fradrive/src/Jobs.hs
2019-05-30 23:37:48 +02:00

354 lines
15 KiB
Haskell

module Jobs
( module Types
, module Jobs.Queue
, handleJobs
, stopJobCtl
) where
import Import
import Utils.Lens
import Handler.Utils
import Jobs.Types as Types hiding (JobCtl(JobCtlQueue))
import Jobs.Types (JobCtl(JobCtlQueue))
import Jobs.Queue
import Jobs.Crontab
import Data.Conduit.TMChan
import qualified Data.Conduit.List as C
import qualified Data.Text.Lazy as LT
import Data.Aeson (fromJSON, toJSON)
import qualified Data.Aeson as Aeson
import qualified Data.Aeson.Types as Aeson
import Database.Persist.Sql (fromSqlKey)
import Data.Semigroup (Max(..))
import Utils.Sql
import Control.Monad.Random (evalRand, mkStdGen, getRandomR)
import Cron
import qualified Data.HashMap.Strict as HashMap
import Data.HashMap.Strict (HashMap)
import qualified Data.Set as Set
import qualified Data.List.NonEmpty as NonEmpty
import qualified Data.Map.Strict as Map
import Data.Foldable (foldrM)
import Control.Monad.Trans.Reader (mapReaderT)
import Control.Monad.Trans.State (evalStateT, mapStateT)
import qualified Control.Monad.State.Class as State
import Control.Monad.Reader.Class (MonadReader(..))
import Control.Monad.Trans.Resource (MonadResourceBase, runResourceT, allocate, release)
import Control.Monad.Trans.Maybe (MaybeT(..))
import Control.Monad.Logger
import Data.Time.Zones
import Control.Concurrent.STM (retry)
import Jobs.Handler.SendNotification
import Jobs.Handler.SendTestEmail
import Jobs.Handler.QueueNotification
import Jobs.Handler.HelpRequest
import Jobs.Handler.SetLogSettings
import Jobs.Handler.DistributeCorrections
import Jobs.Handler.SendCourseCommunication
import Jobs.Handler.Invitation
import Jobs.HealthReport
data JobQueueException = JInvalid QueuedJobId QueuedJob
| JLocked QueuedJobId InstanceId UTCTime
| JNonexistant QueuedJobId
deriving (Read, Show, Eq, Generic, Typeable)
instance Exception JobQueueException
handleJobs :: ( MonadResource m
, MonadIO m
)
=> UniWorX -> m ()
-- | Spawn a set of workers that read control commands from `appJobCtl` and address them as they come in
--
-- Uses `unsafeHandler`, as per documentation all HTTP-related fields of state/environment are meaningless placeholders.
-- Handling commands in `HandlerT` provides us with the facilities to render urls, unifies logging, provides a value of the foundation type, ...
handleJobs foundation@UniWorX{..} = do
let num = foundation ^. _appJobWorkers
jobCrontab <- liftIO $ newTMVarIO HashMap.empty
jobConfirm <- liftIO $ newTVarIO HashMap.empty
forM_ [1..num] $ \n -> do
(bChan, chan) <- atomically $ newBroadcastTMChan >>= (\c -> (c, ) <$> dupTMChan c)
let
logStart = $logDebugS ("Jobs #" <> tshow n) "Starting"
logStop = $logDebugS ("Jobs #" <> tshow n) "Stopping"
removeChan = atomically . modifyTVar' appJobCtl . Map.delete =<< myThreadId
doFork = flip forkFinally (\_ -> removeChan) . runAppLoggingT foundation . bracket_ logStart logStop . flip runReaderT JobContext{..} . runConduit $ sourceTMChan chan .| handleJobs' foundation n
(_, tId) <- allocate (liftIO doFork) (\_ -> liftIO . atomically $ closeTMChan chan)
atomically . modifyTVar' appJobCtl $ Map.insert tId bChan
-- Start cron operation
when (num > 0) $ do
