path: root/source/l/qt5/patches/24.diff

diff --git a/src/client/qwaylanddisplay.cpp b/src/client/qwaylanddisplay.cpp
index ea344c61c3a4643f7c725a6287f20d742b210d24..a7ce280a5df538917758e50ba8d2ee117378d546 100644
--- a/src/client/qwaylanddisplay.cpp
+++ b/src/client/qwaylanddisplay.cpp
@@ -85,10 +85,203 @@
 
 #include <errno.h>
 
+#include <tuple> // for std::tie
+
+static void checkWaylandError(struct wl_display *display)
+{
+    int ecode = wl_display_get_error(display);
+    if ((ecode == EPIPE || ecode == ECONNRESET)) {
+        // special case this to provide a nicer error
+        qWarning("The Wayland connection broke. Did the Wayland compositor die?");
+    } else {
+        qWarning("The Wayland connection experienced a fatal error: %s", strerror(ecode));
+    }
+    _exit(1);
+}
+
 QT_BEGIN_NAMESPACE
 
 namespace QtWaylandClient {
 
+class EventThread : public QThread
+{
+    Q_OBJECT
+public:
+    enum OperatingMode {
+        EmitToDispatch, // Emit the signal, allow dispatching in a differnt thread.
+        SelfDispatch, // Dispatch the events inside this thread.
+    };
+
+    EventThread(struct wl_display * wl, struct wl_event_queue * ev_queue,
+                OperatingMode mode)
+        : m_fd(wl_display_get_fd(wl))
+        , m_pipefd{ -1, -1 }
+        , m_wldisplay(wl)
+        , m_wlevqueue(ev_queue)
+        , m_mode(mode)
+        , m_reading(true)
+        , m_quitting(false)
+    {
+        setObjectName(QStringLiteral("WaylandEventThread"));
+    }
+
+    void readAndDispatchEvents()
+    {
+        /*
+         * Dispatch pending events and flush the requests at least once. If the event thread
+         * is not reading, try to call _prepare_read() to allow the event thread to poll().
+         * If that fails, re-try dispatch & flush again until _prepare_read() is successful.
+         *
+         * This allow any call to readAndDispatchEvents() to start event thread's polling,
+         * not only the one issued from event thread's waitForReading(), which means functions
+         * called from dispatch_pending() can safely spin an event loop.
+         */
+        for (;;) {
+            if (dispatchQueuePending() < 0) {
+                checkWaylandError(m_wldisplay);
+                return;
+            }
+
+            wl_display_flush(m_wldisplay);
+
+            // We have to check if event thread is reading every time we dispatch
+            // something, as that may recursively call this function.
+            if (m_reading.loadAcquire())
+                break;
+
+            if (prepareReadQueue() == 0) {
+                QMutexLocker l(&m_mutex);
+                m_reading.storeRelease(true);
+                m_cond.wakeOne();
+                break;
+            }
+        }
+    }
+
+    void stop()
+    {
+        // We have to both write to the pipe and set the flag, as the thread may be
+        // either in the poll() or waiting for _prepare_read().
+        if (m_pipefd[1] != -1 && write(m_pipefd[1], "\0", 1) == -1)
+            qWarning("Failed to write to the pipe: %s.", strerror(errno));
+
+        {
+            QMutexLocker l(&m_mutex);
+            m_quitting = true;
+            m_cond.wakeOne();
+        }
+
+        wait();
+    }
+
+Q_SIGNALS:
+    void needReadAndDispatch();
+
+protected:
+    void run() override
+    {
+        // we use this pipe to make the loop exit otherwise if we simply used a flag on the loop condition, if stop() gets
+        // called while poll() is blocking the thread will never quit since there are no wayland messages coming anymore.
