From 2f769726dda4789e3b155816498d2093769f883a Mon Sep 17 00:00:00 2001
From: Julian Sparber <julian@sparber.net>
Date: Fri, 12 Mar 2021 17:02:25 +0100
Subject: [PATCH] matrix-sdk: prevent dupplicated members requests

---
 matrix_sdk/src/client.rs      | 15 +++++++-------
 matrix_sdk/src/room/common.rs | 38 +++++++++++++++++++++++++++--------
 2 files changed, 38 insertions(+), 15 deletions(-)

diff --git a/matrix_sdk/src/client.rs b/matrix_sdk/src/client.rs
index 0639a635..0b7d06c5 100644
--- a/matrix_sdk/src/client.rs
+++ b/matrix_sdk/src/client.rs
@@ -88,16 +88,15 @@ use matrix_sdk_common::{
 };
 
 #[cfg(feature = "encryption")]
-use matrix_sdk_common::{
-    api::r0::{
-        keys::{get_keys, upload_keys, upload_signing_keys::Request as UploadSigningKeysRequest},
-        to_device::send_event_to_device::{
-            Request as RumaToDeviceRequest, Response as ToDeviceResponse,
-        },
+use matrix_sdk_common::api::r0::{
+    keys::{get_keys, upload_keys, upload_signing_keys::Request as UploadSigningKeysRequest},
+    to_device::send_event_to_device::{
+        Request as RumaToDeviceRequest, Response as ToDeviceResponse,
     },
-    locks::Mutex,
 };
 
+use matrix_sdk_common::locks::Mutex;
+
 use crate::{
     error::HttpError,
     http_client::{client_with_config, HttpClient, HttpSend},
@@ -138,6 +137,7 @@ pub struct Client {
     #[cfg(feature = "encryption")]
     /// Lock making sure we're only doing one key claim request at a time.
     key_claim_lock: Arc<Mutex<()>>,
+    pub(crate) members_request_locks: DashMap<RoomId, Arc<Mutex<()>>>,
 }
 
 #[cfg(not(tarpaulin_include))]
@@ -393,6 +393,7 @@ impl Client {
             group_session_locks: DashMap::new(),
             #[cfg(feature = "encryption")]
             key_claim_lock: Arc::new(Mutex::new(())),
+            members_request_locks: DashMap::new(),
         })
     }
 
diff --git a/matrix_sdk/src/room/common.rs b/matrix_sdk/src/room/common.rs
index aa4fd222..2a3fa773 100644
--- a/matrix_sdk/src/room/common.rs
+++ b/matrix_sdk/src/room/common.rs
@@ -2,7 +2,9 @@ use matrix_sdk_common::api::r0::{
     membership::{get_member_events, join_room_by_id, leave_room},
     message::get_message_events,
 };
-use std::ops::Deref;
+use matrix_sdk_common::locks::Mutex;
+
+use std::{ops::Deref, sync::Arc};
 
 use crate::{Client, Result, Room, RoomMember};
 
@@ -96,14 +98,34 @@ impl Common {
     }
 
     pub(crate) async fn request_members(&self) -> Result<()> {
-        // TODO: don't send a request if a request is being sent
-        let request = get_member_events::Request::new(self.inner.room_id());
-        let response = self.client.send(request, None).await?;
+        #[allow(clippy::map_clone)]
+        if let Some(mutex) = self
+            .client
+            .members_request_locks
+            .get(self.inner.room_id())
+            .map(|m| m.clone())
+        {
+            mutex.lock().await;
+        } else {
+            let mutex = Arc::new(Mutex::new(()));
+            self.client
+                .members_request_locks
+                .insert(self.inner.room_id().clone(), mutex.clone());
 
-        self.client
-            .base_client
-            .receive_members(self.inner.room_id(), &response)
-            .await?;
+            let _guard = mutex.lock().await;
+
+            let request = get_member_events::Request::new(self.inner.room_id());
+            let response = self.client.send(request, None).await?;
+
+            self.client
+                .base_client
+                .receive_members(self.inner.room_id(), &response)
+                .await?;
+
+            self.client
+                .members_request_locks
+                .remove(self.inner.room_id());
+        }
 
         Ok(())
     }