Make StreamingPreferences a proper singleton

This removes the need for several hacks in SettingsView to force updates and improves performance by not reloading preferences all over the place.

app/backend/computermanager.cpp

@@ -1,7 +1,7 @@
 #include "computermanager.h"
 #include "boxartmanager.h"
 #include "nvhttp.h"
-#include "settings/streamingpreferences.h"
+#include "nvpairingmanager.h"
 
 #include <Limelight.h>
 #include <QtEndian>
@@ -144,8 +144,8 @@ private:
     NvComputer* m_Computer;
 };
 
-ComputerManager::ComputerManager(QObject *parent)
+ComputerManager::ComputerManager(StreamingPreferences* prefs)
-    : QObject(parent),
+    : m_Prefs(prefs),
       m_PollingRef(0),
       m_MdnsBrowser(nullptr),
       m_CompatFetcher(nullptr),
@@ -352,9 +352,7 @@ void ComputerManager::startPolling()
         return;
     }
 
-    StreamingPreferences prefs;
+    if (m_Prefs->enableMdns) {
-
-    if (prefs.enableMdns) {
         // Start an MDNS query for GameStream hosts
         m_MdnsServer.reset(new QMdnsEngine::Server());
         m_MdnsBrowser = new QMdnsEngine::Browser(m_MdnsServer.data(), "_nvstream._tcp.local.");
@@ -784,10 +782,9 @@ private:
             return serverInfo;
         } catch (...) {
             if (!m_Mdns) {
-                StreamingPreferences prefs;
                 unsigned int portTestResult;
 
-                if (prefs.detectNetworkBlocking) {
+                if (m_ComputerManager->m_Prefs->detectNetworkBlocking) {
                     // We failed to connect to the specified PC. Let's test to make sure this network
                     // isn't blocking Moonlight, so we can tell the user about it.
                     portTestResult = LiTestClientConnectivity("qt.conntest.moonlight-stream.org", 443,

app/backend/computermanager.h

@@ -1,7 +1,7 @@
 #pragma once
 
 #include "nvcomputer.h"
-#include "nvpairingmanager.h"
+#include "settings/streamingpreferences.h"
 #include "settings/compatfetcher.h"
 
 #include <qmdnsengine/server.h>
@@ -218,7 +218,7 @@ class ComputerManager : public QObject
     friend class DelayedFlushThread;
 
 public:
-    explicit ComputerManager(QObject *parent = nullptr);
+    explicit ComputerManager(StreamingPreferences* prefs);
 
     virtual ~ComputerManager();
 
@@ -270,6 +270,7 @@ private:
 
     void startPollingComputer(NvComputer* computer);
 
+    StreamingPreferences* m_Prefs;
     int m_PollingRef;
     QReadWriteLock m_Lock;
     QMap<QString, NvComputer*> m_KnownHosts;

app/gui/SettingsView.qml

@@ -1349,15 +1349,7 @@ Flickable {
                     font.pointSize: 12
                     checked: StreamingPreferences.swapFaceButtons
                     onCheckedChanged: {
-                        // Check if the value changed (this is called on init too)
+                        StreamingPreferences.swapFaceButtons = checked
-                        if (StreamingPreferences.swapFaceButtons !== checked) {
-                            StreamingPreferences.swapFaceButtons = checked
-
-                            // Save and restart SdlGamepadKeyNavigation so it can pull the new value
-                            StreamingPreferences.save()
-                            SdlGamepadKeyNavigation.disable()
-                            SdlGamepadKeyNavigation.enable()
-                        }
                     }
 
                     ToolTip.delay: 1000
@@ -1621,10 +1613,6 @@ Flickable {
                         if (StreamingPreferences.enableMdns != checked) {
                             StreamingPreferences.enableMdns = checked
 
-                            // We must save the updated preference to ensure
-                            // ComputerManager can observe the change internally.
-                            StreamingPreferences.save()
-
                             // Restart polling so the mDNS change takes effect
                             if (window.pollingActive) {
                                 ComputerManager.stopPollingAsync()
@@ -1641,15 +1629,7 @@ Flickable {
                     font.pointSize: 12
                     checked: StreamingPreferences.detectNetworkBlocking
                     onCheckedChanged: {
-                        // This is called on init, so only do the work if we've
+                        StreamingPreferences.detectNetworkBlocking = checked
-                        // actually changed the value.
-                        if (StreamingPreferences.detectNetworkBlocking != checked) {
-                            StreamingPreferences.detectNetworkBlocking = checked
-
-                            // We must save the updated preference to ensure
-                            // ComputerManager can observe the change internally.
-                            StreamingPreferences.save()
-                        }
                     }
                 }
             }

