+) <$> mf <*> mg
mf * mg = (*) <$> mf <*> mg
negate f = f >>= return . negate
abs f = f >>= return . abs
signum f = f >>= return . signum
class AdditionalOperators m where
-- | Run @m a@ discarding its result before running @m b@.
(**>) :: m a -> m b -> m b
-- | Run @m b@ discarding its result, after the whole task set @m a@ is
-- done.
(<**) :: m a -> m b -> m a
atEnd' :: m a -> m b -> m a
atEnd' = (<**)
-- | Run @m b@ discarding its result, once after each task in @m a@, and
-- once again after the whole task set is done.
(<***) :: m a -> m b -> m a
atEnd :: m a -> m b -> m a
atEnd = (<***)
instance AdditionalOperators TransIO where
--(**>) :: TransIO a -> TransIO b -> TransIO b
(**>) x y =
Transient $ do
runTrans x
runTrans y
--(<***) :: TransIO a -> TransIO b -> TransIO a
(<***) ma mb =
Transient $ do
fs <- getContinuations
setContinuation ma (\x -> mb >> return x) fs
a <- runTrans ma
runTrans mb
restoreStack fs
return a
--(<**) :: TransIO a -> TransIO b -> TransIO a
(<**) ma mb =
Transient $ do
a <- runTrans ma
runTrans mb
return a
infixl 4 <***, <**, **>
-- | Run @b@ once, discarding its result when the first task in task set @a@
-- has finished. Useful to start a singleton task after the first task has been
-- setup.
(<|) :: TransIO a -> TransIO b -> TransIO a
(<|) ma mb = Transient $ do
fs <- getContinuations
ref <- liftIO $ newIORef False
setContinuation ma (cont ref) fs
r <- runTrans ma
restoreStack fs
return r
where cont ref x = Transient $ do
n <- liftIO $ readIORef ref
if n == True
then return $ Just x
else do liftIO $ writeIORef ref True
runTrans mb
return $ Just x
-- | Set the current closure and continuation for the current statement
{-# INLINABLE setEventCont #-}
setEventCont :: TransIO a -> (a -> TransIO b) -> StateIO ()
setEventCont x f = modify $ \EventF { fcomp = fs, .. }
-> EventF { xcomp = x
, fcomp = unsafeCoerce f : fs
, .. }
-- | Reset the closure and continuation. Remove inner binds than the previous
-- computations may have stacked in the list of continuations.
-- resetEventCont :: Maybe a -> EventF -> StateIO ()
{-# INLINABLE resetEventCont #-}
resetEventCont mx =
modify $ \EventF { fcomp = fs, .. }
-> EventF { xcomp = case mx of
Nothing -> empty
Just x -> unsafeCoerce (head fs) x
, fcomp = tailsafe fs
, .. }
-- | Total variant of `tail` that returns an empty list when given an empty list.
{-# INLINE tailsafe #-}
tailsafe :: [a] -> [a]
tailsafe [] = []
tailsafe (_:xs) = xs
--instance MonadTrans (Transient ) where
-- lift mx = Transient $ mx >>= return . Just
-- * Threads
waitQSemB onemore sem = atomicModifyIORef sem $ \n ->
let one = if onemore then 1 else 0
in if n + one > 0 then(n - 1, True) else (n, False)
signalQSemB sem = atomicModifyIORef sem $ \n -> (n + 1, ())
-- | Sets the maximum number of threads that can be created for the given task
-- set. When set to 0, new tasks start synchronously in the current thread.
-- New threads are created by 'parallel', and APIs that use parallel.
threads :: Int -> TransIO a -> TransIO a
threads n process = do
msem <- gets maxThread
sem <- liftIO $ newIORef n
modify $ \s -> s { maxThread = Just sem }
r <- process <*** (modify $ \s -> s { maxThread = msem }) -- restore it
return r
-- clone the current state as a child of the current state, with the same thread
cloneInChild name= do
st <- get
rchs <- liftIO $ newMVar []
label <- liftIO $ newIORef (Alive, if not $ null name then BS.pack name else mempty)
let st' = st { parent = Just st
, children = rchs
, labelth = label }
liftIO $ do
atomicModifyIORef (labelth st) $ \(_, label) -> ((Parent,label),())
hangThread st st' -- parent could have more than one children with the same threadId
return st'
-- remove the current child task from the tree of tasks.
-- If the child and parent threads are different, the child is killed
removeChild :: (MonadIO m,TransMonad m) => m ()
removeChild = do
st <- get
let mparent = parent st
case mparent of
Nothing -> return ()
Just parent -> do
sts <- liftIO $ modifyMVar (children parent) $ \ths -> do
let (xs,sts)= partition (\st' -> threadId st' /= threadId st) ths
ys <- case sts of
[] -> return []
st':_ -> readMVar $ children st'
return (xs ++ ys,sts)
put parent
case sts of
[] -> return()
st':_ -> do
(status,_) <- liftIO $ readIORef $ labelth st'
if status == Listener || threadId parent == threadId st then return () else liftIO $ (killThread . threadId) st'
-- | Terminate all the child threads in the given task set and continue
-- execution in the current thread. Useful to reap the children when a task is
-- done, restart a task when a new event happens etc.
--
oneThread :: TransIO a -> TransIO a
oneThread comp = do
st <- cloneInChild "oneThread"
let rchs= children st
x <- comp
th <- liftIO myThreadId
-- !> ("FATHER:", threadId st)
chs <- liftIO $ readMVar rchs
liftIO $ mapM_ (killChildren1 th) chs
-- !> ("KILLEVENT1 ", map threadId chs )
return x
where
killChildren1 :: ThreadId -> EventF -> IO ()
killChildren1 th state = do
forkIO $ do
ths' <- modifyMVar (children state) $ \ths -> do
let (inn, ths')= partition (\st -> threadId st == th) ths
return (inn, ths')
mapM_ (killChildren1 th) ths'
mapM_ (killThread . threadId) ths'
return()
-- | Add a label to the current passing threads so it can be printed by debugging calls like `showThreads`
labelState :: (MonadIO m,TransMonad m) => BS.ByteString -> m ()
labelState l = do
st <- get
liftIO $ atomicModifyIORef (labelth st) $ \(status,prev) -> ((status, prev <> BS.pack "," <> l), ())
-- | return the threadId associated with an state (you can see all of them with the console option 'ps')
threadState thid= do
st <- findState match =<< topState
return $ threadId st :: TransIO ThreadId
where
match st= do
(_,lab) <-liftIO $ readIORef $ labelth st
return $ if lab == thid then True else False
-- | kill the thread subtree labeled as such (you can see all of them with the console option 'ps')
killState thid= do
st <- findState match =<< topState
liftIO $ killBranch' st
where
match st= do
(_,lab) <-liftIO $ readIORef $ labelth st
return $ if lab == thid then True else False
printBlock :: MVar ()
printBlock = unsafePerformIO $ newMVar ()
-- | Show the tree of threads hanging from the state.
