Unify singleton pattern in Profile class

1. Use unified function names `initInstance()` and `freeInstance()` and
make them public.
2. Add `freeInstance()` to avoid noise from memory leak detectors.
3. Let `instance()`return a pointer directly to avoid unnecessary
indirections when invoking functions.

src/app/application.cpp

@@ -149,7 +149,7 @@ Application::Application(const QString &id, int &argc, char **argv)
     const QString profileDir = portableModeEnabled
         ? QDir(QCoreApplication::applicationDirPath()).absoluteFilePath(DEFAULT_PORTABLE_MODE_PROFILE_DIR)
         : m_commandLineArgs.profileDir;
-    Profile::initialize(profileDir, m_commandLineArgs.configurationName,
+    Profile::initInstance(profileDir, m_commandLineArgs.configurationName,
                         (m_commandLineArgs.relativeFastresumePaths || portableModeEnabled));
 
     Logger::initInstance();
@@ -177,7 +177,7 @@ Application::Application(const QString &id, int &argc, char **argv)
             Logger::instance()->addMessage(tr("Redundant command line flag detected: \"%1\". Portable mode implies relative fastresume.").arg("--relative-fastresume"), Log::WARNING); // to avoid translating the `--relative-fastresume` string
     }
     else {
-        Logger::instance()->addMessage(tr("Using config directory: %1").arg(Profile::instance().location(SpecialFolder::Config)));
+        Logger::instance()->addMessage(tr("Using config directory: %1").arg(Profile::instance()->location(SpecialFolder::Config)));
     }
 }
 
@@ -764,6 +764,8 @@ void Application::cleanup()
     }
 #endif // DISABLE_GUI
 
+    Profile::freeInstance();
+
     if (m_shutdownAct != ShutdownDialogAction::Exit) {
         qDebug() << "Sending computer shutdown/suspend/hibernate signal...";
         Utils::Misc::shutdownComputer(m_shutdownAct);

src/base/bittorrent/private/statistics.cpp

@@ -90,7 +90,7 @@ void Statistics::save() const
     if (!m_dirty || ((now - m_lastWrite) < SAVE_INTERVAL))
         return;
 
-    SettingsPtr s = Profile::instance().applicationSettings(QLatin1String("qBittorrent-data"));
+    SettingsPtr s = Profile::instance()->applicationSettings(QLatin1String("qBittorrent-data"));
     QVariantHash v;
     v.insert("AlltimeDL", m_alltimeDL + m_sessionDL);
     v.insert("AlltimeUL", m_alltimeUL + m_sessionUL);
@@ -101,7 +101,7 @@ void Statistics::save() const
 
 void Statistics::load()
 {
-    const SettingsPtr s = Profile::instance().applicationSettings(QLatin1String("qBittorrent-data"));
+    const SettingsPtr s = Profile::instance()->applicationSettings(QLatin1String("qBittorrent-data"));
     const QVariantHash v = s->value("Stats/AllStats").toHash();
 
     m_alltimeDL = v["AlltimeDL"].toULongLong();

src/base/bittorrent/session.cpp

@@ -156,7 +156,7 @@ namespace
         torrentParams.restored = true;
         torrentParams.skipChecking = false;
         torrentParams.name = fromLTString(root.dict_find_string_value("qBt-name"));
-        torrentParams.savePath = Profile::instance().fromPortablePath(
+        torrentParams.savePath = Profile::instance()->fromPortablePath(
             Utils::Fs::toUniformPath(fromLTString(root.dict_find_string_value("qBt-savePath"))));
         torrentParams.disableTempPath = root.dict_find_int_value("qBt-tempPathDisabled");
         torrentParams.sequential = root.dict_find_int_value("qBt-sequential");

src/base/bittorrent/torrenthandle.cpp

@@ -1763,9 +1763,9 @@ void TorrentHandle::handleSaveResumeDataAlert(const lt::save_resume_data_alert *
     }
     else {
         const auto savePath = resumeData.find_key("save_path")->string();
-        resumeData["save_path"] = Profile::instance().toPortablePath(QString::fromStdString(savePath)).toStdString();
+        resumeData["save_path"] = Profile::instance()->toPortablePath(QString::fromStdString(savePath)).toStdString();
     }
-    resumeData["qBt-savePath"] = m_useAutoTMM ? "" : Profile::instance().toPortablePath(m_savePath).toStdString();
+    resumeData["qBt-savePath"] = m_useAutoTMM ? "" : Profile::instance()->toPortablePath(m_savePath).toStdString();
     resumeData["qBt-ratioLimit"] = static_cast<int>(m_ratioLimit * 1000);
     resumeData["qBt-seedingTimeLimit"] = m_seedingTimeLimit;
     resumeData["qBt-category"] = m_category.toStdString();

src/base/profile.cpp

@@ -42,25 +42,30 @@ Profile::Profile(Private::Profile *impl, Private::PathConverter *pathConverter)
     ensureDirectoryExists(SpecialFolder::Data);
 }
 
-// to generate correct call to ProfilePrivate::~ProfileImpl()
-Profile::~Profile() = default;
-
-void Profile::initialize(const QString &rootProfilePath, const QString &configurationName,
-                         bool convertPathsToProfileRelative)
+void Profile::initInstance(const QString &rootProfilePath, const QString &configurationName,
+    const bool convertPathsToProfileRelative)
 {
-    std::unique_ptr<Private::Profile> profile(rootProfilePath.isEmpty()
-                                             ? static_cast<Private::Profile *>(new Private::DefaultProfile(configurationName))
-                                             : static_cast<Private::Profile *>(new Private::CustomProfile(rootProfilePath, configurationName)));
+    if (m_instance)
+        return;
 
