{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE NamedFieldPuns #-}
{-# LANGUAGE Rank2Types #-}
{-# LANGUAGE ScopedTypeVariables #-}
-----------------------------------------------------------------------------
-- |
-- Module : Test.StateMachine.Parallel
-- Copyright : (C) 2017, ATS Advanced Telematic Systems GmbH
-- License : BSD-style (see the file LICENSE)
--
-- Maintainer : Stevan Andjelkovic <stevan@advancedtelematic.com>
-- Stability : provisional
-- Portability : non-portable (GHC extensions)
--
-- This module contains helpers for generating, shrinking, and checking
-- parallel programs.
--
-----------------------------------------------------------------------------
module Test.StateMachine.Parallel
( forAllParallelCommands
, generateParallelCommands
, shrinkParallelCommands
, validParallelCommands
, prop_splitCombine
, runParallelCommands
, runParallelCommandsNTimes
, linearise
, toBoxDrawings
, prettyParallelCommands
) where
import Control.Arrow
((***))
import Control.Concurrent.Async.Lifted
(concurrently)
import Control.Concurrent.STM.TChan
(newTChanIO)
import Control.Monad
(foldM, replicateM)
import Control.Monad.Catch
(MonadCatch)
import Control.Monad.State
(MonadIO, State, evalState, put, runStateT)
import Control.Monad.Trans.Control
(MonadBaseControl, liftBaseWith)
import Data.Bifunctor
(bimap)
import Data.List
(partition, permutations)
import Data.List.Split
(splitPlacesBlanks)
import Data.Monoid
((<>))
import Data.Set
(Set)
import qualified Data.Set as S
import Data.Tree
(Tree(Node))
import GHC.Generics
(Generic1, Rep1)
import Prelude
import Test.QuickCheck
(Gen, Property, Testable, choose, property,
shrinkList, sized)
import Test.QuickCheck.Monadic
(PropertyM, run)
import Text.PrettyPrint.ANSI.Leijen
(Doc)
import Text.Show.Pretty
(ppShow)
import Test.StateMachine.BoxDrawer
import Test.StateMachine.ConstructorName
import Test.StateMachine.Logic
(boolean)
import Test.StateMachine.Sequential
import Test.StateMachine.Types
import qualified Test.StateMachine.Types.Rank2 as Rank2
import Test.StateMachine.Utils
------------------------------------------------------------------------
forAllParallelCommands :: Testable prop
=> (Show (cmd Symbolic), Show (model Symbolic))
=> (Generic1 cmd, GConName1 (Rep1 cmd))
=> (Rank2.Foldable cmd, Rank2.Foldable resp)
=> StateMachine model cmd m resp
-> (ParallelCommands cmd -> prop) -- ^ Predicate.
-> Property
forAllParallelCommands sm =
forAllShrinkShow (generateParallelCommands sm) (shrinkParallelCommands sm) ppShow
generateParallelCommands :: forall model cmd m resp
. (Rank2.Foldable resp, Show (model Symbolic))
=> (Generic1 cmd, GConName1 (Rep1 cmd))
=> StateMachine model cmd m resp
-> Gen (ParallelCommands cmd)
generateParallelCommands sm@StateMachine { initModel } = do
Commands cmds <- generateCommands sm Nothing
prefixLength <- sized (\k -> choose (0, k `div` 3))
let (prefix, rest) = bimap Commands Commands (splitAt prefixLength cmds)
return (ParallelCommands prefix
(makeSuffixes (advanceModel sm initModel newCounter prefix) rest))
where
makeSuffixes :: (model Symbolic, Counter) -> Commands cmd -> [Pair (Commands cmd)]
makeSuffixes (model0, counter0) = go (model0, counter0) [] . unCommands
where
go _ acc [] = reverse acc
go (model, counter) acc cmds = go (advanceModel sm model counter (Commands safe))
(Pair (Commands safe1) (Commands safe2) : acc)
rest
where
(safe, rest) = spanSafe model counter [] cmds
(safe1, safe2) = splitAt (length safe `div` 2) safe
suffixLength = 5
spanSafe :: model Symbolic -> Counter -> [Command cmd] -> [Command cmd]
-> ([Command cmd], [Command cmd])
spanSafe _ _ safe [] = (reverse safe, [])
spanSafe model counter safe (cmd@(Command _ _) : cmds)
| length safe <= suffixLength &&
parallelSafe sm model counter (Commands (cmd : safe)) =
spanSafe model counter (cmd : safe) cmds
| otherwise = (reverse safe, cmd : cmds)
-- | A list of commands is parallel safe if the pre-conditions for all commands
-- hold in all permutations of the list.