showThreads :: MonadIO m => EventF -> m ()
showThreads st = liftIO $ withMVar printBlock $ const $ do
mythread <- myThreadId
putStrLn "---------Threads-----------"
let showTree n ch = do
liftIO $ do
putStr $ take n $ repeat ' '
(state, label) <- readIORef $ labelth ch
if BS.null label
then putStr . show $ threadId ch
else do BS.putStr label; putStr . drop 8 . show $ threadId ch
when (state == Dead) $ putStr " dead" -- putStr " " >> putStr (take 3 $ show state) --
putStrLn $ if mythread == threadId ch then " <--" else ""
chs <- readMVar $ children ch
mapM_ (showTree $ n + 2) $ reverse chs
showTree 0 st
-- | Return the state of the thread that initiated the transient computation
-- topState :: TransIO EventF
topState :: TransMonad m => m EventF
topState = do
st <- get
return $ toplevel st
where toplevel st = case parent st of
Nothing -> st
Just p -> toplevel p
{-
getStateFromThread th top = resp
where
resp = do
let thstring = drop 9 . show $ threadId top
if thstring == th
then getstate top
else do
sts <- liftIO $ readMVar $ children top
foldl (<|>) empty $ map (getStateFromThread th) sts
getstate st =
case M.lookup (typeOf $ typeResp resp) $ mfData st of
Just x -> return . Just $ unsafeCoerce x
Nothing -> return Nothing
typeResp :: m (Maybe x) -> x
typeResp = undefined
-}
-- | find the first computation state which match a filter in the subthree of states
findState :: (MonadIO m, Alternative m) => (EventF -> m Bool) -> EventF -> m EventF
findState filter top= do
r <- filter top
if r then return top
else do
sts <- liftIO $ readMVar $ children top
foldl (<|>) empty $ map (findState filter) sts
-- | Return the state variable of the type desired for a thread number
getStateFromThread :: (Typeable a, MonadIO m, Alternative m) => String -> EventF -> m (Maybe a)
getStateFromThread th top= getstate =<< findState (matchth th) top
where
matchth th th'= do
let thstring = drop 9 . show $ threadId th'
return $ if thstring == th then True else False
getstate st = resp
where resp= case M.lookup (typeOf $ typeResp resp) $ mfData st of
Just x -> return . Just $ unsafeCoerce x
Nothing -> return Nothing
typeResp :: m (Maybe x) -> x
typeResp = undefined
-- | execute all the states of the type desired that are created by direct child threads
processStates :: Typeable a => (a-> TransIO ()) -> EventF -> TransIO()
processStates display st = do
getstate st >>= display
liftIO $ print $ threadId st
sts <- liftIO $ readMVar $ children st
mapM_ (processStates display) sts
where
getstate st =
case M.lookup (typeOf $ typeResp display) $ mfData st of
Just x -> return $ unsafeCoerce x
Nothing -> empty
typeResp :: (a -> TransIO()) -> a
typeResp = undefined
-- | Add n threads to the limit of threads. If there is no limit, the limit is set.
addThreads' :: Int -> TransIO ()
addThreads' n= noTrans $ do
msem <- gets maxThread
case msem of
Just sem -> liftIO $ modifyIORef sem $ \n' -> n + n'
Nothing -> do
sem <- liftIO (newIORef n)
modify $ \ s -> s { maxThread = Just sem }
-- | Ensure that at least n threads are available for the current task set.
addThreads :: Int -> TransIO ()
addThreads n = noTrans $ do
msem <- gets maxThread
case msem of
Nothing -> return ()
Just sem -> liftIO $ modifyIORef sem $ \n' -> if n' > n then n' else n
--getNonUsedThreads :: TransIO (Maybe Int)
--getNonUsedThreads= Transient $ do
-- msem <- gets maxThread
-- case msem of
-- Just sem -> liftIO $ Just <$> readIORef sem
-- Nothing -> return Nothing
-- | Disable tracking and therefore the ability to terminate the child threads.
-- By default, child threads are terminated automatically when the parent
-- thread dies, or they can be terminated using the kill primitives. Disabling
-- it may improve performance a bit, however, all threads must be well-behaved
-- to exit on their own to avoid a leak.
freeThreads :: TransIO a -> TransIO a
freeThreads process = Transient $ do
st <- get
put st { freeTh = True }
r <- runTrans process
modify $ \s -> s { freeTh = freeTh st }
return r
-- | Enable tracking and therefore the ability to terminate the child threads.
-- This is the default but can be used to re-enable tracking if it was
-- previously disabled with 'freeThreads'.
hookedThreads :: TransIO a -> TransIO a
hookedThreads process = Transient $ do
st <- get
put st {freeTh = False}
r <- runTrans process
modify $ \s -> s { freeTh = freeTh st }
return r
-- | Kill all the child threads of the current thread.
killChilds :: TransIO ()
killChilds = noTrans $ do
cont <- get
liftIO $ do
killChildren $ children cont
writeIORef (labelth cont) (Alive, mempty)
-- !> (threadId cont,"relabeled")
return ()
-- | Kill the current thread and the childs.
killBranch :: TransIO ()
killBranch = noTrans $ do
st <- get
liftIO $ killBranch' st
-- | Kill the childs and the thread of an state
killBranch' :: EventF -> IO ()
killBranch' cont = do
forkIO $ do
killChildren $ children cont
let thisth = threadId cont
mparent = parent cont
when (isJust mparent) $
modifyMVar_ (children $ fromJust mparent) $ \sts ->
return $ filter (\st -> threadId st /= thisth) sts
killThread $ thisth !> ("kill this thread:",thisth)
return ()
-- * Extensible State: Session Data Management
-- | Same as 'getSData' but with a more conventional interface. If the data is found, a
-- 'Just' value is returned. Otherwise, a 'Nothing' value is returned.
getData :: (TransMonad m, Typeable a) => m (Maybe a)
getData = resp
where resp = do
list <- gets mfData
case M.lookup (typeOf $ typeResp resp) list of
Just x -> return . Just $ unsafeCoerce x
Nothing -> return Nothing
typeResp :: m (Maybe x) -> x
typeResp = undefined
-- | Retrieve a previously stored data item of the given data type from the
-- monad state. The data type to retrieve is implicitly determined by the data type.
-- If the data item is not found, empty is executed, so the alternative computation will be executed, if any.
-- Otherwise, the computation will stop.