+    std::unique_ptr<Private::Profile> profile(rootProfilePath.isEmpty()
+        ? static_cast<Private::Profile *>(new Private::DefaultProfile(configurationName))
+        : static_cast<Private::Profile *>(new Private::CustomProfile(rootProfilePath, configurationName)));
     std::unique_ptr<Private::PathConverter> converter(convertPathsToProfileRelative
-                                                     ? static_cast<Private::PathConverter *>(new Private::Converter(profile->baseDirectory()))
-                                                     : static_cast<Private::PathConverter *>(new Private::NoConvertConverter()));
+        ? static_cast<Private::PathConverter *>(new Private::Converter(profile->baseDirectory()))
+        : static_cast<Private::PathConverter *>(new Private::NoConvertConverter()));
     m_instance = new Profile(profile.release(), converter.release());
 }
 
-const Profile &Profile::instance()
+void Profile::freeInstance()
 {
-    return *m_instance;
+    delete m_instance;
+    m_instance = nullptr;
+}
+
+const Profile *Profile::instance()
+{
+    return m_instance;
 }
 
 QString Profile::location(const SpecialFolder folder) const
@@ -96,7 +101,7 @@ SettingsPtr Profile::applicationSettings(const QString &name) const
     return m_profileImpl->applicationSettings(name);
 }
 
-void Profile::ensureDirectoryExists(const SpecialFolder folder)
+void Profile::ensureDirectoryExists(const SpecialFolder folder) const
 {
     const QString locationPath = location(folder);
     if (!locationPath.isEmpty() && !QDir().mkpath(locationPath))
@@ -115,5 +120,5 @@ QString Profile::fromPortablePath(const QString &portablePath) const
 
 QString specialFolderLocation(const SpecialFolder folder)
 {
-    return Profile::instance().location(folder);
+    return Profile::instance()->location(folder);
 }

src/base/profile.h

@@ -36,8 +36,6 @@
 
 class QString;
 
-class Application;
-
 namespace Private
 {
     class Profile;
@@ -57,6 +55,11 @@ enum class SpecialFolder
 class Profile
 {
 public:
+    static void initInstance(const QString &rootProfilePath, const QString &configurationName,
+        bool convertPathsToProfileRelative);
+    static void freeInstance();
+    static const Profile *instance();
+
     QString location(SpecialFolder folder) const;
     SettingsPtr applicationSettings(const QString &name) const;
 
@@ -67,16 +70,11 @@ public:
     QString toPortablePath(const QString &absolutePath) const;
     QString fromPortablePath(const QString &portablePath) const;
 
-    static const Profile &instance();
-
 private:
     Profile(Private::Profile *impl, Private::PathConverter *pathConverter);
-    ~Profile();
+    ~Profile() = default;  // to generate correct call to ProfilePrivate::~ProfileImpl()
 
-    friend class ::Application;
-    static void initialize(const QString &rootProfilePath, const QString &configurationName,
-                                             bool convertPathsToProfileRelative);
-    void ensureDirectoryExists(SpecialFolder folder);
+    void ensureDirectoryExists(SpecialFolder folder) const;
 
     const std::unique_ptr<Private::Profile> m_profileImpl;
     const std::unique_ptr<Private::PathConverter> m_pathConverterImpl;

src/base/rss/rss_autodownloader.cpp

@@ -435,7 +435,7 @@ void AutoDownloader::loadRules(const QByteArray &data)
 
 void AutoDownloader::loadRulesLegacy()
 {
-    const SettingsPtr settings = Profile::instance().applicationSettings(QStringLiteral("qBittorrent-rss"));
+    const SettingsPtr settings = Profile::instance()->applicationSettings(QStringLiteral("qBittorrent-rss"));
     const QVariantHash rules = settings->value(QStringLiteral("download_rules")).toHash();
     for (const QVariant &ruleVar : rules) {
         const auto rule = AutoDownloadRule::fromLegacyDict(ruleVar.toHash());

src/base/rss/rss_feed.cpp

@@ -299,7 +299,7 @@ void Feed::loadArticles(const QByteArray &data)
 
 void Feed::loadArticlesLegacy()
 {
-    const SettingsPtr qBTRSSFeeds = Profile::instance().applicationSettings(QStringLiteral("qBittorrent-rss-feeds"));
+    const SettingsPtr qBTRSSFeeds = Profile::instance()->applicationSettings(QStringLiteral("qBittorrent-rss-feeds"));
     const QVariantHash allOldItems = qBTRSSFeeds->value("old_items").toHash();
 
     for (const QVariant &var : asConst(allOldItems.value(m_url).toList())) {

src/base/settingsstorage.cpp

@@ -279,7 +279,7 @@ bool TransactionalSettings::write(const QVariantHash &data) const
 
 QString TransactionalSettings::deserialize(const QString &name, QVariantHash &data) const
 {
-    SettingsPtr settings = Profile::instance().applicationSettings(name);
+    SettingsPtr settings = Profile::instance()->applicationSettings(name);
 
     if (settings->allKeys().isEmpty())
         return {};
@@ -295,7 +295,7 @@ QString TransactionalSettings::deserialize(const QString &name, QVariantHash &da
 
 QString TransactionalSettings::serialize(const QString &name, const QVariantHash &data) const
 {
-    SettingsPtr settings = Profile::instance().applicationSettings(name);
+    SettingsPtr settings = Profile::instance()->applicationSettings(name);
     for (auto i = data.begin(); i != data.end(); ++i)
         settings->setValue(i.key(), i.value());