fix race on repository watch

1 files changed, 13 insertions, 4 deletions

diff --git a/backend/app/Main.hs b/backend/app/Main.hs
index c31ea7d..917a6d9 100644
--- a/backend/app/Main.hs
+++ b/backend/app/Main.hs
@@ -13,7 +13,7 @@ import Control.Concurrent
 import Control.Concurrent.STM
 import Control.Exception (throwIO)
 import Control.Monad
-import Control.Monad.Catch (Exception)
+import Control.Monad.Catch (Exception, SomeException, catch, displayException)
 import Control.Monad.Trans (liftIO)
 import Data.Aeson qualified as J
 import Data.Aeson.KeyMap qualified as JM
@@ -127,13 +127,22 @@ watch repoT root ref = do
     addWatch i [Create, MoveIn] ".git/refs/heads" $ \e -> do
       when (e.filePath == B.fromString (takeBaseName (T.unpack ref))) do
         atomically (writeTQueue qT e)
+  repo <- initRepo root ref
+  atomically do putTMVar repoT repo
   forever do
-    repo <- initRepo root ref
-    atomically do putTMVar repoT repo
     _ <- atomically do
       let loop = maybe (pure ()) (const loop) =<< tryReadTQueue qT
       readTQueue qT >> loop
-    _ <- atomically do takeTMVar repoT
+    repo' <- atomically do takeTMVar repoT
+    catch
+      ( do
+          repo <- initRepo root ref
+          atomically do putTMVar repoT repo
+      )
+      ( \(e :: SomeException) -> do
+          printf "warning: %s\n" (displayException e)
+          atomically do putTMVar repoT repo'
+      )
     pure ()
 
 initRepo :: FilePath -> G.RefName -> IO Repo