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{-# LANGUAGE FlexibleInstances, FlexibleContexts, MultiParamTypeClasses #-}
{-# LANGUAGE ViewPatterns #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE DeriveGeneric, DeriveAnyClass #-}
{-# LANGUAGE ExistentialQuantification #-}
module Thermoprint.Server.Queue
( Queue(..), QueueEntry(..)
, fromZipper, toZipper, QueueItem(..)
, HasQueue(..)
, QueueManager, QueueManagerM, runQM
, jobGC
, intersection, idQM
, union, nullQM
) where
import Thermoprint.API (PrintingError(..), Printout)
import qualified Thermoprint.API as API (JobStatus(..))
import Thermoprint.Server.Database
import Data.Sequence (Seq, ViewL(..), viewl, (|>), (<|))
import qualified Data.Sequence as Seq
import Data.Set (Set)
import qualified Data.Set as Set
import Data.Time
import Data.ExtendedReal
import Data.Fixed
import Control.DeepSeq
import Data.Typeable (Typeable)
import GHC.Generics (Generic)
import Control.Concurrent
import Control.Concurrent.STM
import Control.Monad.State
import Data.Default.Class
import Control.Monad
import Control.Monad.Morph
import Control.Monad.Trans.Compose
import Control.Monad.Trans.Resource
import Control.Monad.Reader
import Data.Function
import Data.Foldable
import Data.Monoid
import Data.Ord
import Database.Persist (delete)
import Database.Persist.Sql (ConnectionPool, runSqlPool)
import Test.QuickCheck.Arbitrary (Arbitrary(..), CoArbitrary(..))
import Test.QuickCheck.Gen (Gen, scale)
import Test.QuickCheck.Instances
import Test.QuickCheck.Modifiers (NonNegative(..))
-- | Zipper for 'Seq QueueEntry' with additional support for 'PrintingError' in the section after point
data Queue = Queue
{ pending :: Seq QueueEntry -- ^ Pending jobs, closest last
, current :: Maybe QueueEntry
, history :: Seq (QueueEntry, Maybe PrintingError) -- ^ Completed jobs, closest first
}
deriving (Typeable, Generic, NFData, Show)
instance Arbitrary Queue where
arbitrary = Queue
<$> scale (`div` 2) arbitrary
<*> arbitrary
<*> scale (`div` 2) arbitrary
instance CoArbitrary Queue
class HasQueue a where
extractQueue :: a -> TVar Queue
instance HasQueue (TVar Queue) where
extractQueue = id
instance Default Queue where
def = Queue
{ pending = Seq.empty
, current = Nothing
, history = Seq.empty
}
data QueueEntry = QueueEntry
{ jobId :: JobId
, created :: UTCTime
}
deriving (Typeable, Generic, NFData, Eq, Ord, Show)
instance Arbitrary QueueEntry where
arbitrary = QueueEntry <$> (fromIntegral . getNonNegative <$> (arbitrary :: Gen (NonNegative Integer))) <*> arbitrary
instance CoArbitrary QueueEntry where
coarbitrary QueueEntry{..} = coarbitrary created . coarbitrary (fromIntegral jobId :: Integer)
data QueueItem = Pending { pos :: Int, entry :: QueueEntry }
| Current { entry :: QueueEntry }
| History { pos :: Int, entry :: QueueEntry, err :: Maybe PrintingError }
instance Eq QueueItem where
(Pending i a ) == (Pending j b ) = i == j && a == b
(Current a ) == (Current b ) = a == b
(History i a _) == (History j b _) = i == j && a == b
_ == _ = False
instance Ord QueueItem where
(Pending i a ) `compare` (Pending j b ) = compare i j <> compare a b
(Current a ) `compare` (Current b ) = compare a b
(History i a _) `compare` (History j b _) = compare i j <> compare a b
(Pending _ _ ) `compare` _ = LT
(Current _ ) `compare` (Pending _ _ ) = GT
(Current _ ) `compare` _ = LT
(History _ _ _) `compare` _ = GT
newtype PlainQueueItem = Plain { unPlain :: QueueItem }
instance Eq PlainQueueItem where
(unPlain -> Pending _ a ) == (unPlain -> Pending _ b ) = a == b
(unPlain -> Current a ) == (unPlain -> Current b ) = a == b
(unPlain -> History _ a _) == (unPlain -> History _ b _) = a == b
_ == _ = False
instance Ord PlainQueueItem where
