Cleanup

models

@@ -223,7 +223,8 @@ Exam
 -- By default this file is used in Model.hs (which is imported by Foundation.hs)
 QueuedJob
     content             Value
-    created             UTCTime
-    lockInstance        UUID Maybe
+    creationInstance    InstanceId
+    creationTime        UTCTime
+    lockInstance        InstanceId Maybe
     lockTime            UTCTime Maybe
     deriving Eq Read Show Generic Typeable

package.yaml

@@ -77,6 +77,8 @@ dependencies:
 - parsec
 - uuid
 - exceptions
+- stm
+- stm-chans
 - stm-conduit
 - lens
 - MonadRandom

src/Foundation.hs

@@ -20,12 +20,12 @@ import Database.Persist.Sql (ConnectionPool, runSqlPool)
 import Text.Hamlet          (hamletFile)
 import Text.Jasmine         (minifym)
 
--- Used only when in "auth-dummy-login" setting is enabled.
 import Yesod.Auth.Message
 import Yesod.Auth.Dummy
 import Auth.LDAP
 import Auth.PWHash
 import Auth.Dummy
+import Jobs.Types
 
 import qualified Network.Wai as W (requestMethod, pathInfo)
 
@@ -115,14 +115,10 @@ data UniWorX = UniWorX
     , appHttpManager :: Manager
     , appLogger      :: Logger
     , appCryptoIDKey :: CryptoIDKey
-    , appInstanceID  :: UUID
-    , appJobCtl :: TMChan JobCtl
+    , appInstanceID  :: InstanceId
+    , appJobCtl      :: TMChan JobCtl
     }
 
-data JobCtl = NCtlFlush
-            | NCtlPerform QueuedJobId
-  deriving (Eq, Ord, Read, Show)
-
 -- This is where we define all of the routes in our application. For a full
 -- explanation of the syntax, please see:
 -- http://www.yesodweb.com/book/routing-and-handlers

src/Import.hs

@@ -4,4 +4,3 @@ module Import
 
 import Foundation            as Import
 import Import.NoFoundation   as Import
-

src/Jobs.hs

@@ -7,50 +7,41 @@
            , TypeFamilies
            , DeriveGeneric
            , DeriveDataTypeable
+           , QuasiQuotes
   #-}
 
 module Jobs
-  ( handleJobs
-  , Job(..), Notification(..)
+  ( module Jobs.Types
+  , writeJobCtl
+  , queueJob
+  , handleJobs
   ) where
 
 import Import
 
+import Jobs.Types
+
 import Data.Conduit.TMChan
 import qualified Data.Conduit.List as C
 
-import Data.Aeson (fromJSON, Result(..), defaultOptions, Options(..))
+import Data.Aeson (fromJSON, toJSON)
 import qualified Data.Aeson as Aeson
-import Data.Aeson.TH (deriveJSON)
-import Database.Persist.Sql (rawExecute, fromSqlKey)
+import Database.Persist.Sql (executeQQ, fromSqlKey)
 
   
-data Job = JobSendNotification { jRecipient :: UserId, jNotification :: Notification }
-  deriving (Eq, Ord, Show, Read)
-data Notification = NotificationSubmissionRated { nSubmission :: SubmissionId, nTimestamp :: UTCTime }
-  deriving (Eq, Ord, Show, Read)
-
-deriveJSON defaultOptions
-  { constructorTagModifier = intercalate "-" . map toLower . drop 1 . splitCamel
-  , fieldLabelModifier = intercalate "-" . map toLower . drop 1 . splitCamel
-  , tagSingleConstructors = True
-  } ''Job
-
-deriveJSON defaultOptions
-  { constructorTagModifier = intercalate "-" . map toLower . drop 1 . splitCamel
-  , fieldLabelModifier = intercalate "-" . map toLower . drop 1 . splitCamel
-  , tagSingleConstructors = True
-  } ''Notification
-
-data JobQueueException = JInvalid QueuedJob
-                       | JLocked QueuedJobId UUID UTCTime
+data JobQueueException = JInvalid QueuedJobId QueuedJob
+                       | JLocked QueuedJobId InstanceId UTCTime
                        | JNonexistant QueuedJobId
   deriving (Read, Show, Eq, Generic, Typeable)
 
