[vlc-commits] [Git][videolan/vlc][master] 2 commits: qt: add `priority` parameter in `AsyncTask::start()`

[Jean-Baptiste Kempf (@jbk)]

Jean-Baptiste Kempf pushed to branch master at VideoLAN / VLC


Commits:
ba85af7d by Fatih Uzunoglu at 2026-06-09T14:03:34+02:00
qt: add `priority` parameter in `AsyncTask::start()`

- - - - -
cb361557 by Fatih Uzunoglu at 2026-06-09T14:03:34+02:00
qt: do asynchronous rhi probing at start in a separate thread

Qt Rhi docs clearly notes [1] that QRhi instance may be created
in any thread. With this change, we make sure to not slow down
the start.

Non-threaded asynchronous probing does not guarantee that the
start of the interface is not slowed down, because many things
in the interface depends on queued events.

[1] https://doc.qt.io/qt-6/qrhi.html#threading

- - - - -


2 changed files:

- modules/gui/qt/qt.cpp
- modules/gui/qt/util/asynctask.hpp


Changes:

=====================================
modules/gui/qt/qt.cpp
=====================================
@@ -61,6 +61,8 @@ extern "C" char **environ;
 #include <QTranslator>
 #ifdef _WIN32
 #include <QOperatingSystemVersion>
+#include <QThreadPool>
+#include "util/asynctask.hpp"
 #if QT_VERSION >= QT_VERSION_CHECK(6, 6, 0)
 #include <rhi/qrhi.h>
 #include <QOffscreenSurface>
@@ -1062,19 +1064,42 @@ static void *Thread( void *obj )
             // item. Currently the player waits for the interface, and QQuickWindow initialization
             // is therefore not enforced to be synchronous (`QWindow::setVisible(true)` which
             // initializes the scene graph thus rhi is asynchronous).
-            QMetaObject::invokeMethod(&app, [&app, settings = QPointer(p_intf->mainSettings)]() {
+
+            class RhiProbeTask : public AsyncTask<QPair<QSGRendererInterface::GraphicsApi, bool>>
+            {
+            public:
+                RhiProbeTask() = default;
+
+                QPair<QSGRendererInterface::GraphicsApi, bool> execute() override
+                {
+                    return probeRhi();
+                }
+            };
+
+            const auto rhiProbeTask = QPointer(new RhiProbeTask);
+            QObject::connect(rhiProbeTask, &BaseAsyncTask::result, qApp, [rhiProbeTask, settings = QPointer(p_intf->mainSettings)]() {
                 // We can not use `QQuickWindow::setGraphicsApi()` here, as QQuickWindow
                 // may have already tried to initialize the scene graph hence rhi. If the
                 // cached graphics api is not optimal or not available anymore, the next
                 // startup will use the refreshed value. That's the best we can do here
                 // without forcing QQuickWindow to wait (hence delaying startup).
                 assert(settings);
-                const auto rhiResult = probeRhi();
+                const QPair<QSGRendererInterface::GraphicsApi, bool> rhiResult = rhiProbeTask->takeResult();
                 settings->setValue(graphicsApiKey, static_cast<int>(rhiResult.first));
                 settings->setValue(graphicsApiRhiSoftwareKey, rhiResult.second);
                 settings->sync();
-                app.setProperty(asyncRhiProbeCompletedProperty, true);
-            }, Qt::QueuedConnection); // Asynchronous, so probing here does not cause start-up slowdown.
+                qApp->setProperty(asyncRhiProbeCompletedProperty, true);
+                qDebug() << "Asynchronous rhi re-probe completed. Graphics api (QSGRendererInterface::GraphicsApi):"
+                         << rhiResult.first
+                         << "Prefer software renderer:"
+                         << rhiResult.second;
+                rhiProbeTask->abandon();
+            }, Qt::QueuedConnection);
+
+            const auto globalThreadPool = QThreadPool::globalInstance();
+            assert(globalThreadPool);
+
+            rhiProbeTask->start(*globalThreadPool, -1);
         }
         else
         {


=====================================
modules/gui/qt/util/asynctask.hpp
=====================================
@@ -157,11 +157,11 @@ public:
     /**
      * Start the task on the thread pool
      */
-    void start(QThreadPool &threadPool)
+    void start(QThreadPool &threadPool, int priority = 0)
     {
         m_threadPool = &threadPool;
         m_runnable = std::make_unique<Runnable>(this);
-        threadPool.start(&*m_runnable);
+        threadPool.start(&*m_runnable, priority);
     }
 
     /**



View it on GitLab: https://code.videolan.org/videolan/vlc/-/compare/e8f4a3d3ac7e94b95762e0bbc8b7010c06ad1d2b...cb361557b790d891fbf6b1fd3eb030f5bfc018da

-- 
View it on GitLab: https://code.videolan.org/videolan/vlc/-/compare/e8f4a3d3ac7e94b95762e0bbc8b7010c06ad1d2b...cb361557b790d891fbf6b1fd3eb030f5bfc018da
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