-- If you want to print an error message or return a default value, you can use an 'Alternative' composition. For example:
--
-- > getSData <|> error "no data of the type desired"
-- > getInt = getSData <|> return (0 :: Int)
--
-- The later return either the value set or 0.
--
-- It is highly recommended not to use it directly, since his relatively complex behaviour may be confusing sometimes.
-- Use instead a monomorphic alias like "getInt" defined above.
getSData :: Typeable a => TransIO a
getSData = Transient getData
-- | Same as `getSData`
getState :: Typeable a => TransIO a
getState = getSData
-- | 'setData' stores a data item in the monad state which can be retrieved
-- later using 'getData' or 'getSData'. Stored data items are keyed by their
-- data type, and therefore only one item of a given type can be stored. A
-- newtype wrapper can be used to distinguish two data items of the same type.
--
-- @
-- import Control.Monad.IO.Class (liftIO)
-- import Transient.Base
-- import Data.Typeable
--
-- data Person = Person
-- { name :: String
-- , age :: Int
-- } deriving Typeable
--
-- main = keep $ do
-- setData $ Person "Alberto" 55
-- Person name age <- getSData
-- liftIO $ print (name, age)
-- @
setData :: (TransMonad m, Typeable a) => a -> m ()
setData x = modify $ \st -> st { mfData = M.insert t (unsafeCoerce x) (mfData st) }
where t = typeOf x
-- | Accepts a function which takes the current value of the stored data type
-- and returns the modified value. If the function returns 'Nothing' the value
-- is deleted otherwise updated.
modifyData :: (TransMonad m, Typeable a) => (Maybe a -> Maybe a) -> m ()
modifyData f = modify $ \st -> st { mfData = M.alter alterf t (mfData st) }
where typeResp :: (Maybe a -> b) -> a
typeResp = undefined
t = typeOf (typeResp f)
alterf mx = unsafeCoerce $ f x'
where x' = case mx of
Just x -> Just $ unsafeCoerce x
Nothing -> Nothing
-- | Either modify according with the first parameter or insert according with the second, depending on if the data exist or not. It returns the
-- old value or the new value accordingly.
--
-- > runTransient $ do modifyData' (\h -> h ++ " world") "hello new" ; r <- getSData ; liftIO $ putStrLn r -- > "hello new"
-- > runTransient $ do setData "hello" ; modifyData' (\h -> h ++ " world") "hello new" ; r <- getSData ; liftIO $ putStrLn r -- > "hello world"
modifyData' :: (TransMonad m, Typeable a) => (a -> a) -> a -> m a
modifyData' f v= do
st <- get
let (ma,nmap)= M.insertLookupWithKey alterf t (unsafeCoerce v) (mfData st)
put st { mfData =nmap}
return $ if isNothing ma then v else unsafeCoerce $ fromJust ma
where t = typeOf v
alterf _ _ x = unsafeCoerce $ f $ unsafeCoerce x
-- | Same as `modifyData`
modifyState :: (TransMonad m, Typeable a) => (Maybe a -> Maybe a) -> m ()
modifyState = modifyData
-- | Same as `setData`
setState :: (TransMonad m, Typeable a) => a -> m ()
setState = setData
-- | Delete the data item of the given type from the monad state.
delData :: (TransMonad m, Typeable a) => a -> m ()
delData x = modify $ \st -> st { mfData = M.delete (typeOf x) (mfData st) }
-- | Same as `delData`
delState :: (TransMonad m, Typeable a) => a -> m ()
delState = delData
-- STRefs for the Transient monad
newtype Ref a = Ref (IORef a)
-- | Initializes a new mutable reference (similar to STRef in the state monad)
-- It is polimorphic. Each type has his own reference
-- It return the associated IORef, so it can be updated in the IO monad
newRState:: (MonadIO m,TransMonad m, Typeable a) => a -> m (IORef a)
newRState x= do
ref@(Ref rx) <- Ref <$> liftIO (newIORef x)
setData ref
return rx
-- | mutable state reference that can be updated (similar to STRef in the state monad)
-- They are identified by his type.
-- Initialized the first time it is set.
setRState:: (MonadIO m,TransMonad m, Typeable a) => a -> m ()
setRState x= do
Ref ref <- getData `onNothing` do
ref <- Ref <$> liftIO (newIORef x)
setData ref
return ref
liftIO $ atomicModifyIORef ref $ const (x,())
getRData :: (MonadIO m, TransMonad m, Typeable a) => m (Maybe a)
getRData= do
mref <- getData
case mref of
Just (Ref ref) -> Just <$> (liftIO $ readIORef ref)
Nothing -> return Nothing
getRState :: Typeable a => TransIO a
getRState= Transient getRData
delRState x= delState (undefined `asTypeOf` ref x)
where ref :: a -> Ref a
ref = undefined
-- | Run an action, if it does not succeed, undo any state changes
-- that may have been caused by the action and allow aternative actions to run with the original state
try :: TransIO a -> TransIO a
try mx = do
s <- get
mx <|> (modify (const s) >> empty)
-- | Executes the computation and reset the state either if it fails or not.
sandbox :: TransIO a -> TransIO a
sandbox mx = do
sd <- gets mfData
mx <*** modify (\s ->s { mfData = sd})
-- | generates an identifier that is unique within the current program execution
genGlobalId :: MonadIO m => m Int
genGlobalId= liftIO $ atomicModifyIORef rglobalId $ \n -> (n +1,n)
rglobalId= unsafePerformIO $ newIORef (0 :: Int)
-- | Generator of identifiers that are unique within the current monadic
-- sequence They are not unique in the whole program.
genId :: TransMonad m => m Int
genId = do
st <- get
let n = mfSequence st
put st { mfSequence = n + 1 }
return n
getPrevId :: TransMonad m => m Int
getPrevId = gets mfSequence
instance Read SomeException where
readsPrec n str = [(SomeException $ ErrorCall s, r)]
where [(s , r)] = readsPrec n str
-- | 'StreamData' represents an result in an stream being generated.
data StreamData a =
SMore a -- ^ More to come
| SLast a -- ^ This is the last one
| SDone -- ^ No more, we are done
| SError SomeException -- ^ An error occurred
deriving (Typeable, Show,Read)
instance Functor StreamData where
fmap f (SMore a)= SMore (f a)
fmap f (SLast a)= SLast (f a)
fmap _ SDone= SDone
-- | A task stream generator that produces an infinite stream of results by
-- running an IO computation in a loop, each result may be processed in different threads (tasks)
-- depending on the thread limits stablished with `threads`.
waitEvents :: IO a -> TransIO a
waitEvents io = do
mr <- parallel (SMore <$> io)
case mr of
SMore x -> return x
SError e -> back e
-- | Run an IO computation asynchronously carrying
-- the result of the computation in a new thread when it completes.