 instance Exception JobQueueException
-  
+ 
 
 handleJobs :: UniWorX -> IO ()
+-- | 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{..} = unsafeHandler foundation . bracket_ logStart logStop . runConduit $ sourceTMChan appJobCtl .| handleJobs'
   where
     logStart = $(logDebugS) "Jobs" "Started"
@@ -60,14 +51,12 @@ handleJobs' :: Sink JobCtl Handler ()
 handleJobs' = C.mapM_ $ void . handleAny ($(logErrorS) "Jobs" . tshow) . handleCmd
   where
     handleQueueException :: MonadLogger m => JobQueueException -> m ()
-    handleQueueException (JInvalid j) = $(logWarnS) "Jobs" $ "Invalid QueuedJob: " ++ tshow j
+    handleQueueException (JInvalid jId j) = $(logWarnS) "Jobs" $ "Invalid QueuedJob (#" ++ tshow (fromSqlKey jId) ++ "): " ++ tshow j
     handleQueueException (JNonexistant jId) = $(logInfoS) "Jobs" $ "Saw nonexistant queue id: " ++ tshow (fromSqlKey jId)
-    handleQueueException (JLocked jId lInstance lTime)  = $(logDebugS) "Jobs" $ "Saw locked QueuedJob: " ++ tshow (jId, lInstance, lTime)
+    handleQueueException (JLocked jId lInstance lTime)  = $(logDebugS) "Jobs" $ "Saw locked QueuedJob: " ++ tshow (fromSqlKey jId, lInstance, lTime)
     
-    handleCmd NCtlFlush = void . fork . runDB . runConduit $ selectKeys [] [ Asc QueuedJobCreated ] .| C.mapM_ cmdPerform
-    handleCmd (NCtlPerform jId) = handle handleQueueException . (`finally` jUnlock jId) $ do
-      j@QueuedJob{..} <- jLock jId
-
+    handleCmd JobCtlFlush = void . fork . runDB . runConduit $ selectKeys [] [ Asc QueuedJobCreationTime ] .| C.mapM_ (writeJobCtl . JobCtlPerform)
+    handleCmd (JobCtlPerform jId) = handle handleQueueException . jLocked jId $ \QueuedJob{..} -> do
       let
         content :: Job
         Aeson.Success content = fromJSON queuedJobContent
@@ -76,29 +65,51 @@ handleJobs' = C.mapM_ $ void . handleAny ($(logErrorS) "Jobs" . tshow) . handleC
 
       runDB $ delete jId
 
-jLock :: QueuedJobId -> Handler QueuedJob
-jLock jId = runDB $ do
-  rawExecute "SET TRANSACTION ISOLATION LEVEL SERIALIZABLE" []
-  j@QueuedJob{..} <- maybe (throwM $ JNonexistant jId) return =<< get jId
-  maybe (return ()) throwM $ JLocked <$> pure jId <*> queuedJobLockInstance <*> queuedJobLockTime
-  let isSuccess (Aeson.Success _) = True
-      isSuccess _ = False
-  unless (isSuccess (fromJSON queuedJobContent :: Result Job)) . throwM $ JInvalid j
-  instanceID <- getsYesod appInstanceID
-  now <- liftIO getCurrentTime
-  updateGet jId [ QueuedJobLockInstance =. Just instanceID
-                , QueuedJobLockTime =. Just now
-                ]
-
-jUnlock :: QueuedJobId -> Handler ()
-jUnlock jId = runDB $ update jId [ QueuedJobLockInstance =. Nothing
+jLocked :: QueuedJobId -> (QueuedJob -> Handler a) -> Handler a
+jLocked jId act = do
+  hasLock <- liftIO $ newTVarIO False
+  val <- runDB $ do
+    [executeQQ|
+      SET TRANSACTION ISOLATION LEVEL SERIALIZABLE
+    |]
+    j@QueuedJob{..} <- maybe (throwM $ JNonexistant jId) return =<< get jId
+    maybe (return ()) throwM $ JLocked <$> pure jId <*> queuedJobLockInstance <*> queuedJobLockTime
+    case fromJSON queuedJobContent :: Aeson.Result Job of
+      Aeson.Success _ -> return ()
+      Aeson.Error t -> do
+        $logErrorS "Jobs" $ "Aeson decoding error: " <> pack t
+        throwM $ JInvalid jId j
+    instanceID <- getsYesod appInstanceID
+    now <- liftIO getCurrentTime
+    val <- updateGet jId [ QueuedJobLockInstance =. Just instanceID
+                         , QueuedJobLockTime =. Just now
+                         ]
+    liftIO . atomically $ writeTVar hasLock True
+    return val
+  act val `finally` whenM (liftIO . atomically $ readTVar hasLock) jUnlock
+  where
+    jUnlock :: Handler ()
+    jUnlock = runDB $ update jId [ QueuedJobLockInstance =. Nothing
                                  , QueuedJobLockTime =. Nothing
                                  ]
 