parallelSafe :: StateMachine model cmd m resp -> model Symbolic
-> Counter -> Commands cmd -> Bool
parallelSafe StateMachine { precondition, transition, mock } model0 counter0
= and
. map (preconditionsHold model0 counter0)
. permutations
. unCommands
where
preconditionsHold _ _ [] = True
preconditionsHold model counter (Command cmd _vars : cmds) =
let
(resp, counter') = runGenSym (mock model cmd) counter
in
boolean (precondition model cmd) &&
preconditionsHold (transition model cmd resp) counter' cmds
-- | Apply the transition of some commands to a model.
advanceModel :: StateMachine model cmd m resp
-> model Symbolic -- ^ The model.
-> Counter
-> Commands cmd -- ^ The commands.
-> (model Symbolic, Counter)
advanceModel StateMachine { transition, mock } model0 counter0 =
go model0 counter0 . unCommands
where
go model counter [] = (model, counter)
go model counter (Command cmd _vars : cmds) =
let
(resp, counter') = runGenSym (mock model cmd) counter
in
go (transition model cmd resp) counter' cmds
------------------------------------------------------------------------
-- | Shrink a parallel program in a pre-condition and scope respecting
-- way.
shrinkParallelCommands
:: forall cmd model m resp. Rank2.Foldable cmd
=> Rank2.Foldable resp
=> StateMachine model cmd m resp
-> (ParallelCommands cmd -> [ParallelCommands cmd])
shrinkParallelCommands sm@StateMachine { shrinker, initModel }
(ParallelCommands prefix suffixes)
= filterMaybe (flip evalState (initModel, S.empty, newCounter) . validParallelCommands sm)
[ ParallelCommands prefix' (map toPair suffixes')
| (prefix', suffixes') <- shrinkPair' shrinkCommands' shrinkSuffixes
(prefix, map fromPair suffixes)
]
++
shrinkMoveSuffixToPrefix
where
shrinkCommands' :: Commands cmd -> [Commands cmd]
shrinkCommands'
= map Commands
. shrinkList (liftShrinkCommand shrinker)
. unCommands
shrinkSuffixes :: [(Commands cmd, Commands cmd)] -> [[(Commands cmd, Commands cmd)]]
shrinkSuffixes = shrinkList (shrinkPair shrinkCommands')
shrinkMoveSuffixToPrefix :: [ParallelCommands cmd]
shrinkMoveSuffixToPrefix = case suffixes of
[] -> []
(suffix : suffixes') ->
[ ParallelCommands (prefix <> Commands [prefix'])
(fmap Commands (toPair suffix') : suffixes')
| (prefix', suffix') <- pickOneReturnRest2 (unCommands (proj1 suffix),
unCommands (proj2 suffix))
]
pickOneReturnRest :: [a] -> [(a, [a])]
pickOneReturnRest [] = []
pickOneReturnRest (x : xs) = (x, xs) : map (id *** (x :)) (pickOneReturnRest xs)
pickOneReturnRest2 :: ([a], [a]) -> [(a, ([a],[a]))]
pickOneReturnRest2 (xs, ys) =
map (id *** flip (,) ys) (pickOneReturnRest xs) ++
map (id *** (,) xs) (pickOneReturnRest ys)
validParallelCommands :: forall model cmd m resp. (Rank2.Foldable cmd, Rank2.Foldable resp)
=> StateMachine model cmd m resp -> ParallelCommands cmd
-> State (model Symbolic, Set Var, Counter) (Maybe (ParallelCommands cmd))
validParallelCommands sm@StateMachine { initModel } (ParallelCommands prefix suffixes) = do
let prefixLength = lengthCommands prefix
leftSuffixes = map (\(Pair l _r) -> l) suffixes
rightSuffixes = map (\(Pair _l r) -> r) suffixes
leftSuffixLengths = map lengthCommands leftSuffixes
rightSuffixLengths = map lengthCommands rightSuffixes