registeredCron <- liftIO newEmptyTMVarIO
let execCrontab' = whenM (atomically $ readTMVar registeredCron) $
runReaderT (execCrontab foundation) JobContext{..}
unregister = atomically . whenM (fromMaybe False <$> tryReadTMVar registeredCron) . void $ tryTakeTMVar appCronThread
cData <- allocate (liftIO . forkFinally execCrontab' $ \_ -> unregister) (\_ -> liftIO . atomically . void $ tryTakeTMVar jobCrontab)
registeredCron' <- atomically $ do
registeredCron' <- tryPutTMVar appCronThread cData
registeredCron' <$ putTMVar registeredCron registeredCron'
when registeredCron' $
liftIO . unsafeHandler foundation . flip runReaderT JobContext{..} $
writeJobCtlBlock JobCtlDetermineCrontab
stopJobCtl :: MonadIO m => UniWorX -> m ()
-- ^ Stop all worker threads currently running
stopJobCtl UniWorX{appJobCtl, appCronThread} = do
mcData <- atomically $ tryReadTMVar appCronThread
whenIsJust mcData $ \(rKey, _) -> do
liftIO $ release rKey
atomically . guardM $ isEmptyTMVar appCronThread
wMap <- liftIO $ readTVarIO appJobCtl
atomically $ forM_ wMap closeTMChan
atomically $ do
wMap' <- readTVar appJobCtl
guard . none (`Map.member` wMap') $ Map.keysSet wMap
execCrontab :: MonadIO m => UniWorX -> ReaderT JobContext m ()
-- ^ Keeping a `HashMap` of the latest execution times of `JobCtl`s we have
-- seen, wait for the time of the next job and fire it
execCrontab foundation = evalStateT go HashMap.empty
where
go = do
cont <- mapStateT (mapReaderT $ liftIO . unsafeHandler foundation) $ do
mapStateT (liftHandlerT . runDB . setSerializable) $ do
let
merge (Entity leId CronLastExec{..})
| Just job <- Aeson.parseMaybe parseJSON cronLastExecJob
= State.modify $ HashMap.insertWith (<>) (JobCtlQueue job) (Max cronLastExecTime)
| otherwise = lift $ delete leId
runConduit $ transPipe lift (selectSource [] []) .| C.mapM_ merge
refT <- liftIO getCurrentTime
settings <- getsYesod appSettings'
currentState <- mapStateT (mapReaderT $ liftIO . atomically) $ do
crontab' <- liftBase . tryReadTMVar =<< asks jobCrontab
case crontab' of
Nothing -> return Nothing
Just crontab -> Just <$> do
State.modify . HashMap.filterWithKey $ \k _ -> HashMap.member k crontab
prevExec <- State.get
case earliestJob settings prevExec crontab refT of
Nothing -> liftBase retry
Just (_, MatchNone) -> liftBase retry
Just x -> return (crontab, x)
case currentState of
Nothing -> return False
Just (currentCrontab, (jobCtl, nextMatch)) -> do
let doJob = mapStateT (mapReaderT $ liftHandlerT . runDBJobs . setSerializable) $ do
newCrontab <- lift . lift . hoist lift $ determineCrontab'
if
| ((==) `on` HashMap.lookup jobCtl) newCrontab currentCrontab
-> do
now <- liftIO $ getCurrentTime
instanceID' <- getsYesod appInstanceID
State.modify $ HashMap.alter (Just . ($ Max now) . maybe id (<>)) jobCtl
case jobCtl of
JobCtlQueue job -> do
void . lift . lift $ upsertBy
(UniqueCronLastExec $ toJSON job)
CronLastExec
{ cronLastExecJob = toJSON job
, cronLastExecTime = now
, cronLastExecInstance = instanceID'
}
[ CronLastExecTime =. now ]
lift . lift $ queueDBJob job
other -> writeJobCtl other
| otherwise
-> lift . mapReaderT (liftIO . atomically) $
lift . void . flip swapTMVar newCrontab =<< asks jobCrontab
case nextMatch of
MatchAsap -> doJob
