From 53c2aec704a9e05bd0b4c2157590683443987b1d Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Tue, 9 Jul 2024 04:33:48 +0000
Subject: [PATCH] fix ABA

Signed-off-by: Jason Volk <jason@zemos.net>
---
 src/api/client_server/membership.rs | 78 ++++++++++++++---------------
 1 file changed, 39 insertions(+), 39 deletions(-)

diff --git a/src/api/client_server/membership.rs b/src/api/client_server/membership.rs
index 3f3d25d5..37e54ce6 100644
--- a/src/api/client_server/membership.rs
+++ b/src/api/client_server/membership.rs
@@ -188,6 +188,17 @@ pub async fn kick_user_route(
 ) -> Result<kick_user::v3::Response> {
     let sender_user = body.sender_user.as_ref().expect("user is authenticated");
 
+    let mutex_state = Arc::clone(
+        services()
+            .globals
+            .roomid_mutex_state
+            .write()
+            .await
+            .entry(body.room_id.clone())
+            .or_default(),
+    );
+    let state_lock = mutex_state.lock().await;
+
     let event: RoomMemberEventContent = serde_json::from_str(
         services()
             .rooms
@@ -220,17 +231,6 @@ pub async fn kick_user_route(
         ..event
     };
 
-    let mutex_state = Arc::clone(
-        services()
-            .globals
-            .roomid_mutex_state
-            .write()
-            .await
-            .entry(body.room_id.clone())
-            .or_default(),
-    );
-    let state_lock = mutex_state.lock().await;
-
     services()
         .rooms
         .timeline
@@ -260,6 +260,17 @@ pub async fn kick_user_route(
 pub async fn ban_user_route(body: Ruma<ban_user::v3::Request>) -> Result<ban_user::v3::Response> {
     let sender_user = body.sender_user.as_ref().expect("user is authenticated");
 
+    let mutex_state = Arc::clone(
+        services()
+            .globals
+            .roomid_mutex_state
+            .write()
+            .await
+            .entry(body.room_id.clone())
+            .or_default(),
+    );
+    let state_lock = mutex_state.lock().await;
+
     let event = if let Some(event) = services()
         .rooms
         .state_accessor
@@ -293,17 +304,6 @@ pub async fn ban_user_route(body: Ruma<ban_user::v3::Request>) -> Result<ban_use
         }
     };
 
-    let mutex_state = Arc::clone(
-        services()
-            .globals
-            .roomid_mutex_state
-            .write()
-            .await
-            .entry(body.room_id.clone())
-            .or_default(),
-    );
-    let state_lock = mutex_state.lock().await;
-
     services()
         .rooms
         .timeline
@@ -335,6 +335,17 @@ pub async fn unban_user_route(
 ) -> Result<unban_user::v3::Response> {
     let sender_user = body.sender_user.as_ref().expect("user is authenticated");
 
+    let mutex_state = Arc::clone(
+        services()
+            .globals
+            .roomid_mutex_state
+            .write()
+            .await
+            .entry(body.room_id.clone())
+            .or_default(),
+    );
+    let state_lock = mutex_state.lock().await;
+
     let event: RoomMemberEventContent = serde_json::from_str(
         services()
             .rooms
@@ -367,17 +378,6 @@ pub async fn unban_user_route(
         ..event
     };
 
-    let mutex_state = Arc::clone(
-        services()
-            .globals
-            .roomid_mutex_state
-            .write()
-            .await
-            .entry(body.room_id.clone())
-            .or_default(),
-    );
-    let state_lock = mutex_state.lock().await;
-
     services()
         .rooms
         .timeline
@@ -527,12 +527,6 @@ async fn join_room_by_id_helper(
 ) -> Result<join_room_by_id::v3::Response> {
     let sender_user = sender_user.expect("user is authenticated");
 
-    if let Ok(true) = services().rooms.state_cache.is_joined(sender_user, room_id) {
-        return Ok(join_room_by_id::v3::Response {
-            room_id: room_id.into(),
-        });
-    }
-
     let mutex_state = Arc::clone(
         services()
             .globals
@@ -544,6 +538,12 @@ async fn join_room_by_id_helper(
     );
     let state_lock = mutex_state.lock().await;
 
+    if let Ok(true) = services().rooms.state_cache.is_joined(sender_user, room_id) {
+        return Ok(join_room_by_id::v3::Response {
+            room_id: room_id.into(),
+        });
+    }
+
     // Ask a remote server if we are not participating in this room
     if !services()
         .rooms