+        struct Pipe
+        {
+            Pipe(int *fds)
+                : fds(fds)
+            {
+                if (qt_safe_pipe(fds) != 0)
+                    qWarning("Pipe creation failed. Quitting may hang.");
+            }
+            ~Pipe()
+            {
+                if (fds[0] != -1) {
+                    close(fds[0]);
+                    close(fds[1]);
+                }
+            }
+
+            int *fds;
+        } pipe(m_pipefd);
+
+        // Make the main thread call wl_prepare_read(), dispatch the pending messages and flush the
+        // outbound ones. Wait until it's done before proceeding, unless we're told to quit.
+        while (waitForReading()) {
+            pollfd fds[2] = { { m_fd, POLLIN, 0 }, { m_pipefd[0], POLLIN, 0 } };
+            poll(fds, 2, -1);
+
+            if (fds[1].revents & POLLIN) {
+                // we don't really care to read the byte that was written here since we're closing down
+                wl_display_cancel_read(m_wldisplay);
+                break;
+            }
+
+            if (fds[0].revents & POLLIN)
+                wl_display_read_events(m_wldisplay);
+                // The polll was succesfull and the event thread did the wl_display_read_events(). On the next iteration of the loop
+                // the event sent to the main thread will cause it to dispatch the messages just read, unless the loop exits in which
+                // case we don't care anymore about them.
+            else
+                wl_display_cancel_read(m_wldisplay);
+        }
+    }
+
+private:
+    bool waitForReading()
+    {
+        Q_ASSERT(QThread::currentThread() == this);
+
+        m_reading.storeRelease(false);
+
+        if (m_mode == SelfDispatch) {
+            readAndDispatchEvents();
+        } else {
+            Q_EMIT needReadAndDispatch();
+
+            QMutexLocker lock(&m_mutex);
+            // m_reading might be set from our emit or some other invocation of
+            // readAndDispatchEvents().
+            while (!m_reading.loadRelaxed() && !m_quitting)
+                m_cond.wait(&m_mutex);
+        }
+
+        return !m_quitting;
+    }
+
+    int dispatchQueuePending()
+    {
+        if (m_wlevqueue)
+            return wl_display_dispatch_queue_pending(m_wldisplay, m_wlevqueue);
+        else
+            return wl_display_dispatch_pending(m_wldisplay);
+    }
+
+    int prepareReadQueue()
+    {
+        if (m_wlevqueue)
+            return wl_display_prepare_read_queue(m_wldisplay, m_wlevqueue);
+        else
+            return wl_display_prepare_read(m_wldisplay);
+    }
+
+    int m_fd;
+    int m_pipefd[2];
+    wl_display *m_wldisplay;
+    wl_event_queue *m_wlevqueue;
+    OperatingMode m_mode;
+
+    /* Concurrency note when operating in EmitToDispatch mode:
+     * m_reading is set to false inside event thread's waitForReading(), and is
+     * set to true inside main thread's readAndDispatchEvents().
+     * The lock is not taken when setting m_reading to false, as the main thread
+     * is not actively waiting for it to turn false. However, the lock is taken
+     * inside readAndDispatchEvents() before setting m_reading to true,
+     * as the event thread is actively waiting for it under the wait condition.
+     */
+
+    QAtomicInteger<bool> m_reading;
+    bool m_quitting;
+    QMutex m_mutex;
+    QWaitCondition m_cond;
+};
+
 Q_LOGGING_CATEGORY(lcQpaWayland, "qt.qpa.wayland"); // for general (uncategorized) Wayland platform logging
 