-- If there are no threads available, the async computation and his continuation is executed
-- in the same thread before any alternative computation.
async :: IO a -> TransIO a
async io = do
mr <- parallel (SLast <$> io)
case mr of
SLast x -> return x
SError e -> back e
-- | Avoid the execution of alternative computations when the computation is asynchronous
--
-- > sync (async whatever) <|> liftIO (print "hello") -- never print "hello"
sync :: TransIO a -> TransIO a
sync x = do
was <- gets execMode -- getSData <|> return Serial
r <- x <** modify (\s ->s{execMode= Remote}) -- setData Remote
modify $ \s -> s{execMode= was}
return r
-- | create task threads faster, but with no thread control: @spawn = freeThreads . waitEvents@
spawn :: IO a -> TransIO a
spawn = freeThreads . waitEvents
-- | An stream generator that run an IO computation periodically at the specified time interval. The
-- task carries the result of the computation. A new result is generated only if
-- the output of the computation is different from the previous one.
sample :: Eq a => IO a -> Int -> TransIO a
sample action interval = do
v <- liftIO action
prev <- liftIO $ newIORef v
waitEvents (loop action prev) <|> return v
where
loop action prev = loop'
where
loop' = do
threadDelay interval
v <- action
v' <- readIORef prev
if v /= v' then writeIORef prev v >> return v else loop'
-- | Runs the rest of the computation in a new thread. Returns 'empty' to the current thread
abduce = async $ return ()
-- | fork an independent process. It is equivalent to forkIO. The thread created
-- is managed with the thread control primitives of transient
fork :: TransIO () -> TransIO ()
fork proc= (abduce >> proc >> empty) <|> return()
-- | Run an IO action one or more times to generate a stream of tasks. The IO
-- action returns a 'StreamData'. When it returns an 'SMore' or 'SLast' a new
-- result is returned with the result value. If there are threads available, the res of the
-- computation is executed in a new thread. If the return value is 'SMore', the
-- action is run again to generate the next result, otherwise task creation
-- stop.
--
-- Unless the maximum number of threads (set with 'threads') has been reached,
-- the task is generated in a new thread and the current thread returns a void
-- task.
parallel :: IO (StreamData b) -> TransIO (StreamData b)
parallel ioaction = Transient $ do
--was <- gets execMode -- getData `onNothing` return Serial
--when (was /= Remote) $ modify $ \s -> s{execMode= Parallel}
modify $ \s -> s{execMode=let rs= execMode s in if rs /= Remote then Parallel else rs}
cont <- get
-- !> "PARALLEL"
case event cont of
j@(Just _) -> do
put cont { event = Nothing }
return $ unsafeCoerce j
Nothing -> do
liftIO $ atomicModifyIORef (labelth cont) $ \(_, lab) -> ((Parent, lab), ())
liftIO $ loop cont ioaction
return Nothing
-- | Execute the IO action and the continuation
loop :: EventF -> IO (StreamData t) -> IO ()
loop parentc rec = forkMaybe True parentc $ \cont -> do
-- Execute the IO computation and then the closure-continuation
liftIO $ atomicModifyIORef (labelth cont) $ \(_,label) -> ((Listener,label),())
let loop'= do
mdat <- rec `catch` \(e :: SomeException) -> return $ SError e
case mdat of
se@(SError _) -> setworker cont >> iocont se cont
SDone -> setworker cont >> iocont SDone cont
last@(SLast _) -> setworker cont >> iocont last cont
more@(SMore _) -> do
forkMaybe False cont $ iocont more
loop'
where
setworker cont= liftIO $ atomicModifyIORef (labelth cont) $ \(_,lab) -> ((Alive,lab),())
iocont dat cont = do
let cont'= cont{event= Just $ unsafeCoerce dat}
runStateT (runCont cont') cont'
return ()
loop'
return ()
where
{-# INLINABLE forkMaybe #-}
forkMaybe :: Bool -> EventF -> (EventF -> IO ()) -> IO ()
forkMaybe onemore parent proc = do
case maxThread parent of
Nothing -> forkIt parent proc
Just sem -> do
dofork <- waitQSemB onemore sem
if dofork then forkIt parent proc
else proc parent
`catch` \e ->exceptBack parent e >> return()
forkIt parent proc= do
chs <- liftIO $ newMVar []
label <- newIORef (Alive, BS.pack "work")
let cont = parent{parent=Just parent,children= chs, labelth= label}
forkFinally1 (do
th <- myThreadId
let cont'= cont{threadId=th}
when(not $ freeTh parent )$ hangThread parent cont'
-- !> ("thread created: ",th,"in",threadId parent )
proc cont')
$ \me -> do
case me of
Left e -> (exceptBack cont e >> return ()) -- !> "exceptBack 2"
_ -> return ()
case maxThread cont of
Just sem -> signalQSemB sem -- !> "freed thread"
Nothing -> return ()
when(not $ freeTh parent ) $ do -- if was not a free thread
th <- myThreadId
(can,label) <- atomicModifyIORef (labelth cont) $ \(l@(status,label)) ->
((if status== Alive then Dead else status, label),l)
when (can /= Parent ) $ free th parent
return ()
forkFinally1 :: IO a -> (Either SomeException a -> IO ()) -> IO ThreadId
forkFinally1 action and_then =
mask $ \restore -> forkIO $ Control.Exception.try (restore action) >>= and_then
free th env= do
-- return () !> ("freeing",th,"in",threadId env)
threadDelay 1000 -- wait for some activity in the children of the parent thread, to avoid
-- an early elimination
let sibling= children env
(sbs',found) <- modifyMVar sibling $ \sbs -> do
let (sbs', found) = drop [] th sbs
return (sbs',(sbs',found))
if found
then do
-- !> ("new list for",threadId env,map threadId sbs')
(typ,_) <- readIORef $ labelth env
if (null sbs' && typ /= Listener && isJust (parent env))
-- free the parent
then free (threadId env) ( fromJust $ parent env)
else return ()
else return () -- putMVar sibling sbs
-- !> (th,"orphan")
where
drop processed th []= (processed,False)
drop processed th (ev:evts)| th == threadId ev= (processed ++ evts, True)
| otherwise= drop (ev:processed) th evts
hangThread parentProc child = do
let headpths= children parentProc
modifyMVar_ headpths $ \ths -> return (child:ths)
-- !> ("hang", threadId child, threadId parentProc,map threadId ths,unsafePerformIO $ readIORef $ labelth parentProc)
-- | kill all the child threads associated with the continuation context
killChildren childs = do
forkIO $ do
ths <- modifyMVar childs $ \ths -> return ([],ths)
mapM_ (killChildren . children) ths
mapM_ (\th -> do
(status,_) <- readIORef $ labelth th
when (status /= Listener && status /= Parent) $ killThread $ threadId th !> ("killChildren",threadId th, status)) ths >> return ()
return ()
-- | capture a callback handler so that the execution of the current computation continues
-- whenever an event occurs. The effect is called "de-inversion of control"
--
-- The first parameter is a callback setter. The second parameter is a value to be
-- returned to the callback; if the callback expects no return value it
-- can just be @return ()@. The callback setter expects a function taking the
-- @eventdata@ as an argument and returning a value; this
-- function is the continuation, which is supplied by 'react'.
