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{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE RecordWildCards #-}
module Server.Ingest (handleTrackerRegister, handleTrainPing, handleWS) where
import API (Metrics (..),
RegisterJson (..))
import Control.Concurrent.STM (atomically, readTVar,
writeTQueue)
import Control.Monad (forever, void, when)
import Control.Monad.Catch (handle)
import Control.Monad.Extra (ifM, mapMaybeM, whenJust)
import Control.Monad.IO.Class (MonadIO (liftIO))
import Control.Monad.Logger (LoggingT, logInfoN,
logWarnN)
import Control.Monad.Reader (ReaderT)
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.Text (Text)
import Data.Text.Encoding (decodeASCII, decodeUtf8)
import Data.Time (NominalDiffTime,
UTCTime (..), addUTCTime,
getCurrentTime,
nominalDay)
import qualified Data.Vector as V
import Database.Persist
import Database.Persist.Postgresql (SqlBackend)
import Fmt ((+|), (|+))
import qualified GTFS
import qualified Network.WebSockets as WS
import Persist
import Servant (err400, throwError)
import Servant.Server (Handler)
import Server.Util (ServiceM, getTzseries,
utcToSeconds)
import Config (LoggingConfig,
ServerConfig)
import Data.ByteString (ByteString)
import Data.ByteString.Lazy (toStrict)
import Data.Foldable (minimumBy)
import Data.Function (on, (&))
import qualified Data.Text as T
import Data.Time.LocalTime.TimeZone.Series (TimeZoneSeries)
import qualified Data.UUID as UUID
import Extrapolation (Extrapolator (..),
LinearExtrapolator (..),
euclid)
import GTFS (seconds2Double)
import Prometheus (decGauge, incGauge)
import Server.Base (ServerState)
handleTrackerRegister
:: Pool SqlBackend
-> RegisterJson
-> ServiceM Token
handleTrackerRegister dbpool RegisterJson{..} = do
today <- liftIO getCurrentTime <&> utctDay
expires <- liftIO $ getCurrentTime <&> addUTCTime validityPeriod
runSql dbpool $ do
TrackerKey tracker <- insert (Tracker expires False registerAgent Nothing)
pure tracker
where
validityPeriod :: NominalDiffTime
validityPeriod = nominalDay
handleTrainPing
:: Pool SqlBackend
-> ServerState
-> ServerConfig
-> LoggingT (ReaderT LoggingConfig Handler) a
-> TrainPing
-> LoggingT (ReaderT LoggingConfig Handler) (Maybe TrainAnchor)
handleTrainPing dbpool subscribers cfg onError ping@TrainPing{..} =
isTokenValid dbpool trainPingToken >>= \case
Nothing -> onError >> pure Nothing
Just tracker@Tracker{..} -> do
-- if the tracker is not associated with a ticket, it is probably
-- just starting out on a new trip, or has finished an old one.
maybeTicketId <- case trackerCurrentTicket of
Just ticketId -> pure (Just ticketId)
Nothing -> runSql dbpool $ do
now <- liftIO getCurrentTime
tickets <- selectList [ TicketDay ==. utctDay now, TicketCompleted ==. False ] []
ticketsWithFirstStation <- flip mapMaybeM tickets
(\ticket@(Entity ticketId _) -> do
selectFirst [StopTicket ==. ticketId] [Asc StopSequence] >>= \case
Nothing -> pure Nothing
Just (Entity _ stop) -> do
station <- getJust (stopStation stop)
tzseries <- liftIO $ getTzseries cfg (GTFS.tzname (stopDeparture stop))
pure (Just (ticket, station, stop, tzseries)))
if null ticketsWithFirstStation then pure Nothing else do
let (closestTicket, _, _, _) = minimumBy
-- (compare `on` euclid trainPingGeopos . stationGeopos . snd)
(compare `on`
(\(Entity _ ticket, station, stop, tzseries) ->
let
runningDay = ticketDay ticket
spaceDistance = euclid trainPingGeopos (stationGeopos station)
timeDiff =
GTFS.toSeconds (stopDeparture stop) tzseries runningDay
- utcToSeconds now runningDay
in
euclid trainPingGeopos (stationGeopos station)
+ abs (seconds2Double timeDiff / 3600)))
ticketsWithFirstStation
logInfoN
$ "Tracker "+|UUID.toString (coerce trainPingToken)|+
" is now handling ticket "+|UUID.toString (coerce (entityKey closestTicket))|+
" (trip "+|ticketTripName (entityVal closestTicket)|+")."