 struct wl_surface *QWaylandDisplay::createSurface(void *handle)
@@ -158,17 +351,16 @@ QWaylandDisplay::QWaylandDisplay(QWaylandIntegration *waylandIntegration)
     if (!mXkbContext)
         qCWarning(lcQpaWayland, "failed to create xkb context");
 #endif
-
-    forceRoundTrip();
-
-    if (!mWaitingScreens.isEmpty()) {
-        // Give wl_output.done and zxdg_output_v1.done events a chance to arrive
-        forceRoundTrip();
-    }
 }
 
 QWaylandDisplay::~QWaylandDisplay(void)
 {
+    if (m_eventThread)
+        m_eventThread->stop();
+
+    if (m_frameEventQueueThread)
+        m_frameEventQueueThread->stop();
+
     if (mSyncCallback)
         wl_callback_destroy(mSyncCallback);
 
@@ -189,6 +381,18 @@ QWaylandDisplay::~QWaylandDisplay(void)
         wl_display_disconnect(mDisplay);
 }
 
+// Steps which is called just after constructor. This separates registry_global() out of the constructor
+// so that factory functions in integration can be overridden.
+void QWaylandDisplay::initialize()
+{
+    forceRoundTrip();
+
+    if (!mWaitingScreens.isEmpty()) {
+        // Give wl_output.done and zxdg_output_v1.done events a chance to arrive
+        forceRoundTrip();
+    }
+}
+
 void QWaylandDisplay::ensureScreen()
 {
     if (!mScreens.empty() || mPlaceholderScreen)
@@ -203,98 +407,37 @@ void QWaylandDisplay::ensureScreen()
 
 void QWaylandDisplay::checkError() const
 {
-    int ecode = wl_display_get_error(mDisplay);
-    if ((ecode == EPIPE || ecode == ECONNRESET)) {
-        // special case this to provide a nicer error
-        qWarning("The Wayland connection broke. Did the Wayland compositor die?");
-    } else {
-        qWarning("The Wayland connection experienced a fatal error: %s", strerror(ecode));
-    }
-    _exit(1);
+    checkWaylandError(mDisplay);
 }
 
+// Called in main thread, either from queued signal or directly.
 void QWaylandDisplay::flushRequests()
 {
-    if (wl_display_prepare_read(mDisplay) == 0) {
-        wl_display_read_events(mDisplay);
-    }
-
-    if (wl_display_dispatch_pending(mDisplay) < 0)
-        checkError();
-
-    {
-        QReadLocker locker(&m_frameQueueLock);
-        for (const FrameQueue &q : mExternalQueues) {
-            QMutexLocker locker(q.mutex);
-            while (wl_display_prepare_read_queue(mDisplay, q.queue) != 0)
-                wl_display_dispatch_queue_pending(mDisplay, q.queue);
-            wl_display_read_events(mDisplay);
-            wl_display_dispatch_queue_pending(mDisplay, q.queue);
-        }
-    }
-
-    wl_display_flush(mDisplay);
-}
-
-void QWaylandDisplay::blockingReadEvents()
-{
-    if (wl_display_dispatch(mDisplay) < 0)
-        checkError();
-}
-
-void QWaylandDisplay::destroyFrameQueue(const QWaylandDisplay::FrameQueue &q)
-{
-    QWriteLocker locker(&m_frameQueueLock);
-    auto it = std::find_if(mExternalQueues.begin(),
-                           mExternalQueues.end(),
-                           [&q] (const QWaylandDisplay::FrameQueue &other){ return other.queue == q.queue; });
-    Q_ASSERT(it != mExternalQueues.end());
-    mExternalQueues.erase(it);
-    if (q.queue != nullptr)
-        wl_event_queue_destroy(q.queue);
-    delete q.mutex;
+    m_eventThread->readAndDispatchEvents();
 }
 
-QWaylandDisplay::FrameQueue QWaylandDisplay::createFrameQueue()
+// We have to wait until we have an eventDispatcher before creating the eventThread,
+// otherwise forceRoundTrip() may block inside _events_read() because eventThread is
+// polling.
+void QWaylandDisplay::initEventThread()
 {
-    QWriteLocker locker(&m_frameQueueLock);
-    FrameQueue q{createEventQueue()};
-    mExternalQueues.append(q);
-    return q;
-}
+    m_eventThread.reset(
+            new EventThread(mDisplay, /* default queue */ nullptr, EventThread::EmitToDispatch));
+    connect(m_eventThread.get(), &EventThread::needReadAndDispatch, this,
+            &QWaylandDisplay::flushRequests, Qt::QueuedConnection);
+    m_eventThread->start();
 
-wl_event_queue *QWaylandDisplay::createEventQueue()
-{
-    return wl_display_create_queue(mDisplay);
+    // wl_display_disconnect() free this.
+    m_frameEventQueue = wl_display_create_queue(mDisplay);
+    m_frameEventQueueThread.reset(
+            new EventThread(mDisplay, m_frameEventQueue, EventThread::SelfDispatch));
+    m_frameEventQueueThread->start();
 }
 