--
-- Callbacks from foreign code can be wrapped into such a handler and hooked
-- into the transient monad using 'react'. Every time the callback is called it
-- continues the execution on the current transient computation.
--
-- >
-- > do
-- > event <- react onEvent $ return ()
-- > ....
-- >
react
:: ((eventdata -> IO response) -> IO ())
-> IO response
-> TransIO eventdata
react setHandler iob= do
st <- cloneInChild "react"
liftIO $ atomicModifyIORef (labelth st) $ \(_,label) -> ((Listener,label),())
Transient $ do
modify $ \s -> s{execMode=let rs= execMode s in if rs /= Remote then Parallel else rs}
cont <- get
case event cont of
Nothing -> do
liftIO $ setHandler $ \dat ->do
runStateT (runCont cont) st{event= Just $ unsafeCoerce dat} `catch` exceptBack cont
iob
return Nothing
j@(Just _) -> do
put cont{event=Nothing}
return $ unsafeCoerce j
-- * Non-blocking keyboard input
-- getLineRef= unsafePerformIO $ newTVarIO Nothing
-- | listen stdin and triggers a new task every time the input data
-- matches the first parameter. The value contained by the task is the matched
-- value i.e. the first argument itself. The second parameter is a message for
-- the user. The label is displayed in the console when the option match.
option :: (Typeable b, Show b, Read b, Eq b) =>
b -> String -> TransIO b
option = optionf False
-- Implements the same functionality than `option` but only wait for one input
option1 :: (Typeable b, Show b, Read b, Eq b) =>
b -> String -> TransIO b
option1= optionf True
optionf :: (Typeable b, Show b, Read b, Eq b) =>
Bool -> b -> String -> TransIO b
optionf flag ret message = do
let sret= if typeOf ret == typeOf "" then unsafeCoerce ret else show ret
let msg= "Enter "++sret++"\t\tto: " ++ message++"\n"
inputf flag sret msg Nothing ( == sret)
liftIO $ putStr "\noption: " >> putStrLn sret
-- abduce
return ret
-- | General asynchronous console input.
--
-- inputf <remove input listener after sucessful or not> <listener identifier> <prompt>
-- <Maybe default value> <validation proc>
inputf :: (Show a, Read a,Typeable a) => Bool -> String -> String -> Maybe a -> (a -> Bool) -> TransIO a
inputf remove ident message mv cond = do
let loop= do
liftIO $ putStr message >> hFlush stdout
str <- react (addConsoleAction ident message) (return ())
when remove $ do removeChild; liftIO $ delConsoleAction ident
c <- liftIO $ readIORef rconsumed
if c then returnm mv else do
let rr = read1 str
case (rr,str) of
(Nothing,_) -> do (liftIO $ when (isJust mv) $ putStrLn ""); returnm mv
(Just x,"") -> do (liftIO $ do writeIORef rconsumed True; print x); returnm mv
(Just x,_) -> if cond x
then liftIO $ do
writeIORef rconsumed True
print x
-- hFlush stdout
return x
else do liftIO $ when (isJust mv) $ putStrLn ""
returnm mv
loop
where
returnm (Just x)= return x
returnm _ = empty
-- read1 :: String -> Maybe a
read1 s= r
where
typ= typeOf $ fromJust r
r = if typ == typeOf "" then Just $ unsafeCoerce s
else if typ == typeOf (BS.pack "") then Just $ unsafeCoerce $ BS.pack s
else if typ == typeOf (BSL.pack "") then Just $ unsafeCoerce $ BSL.pack s
else case reads s of
[] -> Nothing
[(x,"")] -> Just x
-- | Waits on stdin and return a value when a console input matches the
-- predicate specified in the first argument. The second parameter is a string
-- to be displayed on the console before waiting.
input :: (Typeable a, Read a,Show a) => (a -> Bool) -> String -> TransIO a
input= input' Nothing
-- | `input` with a default value
input' :: (Typeable a, Read a,Show a) => Maybe a -> (a -> Bool) -> String -> TransIO a
input' mv cond prompt= do
--liftIO $ putStr prompt >> hFlush stdout
inputf True "input" prompt mv cond
rcb= unsafePerformIO $ newIORef [] :: IORef [ (String,String,String -> IO())]
addConsoleAction :: String -> String -> (String -> IO ()) -> IO ()
addConsoleAction name message cb= atomicModifyIORef rcb $ \cbs ->
((name,message, cb) : filter ((/=) name . fst) cbs ,())
where
fst (x,_,_)= x
delConsoleAction :: String -> IO ()
delConsoleAction name= atomicModifyIORef rcb $ \cbs -> (filter ((/=) name . fst) cbs,())
where
fst (x,_,_)= x
reads1 s=x where
x= if typeOf(typeOfr x) == typeOf "" then unsafeCoerce[(s,"")] else readsPrec' 0 s
typeOfr :: [(a,String)] -> a
typeOfr = undefined
read1 s= let [(x,"")]= reads1 s in x
rprompt= unsafePerformIO $ newIORef "> "
inputLoop= do
prompt <- readIORef rprompt
when (not $ null prompt) $ do putStr prompt ; hFlush stdout
line <- getLine
--threadDelay 1000000
processLine line
inputLoop
`catch` \(SomeException _) -> inputLoop -- myThreadId >>= killThread
{-# NOINLINE rconsumed #-}
rconsumed = unsafePerformIO $ newIORef False
{-# NOINLINE lineprocessmode #-}
lineprocessmode= unsafePerformIO $ newIORef False
processLine r = do
linepro <- readIORef lineprocessmode
if linepro then do
mapM' invokeParsers [r]
else do
let rs = breakSlash [] r
mapM' invokeParsers rs
where
invokeParsers x= do
mbs <- readIORef rcb
mapM_ (\cb -> cb x) $ map (\(_,_,p)-> p) mbs
mapM' _ []= return ()
mapM' f (xss@(x:xs)) =do
f x
r <- readIORef rconsumed
if r
then do
writeIORef riterloop 0
writeIORef rconsumed False
mapM' f xs
else do
threadDelay 1000
n <- atomicModifyIORef riterloop $ \n -> (n+1,n)
if n==1
then do
when (not $ null x) $ hPutStr stderr x >> hPutStrLn stderr ": can't read, skip"
writeIORef riterloop 0
writeIORef rconsumed False
mapM' f xs
else mapM' f xss
riterloop= unsafePerformIO $ newIORef 0
breakSlash :: [String] -> String -> [String]
breakSlash [] ""= [""]
breakSlash s ""= s
breakSlash res ('\"':s)=
let (r,rest) = span(/= '\"') s
in breakSlash (res++[r]) $ tail1 rest
breakSlash res s=
let (r,rest) = span(\x -> (not $ elem x "/,:") && x /= ' ') s
in breakSlash (res++[r]) $ tail1 rest
tail1 []= []
tail1 x= tail x
-- >>> breakSlash [] "test.hs/0/\"-prof -auto\""
-- ["test.hs","0","-prof -auto"]
--
-- | Wait for the execution of `exit` and return the result or the exhaustion of thread activity
stay rexit= takeMVar rexit
`catch` \(e :: BlockedIndefinitelyOnMVar) -> return Nothing
newtype Exit a= Exit a deriving Typeable
-- | Runs the transient computation in a child thread and keeps the main thread
-- running until all the user threads exit or some thread 'exit'.