app/gui/sdlgamepadkeynavigation.cpp

@@ -8,8 +8,9 @@
 
 #define AXIS_NAVIGATION_REPEAT_DELAY 150
 
-SdlGamepadKeyNavigation::SdlGamepadKeyNavigation()
+SdlGamepadKeyNavigation::SdlGamepadKeyNavigation(StreamingPreferences* prefs)
-    : m_Enabled(false),
+    : m_Prefs(prefs),
+      m_Enabled(false),
       m_UiNavMode(false),
       m_FirstPoll(false),
       m_LastAxisNavigationEventTime(0)
@@ -119,7 +120,7 @@ void SdlGamepadKeyNavigation::onPollingTimerFired()
                         QEvent::Type::KeyPress : QEvent::Type::KeyRelease;
 
             // Swap face buttons if needed
-            if (m_Prefs.swapFaceButtons) {
+            if (m_Prefs->swapFaceButtons) {
                 switch (event.cbutton.button) {
                 case SDL_CONTROLLER_BUTTON_A:
                     event.cbutton.button = SDL_CONTROLLER_BUTTON_B;

app/gui/sdlgamepadkeynavigation.h

@@ -12,7 +12,7 @@ class SdlGamepadKeyNavigation : public QObject
     Q_OBJECT
 
 public:
-    SdlGamepadKeyNavigation();
+    SdlGamepadKeyNavigation(StreamingPreferences* prefs);
 
     ~SdlGamepadKeyNavigation();
 
@@ -31,11 +31,11 @@ private slots:
     void onPollingTimerFired();
 
 private:
+    StreamingPreferences* m_Prefs;
     QTimer* m_PollingTimer;
     QList<SDL_GameController*> m_Gamepads;
     bool m_Enabled;
     bool m_UiNavMode;
     bool m_FirstPoll;
     Uint32 m_LastAxisNavigationEventTime;
-    StreamingPreferences m_Prefs;
 };

app/main.cpp

@@ -570,8 +570,7 @@ int main(int argc, char *argv[])
                 runtimeVersion.major, runtimeVersion.minor, runtimeVersion.patch);
 
     // Apply the initial translation based on user preference
-    StreamingPreferences prefs;
+    StreamingPreferences::get()->retranslate();
-    prefs.retranslate();
 
     // Trickily declare the translation for dialog buttons
     QCoreApplication::translate("QPlatformTheme", "&Yes");
@@ -636,8 +635,8 @@ int main(int argc, char *argv[])
     qmlRegisterUncreatableType<Session>("Session", 1, 0, "Session", "Session cannot be created from QML");
     qmlRegisterSingletonType<ComputerManager>("ComputerManager", 1, 0,
                                               "ComputerManager",
-                                              [](QQmlEngine*, QJSEngine*) -> QObject* {
+                                              [](QQmlEngine* qmlEngine, QJSEngine*) -> QObject* {
-                                                  return new ComputerManager();
+                                                  return new ComputerManager(StreamingPreferences::get(qmlEngine));
                                               });
     qmlRegisterSingletonType<AutoUpdateChecker>("AutoUpdateChecker", 1, 0,
                                                 "AutoUpdateChecker",
@@ -651,13 +650,13 @@ int main(int argc, char *argv[])
                                                });
     qmlRegisterSingletonType<SdlGamepadKeyNavigation>("SdlGamepadKeyNavigation", 1, 0,
                                                       "SdlGamepadKeyNavigation",
-                                                      [](QQmlEngine*, QJSEngine*) -> QObject* {
+                                                      [](QQmlEngine* qmlEngine, QJSEngine*) -> QObject* {
-                                                          return new SdlGamepadKeyNavigation();
+                                                          return new SdlGamepadKeyNavigation(StreamingPreferences::get(qmlEngine));
                                                       });
     qmlRegisterSingletonType<StreamingPreferences>("StreamingPreferences", 1, 0,
                                                    "StreamingPreferences",
                                                    [](QQmlEngine* qmlEngine, QJSEngine*) -> QObject* {
-                                                       return new StreamingPreferences(qmlEngine);
+                                                       return StreamingPreferences::get(qmlEngine);
                                                    });
 