-void QWaylandDisplay::dispatchQueueWhile(wl_event_queue *queue, std::function<bool ()> condition, int timeout)
+void QWaylandDisplay::blockingReadEvents()
 {
-    if (!condition())
-        return;
-
-    QElapsedTimer timer;
-    timer.start();
-    struct pollfd pFd = qt_make_pollfd(wl_display_get_fd(mDisplay), POLLIN);
-    while (timeout == -1 || timer.elapsed() < timeout) {
-        while (wl_display_prepare_read_queue(mDisplay, queue) != 0)
-            wl_display_dispatch_queue_pending(mDisplay, queue);
-
-        wl_display_flush(mDisplay);
-
-        const int remaining = qMax(timeout - timer.elapsed(), 0ll);
-        const int pollTimeout = timeout == -1 ? -1 : remaining;
-        if (qt_poll_msecs(&pFd, 1, pollTimeout) > 0)
-            wl_display_read_events(mDisplay);
-        else
-            wl_display_cancel_read(mDisplay);
-
-        if (wl_display_dispatch_queue_pending(mDisplay, queue) < 0)
-            checkError();
-
-        if (!condition())
-            break;
-    }
+    if (wl_display_dispatch(mDisplay) < 0)
+        checkWaylandError(mDisplay);
 }
 
 QWaylandScreen *QWaylandDisplay::screenForOutput(struct wl_output *output) const
@@ -669,4 +812,6 @@ QWaylandCursorTheme *QWaylandDisplay::loadCursorTheme(const QString &name, int p
 
 } // namespace QtWaylandClient
 
+#include "qwaylanddisplay.moc"
+
 QT_END_NAMESPACE
diff --git a/src/client/qwaylanddisplay_p.h b/src/client/qwaylanddisplay_p.h
index 09a1736a267d2816873667e9f1ecb4f4892f0ed0..42bc661d3064d770aa9fde8bd62ecdbbc89732a2 100644
--- a/src/client/qwaylanddisplay_p.h
+++ b/src/client/qwaylanddisplay_p.h
@@ -109,6 +109,7 @@ class QWaylandSurface;
 class QWaylandShellIntegration;
 class QWaylandCursor;
 class QWaylandCursorTheme;
+class EventThread;
 
 typedef void (*RegistryListener)(void *data,
                                  struct wl_registry *registry,
@@ -120,15 +121,11 @@ class Q_WAYLAND_CLIENT_EXPORT QWaylandDisplay : public QObject, public QtWayland
     Q_OBJECT
 
 public:
-    struct FrameQueue {
-        FrameQueue(wl_event_queue *q = nullptr) : queue(q), mutex(new QMutex) {}
-        wl_event_queue *queue;
-        QMutex *mutex;
-    };
-
     QWaylandDisplay(QWaylandIntegration *waylandIntegration);
     ~QWaylandDisplay(void) override;
 
+    void initialize();
+
 #if QT_CONFIG(xkbcommon)
     struct xkb_context *xkbContext() const { return mXkbContext.get(); }
 #endif
@@ -210,12 +207,11 @@ public:
     void handleKeyboardFocusChanged(QWaylandInputDevice *inputDevice);
     void handleWindowDestroyed(QWaylandWindow *window);
 
-    wl_event_queue *createEventQueue();
-    FrameQueue createFrameQueue();
-    void destroyFrameQueue(const FrameQueue &q);
-    void dispatchQueueWhile(wl_event_queue *queue, std::function<bool()> condition, int timeout = -1);
+    wl_event_queue *frameEventQueue() { return m_frameEventQueue; };
 
     bool isKeyboardAvailable() const;
+
+    void initEventThread();
 public slots:
     void blockingReadEvents();
     void flushRequests();
@@ -238,6 +234,9 @@ private:
     };
 
     struct wl_display *mDisplay = nullptr;
+    QScopedPointer<EventThread> m_eventThread;
+    wl_event_queue *m_frameEventQueue = nullptr;
+    QScopedPointer<EventThread> m_frameEventQueueThread;
     QtWayland::wl_compositor mCompositor;
     QScopedPointer<QWaylandShm> mShm;
     QList<QWaylandScreen *> mWaitingScreens;
@@ -274,11 +273,9 @@ private:
     QWaylandInputDevice *mLastInputDevice = nullptr;
     QPointer<QWaylandWindow> mLastInputWindow;
     QPointer<QWaylandWindow> mLastKeyboardFocus;
-    QVector<QWaylandWindow *> mActiveWindows;
-    QVector<FrameQueue> mExternalQueues;
+    QList<QWaylandWindow *> mActiveWindows;
     struct wl_callback *mSyncCallback = nullptr;
     static const wl_callback_listener syncCallbackListener;
-    QReadWriteLock m_frameQueueLock;
 
