From c31b9e27939a2f756056a818d83c64c9e43b721d Mon Sep 17 00:00:00 2001
From: Nicolas Werner <nicolas.werner@hotmail.de>
Date: Wed, 25 Nov 2020 23:43:31 +0100
Subject: [PATCH] Fix race when reading members from db

---
 src/Cache.cpp                  | 27 ++++++++++++++++++++++-----
 src/ChatPage.cpp               | 15 ++++++++-------
 src/Utils.cpp                  | 30 +++++++++++++++---------------
 src/Utils.h                    |  4 +++-
 src/timeline/TimelineModel.cpp |  5 ++++-
 5 files changed, 52 insertions(+), 29 deletions(-)

diff --git a/src/Cache.cpp b/src/Cache.cpp
index bd0f3733..be9af8ee 100644
--- a/src/Cache.cpp
+++ b/src/Cache.cpp
@@ -1162,10 +1162,10 @@ Cache::saveState(const mtx::responses::Sync &res)
                 saveTimelineMessages(txn, room.first, room.second.timeline);
 
                 RoomInfo updatedInfo;
-                updatedInfo.name  = getRoomName(txn, statesdb, membersdb).toStdString();
-                updatedInfo.topic = getRoomTopic(txn, statesdb).toStdString();
+                updatedInfo.name       = getRoomName(txn, statesdb, membersdb).toStdString();
+                updatedInfo.topic      = getRoomTopic(txn, statesdb).toStdString();
                 updatedInfo.avatar_url = getRoomAvatarUrl(txn, statesdb, membersdb).toStdString();
-                updatedInfo.version = getRoomVersion(txn, statesdb).toStdString();
+                updatedInfo.version    = getRoomVersion(txn, statesdb).toStdString();
 
                 // Process the account_data associated with this room
                 if (!room.second.account_data.events.empty()) {
@@ -1808,6 +1808,17 @@ Cache::getLastMessageInfo(lmdb::txn &txn, const std::string &room_id)
                                    e.what());
                 return {};
         }
+        auto membersdb{0};
+
+        try {
+                membersdb = getMembersDb(txn, room_id);
+        } catch (lmdb::runtime_error &e) {
+                nhlog::db()->error("Can't open db for room '{}', probably doesn't exist yet. ({})",
+                                   room_id,
+                                   e.what());
+                return {};
+        }
+
         if (orderDb.size(txn) == 0)
                 return DescInfo{};
 
@@ -1850,9 +1861,16 @@ Cache::getLastMessageInfo(lmdb::txn &txn, const std::string &room_id)
                 mtx::events::collections::TimelineEvent te;
                 mtx::events::collections::from_json(obj, te);
 
+                lmdb::val info;
+                MemberInfo m;
+                if (lmdb::dbi_get(
+                      txn, membersdb, lmdb::val(obj["sender"].get<std::string>()), info)) {
+                        m = json::parse(std::string_view(info.data(), info.size()));
+                }
+
                 cursor.close();
                 return utils::getMessageDescription(
-                  te.data, local_user, QString::fromStdString(room_id));
+                  te.data, local_user, QString::fromStdString(m.name));
         }
         cursor.close();
 
@@ -1911,7 +1929,6 @@ Cache::getRoomAvatarUrl(lmdb::txn &txn, lmdb::dbi &statesdb, lmdb::dbi &membersd
 
         // Resolve avatar for 1-1 chats.
         while (cursor.get(user_id, member_data, MDB_NEXT)) {
-
                 try {
                         MemberInfo m = json::parse(member_data);
                         if (user_id == localUserId_.toStdString()) {
diff --git a/src/ChatPage.cpp b/src/ChatPage.cpp
index 1fd9b9bc..6dfa62ef 100644
--- a/src/ChatPage.cpp
+++ b/src/ChatPage.cpp
@@ -20,7 +20,6 @@
 #include <QMessageBox>
 #include <QSettings>
 #include <QShortcut>
-#include <QtConcurrent>
 
 #include <mtx/responses.hpp>
 
@@ -281,10 +280,12 @@ ChatPage::ChatPage(QSharedPointer<UserSettings> userSettings, QWidget *parent)
                 &ChatPage::setGroupViewState);
 
         connect(this, &ChatPage::initializeRoomList, room_list_, &RoomList::initialize);
-        connect(this,
-                &ChatPage::initializeViews,
-                view_manager_,
-                [this](const mtx::responses::Rooms &rooms) { view_manager_->sync(rooms); });
+        connect(
+          this,
+          &ChatPage::initializeViews,
+          view_manager_,
+          [this](const mtx::responses::Rooms &rooms) { view_manager_->sync(rooms); },
+          Qt::QueuedConnection);
         connect(this,
                 &ChatPage::initializeEmptyViews,
                 view_manager_,
@@ -522,8 +523,6 @@ ChatPage::bootstrap(QString userid, QString homeserver, QString token)
 void
 ChatPage::loadStateFromCache()
 {
-        emit contentLoaded();
-
         nhlog::db()->info("restoring state from cache");
 
         try {
@@ -555,6 +554,8 @@ ChatPage::loadStateFromCache()
 
         getProfileInfo();
 
