Prevent loading older messages while loading older messages

src/models/roommodel.cpp

@@ -136,7 +136,7 @@ template <class T>::EventType::Type toRoomEventType(const Event<T> &e) {
 ::EventType::Type toRoomEventType(const Event<mtx::events::msg::Video> &e) { return ::EventType::VideoMessage; }
 } // namespace
 
-Room::Room(QObject *parent) {
+Room::Room(QObject *parent) : loadingOlderMessages(false) {
     Q_UNUSED(parent);
     connect(this, &Room::newEvents, this, &Room::addEvents, Qt::QueuedConnection);
     connect(this, &Room::newTags, this, &Room::setTags, Qt::QueuedConnection);
@@ -291,6 +291,10 @@ void Room::addEvents(std::vector<mtx::events::collections::TimelineEvents> event
 }
 
 void Room::fetchOlderMessages() {
+    if (this->loadingOlderMessages.exchange(true)) {
+        qDebug() << "Already loading older messages";
+        return;
+    }
     mtx::http::MessagesOpts opts = {};
     opts.from = this->prev_batch;
     opts.limit = 100;
@@ -298,10 +302,12 @@ void Room::fetchOlderMessages() {
     http::client().messages(opts, [this](const mtx::responses::Messages &res, mtx::http::RequestErr err) {
         if (err) {
             qDebug() << "failed to retrieve messages: " << *err;
+            this->loadingOlderMessages = false;
             return;
         }
 
         emit newEvents({res.chunk.rbegin(), res.chunk.rend()}, res.end, res.start);
+        this->loadingOlderMessages = false;
     });
 }
 

src/models/roommodel.h

 #pragma once
 
+#include <atomic>
 #include <map>
 #include <set>
 #include <string>
@@ -163,6 +164,7 @@ struct Room : public QAbstractListModel {
     std::vector<mtx::events::collections::TimelineEvents> events;
     std::string prev_batch;
     std::string next_batch;
+    std::atomic<bool> loadingOlderMessages;
 
     std::map<QString, QColor> userColors;
 };