     bool mClientSideInputContextRequested = !QPlatformInputContextFactory::requested().isNull();
 
diff --git a/src/client/qwaylandintegration.cpp b/src/client/qwaylandintegration.cpp
index e5e7dd42c9b0145f4c9852f7e15dcc83106c321d..3b876047293887d17eeb28819c7386ded9e1f131 100644
--- a/src/client/qwaylandintegration.cpp
+++ b/src/client/qwaylandintegration.cpp
@@ -192,14 +192,18 @@ QAbstractEventDispatcher *QWaylandIntegration::createEventDispatcher() const
 
 void QWaylandIntegration::initialize()
 {
+    mDisplay->initEventThread();
+
+    // Call after eventDispatcher is fully connected, for QWaylandDisplay::forceRoundTrip()
+    mDisplay->initialize();
+
+    // But the aboutToBlock() and awake() should be connected after initializePlatform().
+    // Otherwise the connected flushRequests() may consumes up all events before processEvents starts to wait,
+    // so that processEvents(QEventLoop::WaitForMoreEvents) may be blocked in the forceRoundTrip().
     QAbstractEventDispatcher *dispatcher = QGuiApplicationPrivate::eventDispatcher;
     QObject::connect(dispatcher, SIGNAL(aboutToBlock()), mDisplay.data(), SLOT(flushRequests()));
     QObject::connect(dispatcher, SIGNAL(awake()), mDisplay.data(), SLOT(flushRequests()));
 
-    int fd = wl_display_get_fd(mDisplay->wl_display());
-    QSocketNotifier *sn = new QSocketNotifier(fd, QSocketNotifier::Read, mDisplay.data());
-    QObject::connect(sn, SIGNAL(activated(QSocketDescriptor)), mDisplay.data(), SLOT(flushRequests()));
-
     // Qt does not support running with no screens
     mDisplay->ensureScreen();
 }
diff --git a/src/client/qwaylandwindow.cpp b/src/client/qwaylandwindow.cpp
index 1597f67e63ae7834ded50e25b0acf86b71abcd73..7de19a742b6d3f6a3ce0955f59a5bf2879d29c9e 100644
--- a/src/client/qwaylandwindow.cpp
+++ b/src/client/qwaylandwindow.cpp
@@ -76,7 +76,6 @@ QWaylandWindow *QWaylandWindow::mMouseGrab = nullptr;
 QWaylandWindow::QWaylandWindow(QWindow *window, QWaylandDisplay *display)
     : QPlatformWindow(window)
     , mDisplay(display)
-    , mFrameQueue(mDisplay->createFrameQueue())
     , mResizeAfterSwap(qEnvironmentVariableIsSet("QT_WAYLAND_RESIZE_AFTER_SWAP"))
 {
     {
@@ -95,8 +94,6 @@ QWaylandWindow::QWaylandWindow(QWindow *window, QWaylandDisplay *display)
 
 QWaylandWindow::~QWaylandWindow()
 {
-    mDisplay->destroyFrameQueue(mFrameQueue);
-
     delete mWindowDecoration;
 
     if (mSurface)
@@ -635,6 +632,8 @@ const wl_callback_listener QWaylandWindow::callbackListener = {
 
 void QWaylandWindow::handleFrameCallback()
 {
+    QMutexLocker locker(&mFrameSyncMutex);
+
     mWaitingForFrameCallback = false;
     mFrameCallbackElapsedTimer.invalidate();
 
