Add schedule module move some ExceptTs around

app/Main.hs

@@ -11,10 +11,10 @@
 module Main (main) where
 
 import Control.Monad.IO.Class (liftIO)
-import Control.Monad.Trans.Except (ExceptT (..), runExceptT)
+import Control.Monad.Trans.Except (ExceptT (..), catchE, runExceptT)
 import Data.Proxy (Proxy (..))
 import Data.Text (Text)
-import Data.Time (Day, toGregorian)
+import Data.Time (Day, addDays, toGregorian)
 import GHC.Generics (Generic)
 import Network.HTTP.Media ((//), (/:))
 import Network.HTTP.Types (Status (..), mkStatus, status200)
@@ -54,10 +54,12 @@ import qualified Text.Blaze.Html5 as H
 import qualified Text.Blaze.Html5.Attributes as A
 
 import Envy (type (=@!), type (=@@), type (?))
-import Yore.DB (DayFile (..))
+import Yore.DB (DB, DayFile (..))
 import Yore.Error (Error (..))
+import Yore.Schedule (schedule)
 import Yore.Time (addYears, getCurrentDay, getSecondsUntilMidnight)
 
+import Control.Concurrent (forkIO)
 import Control.Monad (forM, forM_)
 import Data.Bifunctor (Bifunctor (..))
 import qualified Envy
@@ -93,7 +95,37 @@ main = do
       Right c ->
         pure c
 
-  let
+  db <- DB.initDB cfg.yoreDb
+  _ <-
+    runExceptT $
+      catchE
+        ( DB.withConn db $ \conn -> do
+            dayThen <- getTodayWithYearOffset (-100)
+            indexDay cfg dayThen conn
+        )
+        (Log.error . show)
+
+  _ <- forkIO $ runIndexer cfg db
+  runServer cfg db
+
+runIndexer :: Config -> DB -> IO ()
+runIndexer cfg db = schedule (const True) $ do
+  _ <-
+    runExceptT $
+      catchE
+        ( DB.withTransaction db $ \conn -> do
+            dayThen <- getTodayWithYearOffset (-100)
+            indexDay cfg dayThen conn
+            dayThen2 <- addDays 1 <$> getTodayWithYearOffset (-100)
+            indexDay cfg dayThen2 conn
+        )
+        (Log.error . show)
+  pure ()
+
+runServer :: Config -> DB -> IO ()
+runServer cfg db =
+  Warp.runSettings settings $ serve (Proxy @API) $ hoistServer (Proxy @API) nt $ server cfg db
+  where
     settings =
       foldr
         ($)
@@ -104,13 +136,6 @@ main = do
         , Warp.setOnException onException
         ]
 
-  db <- DB.initDB cfg.yoreDb
-  DB.withConn db (runExceptT . indexDayWithOffset cfg (-100)) >>= \case
-    Left err -> Log.error $ show err
-    Right _ -> pure ()
-
-  Warp.runSettings settings $ serve (Proxy @API) $ hoistServer (Proxy @API) nt $ server cfg db
-  where
     logger req status _ = do
       Log.info $
         printf
@@ -166,20 +191,20 @@ handlerToRaw handler = Tagged $ \_ respond -> do
     Right response ->
       respond response
 
-server :: Config -> DB.DB -> ServerT API (ExceptT Error IO)
+server :: Config -> DB -> ServerT API (ExceptT Error IO)
 server cfg db = rootR :<|> todayR :<|> apiTodayR
   where
     rootR = todayR 0
 
     todayR issue = do
       dateThen <- ExceptT get100YearsAgo
-      count <- ExceptT $ DB.withConn' db $ DB.getNumberOfIssues dateThen
-      dayFile <- ExceptT $ DB.withConn' db $ DB.getDayFileByIssue dateThen issue
+      count <- DB.withConn db $ DB.lift . DB.getNumberOfIssues dateThen
+      dayFile <- DB.withConn db $ DB.lift . DB.getDayFileByIssue dateThen issue
       pure $ RootModel dateThen dayFile issue count
 
     apiTodayR issue = handlerToRaw $ do
       dateThen <- ExceptT get100YearsAgo
-      dayFile <- ExceptT $ DB.withConn' db $ DB.getDayFileByIssue dateThen issue
+      dayFile <- DB.withConn db $ DB.lift . DB.getDayFileByIssue dateThen issue
       let fullPath = cfg.yoreDownloadDir </> dayFile.relative_path
       secondsUntilMidnight <- liftIO getSecondsUntilMidnight
       pure $
@@ -231,36 +256,30 @@ instance Accept HTML where
   contentType _ = "text" // "html" /: ("charset", "utf-8")
 
 get100YearsAgo :: IO (Either Error Day)
-get100YearsAgo = getTodayWithYearOffset (-100)
+get100YearsAgo = runExceptT $ getTodayWithYearOffset (-100)
 
-getTodayWithYearOffset :: Integer -> IO (Either Error Day)
+getTodayWithYearOffset :: Integer -> ExceptT Error IO Day
 getTodayWithYearOffset offset =
-  first (GenericError . (Text.pack (printf "can't go back %s years: " (-offset)) <>)) . addYears offset <$> getCurrentDay
+  ExceptT $
+    first (GenericError . (Text.pack (printf "can't go back %s years: " (-offset)) <>)) . addYears offset <$> getCurrentDay
 
-indexDayWithOffset :: Config -> Integer -> Opium.Connection -> ExceptT Error IO ()
-indexDayWithOffset cfg offset conn = do
-  dayThen <- ExceptT $ getTodayWithYearOffset offset
-  runDb $ Opium.execute_ "BEGIN" conn
+indexDay :: Config -> Day -> Opium.Connection -> ExceptT Error IO ()
+indexDay cfg dayThen conn = do
   -- Transaction-level lock released automatically after transaction
-  runDb $ Opium.execute_ "SELECT pg_advisory_xact_lock(42);" conn
-  mbDi <- runDb $ DB.readDayIndex dayThen conn
+  DB.lift $ Opium.execute_ "SELECT pg_advisory_xact_lock(42);" conn
+  mbDi <- DB.lift $ DB.readDayIndex dayThen conn
   case mbDi of
     Just _ ->
-      liftIO $ Log.info $ printf "index for %s already exists." (show dayThen)
+      Log.info $ printf "index for %s already exists." (show dayThen)
     Nothing -> do
-      liftIO $ Log.info $ printf "scraping issues for %s" (show dayThen)
+      Log.info $ printf "scraping issues for %s" (show dayThen)
       issues <- liftIO $ getIssuesByDay dayThen
       paths <- forM issues $ \issue -> do
-        liftIO $ Log.info $ printf "downloading %s" issue.url
+        Log.info $ printf "downloading %s" issue.url
         path <- liftIO $ downloadInto cfg.yoreDownloadDir issue.url
         pure (issue.label, path)
-      liftIO $ Log.info "creating DB entries"
-      dayIndex <- runDb $ DB.createDayIndex dayThen conn
+      Log.info "creating DB entries"
+      dayIndex <- DB.lift $ DB.createDayIndex dayThen conn
       forM_ paths $ \(text, url) ->
-        runDb $ DB.createDayFile dayIndex.day_index_id text url conn
-      runDb $ Opium.execute_ "COMMIT" conn
-      liftIO $ Log.info "done."
-
-runDb :: IO (Either Opium.Error a) -> ExceptT Error IO a
-runDb f =
-  ExceptT $ first DBError <$> f
+        DB.lift $ DB.createDayFile dayIndex.day_index_id text url conn
+      Log.info "done."