update trainPingToken
[TrackerCurrentTicket =. Just (entityKey closestTicket)]
pure (Just (entityKey closestTicket))
ticketId <- case maybeTicketId of
Just ticketId -> pure ticketId
Nothing -> do
logWarnN $ "Tracker "+|UUID.toString (coerce trainPingToken)|+
" sent a ping, but no trips are running today."
throwError err400
runSql dbpool $ do
ticket@Ticket{..} <- getJust ticketId
stations <- selectList [ StopTicket ==. ticketId ] [Asc StopArrival]
>>= mapM (\stop -> do
station <- getJust (stopStation (entityVal stop))
tzseries <- liftIO $ getTzseries cfg (GTFS.tzname (stopArrival (entityVal stop)))
pure (entityVal stop, station, tzseries))
<&> V.fromList
shapePoints <- selectList [ShapePointShape ==. ticketShape] [Asc ShapePointIndex]
<&> (V.fromList . fmap entityVal)
let anchor = extrapolateAnchorFromPing LinearExtrapolator
ticketId ticket stations shapePoints ping
insert ping
last <- selectFirst [TrainAnchorTicket ==. ticketId] [Desc TrainAnchorWhen]
-- only insert new estimates if they've actually changed anything
when (fmap (trainAnchorDelay . entityVal) last /= Just (trainAnchorDelay anchor))
$ void $ insert anchor
-- are we at the final stop? if so, mark this ticket as done
-- & the tracker as free
let maxSequence = V.last stations
& (\(stop, _, _) -> stopSequence stop)
& fromIntegral
when (trainAnchorSequence anchor + 0.1 >= maxSequence) $ do
update trainPingToken
[TrackerCurrentTicket =. Nothing]
update ticketId
[TicketCompleted =. True]
logInfoN $ "Tracker "+|UUID.toString (coerce trainPingToken)|+
" has completed ticket "+|UUID.toString (coerce ticketId)|+
" (trip "+|ticketTripName|+")"
queues <- liftIO $ atomically $ do
queues <- readTVar subscribers <&> M.lookup (coerce ticketId)
whenJust queues $
mapM_ (\q -> writeTQueue q (Just ping))
pure queues
pure (Just anchor)
handleWS
:: Pool SqlBackend
-> ServerState
-> ServerConfig
-> Metrics
-> WS.Connection -> ServiceM ()
handleWS dbpool subscribers cfg Metrics{..} 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: "+|decodeASCII (toStrict 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 -> do
-- 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.
handleTrainPing dbpool subscribers cfg (liftIO $ WS.sendClose conn ("" :: ByteString)) ping >>= \case
Just anchor -> liftIO $ WS.sendTextData conn (A.encode anchor)
Nothing -> pure ()
-- TODO: proper debug logging for expired tokens
isTokenValid :: Pool SqlBackend -> TrackerId -> ServiceM (Maybe Tracker)
isTokenValid dbpool token = runSql dbpool $ get token >>= \case
Just tracker | not (trackerBlocked tracker) -> do
ifM (hasExpired (trackerExpires tracker))
(pure Nothing)
(pure (Just tracker))
_ -> pure Nothing
hasExpired :: MonadIO m => UTCTime -> m Bool
hasExpired limit = do
now <- liftIO getCurrentTime
pure (now > limit)
|