 
-cmdPerform :: ( MonadHandler m
-              , HandlerSite m ~ UniWorX
-              ) => QueuedJobId -> m ()
-cmdPerform (NCtlPerform -> cmd) = do
-  chan <- getsYesod appJobCtl 
+writeJobCtl :: (MonadHandler m, HandlerSite m ~ UniWorX) => JobCtl -> m ()
+writeJobCtl cmd = do
+  chan <- getsYesod appJobCtl
   liftIO . atomically $ writeTMChan chan cmd
+
+queueJob :: Job -> YesodDB UniWorX QueuedJobId
+queueJob job = do
+  now <- liftIO getCurrentTime
+  self <- getsYesod appInstanceID
+  jId <- insert QueuedJob
+    { queuedJobContent = toJSON job
+    , queuedJobCreationInstance = self
+    , queuedJobCreationTime = now
+    , queuedJobLockInstance = Nothing
+    , queuedJobLockTime = Nothing
+    }
+  writeJobCtl $ JobCtlPerform jId -- FIXME: Should do fancy load balancing across instances (or something)
+  return jId
+

src/Jobs/Types.hs

@@ -0,0 +1,38 @@
+{-# LANGUAGE TemplateHaskell
+           , NoImplicitPrelude
+  #-}
+
+module Jobs.Types
+  ( Job(..), Notification(..)
+  , JobCtl(..)
+  ) where
+
+import Import.NoFoundation
+
+import Data.Aeson (defaultOptions, Options(..), SumEncoding(..))
+import Data.Aeson.TH (deriveJSON)
+
+
+data Job = JobSendNotification { jRecipient :: UserId, jNotification :: Notification }
+  deriving (Eq, Ord, Show, Read)
+data Notification = NotificationSubmissionRated { nSubmission :: SubmissionId, nTimestamp :: UTCTime }
+  deriving (Eq, Ord, Show, Read)
+
+deriveJSON defaultOptions
+  { constructorTagModifier = intercalate "-" . map toLower . drop 1 . splitCamel
+  , fieldLabelModifier = intercalate "-" . map toLower . drop 1 . splitCamel
+  , tagSingleConstructors = True
+  , sumEncoding = TaggedObject "job" "data"
+  } ''Job
+
+deriveJSON defaultOptions
+  { constructorTagModifier = intercalate "-" . map toLower . drop 1 . splitCamel
+  , fieldLabelModifier = intercalate "-" . map toLower . drop 1 . splitCamel
+  , tagSingleConstructors = True
+  , sumEncoding = TaggedObject "notification" "data"
+  } ''Notification
+
+
+data JobCtl = JobCtlFlush
+            | JobCtlPerform QueuedJobId
+  deriving (Eq, Ord, Read, Show)

src/Model.hs

@@ -24,7 +24,6 @@ import Database.Persist.Quasi
 -- import Data.ByteString
 import Model.Types
 
-import Data.UUID
 import Data.Aeson (Value)
 import Data.Aeson.TH (deriveJSON, defaultOptions)
 

src/Model/Types.hs

@@ -453,3 +453,4 @@ type SheetName       = CI Text
 type UserEmail       = CI Text
 
 type PWHashAlgorithm = ByteString -> PWStore.Salt -> Int -> ByteString
+type InstanceId      = UUID

src/Utils/Message.hs

@@ -1,5 +1,6 @@
 {-# LANGUAGE FlexibleInstances, FlexibleContexts #-}
 {-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE NoImplicitPrelude #-}
 
 
 module Utils.Message
@@ -13,7 +14,7 @@ import Data.Universe
 import Utils.PathPiece (finiteFromPathPiece, nullaryToPathPiece)
 
 import qualified ClassyPrelude.Yesod (addMessage, addMessageI)
-import ClassyPrelude.Yesod (PathPiece(..),MonadHandler,HandlerSite,RenderMessage,Html)
+import ClassyPrelude.Yesod hiding (addMessage, addMessageI)
 
 
 data MessageClass = Error | Warning | Info | Success

src/Utils/TH.hs

@@ -1,11 +1,13 @@
 {-# LANGUAGE TemplateHaskell #-}
 {-# LANGUAGE QuasiQuotes #-}
+{-# LANGUAGE NoImplicitPrelude #-}
 
 module Utils.TH where
 -- Common Utility Functions that require TemplateHaskell
 
 -- import Data.Char
 
+import Prelude
 import Language.Haskell.TH
 -- import Control.Monad
 -- import Control.Monad.Trans.Class