     // Create the identity manager on the main thread
@@ -688,7 +687,7 @@ int main(int argc, char *argv[])
     case GlobalCommandLineParser::StreamRequested:
         {
             initialView = "qrc:/gui/CliStartStreamSegue.qml";
-            StreamingPreferences* preferences = new StreamingPreferences(&app);
+            StreamingPreferences* preferences = StreamingPreferences::get();
             StreamCommandLineParser streamParser;
             streamParser.parse(app.arguments(), preferences);
             QString host    = streamParser.getHost();
@@ -720,7 +719,7 @@ int main(int argc, char *argv[])
             ListCommandLineParser listParser;
             listParser.parse(app.arguments());
             auto launcher = new CliListApps::Launcher(listParser.getHost(), listParser, &app);
-            launcher->execute(new ComputerManager(&app));
+            launcher->execute(new ComputerManager(StreamingPreferences::get()));
             hasGUI = false;
             break;
         }

app/settings/streamingpreferences.cpp

@@ -5,6 +5,7 @@
 #include <QTranslator>
 #include <QCoreApplication>
 #include <QLocale>
+#include <QReadWriteLock>
 #include <QtMath>
 
 #include <QtDebug>
@@ -48,18 +49,50 @@
 
 #define CURRENT_DEFAULT_VER 2
 
-StreamingPreferences::StreamingPreferences(QObject *parent)
+static StreamingPreferences* s_GlobalPrefs;
-    : QObject(parent),
+static QReadWriteLock s_GlobalPrefsLock;
-      m_QmlEngine(nullptr)
+
+StreamingPreferences::StreamingPreferences(QQmlEngine *qmlEngine)
+    : m_QmlEngine(qmlEngine)
 {
     reload();
 }
 
-StreamingPreferences::StreamingPreferences(QQmlEngine *qmlEngine, QObject *parent)
+StreamingPreferences* StreamingPreferences::get(QQmlEngine *qmlEngine)
-    : QObject(parent),
-      m_QmlEngine(qmlEngine)
 {
-    reload();
+    {
+        QReadLocker readGuard(&s_GlobalPrefsLock);
+
+        // If we have a preference object and it's associated with a QML engine or
+        // if the caller didn't specify a QML engine, return the existing object.
+        if (s_GlobalPrefs && (s_GlobalPrefs->m_QmlEngine || !qmlEngine)) {
+            // The lifetime logic here relies on the QML engine also being a singleton.
+            Q_ASSERT(!qmlEngine || s_GlobalPrefs->m_QmlEngine == qmlEngine);
+            return s_GlobalPrefs;
+        }
+    }
+
+    {
+        QWriteLocker writeGuard(&s_GlobalPrefsLock);
+
+        // If we already have an preference object but the QML engine is now available,
+        // associate the QML engine with the preferences.
+        if (s_GlobalPrefs) {
+            if (!s_GlobalPrefs->m_QmlEngine) {
+                s_GlobalPrefs->m_QmlEngine = qmlEngine;
+            }
+            else {
+                // We could reach this codepath if another thread raced with us
+                // and created the object while we were outside the pref lock.
+                Q_ASSERT(!qmlEngine || s_GlobalPrefs->m_QmlEngine == qmlEngine);
+            }
+        }
+        else {
+            s_GlobalPrefs = new StreamingPreferences(qmlEngine);
+        }
+
+        return s_GlobalPrefs;
+    }
 }
 
 void StreamingPreferences::reload()

app/settings/streamingpreferences.h

@@ -9,8 +9,7 @@ class StreamingPreferences : public QObject
     Q_OBJECT
 
 public:
-    StreamingPreferences(QObject *parent = nullptr);
+    static StreamingPreferences* get(QQmlEngine *qmlEngine = nullptr);
-    StreamingPreferences(QQmlEngine *qmlEngine, QObject *parent = nullptr);
 
     Q_INVOKABLE static int
     getDefaultBitrate(int width, int height, int fps);
@@ -206,6 +205,8 @@ signals:
     void languageChanged();
 
 private:
+    explicit StreamingPreferences(QQmlEngine *qmlEngine);
+
     QString getSuffixFromLanguage(Language lang);
 
     QQmlEngine* m_QmlEngine;

app/streaming/session.cpp

@@ -541,7 +541,7 @@ bool Session::populateDecoderProperties(SDL_Window* window)
 }
 
 Session::Session(NvComputer* computer, NvApp& app, StreamingPreferences *preferences)
-    : m_Preferences(preferences ? preferences : new StreamingPreferences(this)),
+    : m_Preferences(preferences ? preferences : StreamingPreferences::get()),
       m_IsFullScreen(m_Preferences->windowMode != StreamingPreferences::WM_WINDOWED || !WMUtils::isRunningDesktopEnvironment()),
       m_Computer(computer),
       m_App(app),