From afcb68cc0ed004aa2ece5a9d92e5b3e137fa4e5e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Damir=20Jeli=C4=87?= <poljar@termina.org.uk>
Date: Tue, 26 Nov 2019 20:34:11 +0100
Subject: [PATCH] async_client: Make our sync method threadsafe across yield
 points.

---
 src/async_client.rs | 59 ++++++++++++++++++++++++++++-----------------
 1 file changed, 37 insertions(+), 22 deletions(-)

diff --git a/src/async_client.rs b/src/async_client.rs
index b6534f3e..ff1808b6 100644
--- a/src/async_client.rs
+++ b/src/async_client.rs
@@ -1,7 +1,7 @@
 use futures::future::{BoxFuture, Future, FutureExt};
 use std::convert::{TryFrom, TryInto};
 use std::sync::atomic::{AtomicU64, Ordering};
-use std::sync::{Arc, RwLock};
+use std::sync::{Arc, Mutex, RwLock};
 
 use http::Method as HttpMethod;
 use http::Response as HttpResponse;
@@ -12,6 +12,7 @@ use url::Url;
 use ruma_api::Endpoint;
 use ruma_events::collections::all::RoomEvent;
 use ruma_events::room::message::MessageEventContent;
+use ruma_events::EventResult;
 pub use ruma_events::EventType;
 use ruma_identifiers::RoomId;
 
@@ -23,7 +24,7 @@ use crate::session::Session;
 use crate::VERSION;
 
 type RoomEventCallbackF =
-    Box<dyn FnMut(Arc<RwLock<Room>>, Arc<RoomEvent>) -> BoxFuture<'static, ()>>;
+    Box<dyn FnMut(Arc<RwLock<Room>>, Arc<RoomEvent>) -> BoxFuture<'static, ()> + Send>;
 
 #[derive(Clone)]
 pub struct AsyncClient {
@@ -36,7 +37,7 @@ pub struct AsyncClient {
     /// The transaction id.
     transaction_id: Arc<AtomicU64>,
     /// Event futures
-    event_futures: Arc<RwLock<Vec<RoomEventCallbackF>>>,
+    event_futures: Arc<Mutex<Vec<RoomEventCallbackF>>>,
 }
 
 #[derive(Default, Debug)]
@@ -152,8 +153,7 @@ impl AsyncClient {
             http_client,
             base_client: Arc::new(RwLock::new(BaseClient::new(session))),
             transaction_id: Arc::new(AtomicU64::new(0)),
-            // event_callbacks: Vec::new(),
-            event_futures: Arc::new(RwLock::new(Vec::new())),
+            event_futures: Arc::new(Mutex::new(Vec::new())),
         })
     }
 
@@ -163,11 +163,11 @@ impl AsyncClient {
 
     pub fn add_event_future<C: 'static>(
         &mut self,
-        mut callback: impl FnMut(Arc<RwLock<Room>>, Arc<RoomEvent>) -> C + 'static,
+        mut callback: impl FnMut(Arc<RwLock<Room>>, Arc<RoomEvent>) -> C + 'static + Send,
     ) where
         C: Future<Output = ()> + Send,
     {
-        let mut futures = self.event_futures.write().unwrap();
+        let mut futures = self.event_futures.lock().unwrap();
 
         let future = move |room, event| callback(room, event).boxed();
 
@@ -210,19 +210,20 @@ impl AsyncClient {
 
         let response = self.send(request).await?;
 
-        let mut client = self.base_client.write().unwrap();
-
         for (room_id, room) in &response.rooms.join {
             let room_id = room_id.to_string();
 
-            for event in &room.state.events {
-                let event = match event.clone().into_result() {
-                    Ok(e) => e,
-                    Err(e) => continue,
-                };
+            let matrix_room = {
+                let mut client = self.base_client.write().unwrap();
 
-                client.receive_joined_state_event(&room_id, &event);
-            }
+                for event in &room.state.events {
+                    if let EventResult::Ok(e) = event {
+                        client.receive_joined_state_event(&room_id, &e);
+                    }
+                }
+
+                client.joined_rooms.get(&room_id).unwrap().clone()
+            };
 
             for event in &room.timeline.events {
                 let event = match event.clone().into_result() {
@@ -230,24 +231,38 @@ impl AsyncClient {
                     Err(e) => continue,
                 };
 
-                client.receive_joined_timeline_event(&room_id, &event);
-
-                let room = client.joined_rooms.get(&room_id).unwrap();
-                let mut cb_futures = self.event_futures.write().unwrap();
+                {
+                    let mut client = self.base_client.write().unwrap();
+                    client.receive_joined_timeline_event(&room_id, &event);
+                }
 
                 let event = Arc::new(event.clone());
 
-                for cb in &mut cb_futures.iter_mut() {
-                    cb(room.clone(), event.clone()).await;
+                let callbacks = {
+                    let mut cb_futures = self.event_futures.lock().unwrap();
+                    let mut callbacks = Vec::new();
+
+                    for cb in &mut cb_futures.iter_mut() {
+                        callbacks.push(cb(matrix_room.clone(), event.clone()));
+                    }
+
+                    callbacks
+                };
+
+                for cb in callbacks {
+                    cb.await;
                 }
             }
 
+            let mut client = self.base_client.write().unwrap();
             client.receive_sync_response(&response);
         }
 
         Ok(response)
     }
 
+    async fn sync_forever() {}
+
     async fn send<Request: Endpoint>(&self, request: Request) -> Result<Request::Response, Error> {
         let request: http::Request<Vec<u8>> = request.try_into()?;
         let url = request.uri();