leftSuffix = mconcat leftSuffixes
rightSuffix = mconcat rightSuffixes
mleft <- validCommands sm (prefix <> leftSuffix)
put (initModel, S.empty, newCounter)
mright <- validCommands sm (prefix <> rightSuffix)
case (mleft, mright) of
(Nothing, Nothing) -> return Nothing
(Just _, Nothing) -> return Nothing
(Nothing, Just _) -> return Nothing
(Just left, Just right) ->
case (splitPlacesBlanks (prefixLength : leftSuffixLengths) (unCommands left),
splitPlacesBlanks (prefixLength : rightSuffixLengths) (unCommands right)) of
([] , []) -> error "validParallelCommands: impossible"
([] , _ : _) -> error "validParallelCommands: impossible"
(_ : _ , []) -> error "validParallelCommands: impossible"
(prefix' : leftSuffixes', _ : rightSuffixes') -> do
let suffixes' = zipWith Pair (map Commands leftSuffixes')
(map Commands rightSuffixes')
(model', counter') = advanceModel sm initModel newCounter (Commands prefix')
if parallelSafeMany sm model' counter' suffixes'
then return (Just (ParallelCommands (Commands prefix') suffixes'))
else return Nothing
parallelSafeMany :: StateMachine model cmd m resp -> model Symbolic
-> Counter -> [Pair (Commands cmd)] -> Bool
parallelSafeMany sm = go
where
go _ _ [] = True
go model counter (Pair cmds1 cmds2 : cmdss) = parallelSafe sm model counter cmds
&& go model' counter' cmdss
where
cmds = cmds1 <> cmds2
(model', counter') = advanceModel sm model counter cmds
prop_splitCombine :: [[Int]] -> Bool
prop_splitCombine xs = splitPlacesBlanks (map length xs) (concat xs) == xs
------------------------------------------------------------------------
runParallelCommands :: (Rank2.Traversable cmd, Rank2.Foldable resp)
=> (MonadCatch m, MonadBaseControl IO m)
=> StateMachine model cmd m resp
-> ParallelCommands cmd
-> PropertyM m [(History cmd resp, Bool)]
runParallelCommands sm = runParallelCommandsNTimes 10 sm
runParallelCommandsNTimes :: (Rank2.Traversable cmd, Rank2.Foldable resp)
=> (MonadCatch m, MonadBaseControl IO m)
=> Int -- ^ How many times to execute the parallel program.
-> StateMachine model cmd m resp
-> ParallelCommands cmd
-> PropertyM m [(History cmd resp, Bool)]
runParallelCommandsNTimes n sm cmds =
replicateM n $ do
(hist, _reason) <- run (executeParallelCommands sm cmds)
return (hist, linearise sm hist)
executeParallelCommands :: (Rank2.Traversable cmd, Rank2.Foldable resp)
=> (MonadCatch m, MonadBaseControl IO m)
=> StateMachine model cmd m resp
-> ParallelCommands cmd
-> m (History cmd resp, Reason)
executeParallelCommands sm@StateMachine{ initModel } (ParallelCommands prefix suffixes) = do
hchan <- liftBaseWith (const newTChanIO)
(reason0, (env0, _cmodel)) <- runStateT
(executeCommands sm hchan (Pid 0) True prefix)
(emptyEnvironment, initModel)
if reason0 /= Ok
then do
hist <- liftBaseWith (const (getChanContents hchan))
return (History hist, reason0)
else do
(reason, _) <- foldM (go hchan) (reason0, env0) suffixes
hist <- liftBaseWith (const (getChanContents hchan))
return (History hist, reason)
where
go hchan (_, env) (Pair cmds1 cmds2) = do
((reason1, (env1, _)), (reason2, (env2, _))) <- concurrently
-- XXX: Post-conditions not checked, so we can pass in initModel here...
