Client: Remove mWaitingForUpdateDelivery

Currently, mWaitingForUpdateDelivery is shared between the main thread
(doHandleFrameCallback()) and the frame callback event thread
(handleFrameCallback()), however the access to it is not synchronized
between both threads. On the other hand, QWaylandWindow
already ensures not to create a frame callback if there's already one
pending.

This change removes mWaitingForUpdateDelivery flag because it should be
already covered by mWaitingForFrameCallback and to remove unsynchronized
shared state between threads.

Change-Id: I0e5a25d18d1e66c4d7683e7e972330c4d7cbbf38
Reviewed-by: David Edmundson <davidedmundson@kde.org>

2 files changed, 3 insertions, 9 deletions

diff --git a/src/client/qwaylandwindow.cpp b/src/client/qwaylandwindow.cpp
index 812373a2..29e6ef67 100644
--- a/src/client/qwaylandwindow.cpp
+++ b/src/client/qwaylandwindow.cpp
@@ -715,12 +715,9 @@ void QWaylandWindow::handleFrameCallback()
     mFrameCallbackElapsedTimer.invalidate();
 
     // The rest can wait until we can run it on the correct thread
-    if (!mWaitingForUpdateDelivery) {
-        // Queued connection, to make sure we don't call handleUpdate() from inside waitForFrameSync()
-        // in the single-threaded case.
-        mWaitingForUpdateDelivery = true;
-        QMetaObject::invokeMethod(this, &QWaylandWindow::doHandleFrameCallback, Qt::QueuedConnection);
-    }
+    // Queued connection, to make sure we don't call handleUpdate() from inside waitForFrameSync()
+    // in the single-threaded case.
+    QMetaObject::invokeMethod(this, &QWaylandWindow::doHandleFrameCallback, Qt::QueuedConnection);
 
     mFrameSyncWait.notify_all();
 }
@@ -733,8 +730,6 @@ void QWaylandWindow::doHandleFrameCallback()
         sendExposeEvent(QRect(QPoint(), geometry().size()));
     if (wasExposed && hasPendingUpdateRequest())
         deliverUpdateRequest();
-
-    mWaitingForUpdateDelivery = false;
 }
 
 bool QWaylandWindow::waitForFrameSync(int timeout)
diff --git a/src/client/qwaylandwindow_p.h b/src/client/qwaylandwindow_p.h
index d64c80c4..6eb8053b 100644
--- a/src/client/qwaylandwindow_p.h
+++ b/src/client/qwaylandwindow_p.h
@@ -280,7 +280,6 @@ protected:
     WId mWindowId;
     bool mWaitingForFrameCallback = false;
     bool mFrameCallbackTimedOut = false; // Whether the frame callback has timed out
-    bool mWaitingForUpdateDelivery = false;
     int mFrameCallbackCheckIntervalTimerId = -1;
     QElapsedTimer mFrameCallbackElapsedTimer;
     struct ::wl_callback *mFrameCallback = nullptr;