From 2b20d5b2602889c8fb3a04bde9e0ecb841760d7f Mon Sep 17 00:00:00 2001
From: Vladimir Golovnev <glassez@yandex.ru>
Date: Mon, 16 Jan 2023 14:45:12 +0300
Subject: [PATCH] Fix startup performance on Qt5

Use more appropriate container (QList) for resume data queue buffer.
QVector in Qt5 has poor performance of the first element taking operation,
which is used to process the resume data queue. In Qt6, QVector is just an
alias for QList, so there was no problem there.

PR #18387.
Fixes #18341.
---
 src/base/bittorrent/resumedatastorage.cpp | 5 +++--
 src/base/bittorrent/resumedatastorage.h   | 6 +++---
 src/base/bittorrent/sessionimpl.cpp       | 2 +-
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/base/bittorrent/resumedatastorage.cpp b/src/base/bittorrent/resumedatastorage.cpp
index 0b640a95e..6e67a5b58 100644
--- a/src/base/bittorrent/resumedatastorage.cpp
+++ b/src/base/bittorrent/resumedatastorage.cpp
@@ -33,6 +33,7 @@
 #include <QMetaObject>
 #include <QMutexLocker>
 #include <QThread>
+#include <QVector>
 
 const int TORRENTIDLIST_TYPEID = qRegisterMetaType<QVector<BitTorrent::TorrentID>>();
 
@@ -59,11 +60,11 @@ void BitTorrent::ResumeDataStorage::loadAll() const
     loadingThread->start();
 }
 
-QVector<BitTorrent::LoadedResumeData> BitTorrent::ResumeDataStorage::fetchLoadedResumeData() const
+QList<BitTorrent::LoadedResumeData> BitTorrent::ResumeDataStorage::fetchLoadedResumeData() const
 {
     const QMutexLocker locker {&m_loadedResumeDataMutex};
 
-    const QVector<BitTorrent::LoadedResumeData> loadedResumeData = m_loadedResumeData;
+    const QList<BitTorrent::LoadedResumeData> loadedResumeData = m_loadedResumeData;
     m_loadedResumeData.clear();
 
     return loadedResumeData;
diff --git a/src/base/bittorrent/resumedatastorage.h b/src/base/bittorrent/resumedatastorage.h
index 3faf63494..b583da60a 100644
--- a/src/base/bittorrent/resumedatastorage.h
+++ b/src/base/bittorrent/resumedatastorage.h
@@ -29,9 +29,9 @@
 #pragma once
 
 #include <QtContainerFwd>
+#include <QList>
 #include <QMutex>
 #include <QObject>
-#include <QVector>
 
 #include "base/3rdparty/expected.hpp"
 #include "base/path.h"
@@ -65,7 +65,7 @@ namespace BitTorrent
         virtual void storeQueue(const QVector<TorrentID> &queue) const = 0;
 
         void loadAll() const;
-        QVector<LoadedResumeData> fetchLoadedResumeData() const;
+        QList<LoadedResumeData> fetchLoadedResumeData() const;
 
     signals:
         void loadStarted(const QVector<BitTorrent::TorrentID> &torrents);
@@ -78,7 +78,7 @@ namespace BitTorrent
         virtual void doLoadAll() const = 0;
 
         const Path m_path;
-        mutable QVector<LoadedResumeData> m_loadedResumeData;
+        mutable QList<LoadedResumeData> m_loadedResumeData;
         mutable QMutex m_loadedResumeDataMutex;
     };
 }
diff --git a/src/base/bittorrent/sessionimpl.cpp b/src/base/bittorrent/sessionimpl.cpp
index 14a5735fe..5fa4cb699 100644
--- a/src/base/bittorrent/sessionimpl.cpp
+++ b/src/base/bittorrent/sessionimpl.cpp
@@ -340,7 +340,7 @@ struct BitTorrent::SessionImpl::ResumeSessionContext final : public QObject
 
     ResumeDataStorage *startupStorage = nullptr;
     ResumeDataStorageType currentStorageType = ResumeDataStorageType::Legacy;
-    QVector<LoadedResumeData> loadedResumeData;
+    QList<LoadedResumeData> loadedResumeData;
     int processingResumeDataCount = 0;
     int64_t totalResumeDataCount = 0;
     int64_t finishedResumeDataCount = 0;