-- It would be better if we made executeCommands take a Maybe model
-- instead of the boolean...
(runStateT (executeCommands sm hchan (Pid 1) False cmds1) (env, initModel))
(runStateT (executeCommands sm hchan (Pid 2) False cmds2) (env, initModel))
return ( reason1 `combineReason` reason2
, env1 <> env2
)
where
combineReason :: Reason -> Reason -> Reason
combineReason Ok r2 = r2
combineReason r1 _ = r1
------------------------------------------------------------------------
-- | Try to linearise a history of a parallel program execution using a
-- sequential model. See the *Linearizability: a correctness condition for
-- concurrent objects* paper linked to from the README for more info.
linearise :: forall model cmd m resp. StateMachine model cmd m resp
-> History cmd resp -> Bool
linearise StateMachine { transition, postcondition, initModel } = go . unHistory
where
go :: [(Pid, HistoryEvent cmd resp)] -> Bool
go [] = True
go es = any (step initModel) (interleavings es)
step :: model Concrete -> Tree (Operation cmd resp) -> Bool
step model (Node (Operation cmd resp _) roses) =
boolean (postcondition model cmd resp) &&
any' (step (transition model cmd resp)) roses
any' :: (a -> Bool) -> [a] -> Bool
any' _ [] = True
any' p xs = any p xs
------------------------------------------------------------------------
-- | Takes the output of parallel program runs and pretty prints a
-- counterexample if any of the runs fail.
prettyParallelCommands :: (MonadIO m, Rank2.Foldable cmd)
=> (Show (cmd Concrete), Show (resp Concrete))
=> ParallelCommands cmd
-> [(History cmd resp, Bool)] -- ^ Output of 'runParallelCommands'.
-> PropertyM m ()
prettyParallelCommands cmds =
mapM_ (\(hist, bool) -> print (toBoxDrawings cmds hist) `whenFailM` property bool)
-- | Draw an ASCII diagram of the history of a parallel program. Useful for
-- seeing how a race condition might have occured.
toBoxDrawings :: forall cmd resp. Rank2.Foldable cmd
=> (Show (cmd Concrete), Show (resp Concrete))
=> ParallelCommands cmd -> History cmd resp -> Doc
toBoxDrawings (ParallelCommands prefix suffixes) = toBoxDrawings'' allVars
where
allVars = getAllUsedVars prefix `S.union`
foldMap (foldMap getAllUsedVars) suffixes
toBoxDrawings'' :: Set Var -> History cmd resp -> Doc
toBoxDrawings'' knownVars (History h) = exec evT (fmap (out . snd) <$> Fork l p r)
where
(p, h') = partition (\e -> fst e == Pid 0) h
(l, r) = partition (\e -> fst e == Pid 1) h'
out :: HistoryEvent cmd resp -> String
out (Invocation cmd vars)
| vars `S.isSubsetOf` knownVars = show (S.toList vars) ++ " ← " ++ show cmd
| otherwise = show cmd
out (Response resp) = show resp
toEventType :: History' cmd resp -> [(EventType, Pid)]
toEventType = map go
where
go e = case e of
(pid, Invocation _ _) -> (Open, pid)
(pid, Response _) -> (Close, pid)
evT :: [(EventType, Pid)]
evT = toEventType (filter (\e -> fst e `elem` map Pid [1, 2]) h)
getAllUsedVars :: Rank2.Foldable cmd => Commands cmd -> Set Var
getAllUsedVars = foldMap (\(Command cmd _) -> getUsedVars cmd) . unCommands