From 1d8d9341572901b77841589b1efd042cb7ae5649 Mon Sep 17 00:00:00 2001
From: Puru Gupta <guptapuru304@gmail.com>
Date: Fri, 7 Jul 2023 04:29:49 +0530
Subject: [PATCH] server: fix race condition in `reloadAppContext`

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/9788
GitOrigin-RevId: c6b9441e4f4e12fea6ad4e5b336f3231fc4494d2
---
 server/src-lib/Hasura/Server/AppStateRef.hs | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/server/src-lib/Hasura/Server/AppStateRef.hs b/server/src-lib/Hasura/Server/AppStateRef.hs
index cad6a206de1..a8cb0cba8f2 100644
--- a/server/src-lib/Hasura/Server/AppStateRef.hs
+++ b/server/src-lib/Hasura/Server/AppStateRef.hs
@@ -276,11 +276,12 @@ updateAppStateRef ::
   (MonadIO m, MonadBaseControl IO m) =>
   AppStateRef impl ->
   L.Logger L.Hasura ->
-  RebuildableAppContext impl ->
-  RebuildableSchemaCache ->
+  (RebuildableAppContext impl -> m (RebuildableAppContext impl, RebuildableSchemaCache)) ->
   m ()
-updateAppStateRef (AppStateRef lock cacheRef metadataVersionGauge) logger !newAppCtx !newSC =
+updateAppStateRef appStateRef@(AppStateRef lock cacheRef metadataVersionGauge) logger action =
   withMVarMasked lock $ const do
+    rebuildableAppContext <- liftIO $ readAppContextRef appStateRef
+    (!newAppCtx, !newSC) <- action rebuildableAppContext
     liftIO do
       -- update schemacache in IO reference
       modifyIORef' cacheRef $ \appState ->