+        emit contentLoaded();
+
         // Start receiving events.
         emit trySyncCb();
 }
diff --git a/src/Utils.cpp b/src/Utils.cpp
index 2896e773..743c393f 100644
--- a/src/Utils.cpp
+++ b/src/Utils.cpp
@@ -27,12 +27,12 @@ QHash<QString, QString> authorColors_;
 
 template<class T, class Event>
 static DescInfo
-createDescriptionInfo(const Event &event, const QString &localUser, const QString &room_id)
+createDescriptionInfo(const Event &event, const QString &localUser, const QString &displayName)
 {
         const auto msg    = std::get<T>(event);
         const auto sender = QString::fromStdString(msg.sender);
 
-        const auto username = cache::displayName(room_id, sender);
+        const auto username = displayName;
         const auto ts       = QDateTime::fromMSecsSinceEpoch(msg.origin_server_ts);
 
         return DescInfo{QString::fromStdString(msg.event_id),
@@ -153,7 +153,7 @@ utils::descriptiveTime(const QDateTime &then)
 DescInfo
 utils::getMessageDescription(const TimelineEvent &event,
                              const QString &localUser,
-                             const QString &room_id)
+                             const QString &displayName)
 {
         using Audio      = mtx::events::RoomEvent<mtx::events::msg::Audio>;
         using Emote      = mtx::events::RoomEvent<mtx::events::msg::Emote>;
@@ -168,31 +168,31 @@ utils::getMessageDescription(const TimelineEvent &event,
         using Encrypted  = mtx::events::EncryptedEvent<mtx::events::msg::Encrypted>;
 
         if (std::holds_alternative<Audio>(event)) {
-                return createDescriptionInfo<Audio>(event, localUser, room_id);
+                return createDescriptionInfo<Audio>(event, localUser, displayName);
         } else if (std::holds_alternative<Emote>(event)) {
-                return createDescriptionInfo<Emote>(event, localUser, room_id);
+                return createDescriptionInfo<Emote>(event, localUser, displayName);
         } else if (std::holds_alternative<File>(event)) {
-                return createDescriptionInfo<File>(event, localUser, room_id);
+                return createDescriptionInfo<File>(event, localUser, displayName);
         } else if (std::holds_alternative<Image>(event)) {
-                return createDescriptionInfo<Image>(event, localUser, room_id);
+                return createDescriptionInfo<Image>(event, localUser, displayName);
         } else if (std::holds_alternative<Notice>(event)) {
-                return createDescriptionInfo<Notice>(event, localUser, room_id);
+                return createDescriptionInfo<Notice>(event, localUser, displayName);
         } else if (std::holds_alternative<Text>(event)) {
-                return createDescriptionInfo<Text>(event, localUser, room_id);
+                return createDescriptionInfo<Text>(event, localUser, displayName);
         } else if (std::holds_alternative<Video>(event)) {
-                return createDescriptionInfo<Video>(event, localUser, room_id);
+                return createDescriptionInfo<Video>(event, localUser, displayName);
         } else if (std::holds_alternative<CallInvite>(event)) {
-                return createDescriptionInfo<CallInvite>(event, localUser, room_id);
+                return createDescriptionInfo<CallInvite>(event, localUser, displayName);
         } else if (std::holds_alternative<CallAnswer>(event)) {
-                return createDescriptionInfo<CallAnswer>(event, localUser, room_id);
+                return createDescriptionInfo<CallAnswer>(event, localUser, displayName);
         } else if (std::holds_alternative<CallHangUp>(event)) {
-                return createDescriptionInfo<CallHangUp>(event, localUser, room_id);
+                return createDescriptionInfo<CallHangUp>(event, localUser, displayName);
         } else if (std::holds_alternative<mtx::events::Sticker>(event)) {
-                return createDescriptionInfo<mtx::events::Sticker>(event, localUser, room_id);
+                return createDescriptionInfo<mtx::events::Sticker>(event, localUser, displayName);
         } else if (auto msg = std::get_if<Encrypted>(&event); msg != nullptr) {
                 const auto sender = QString::fromStdString(msg->sender);
 
-                const auto username = cache::displayName(room_id, sender);
+                const auto username = displayName;
                 const auto ts       = QDateTime::fromMSecsSinceEpoch(msg->origin_server_ts);
 
                 DescInfo info;
diff --git a/src/Utils.h b/src/Utils.h
index f59e8673..6de3d458 100644
--- a/src/Utils.h
+++ b/src/Utils.h
@@ -67,7 +67,9 @@ descriptiveTime(const QDateTime &then);
 //! Generate a message description from the event to be displayed
 //! in the RoomList.
 DescInfo
-getMessageDescription(const TimelineEvent &event, const QString &localUser, const QString &room_id);
+getMessageDescription(const TimelineEvent &event,
+                      const QString &localUser,
+                      const QString &displayName);
 
 //! Get the first character of a string, taking into account that
 //! surrogate pairs might be in use.
diff --git a/src/timeline/TimelineModel.cpp b/src/timeline/TimelineModel.cpp
index 4cbd5777..53791c98 100644
--- a/src/timeline/TimelineModel.cpp
+++ b/src/timeline/TimelineModel.cpp
@@ -709,7 +709,10 @@ TimelineModel::updateLastMessage()
                         continue;
 
                 auto description = utils::getMessageDescription(
-                  *event, QString::fromStdString(http::client()->user_id().to_string()), room_id_);
+                  *event,
+                  QString::fromStdString(http::client()->user_id().to_string()),
+                  cache::displayName(room_id_,
+                                     QString::fromStdString(mtx::accessors::sender(*event))));
                 emit manager_->updateRoomsLastMessage(room_id_, description);
                 return;
         }