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{-# LANGUAGE DerivingStrategies #-}
{-# LANGUAGE ExplicitNamespaces #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE OverloadedLists #-}
{-# LANGUAGE PartialTypeSignatures #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE TypeApplications #-}
-- Implementation of the API. This module is the main point of the program.
module Server (application) where
import Control.Concurrent.STM (TQueue, TVar, atomically,
newTQueue, newTVar, readTQueue,
readTVar, writeTQueue, writeTVar)
import Control.Monad (forever, unless, void, when)
import Control.Monad.Catch (handle)
import Control.Monad.Extra (ifM, maybeM, unlessM, whenJust,
whenM)
import Control.Monad.IO.Class (MonadIO (liftIO))
import Control.Monad.Logger (LoggingT, logWarnN)
import Control.Monad.Reader (forM)
import Control.Monad.Trans (lift)
import qualified Data.Aeson as A
import qualified Data.ByteString.Char8 as C8
import Data.Coerce (coerce)
import Data.Functor ((<&>))
import qualified Data.Map as M
import Data.Pool (Pool)
import Data.Proxy (Proxy (Proxy))
import Data.Swagger (toSchema)
import Data.Text (Text)
import Data.Text.Encoding (decodeUtf8)
import Data.Time (NominalDiffTime,
UTCTime (utctDay), addUTCTime,
diffUTCTime, getCurrentTime,
nominalDay)
import qualified Data.Vector as V
import Database.Persist
import Database.Persist.Postgresql (SqlBackend, runMigration)
import Fmt ((+|), (|+))
import qualified Network.WebSockets as WS
import Servant (Application,
ServerError (errBody), err401,
err404, serve, throwError)
import Servant.API (NoContent (..), (:<|>) (..))
import Servant.Server (Handler, hoistServer)
import Servant.Swagger (toSwagger)
import API
import GTFS
import Persist
import Server.ControlRoom
import Server.GTFS_RT (gtfsRealtimeServer)
import Server.Util (Service, ServiceM, runService,
sendErrorMsg)
import Yesod (toWaiAppPlain)
import Extrapolation (Extrapolator (..),
LinearExtrapolator (..))
import System.IO.Unsafe
import Config (ServerConfig)
import Data.ByteString (ByteString)
import Data.ByteString.Lazy (toStrict)
import Prometheus
import Prometheus.Metric.GHC
application :: GTFS -> Pool SqlBackend -> ServerConfig -> IO Application
application gtfs dbpool settings = do
doMigration dbpool
metrics <- Metrics
<$> register (gauge (Info "ws_connections" "Number of WS Connections"))
register ghcMetrics
subscribers <- atomically $ newTVar mempty
pure $ serve (Proxy @CompleteAPI) $ hoistServer (Proxy @CompleteAPI) runService $ server gtfs metrics subscribers dbpool settings
-- databaseMigration :: ConnectionString -> IO ()
doMigration pool = runSql pool $
-- TODO: before that, check if the uuid module is enabled
-- in sql: check if SELECT * FROM pg_extension WHERE extname = 'uuid-ossp';
-- returns an empty list
runMigration migrateAll
server :: GTFS -> Metrics -> TVar (M.Map TripID ([TQueue (Maybe TrainPing)])) -> Pool SqlBackend -> ServerConfig -> Service CompleteAPI
server gtfs@GTFS{..} Metrics{..} subscribers dbpool settings = handleDebugAPI
:<|> (handleStations :<|> handleTimetable :<|> handleTrip
:<|> handleRegister :<|> handleTrainPing (throwError err401) :<|> handleWS
:<|> handleSubscribe :<|> handleDebugState :<|> handleDebugTrain
:<|> handleDebugRegister :<|> gtfsRealtimeServer gtfs dbpool)
:<|> metrics
:<|> pure (unsafePerformIO (toWaiAppPlain (ControlRoom gtfs dbpool settings)))
where handleStations = pure stations
handleTimetable station maybeDay = do
-- TODO: resolve "overlay" trips (perhaps just additional CalendarDates?)
day <- liftIO $ maybeM (getCurrentTime <&> utctDay) pure (pure maybeDay)
pure
-- don't send stations ending at this station
. M.filter ((==) station . stationId . stopStation . V.last . tripStops)
$ tripsOnDay gtfs day
handleTrip trip = case M.lookup trip trips of
Just res -> pure res
Nothing -> throwError err404
handleRegister tripID RegisterJson{..} = do
today <- liftIO getCurrentTime <&> utctDay
unless (runsOnDay gtfs tripID today)
$ sendErrorMsg "this trip does not run today."
