module LaunchDarkly.Server.Network.Streaming (streamingThread) where
import Data.Text (Text)
import qualified Data.Text as T
import Data.Attoparsec.Text as P hiding (Result, try)
import Data.Function (fix)
import Control.Monad (void, mzero)
import Control.Monad.Catch (Exception, MonadCatch, MonadMask, try)
import Control.Exception (throwIO)
import Data.ByteString (ByteString)
import qualified Data.ByteString as B
import Control.Applicative (many)
import Data.Text.Encoding (decodeUtf8, encodeUtf8)
import Network.HTTP.Client (Manager, Response(..), Request, HttpException(..), HttpExceptionContent(..), brRead, throwErrorStatusCodes)
import Control.Monad.Logger (MonadLogger, logInfo, logWarn, logError, logDebug)
import Control.Monad.IO.Class (MonadIO, liftIO)
import Data.Aeson (FromJSON, parseJSON, withObject, eitherDecode, (.:), (.:?), (.!=), fromJSON, Result(..))
import qualified Data.ByteString.Lazy as L
import GHC.Natural (Natural)
import GHC.Generics (Generic)
import Control.Retry (RetryPolicyM, RetryStatus, fullJitterBackoff, capDelay, retrying)
import Network.HTTP.Types.Status (ok200, Status(statusCode))
import System.Timeout (timeout)
import System.Clock (getTime, Clock(Monotonic), TimeSpec(TimeSpec))
import LaunchDarkly.Server.Config.HttpConfiguration (HttpConfiguration(..), prepareRequest)
import LaunchDarkly.Server.Config.ClientContext (ClientContext(..))
import LaunchDarkly.Server.Store.Internal (StoreResult)
import LaunchDarkly.Server.DataSource.Internal (DataSourceUpdates(..))
import LaunchDarkly.Server.Features (Flag, Segment)
import LaunchDarkly.Server.Network.Common (handleUnauthorized, checkAuthorization, withResponseGeneric, tryHTTP)
import LaunchDarkly.AesonCompat (KeyMap)
data PutBody = PutBody
{ flags :: !(KeyMap Flag)
, segments :: !(KeyMap Segment)
} deriving (Generic, Show, FromJSON)
data PathData d = PathData
{ path :: !Text
, pathData :: !d
} deriving (Generic, Show)
data PathVersion = PathVersion
{ path :: !Text
, version :: !Natural
} deriving (Generic, Show, FromJSON)
instance FromJSON a => FromJSON (PathData a) where
parseJSON = withObject "Put" $ \o -> do
pathData <- o .: "data"
path <- o .:? "path" .!= "/"
pure $ PathData { path = path, pathData = pathData }
data SSE = SSE
{ name :: !Text
, buffer :: !Text
, lastEventId :: !(Maybe Text)
, retry :: !(Maybe Text)
} deriving (Generic, Show, Eq)
nameCharPredicate :: Char -> Bool
nameCharPredicate x = x /= '\r' && x /= ':' && x /= '\n'
anyCharPredicate :: Char -> Bool
anyCharPredicate x = x /= '\r' && x /= '\n'
endOfLineSSE :: Parser ()
endOfLineSSE = choice [void $ string "\r\n", void $ string "\r", void $ string "\n", endOfInput]
comment :: Parser ()
comment = char ':' >> P.takeWhile anyCharPredicate >> endOfLineSSE >> pure ()
parseField :: Parser (Text, Text)
parseField = do
fieldName <- P.takeWhile1 nameCharPredicate
void $ option ' ' $ char ':'
void $ option ' ' $ char ' '
fieldValue <- P.takeWhile anyCharPredicate
endOfLineSSE
pure (fieldName, fieldValue)
processField :: (Text, Text) -> SSE -> SSE
processField (fieldName, fieldValue) event = case fieldName of
"event" -> event { name = fieldValue }
"id" -> event { lastEventId = Just fieldValue }
"retry" -> event { retry = Just fieldValue }
"data" -> event { buffer = T.concat [ buffer event, if T.null (buffer event) then "" else "\n", fieldValue] }
_ -> event
parseEvent :: Parser SSE
parseEvent = do
fields <- many (many comment >> parseField >>= pure)
endOfLineSSE
let event = foldr processField (SSE "" "" mzero mzero) fields
if T.null (name event) || T.null (buffer event) then parseEvent else pure event
processPut :: (MonadIO m, MonadLogger m) => DataSourceUpdates -> L.ByteString -> m ()
processPut dataSourceUpdates value = case eitherDecode value of
Right (PathData _ (PutBody flags segments)) -> do
$(logInfo) "initializing dataSourceUpdates with put"
liftIO (dataSourceUpdatesInit dataSourceUpdates flags segments) >>= \case
Left err -> $(logError) $ T.append "dataSourceUpdates failed put: " err
_ -> pure ()
Left err -> $(logError) $ T.append "failed to parse put body" (T.pack err)
processPatch :: forall m. (MonadIO m, MonadLogger m) => DataSourceUpdates -> L.ByteString -> m ()
processPatch dataSourceUpdates value = case eitherDecode value of
Right (PathData path body)
| T.isPrefixOf "/flags/" path -> insPatch "flag" path dataSourceUpdatesInsertFlag (fromJSON body)
| T.isPrefixOf "/segments/" path -> insPatch "segment" path dataSourceUpdatesInsertSegment (fromJSON body)
| otherwise -> $(logError) "unknown patch path"
Left err -> $(logError) $ T.append "failed to parse patch generic" (T.pack err)
where
insPatch :: Text -> Text -> (DataSourceUpdates -> a -> IO (Either Text ())) -> Result a -> m ()