@@ -656,12 +655,16 @@ void QWaylandWindow::handleFrameCallback()
         mWaitingForUpdateDelivery = true;
         QMetaObject::invokeMethod(this, doHandleExpose, Qt::QueuedConnection);
     }
+
+    mFrameSyncWait.notify_all();
 }
 
 bool QWaylandWindow::waitForFrameSync(int timeout)
 {
-    QMutexLocker locker(mFrameQueue.mutex);
-    mDisplay->dispatchQueueWhile(mFrameQueue.queue, [&]() { return mWaitingForFrameCallback; }, timeout);
+    QMutexLocker locker(&mFrameSyncMutex);
+
+    QDeadlineTimer deadline(timeout);
+    while (mWaitingForFrameCallback && mFrameSyncWait.wait(&mFrameSyncMutex, deadline)) { }
 
     if (mWaitingForFrameCallback) {
         qCDebug(lcWaylandBackingstore) << "Didn't receive frame callback in time, window should now be inexposed";
@@ -1157,8 +1160,11 @@ void QWaylandWindow::requestUpdate()
     Q_ASSERT(hasPendingUpdateRequest()); // should be set by QPA
 
     // If we have a frame callback all is good and will be taken care of there
-    if (mWaitingForFrameCallback)
-        return;
+    {
+        QMutexLocker locker(&mFrameSyncMutex);
+        if (mWaitingForFrameCallback)
+            return;
+    }
 
     // If we've already called deliverUpdateRequest(), but haven't seen any attach+commit/swap yet
     // This is a somewhat redundant behavior and might indicate a bug in the calling code, so log
@@ -1171,7 +1177,12 @@ void QWaylandWindow::requestUpdate()
     // so use invokeMethod to delay the delivery a bit.
     QMetaObject::invokeMethod(this, [this] {
         // Things might have changed in the meantime
-        if (hasPendingUpdateRequest() && !mWaitingForFrameCallback)
+        {
+            QMutexLocker locker(&mFrameSyncMutex);
+            if (mWaitingForFrameCallback)
+                return;
+        }
+        if (hasPendingUpdateRequest())
             deliverUpdateRequest();
     }, Qt::QueuedConnection);
 }
@@ -1191,9 +1202,10 @@ void QWaylandWindow::handleUpdate()
     if (!mSurface)
         return;
 
-    QMutexLocker locker(mFrameQueue.mutex);
+    QMutexLocker locker(&mFrameSyncMutex);
+
     struct ::wl_surface *wrappedSurface = reinterpret_cast<struct ::wl_surface *>(wl_proxy_create_wrapper(mSurface->object()));
-    wl_proxy_set_queue(reinterpret_cast<wl_proxy *>(wrappedSurface), mFrameQueue.queue);
+    wl_proxy_set_queue(reinterpret_cast<wl_proxy *>(wrappedSurface), mDisplay->frameEventQueue());
     mFrameCallback = wl_surface_frame(wrappedSurface);
     wl_proxy_wrapper_destroy(wrappedSurface);
     wl_callback_add_listener(mFrameCallback, &QWaylandWindow::callbackListener, this);
@@ -1203,6 +1215,8 @@ void QWaylandWindow::handleUpdate()
     // Start a timer for handling the case when the compositor stops sending frame callbacks.
     if (mFrameCallbackTimeout > 0) {
         QMetaObject::invokeMethod(this, [this] {
+            QMutexLocker locker(&mFrameSyncMutex);
+
             if (mWaitingForFrameCallback) {
                 if (mFrameCallbackCheckIntervalTimerId < 0)
                     mFrameCallbackCheckIntervalTimerId = startTimer(mFrameCallbackTimeout);
diff --git a/src/client/qwaylandwindow_p.h b/src/client/qwaylandwindow_p.h
index e06879620c3d033f093b0866f018ec80a72a97c3..d45980a80e9ecc9c5003fa2144de63e6337bda8a 100644
--- a/src/client/qwaylandwindow_p.h
+++ b/src/client/qwaylandwindow_p.h
@@ -232,7 +232,7 @@ protected:
     int mFrameCallbackCheckIntervalTimerId = -1;
     QElapsedTimer mFrameCallbackElapsedTimer;
     struct ::wl_callback *mFrameCallback = nullptr;
-    QWaylandDisplay::FrameQueue mFrameQueue;
+    QMutex mFrameSyncMutex;
     QWaitCondition mFrameSyncWait;
 
     // True when we have called deliverRequestUpdate, but the client has not yet attached a new buffer