expires <- liftIO $ getCurrentTime <&> addUTCTime validityPeriod
RunningKey token <- runSql dbpool $ insert (Running expires False tripID today Nothing registerAgent)
pure token
handleDebugRegister tripID day = do
expires <- liftIO $ getCurrentTime <&> addUTCTime validityPeriod
RunningKey token <- runSql dbpool $ insert (Running expires False tripID day Nothing "debug key")
pure token
handleTrainPing onError ping = isTokenValid dbpool (coerce $ trainPingToken ping) >>= \case
Nothing -> do
onError
pure Nothing
Just running@Running{..} -> do
let anchor = extrapolateAnchorFromPing LinearExtrapolator gtfs running ping
-- TODO: are these always inserted in order?
runSql dbpool $ do
insert ping
last <- selectFirst
[TrainAnchorTrip ==. runningTrip, TrainAnchorDay ==. runningDay]
[Desc TrainAnchorWhen]
-- only insert new estimates if they've actually changed anything
when (fmap (trainAnchorDelay . entityVal) last /= Just (trainAnchorDelay anchor))
$ void $ insert anchor
queues <- liftIO $ atomically $ do
queues <- readTVar subscribers <&> M.lookup runningTrip
whenJust queues $
mapM_ (\q -> writeTQueue q (Just ping))
pure queues
pure (Just anchor)
handleWS conn = do
liftIO $ WS.forkPingThread conn 30
incGauge metricsWSGauge
handle (\(e :: WS.ConnectionException) -> decGauge metricsWSGauge) $ forever $ do
msg <- liftIO $ WS.receiveData conn
case A.eitherDecode msg of
Left err -> do
logWarnN ("stray websocket message: "+|show msg|+" (could not decode: "+|err|+")")
liftIO $ WS.sendClose conn (C8.pack err)
-- TODO: send a close msg (Nothing) to the subscribed queues? decGauge metricsWSGauge
Right ping ->
-- if invalid token, send a "polite" close request. Note that the client may
-- ignore this and continue sending messages, which will continue to be handled.
liftIO $ handleTrainPing (WS.sendClose conn ("" :: ByteString)) ping >>= \case
Just anchor -> WS.sendTextData conn (A.encode anchor)
Nothing -> pure ()
handleSubscribe tripId day conn = liftIO $ WS.withPingThread conn 30 (pure ()) $ do
queue <- atomically $ do
queue <- newTQueue
qs <- readTVar subscribers
writeTVar subscribers
$ M.insertWith (<>) tripId [queue] qs
pure queue
-- send most recent ping, if any (so we won't have to wait for movement)
lastPing <- runSql dbpool $ do
tokens <- selectList [RunningDay ==. day, RunningTrip ==. tripId] []
<&> fmap entityKey
selectFirst [TrainPingToken <-. tokens] [Desc TrainPingTimestamp]
<&> fmap entityVal
whenJust lastPing $ \ping ->
WS.sendTextData conn (A.encode lastPing)
handle (\(e :: WS.ConnectionException) -> removeSubscriber queue) $ forever $ do
res <- atomically $ readTQueue queue
case res of
Just ping -> WS.sendTextData conn (A.encode ping)
Nothing -> do
removeSubscriber queue
WS.sendClose conn (C8.pack "train ended")
where removeSubscriber queue = atomically $ do
qs <- readTVar subscribers
writeTVar subscribers
$ M.adjust (filter (/= queue)) tripId qs
handleDebugState = do
now <- liftIO getCurrentTime
runSql dbpool $ do
running <- selectList [RunningBlocked ==. False, RunningExpires >=. now] []
pairs <- forM running $ \(Entity token@(RunningKey uuid) _) -> do
entities <- selectList [TrainPingToken ==. token] []
pure (uuid, fmap entityVal entities)
pure (M.fromList pairs)
handleDebugTrain tripId day = do
unless (runsOnDay gtfs tripId day)
$ sendErrorMsg ("this trip does not run on "+|day|+".")
runSql dbpool $ do
tokens <- selectList [RunningTrip ==. tripId, RunningDay ==. day] []
pings <- forM tokens $ \(Entity token _) -> do
selectList [TrainPingToken ==. token] [] <&> fmap entityVal
pure (concat pings)
handleDebugAPI = pure $ toSwagger (Proxy @API)
metrics = exportMetricsAsText <&> (decodeUtf8 . toStrict)
-- TODO: proper debug logging for expired tokens
isTokenValid :: MonadIO m => Pool SqlBackend -> Token -> m (Maybe Running)
isTokenValid dbpool token = runSql dbpool $ get (coerce token) >>= \case
Just trip | not (runningBlocked trip) -> do
ifM (hasExpired (runningExpires trip))
(pure Nothing)
(pure (Just trip))
_ -> pure Nothing
hasExpired :: MonadIO m => UTCTime -> m Bool
hasExpired limit = do
now <- liftIO getCurrentTime
pure (now > limit)
validityPeriod :: NominalDiffTime
validityPeriod = nominalDay
|