MatchNone -> return ()
MatchAt nextTime -> do
JobContext{jobCrontab} <- ask
nextTime' <- applyJitter jobCtl nextTime
$logDebugS "Cron" [st|Waiting until #{tshow (utcToLocalTimeTZ appTZ nextTime')} to execute #{tshow jobCtl}|]
logFunc <- askLoggerIO
whenM (liftIO . flip runLoggingT logFunc $ waitUntil jobCrontab currentCrontab nextTime')
doJob
return True
when cont go
where
acc :: NominalDiffTime
acc = 1e-3
debouncingAcc :: AppSettings -> JobCtl -> NominalDiffTime
debouncingAcc AppSettings{appNotificationRateLimit} = \case
JobCtlQueue (JobQueueNotification _) -> appNotificationRateLimit
_ -> acc
applyJitter :: (MonadHandler m, HandlerSite m ~ UniWorX, Hashable seed) => seed -> UTCTime -> m UTCTime
applyJitter seed t = do
appInstance <- getsYesod appInstanceID
let
halfRange = truncate $ 0.5 / acc
diff = evalRand ( (* acc) . fromInteger <$> getRandomR (- halfRange, halfRange)) $ mkStdGen (hash appInstance `hashWithSalt` seed)
return $ addUTCTime diff t
earliestJob :: AppSettings -> HashMap JobCtl (Max UTCTime) -> Crontab JobCtl -> UTCTime -> Maybe (JobCtl, CronNextMatch UTCTime)
earliestJob settings lastTimes crontab now = foldr go' Nothing $ HashMap.toList crontab
where
go' (jobCtl, cron) mbPrev
| Just (_, t') <- mbPrev
, t' < t
= mbPrev
| otherwise
= Just (jobCtl, t)
where
t = nextCronMatch appTZ (getMax <$> HashMap.lookup jobCtl lastTimes) (debouncingAcc settings jobCtl) now cron
waitUntil :: (Eq a, MonadResourceBase m, MonadLogger m) => TMVar a -> a -> UTCTime -> m Bool
waitUntil crontabTV crontab nextTime = runResourceT $ do
diffT <- diffUTCTime nextTime <$> liftIO getCurrentTime
let waitTime = fromInteger (truncate $ diffT / acc) * toRational acc
waitTime'
| diffT < acc = "Done"
| otherwise = tshow (realToFrac waitTime :: NominalDiffTime)
$logDebugS "waitUntil" [st|#{tshow diffT} (#{waitTime'})|]
if
| diffT < acc -> return True
| otherwise -> do
retVar <- liftIO newEmptyTMVarIO
void . liftIO . forkFinally (threadDelay . round $ waitTime * 1e6) $ atomically . putTMVar retVar
let
awaitDelayThread = False <$ takeTMVar retVar
awaitCrontabChange = do
crontab' <- tryReadTMVar crontabTV
True <$ guard (Just crontab /= crontab')
crontabChanged <- liftIO . atomically $ awaitCrontabChange <|> awaitDelayThread
bool (waitUntil crontabTV crontab nextTime) (return False) crontabChanged
handleJobs' :: (MonadIO m, MonadLogger m, MonadCatch m) => UniWorX -> Natural -> Sink JobCtl (ReaderT JobContext m) ()
handleJobs' foundation wNum = C.mapM_ $ \jctl -> do
$logDebugS logIdent $ tshow jctl
resVars <- mapReaderT (liftIO . atomically) $
HashMap.lookup jctl <$> (lift . readTVar =<< asks jobConfirm)
res <- fmap (either Just $ const Nothing) . try . (mapReaderT $ liftIO . unsafeHandler foundation) $ handleCmd jctl
sentRes <- liftIO . atomically $ foldrM (\resVar -> bool (tryPutTMVar resVar res) $ return True) False (maybe [] NonEmpty.toList resVars)
case res of
Just err
| not sentRes -> $logErrorS logIdent $ tshow err
_other -> return ()
where
logIdent = "Jobs #" <> tshow wNum
handleQueueException :: MonadLogger m => JobQueueException -> m ()
handleQueueException (JInvalid jId j) = $logWarnS logIdent $ "Invalid QueuedJob (#" ++ tshow (fromSqlKey jId) ++ "): " ++ tshow j