--
-- The main thread provides facilities for accepting keyboard input in a
-- non-blocking but line-oriented manner. The program reads the standard input
-- and feeds it to all the async input consumers (e.g. 'option' and 'input').
-- All async input consumers contend for each line entered on the standard
-- input and try to read it atomically. When a consumer consumes the input
-- others do not get to see it, otherwise it is left in the buffer for others
-- to consume. If nobody consumes the input, it is discarded.
--
-- A @/@ in the input line is treated as a newline.
--
-- When using asynchronous input, regular synchronous IO APIs like getLine
-- cannot be used as they will contend for the standard input along with the
-- asynchronous input thread. Instead you can use the asynchronous input APIs
-- provided by transient.
--
-- A built-in interactive command handler also reads the stdin asynchronously.
-- All available options waiting for input are displayed when the
-- program is run. The following commands are available:
--
-- 1. @ps@: show threads
-- 2. @log@: inspect the log of a thread
-- 3. @end@, @exit@: terminate the program
--
-- An input not handled by the command handler can be handled by the program.
--
-- The program's command line is scanned for @-p@ or @--path@ command line
-- options. The arguments to these options are injected into the async input
-- channel as keyboard input to the program. Each line of input is separated by
-- a @/@. For example:
--
-- > foo -p ps/end
--
keep :: Typeable a => TransIO a -> IO (Maybe a)
keep mx = do
liftIO $ hSetBuffering stdout LineBuffering
rexit <- newEmptyMVar
void $ forkIO $ do
-- liftIO $ putMVar rexit $ Right Nothing
let logFile= "trans.log"
void $ runTransient $ do
liftIO $ removeFile logFile `catch` \(e :: IOError) -> return ()
onException $ \(e :: SomeException) -> do
--top <- topState
liftIO $ print e
--showThreads top`
--liftIO $ appendFile logFile $ show e ++ "\n" -- `catch` \(e:: IOError) -> exc
empty
onException $ \(e :: IOException) -> do
when (ioeGetErrorString e == "resource busy") $ do
liftIO $ do print e ; putStrLn "EXITING!!!"; putMVar rexit Nothing
empty
st <- get
setData $ Exit rexit
do
option "options" "show all options"
mbs <- liftIO $ readIORef rcb
liftIO $ mapM_ (\c ->do putStr c; putStr "|") $ map (\(fst,_,_) -> fst)mbs
d <- input' (Just "n") (\x -> x=="y" || x =="n" || x=="Y" || x=="N") "\nDetails? N/y "
when (d == "y") $
let line (x,y,_)= putStr y -- do putStr x; putStr "\t\t"; putStrLn y
in liftIO $ mapM_ line mbs
liftIO $ putStrLn ""
empty
<|> do
option "ps" "show threads"
liftIO $ showThreads st
empty
<|> do
option "errs" "show exceptions log"
c <- liftIO $ readFile logFile `catch` \(e:: IOError) -> return ""
liftIO . putStrLn $ if null c then "no errors logged" else c
empty
{-
<|> do
option "log" "inspect the log of a thread"
th <- input (const True) "thread number>"
ml <- liftIO $ getStateFromThread th st
liftIO $ print $ fmap (\(Log _ _ log _) -> reverse log) ml
empty
-}
<|> do
option "end" "exit"
liftIO $ putStrLn "exiting..."
abduce
killChilds
liftIO $ putMVar rexit Nothing
empty
<|> mx
#ifndef ghcjs_HOST_OS
<|> do
abduce
liftIO $ execCommandLine
labelState (fromString "input")
liftIO inputLoop
empty
#endif
return ()
stay rexit
where
type1 :: TransIO a -> Either String (Maybe a)
type1= undefined
-- | Same as `keep` but does not read from the standard input, and therefore
-- the async input APIs ('option' and 'input') cannot respond interactively.
-- However, input can still be passed via command line arguments as
-- described in 'keep'. Useful for debugging or for creating background tasks,
-- as well as to embed the Transient monad inside another computation. It
-- returns either the value returned by `exit` or Nothing, when there are no
-- more threads running
--
keep' :: Typeable a => TransIO a -> IO (Maybe a)
keep' mx = do
liftIO $ hSetBuffering stdout LineBuffering
rexit <- newEmptyMVar
void $ forkIO $ do
void $ runTransient $ do
onException $ \(e :: SomeException ) -> do
top <- topState
liftIO $ do
th <- myThreadId
putStr $ show th
putStr ": "
print e
putStrLn "Threads:"
showThreads top
empty
onException $ \(e :: IOException) -> do
when (ioeGetErrorString e == "resource busy") $ do
liftIO $ do print e ; putStrLn "EXITING!!!"; putMVar rexit Nothing
liftIO $ putMVar rexit Nothing
empty
setData $ Exit rexit
mx
return ()
threadDelay 10000
forkIO $ execCommandLine
stay rexit
execCommandLine= do
args <- getArgs
let mindex = findIndex (\o -> o == "-p" || o == "--path" ) args
when (isJust mindex) $ do
let i= fromJust mindex +1
when (length args >= i) $ do
let path= args !! i
--print $ drop (i-1) args
--putStr "Executing: " >> print path
processLine path
-- | Exit the main thread with a result, and thus all the Transient threads (and the
-- application if there is no more code)
exit :: Typeable a => a -> TransIO a
exit x= do
Exit rexit <- getSData <|> error "exit: not the type expected" `asTypeOf` type1 x
liftIO $ putMVar rexit $ Just x
stop
where
type1 :: a -> TransIO (Exit (MVar (Maybe a)))
type1= undefined
-- | If the first parameter is 'Nothing' return the second parameter otherwise
-- return the first parameter..
