Load the initial cache data without blocking the UI

CMakeLists.txt

@@ -277,6 +277,7 @@ qt5_wrap_cpp(MOC_HEADERS
     include/ui/ThemeManager.h
 
     include/AvatarProvider.h
+    include/Cache.h
     include/ChatPage.h
     include/CommunitiesListItem.h
     include/CommunitiesList.h

include/Cache.h

@@ -18,11 +18,12 @@
 #pragma once
 
 #include <QDir>
+#include <QMap>
 #include <json.hpp>
 #include <lmdb++.h>
 #include <mtx/responses.hpp>
 
-class RoomState;
+#include "RoomState.h"
 
 //! Used to uniquely identify a list of read receipts.
 struct ReadReceiptKey
@@ -44,17 +45,19 @@ from_json(const json &j, ReadReceiptKey &key)
         key.room_id  = j.at("room_id").get<std::string>();
 }
 
-class Cache
+class Cache : public QObject
 {
+        Q_OBJECT
+
 public:
-        Cache(const QString &userId);
+        Cache(const QString &userId, QObject *parent = nullptr);
 
         void setState(const QString &nextBatchToken,
                       const QMap<QString, QSharedPointer<RoomState>> &states);
         bool isInitialized() const;
 
         QString nextBatchToken() const;
-        QMap<QString, RoomState> states();
+        void states();
 
         using Invites = std::map<std::string, mtx::responses::InvitedRoom>;
         Invites invites();
@@ -86,6 +89,9 @@ public:
         QByteArray image(const QString &url) const;
         void saveImage(const QString &url, const QByteArray &data);
 
+signals:
+        void statesLoaded(QMap<QString, RoomState> states);
+
 private:
         void setNextBatchToken(lmdb::txn &txn, const QString &token);
         void insertRoomState(lmdb::txn &txn,

include/RoomState.h

@@ -77,6 +77,8 @@ private:
         QString userAvatar_;
 };
 
+Q_DECLARE_METATYPE(RoomState)
+
 template<class Collection>
 void
 RoomState::updateFromEvents(const std::vector<Collection> &collection)

src/Cache.cc

@@ -33,8 +33,9 @@ static const lmdb::val CACHE_FORMAT_VERSION_KEY("cache_format_version");
 using CachedReceipts = std::multimap<uint64_t, std::string, std::greater<uint64_t>>;
 using Receipts       = std::map<std::string, std::map<std::string, uint64_t>>;
 
-Cache::Cache(const QString &userId)
+Cache::Cache(const QString &userId, QObject *parent)
-  : env_{nullptr}
+  : QObject{parent}
+  , env_{nullptr}
   , stateDb_{0}
   , roomDb_{0}
   , invitesDb_{0}
@@ -248,7 +249,7 @@ Cache::removeInvite(const QString &room_id)
         txn.commit();
 }
 
-QMap<QString, RoomState>
+void
 Cache::states()
 {
         QMap<QString, RoomState> states;
@@ -301,7 +302,7 @@ Cache::states()
 
         txn.commit();
 
-        return states;
+        emit statesLoaded(states);
 }
 
 void

src/ChatPage.cc

@@ -648,8 +648,12 @@ ChatPage::loadStateFromCache()
         qDebug() << "Restored nextBatchToken" << cache_->nextBatchToken();
         client_->setNextBatchToken(cache_->nextBatchToken());
 
-        // Fetch all the joined room's state.
+        qRegisterMetaType<QMap<QString, RoomState>>();
-        auto rooms = cache_->states();
+
+        QtConcurrent::run(cache_.data(), &Cache::states);
+
+        connect(cache_.data(), &Cache::statesLoaded, this, [this](QMap<QString, RoomState> rooms) {
+                qDebug() << "Cache data loaded";
 
                 for (auto it = rooms.constBegin(); it != rooms.constEnd(); ++it) {
                         auto roomState = QSharedPointer<RoomState>(new RoomState(it.value()));
@@ -663,8 +667,8 @@ ChatPage::loadStateFromCache()
                         roomStates_.insert(it.key(), roomState);
 
                         // Create or restore the settings for this room.
-                roomSettings_.insert(it.key(),
+                        roomSettings_.insert(
-                                     QSharedPointer<RoomSettings>(new RoomSettings(it.key())));
+                          it.key(), QSharedPointer<RoomSettings>(new RoomSettings(it.key())));
 
                         // Resolve user avatars.
                         for (const auto membership : roomState->memberships) {
@@ -688,6 +692,7 @@ ChatPage::loadStateFromCache()
 
                 // Start receiving events.
                 client_->sync();
+        });
 }
 
 void