handleQueueException (JNonexistant jId) = $logInfoS logIdent $ "Saw nonexistant queue id: " ++ tshow (fromSqlKey jId)
handleQueueException (JLocked jId lInstance lTime) = $logDebugS logIdent $ "Saw locked QueuedJob: " ++ tshow (fromSqlKey jId, lInstance, lTime)
handleCmd JobCtlFlush = void . lift . runDB . runConduit $ selectKeys [] [ Asc QueuedJobCreationTime ] .| C.mapM_ (writeJobCtl . JobCtlPerform)
handleCmd (JobCtlQueue job) = lift $ queueJob' job
handleCmd (JobCtlPerform jId) = lift . handle handleQueueException . jLocked jId $ \j@QueuedJob{..} -> do
content <- case fromJSON queuedJobContent of
Aeson.Success c -> return c
Aeson.Error t -> do
$logErrorS logIdent $ "Aeson decoding error: " <> pack t
throwM $ JInvalid jId j
$logDebugS logIdent . LT.toStrict . decodeUtf8 $ Aeson.encode content
performJob content
-- `performJob` is expected to throw an exception if it detects that the job was not done
runDB $ delete jId
handleCmd JobCtlDetermineCrontab = do
newCTab <- liftHandlerT . runDB $ setSerializable determineCrontab'
-- logDebugS logIdent $ tshow newCTab
mapReaderT (liftIO . atomically) $
lift . void . flip swapTMVar newCTab =<< asks jobCrontab
handleCmd (JobCtlGenerateHealthReport kind) = do
hrStorage <- getsYesod appHealthReport
newReport@(healthReportStatus -> newStatus) <- lift $ generateHealthReport kind
$logInfoS (tshow kind) $ toPathPiece newStatus
unless (newStatus == HealthSuccess) $ do
$logErrorS (tshow kind) $ tshow newReport
liftIO $ do
now <- getCurrentTime
let updateReports = Set.insert (now, newReport)
. Set.filter (((/=) `on` classifyHealthReport) newReport . snd)
atomically . modifyTVar' hrStorage $ force . updateReports
jLocked :: QueuedJobId -> (QueuedJob -> Handler a) -> Handler a
jLocked jId act = do
hasLock <- liftIO $ newTVarIO False
let
lock = runDB . setSerializable $ do
qj@QueuedJob{..} <- maybe (throwM $ JNonexistant jId) return =<< get jId
instanceID' <- getsYesod $ view instanceID
threshold <- getsYesod $ view _appJobStaleThreshold
now <- liftIO getCurrentTime
hadStale <- maybeT (return False) $ do
lockTime <- MaybeT $ return queuedJobLockTime
lockInstance <- MaybeT $ return queuedJobLockInstance
if
| lockInstance == instanceID'
, diffUTCTime now lockTime >= threshold
-> return True
| otherwise
-> throwM $ JLocked jId lockInstance lockTime
when hadStale .
$logWarnS "Jobs" $ "Ignored stale lock: " <> tshow qj
val <- updateGet jId [ QueuedJobLockInstance =. Just instanceID'
, QueuedJobLockTime =. Just now
]
liftIO . atomically $ writeTVar hasLock True
return val
unlock = whenM (liftIO . atomically $ readTVar hasLock) $
runDB . setSerializable $
update jId [ QueuedJobLockInstance =. Nothing
, QueuedJobLockTime =. Nothing
]
bracket lock (const unlock) act
pruneLastExecs :: Crontab JobCtl -> DB ()
pruneLastExecs crontab = runConduit $ selectSource [] [] .| C.mapM_ ensureCrontab
where
ensureCrontab (Entity leId CronLastExec{..})
| Just job <- Aeson.parseMaybe parseJSON cronLastExecJob
, HashMap.member (JobCtlQueue job) crontab
= return ()
| otherwise = delete leId
determineCrontab' :: DB (Crontab JobCtl)
determineCrontab' = (\ct -> ct <$ pruneLastExecs ct) =<< determineCrontab
performJob :: Job -> HandlerT UniWorX IO ()
performJob = $(dispatchTH ''Job)