onNothing :: Monad m => m (Maybe b) -> m b -> m b
onNothing iox iox'= do
mx <- iox
case mx of
Just x -> return x
Nothing -> iox'
----------------------------------backtracking ------------------------
data Backtrack b= Show b =>Backtrack{backtracking :: Maybe b
,backStack :: [EventF] }
deriving Typeable
-- | Delete all the undo actions registered till now for the given track id.
backCut :: (Typeable b, Show b) => b -> TransientIO ()
backCut reason= Transient $ do
delData $ Backtrack (Just reason) []
return $ Just ()
-- | 'backCut' for the default track; equivalent to @backCut ()@.
undoCut :: TransientIO ()
undoCut = backCut ()
-- | Run the action in the first parameter and register the second parameter as
-- the undo action. On undo ('back') the second parameter is called with the
-- undo track id as argument.
--
{-# NOINLINE onBack #-}
onBack :: (Typeable b, Show b) => TransientIO a -> ( b -> TransientIO a) -> TransientIO a
onBack ac bac = registerBack (typeof bac) $ Transient $ do
tr "onBack"
Backtrack mreason stack <- getData `onNothing` (return $ backStateOf (typeof bac))
runTrans $ case mreason of
Nothing -> ac -- !> "ONBACK NOTHING"
Just reason -> bac reason -- !> ("ONBACK JUST",reason)
where
typeof :: (b -> TransIO a) -> b
typeof = undefined
-- | 'onBack' for the default track; equivalent to @onBack ()@.
onUndo :: TransientIO a -> TransientIO a -> TransientIO a
onUndo x y= onBack x (\() -> y)
-- | Register an undo action to be executed when backtracking. The first
-- parameter is a "witness" whose data type is used to uniquely identify this
-- backtracking action. The value of the witness parameter is not used.
--
{-# NOINLINE registerUndo #-}
registerBack :: (Typeable b, Show b) => b -> TransientIO a -> TransientIO a
registerBack witness f = Transient $ do
tr "registerBack"
cont@(EventF _ x _ _ _ _ _ _ _ _ _ _ _) <- get
-- if isJust (event cont) then return Nothing else do
md <- getData `asTypeOf` (Just <$> return (backStateOf witness))
case md of
Just (Backtrack b []) -> setData $ Backtrack b [cont]
Just (bss@(Backtrack b (bs@((EventF _ x' _ _ _ _ _ _ _ _ _ _ _):_)))) ->
when (isNothing b) $
setData $ Backtrack b (cont:bs)
Nothing -> setData $ Backtrack mwit [cont]
runTrans $ return () >> f
where
mwit= Nothing `asTypeOf` (Just witness)
--addr x = liftIO $ return . hashStableName =<< (makeStableName $! x)
registerUndo :: TransientIO a -> TransientIO a
registerUndo f= registerBack () f
-- XXX Should we enforce retry of the same track which is being undone? If the
-- user specifies a different track would it make sense?
-- see https://gitter.im/Transient-Transient-Universe-HPlay/Lobby?at=5ef46626e0e5673398d33afb
--
-- | For a given undo track type, stop executing more backtracking actions and
-- resume normal execution in the forward direction. Used inside an undo
-- action.
--
forward :: (Typeable b, Show b) => b -> TransIO ()
forward reason= noTrans $ do
Backtrack _ stack <- getData `onNothing` ( return $ backStateOf reason)
setData $ Backtrack(Nothing `asTypeOf` Just reason) stack
-- | put at the end of an backtrack handler intended to backtrack to other previous handlers.
-- This is the default behaviour in transient. `backtrack` is in order to keep the type compiler happy
backtrack :: TransIO a
backtrack= return $ error "backtrack should be called at the end of an exception handler with no `forward`, `continue` or `retry` on it"
-- | 'forward' for the default undo track; equivalent to @forward ()@.
retry= forward ()
-- | Abort finish. Stop executing more finish actions and resume normal
-- execution. Used inside 'onFinish' actions.
--
noFinish= continue
-- | Start the undo process for a given undo track identifier type. Performs all the undo
-- actions registered for that type in reverse order. An undo action can use
-- 'forward' to stop the undo process and resume forward execution. If there
-- are no more undo actions registered, execution stop
--
back :: (Typeable b, Show b) => b -> TransIO a
back reason = do
tr "back"
bs <- getData `onNothing` return (backStateOf reason)
goBackt bs -- !>"GOBACK"
where
runClosure :: EventF -> TransIO a
runClosure EventF { xcomp = x } = unsafeCoerce x
runContinuation :: EventF -> a -> TransIO b
runContinuation EventF { fcomp = fs } = (unsafeCoerce $ compose fs)
goBackt (Backtrack _ [] )= empty
goBackt (Backtrack b (stack@(first : bs)) )= do
setData $ Backtrack (Just reason) bs --stack
x <- runClosure first !> ("RUNCLOSURE",length stack)
Backtrack back bs' <- getData `onNothing` return (backStateOf reason)
case back of
Nothing -> do
setData $ Backtrack (Just reason) stack
st <- get
runContinuation first x `catcht` (\e -> liftIO(exceptBack st e) >> empty) !> "FORWARD EXEC"
justreason -> do
--setData $ Backtrack justreason bs
goBackt $ Backtrack justreason bs !> ("BACK AGAIN",back)
empty
backStateOf :: (Show a, Typeable a) => a -> Backtrack a
backStateOf reason= Backtrack (Nothing `asTypeOf` (Just reason)) []
data BackPoint a = BackPoint (IORef [a -> TransIO()])
-- | a backpoint is a location in the code where callbacks can be installed and will be called when the backtracing pass trough that point.
-- Normally used for exceptions.
backPoint :: (Typeable reason,Show reason) => TransIO (BackPoint reason)
backPoint = do
point <- liftIO $ newIORef []
return () `onBack` (\e -> do
rs <- liftIO $ readIORef point
mapM_ (\r -> r e) rs)
return $ BackPoint point
-- | install a callback in a backPoint
onBackPoint :: MonadIO m => BackPoint t -> (t -> TransIO ()) -> m ()
onBackPoint (BackPoint ref) handler= liftIO $ atomicModifyIORef ref $ \rs -> (handler:rs,())
-- | 'back' for the default undo track; equivalent to @back ()@.
--
undo :: TransIO a
undo= back ()
------ finalization
newtype Finish= Finish String deriving Show
instance Exception Finish
-- newtype FinishReason= FinishReason (Maybe SomeException) deriving (Typeable, Show)
-- | Clear all finish actions registered till now.