insPatch name _ _ (Error err) = $(logError) $ T.concat ["failed to parse patch ", name, ": ", T.pack err]
insPatch name path insert (Success item) = do
$(logInfo) $ T.concat ["patching ", name, " with path: ", path]
status <- liftIO $ insert dataSourceUpdates item
either (\err -> $(logError) $ T.concat ["dataSourceUpdates failed ", name, " patch: ", err]) pure status
processDelete :: forall m. (MonadIO m, MonadLogger m) => DataSourceUpdates -> L.ByteString -> m ()
processDelete dataSourceUpdates value = case eitherDecode value :: Either String PathVersion of
Right (PathVersion path version)
| T.isPrefixOf "/flags/" path -> logDelete "flag" path (dataSourceUpdatesDeleteFlag dataSourceUpdates (T.drop 7 path) version)
| T.isPrefixOf "/segments/" path -> logDelete "segment" path (dataSourceUpdatesDeleteSegment dataSourceUpdates (T.drop 10 path) version)
| otherwise -> $(logError) "unknown delete path"
Left err -> $(logError) $ T.append "failed to parse delete" (T.pack err)
where logDelete :: Text -> Text -> StoreResult () -> m ()
logDelete name path action = do
$(logInfo) $ T.concat ["deleting ", name, " with path: ", path]
status <- liftIO action
either (\err -> $(logError) $ T.concat ["dataSourceUpdates failed ", name, " delete: ", err]) pure status
processEvent :: (MonadIO m, MonadLogger m) => DataSourceUpdates -> Text -> L.ByteString -> m ()
processEvent dataSourceUpdates name value = case name of
"put" -> processPut dataSourceUpdates value
"patch" -> processPatch dataSourceUpdates value
"delete" -> processDelete dataSourceUpdates value
_ -> $(logWarn) "unknown event type"
data ReadE = ReadETimeout | ReadEClosed deriving (Show, Exception)
tryReadE :: MonadCatch m => m a -> m (Either ReadE a)
tryReadE = try
readWithException :: IO ByteString -> IO Text
readWithException body = timeout (1000000 * 300) (brRead body) >>= \case
Nothing -> throwIO ReadETimeout
Just bytes -> if bytes == B.empty then throwIO ReadEClosed else pure (decodeUtf8 bytes)
readStream :: (MonadIO m, MonadLogger m, MonadMask m) => IO ByteString -> DataSourceUpdates -> m ()
readStream body dataSourceUpdates = loop "" where
loop initial = tryReadE (parseWith (liftIO $ readWithException body) parseEvent initial) >>= \case
(Left ReadETimeout) -> $(logError) "streaming connection unexpectedly closed"
(Left ReadEClosed) -> $(logError) "timeout waiting for SSE event"
(Right parsed) -> case parsed of
Done remaining event -> do
processEvent dataSourceUpdates (name event) (L.fromStrict $ encodeUtf8 $ buffer event)
loop remaining
Fail _ context err ->
$(logError) $ T.intercalate " " ["failed parsing SSE frame", T.pack $ show context, T.pack err]
Partial _ -> $(logError) "failed parsing SSE frame unexpected partial"
retryPolicy :: MonadIO m => RetryPolicyM m
retryPolicy = capDelay (30 * 1000000) $ fullJitterBackoff (1 * 1000000)
data Failure = FailurePermanent | FailureTemporary | FailureReset deriving (Eq)
handleStream :: (MonadIO m, MonadLogger m, MonadMask m) => Manager -> Request -> DataSourceUpdates -> RetryStatus -> m Failure
handleStream manager request dataSourceUpdates _ = do
$(logDebug) "starting new streaming connection"
startTime <- liftIO $ getTime Monotonic
status <- tryHTTP $ withResponseGeneric request manager $ \response -> checkAuthorization response >>
if responseStatus response /= ok200 then throwErrorStatusCodes request response else
readStream (responseBody response) dataSourceUpdates
case status of
(Right ()) -> liftIO (getTime Monotonic) >>= \now -> if now >= startTime + (TimeSpec 60 0)
then do
$(logError) "streaming connection closed after 60 seconds, retrying instantly"
pure FailureReset
else do
$(logError) "streaming connection closed before 60 seconds, retrying after backoff"
pure FailureTemporary
(Left err) -> do
$(logError) (T.intercalate " " ["HTTP Exception", T.pack $ show err])
pure $ case err of
(InvalidUrlException _ _) -> FailurePermanent
(HttpExceptionRequest _ (StatusCodeException response _)) ->
let code = statusCode (responseStatus response) in if code >= 400 && code < 500
then if elem code [400, 408, 429] then FailureTemporary else FailurePermanent
else FailureTemporary
_ -> FailureTemporary
streamingThread :: (MonadIO m, MonadLogger m, MonadMask m) => Text -> ClientContext -> DataSourceUpdates -> m ()
streamingThread streamURI clientContext dataSourceUpdates = do
let manager = tlsManager $ httpConfiguration clientContext
req <- prepareRequest (httpConfiguration clientContext) (T.unpack streamURI ++ "/all")
handleUnauthorized dataSourceUpdates $ fix $ \loop ->
retrying retryPolicy (\_ status -> pure $ status == FailureTemporary) (handleStream manager req dataSourceUpdates) >>=
\case FailureReset -> loop; _ -> pure ()