(unPlain -> Pending _ a ) <= (unPlain -> Pending _ b ) = a <= b
(unPlain -> Current a ) <= (unPlain -> Current b ) = a <= b
(unPlain -> History _ a _) <= (unPlain -> History _ b _) = a <= b
(unPlain -> Current _ ) <= (unPlain -> Pending _ _ ) = False
(unPlain -> History _ _ _) <= (unPlain -> Pending _ _ ) = False
(unPlain -> History _ _ _) <= (unPlain -> Current _ ) = False
(unPlain -> Pending _ _ ) <= _ = True
(unPlain -> Current _ ) <= _ = True
fromZipper :: Queue -> Set QueueItem
fromZipper Queue{..} = foldr Set.insert Set.empty $ mconcat [ Seq.mapWithIndex Pending pending
, maybe Seq.empty (Seq.singleton . Current) current
, Seq.mapWithIndex (\i (a, e) -> History i a e) history
]
toZipper :: Set QueueItem -> Queue
toZipper = Set.foldl' (flip insert) def
where
insert (Pending _ a) q@(Queue{..}) = q { pending = pending |> a }
insert (Current a) q = q { current = Just a }
insert (History _ a e) q@(Queue{..}) = q { history = history |> (a, e) }
-- | A queue manager periodically modifies a 'Queue', e.g. for cleanup of old jobs
type QueueManager t = QueueManagerM t (Extended Micro)
type QueueManagerM t = ComposeT (StateT Queue) t STM
runQM :: ( HasQueue q
, MFunctor t
, MonadTrans t
, MonadIO (t IO)
, Monad (t STM)
) => TChan JobId -- ^ Channel for deleted 'JobId's ready to be garbage collected
-> QueueManager t -> q -> t IO ()
-- ^ Periodically modify a 'Queue'
--
-- We use 'fromZipper' to determine which 'QueueEntry's were deleted by the manager and write
-- those to the garbage collectors channel.
-- Since there is no crosstalk between managers this works only if the relatien between
-- 'JobId's and the 'QueueManager' responsible for them is a single-valued function
runQM gcChan qm (extractQueue -> q) = sleep =<< qm'
where
qm' = hoist atomically $ do
before <- lift $ readTVar q
(delay, after) <- runStateT (getComposeT qm) before
lift $ writeTVar q $!! after
let
deleted = Set.map (jobId . entry . unPlain) $ (Set.difference `on` (Set.map Plain . fromZipper)) before after
mapM_ (lift . writeTChan gcChan) deleted
return delay
sleep (abs -> delay)
| (Finite d) <- delay = liftIO (threadDelay $ fromEnum d) >> runQM gcChan qm q
| otherwise = return ()
jobGC :: ( MonadReader ConnectionPool m
, MonadUnliftIO m
, MonadIO m
) => TChan JobId -> m ()
-- ^ Listen for 'JobId's on a 'TChan' and delete them from the database 'forever'
jobGC gcChan = forever $ liftIO (atomically $ readTChan gcChan) >>= (\jId -> runSqlPool (delete jId) =<< ask)
intersection :: (Foldable f, MonadState Queue (QueueManagerM t)) => f (QueueManager t) -> QueueManager t
-- ^ Combine two 'QueueManager's keeping only 'QueueEntry's both managers decide to keep
--
-- Side effects propagate left to right
intersection = foldr' (qmCombine Set.intersection) idQM
idQM :: Monad (QueueManagerM t) => QueueManager t
-- ^ Identity of 'intersect'
idQM = return PosInf
union :: (Foldable f, MonadState Queue (QueueManagerM t)) => f (QueueManager t) -> QueueManager t
-- ^ Combine two 'QueueManager's keeping all 'QueueEntry's either of the managers decides to keep
--
-- Side effects propagate left to right
union = foldr' (qmCombine Set.union) nullQM
nullQM :: MonadState Queue (QueueManagerM t) => QueueManager t
-- ^ Identity of 'union'
nullQM = put def >> return PosInf
qmCombine :: MonadState Queue (QueueManagerM t)
=> (Set PlainQueueItem -> Set PlainQueueItem -> Set PlainQueueItem)
-> (QueueManager t -> QueueManager t -> QueueManager t)
qmCombine setCombine a b = do
(d1, s1) <- local a
(d2, s2) <- local b
put . toZipper . Set.map unPlain $ on setCombine (Set.map Plain . fromZipper) s1 s2
return $ min d1 d2
where
local x = ((,) <$> get <*> ((,) <$> x <*> get)) >>= (\(oldS, r) -> r <$ put oldS)
|