-- initFinish= backCut (FinishReason Nothing)
-- | Register an action that to be run when 'finish' is called. 'onFinish' can
-- be used multiple times to register multiple actions. Actions are run in
-- reverse order. Used in infix style.
--
onFinish :: (Finish ->TransIO ()) -> TransIO ()
onFinish f= onException' (return ()) f
-- | Run the action specified in the first parameter and register the second
-- parameter as a finish action to be run when 'finish' is called. Used in
-- infix style.
--
onFinish' ::TransIO a ->(Finish ->TransIO a) -> TransIO a
onFinish' proc f= proc `onException'` f
-- | Execute all the finalization actions registered up to the last
-- 'initFinish', in reverse order and continue the execution. Either an exception or 'Nothing' can be
initFinish = cutExceptions
-- passed to 'finish'. The argument passed is made available in the 'onFinish'
--
finish :: String -> TransIO ()
finish reason= (throwt $ Finish reason) <|> return()
-- | trigger finish when the stream of data ends
checkFinalize v=
case v of
SDone -> stop
SLast x -> return x
SError e -> throwt e
SMore x -> return x
------ exceptions ---
--
-- | Install an exception handler. Handlers are executed in reverse (i.e. last in, first out) order when such exception happens in the
-- continuation. Note that multiple handlers can be installed for the same exception type.
--
-- The semantic is, thus, very different than the one of `Control.Exception.Base.onException`
onException :: Exception e => (e -> TransIO ()) -> TransIO ()
onException exc= return () `onException'` exc
-- | set an exception point. Thi is a point in the backtracking in which exception handlers can be inserted with `onExceptionPoint`
-- it is an specialization of `backPoint` for exceptions.
--
-- When an exception backtracking reach the backPoint it executes all the handlers registered for it.
--
-- Use case: suppose that when a connection fails, you need to stop a process.
-- This process may not be started before the connection. Perhaps it was initiated after the socket read
-- so an exception will not backtrack trough the process, since it is downstream, not upstream. The process may
-- be even unrelated to the connection, in other branch of the computation.
--
-- in this case you only need to create a `exceptionPoint` before stablishin the connection, and use `onExceptionPoint`
-- to set a handler that will be called when the connection fail.
exceptionPoint :: Exception e => TransIO (BackPoint e)
exceptionPoint = do
point <- liftIO $ newIORef []
return () `onException'` (\e -> do
rs<- liftIO $ readIORef point
mapM_ (\r -> r e) rs)
return $ BackPoint point
-- | in conjunction with `backPoint` it set a handler that will be called when backtracking pass
-- trough the point
onExceptionPoint :: Exception e => BackPoint e -> (e -> TransIO()) -> TransIO ()
onExceptionPoint= onBackPoint
onException' :: Exception e => TransIO a -> (e -> TransIO a) -> TransIO a
onException' mx f= onAnyException mx $ \e -> do
--return () !> "EXCEPTION HANDLER EXEC"
case fromException e of
Nothing -> do
Backtrack r stack <- getData `onNothing` return (backStateOf e)
setData $ Backtrack r $ tail stack
back e
empty
Just e' -> f e'
where
onAnyException :: TransIO a -> (SomeException ->TransIO a) -> TransIO a
onAnyException mx exc= ioexp `onBack` exc
ioexp = Transient $ do
st <- get
(mr,st') <- liftIO $ (runStateT
(do
case event st of
Nothing -> do
r <- runTrans mx
modify $ \s -> s{event= Just $ unsafeCoerce r}
runCont st
-- was <- gets execMode -- getData `onNothing` return Serial
-- when (was /= Remote) $ modify $ \s -> s{execMode= Parallel}
modify $ \s -> s{execMode=let rs= execMode s in if rs /= Remote then Parallel else rs}
return Nothing
Just r -> do
modify $ \s -> s{event=Nothing}
return $ unsafeCoerce r) st)
`catch` exceptBack st
put st'
return mr
exceptBack st = \(e ::SomeException) -> do
tr "catched"
runStateT ( runTrans $ back e ) st -- !> "EXCEPTBACK"
-- `catch` exceptBack st -- removed
-- re execute the first argument as long as the exception is produced within the argument.
-- The second argument is executed before every re-execution
-- if the second argument executes `empty` the execution is aborted.
whileException :: Exception e => TransIO b -> (e -> TransIO()) -> TransIO b
whileException mx fixexc = mx `catcht` \e -> do fixexc e; whileException mx fixexc
-- | Delete all the exception handlers registered till now.
cutExceptions :: TransIO ()
cutExceptions= backCut (undefined :: SomeException)
-- | Use it inside an exception handler. it stop executing any further exception
-- handlers and resume normal execution from this point on.
continue :: TransIO ()
continue = forward (undefined :: SomeException) -- !> "CONTINUE"
-- | catch an exception in a Transient block
--
-- The semantic is the same than `catch` but the computation and the exception handler can be multirhreaded
catcht :: Exception e => TransIO b -> (e -> TransIO b) -> TransIO b
catcht mx exc= do
st <- get
(mx,st') <- liftIO $ runStateT ( runTrans $ mx ) st `catch` \e -> runStateT ( runTrans $ exc e ) st
put st'
case mx of
Just x -> return x
Nothing -> empty
-- | catch an exception in a Transient block
--
-- The semantic is the same than `catch` but the computation and the exception handler can be multirhreaded
catcht' :: Exception e => TransIO b -> (e -> TransIO b) -> TransIO b
catcht' mx exc= do
rpassed <- liftIO $ newIORef False
sandbox $ do
r <- onException' mx (\e -> do
passed <- liftIO $ readIORef rpassed
return () !> ("CATCHT passed", passed)
if not passed then continue >> exc e else do
Backtrack r stack <- getData `onNothing` return (backStateOf e)
setData $ Backtrack r $ tail stack
back e
return () !> "AFTER BACK"
empty )
liftIO $ writeIORef rpassed True
return r
where
sandbox mx= do
exState <- getState <|> return (backStateOf (undefined :: SomeException))
mx
<*** do setState exState
-- | throw an exception in the Transient monad
-- there is a difference between `throw` and `throwt` since the latter preserves the state, while the former does not.
-- Any exception not thrown with `throwt` does not preserve the state.
--
-- > main= keep $ do
-- > onException $ \(e:: SomeException) -> do
-- > v <- getState <|> return "hello"
-- > liftIO $ print v
-- > setState "world"
-- > throw $ ErrorCall "asdasd"
--
-- the latter print "hello". If you use `throwt` instead, it prints "world"
throwt :: Exception e => e -> TransIO a
throwt = back . toException