Introduce path for surviving compositor restarts

This patch introduces an optional mechanism for clients to survive a
crash and reconnect seemingly seamlessly.

In the event of a disconnect from the compositor socket we simply try to
reconnect again and replay any data needed so that we maintain a
consistent state to where we left off.

From an application point-of-view any open popups will be dismissed and
we we potentially get a new framecallback, but it will be almost
entirely transparent. Users of custom QWaylandClientExtensions will be
notified via the activeChanged signal and rebuild as though the
compositor had withdrawn and re-announced the global.

OpenGL contexts will be marked as invalid, and handled the same way as a
GPU reset. On the next frame RHI will notice these are invalid and
recreate them, only now against a new wl_display and new EGLDisplay.

Users of low level EGL/native objects might be affected, but the
alternative at this point is being closed anyway. The entire codepath is
only activated via an environment variable.

Change-Id: I6c4acc885540e14cead7640794df86dd974fef4f
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

1 files changed, 20 insertions, 0 deletions

diff --git a/src/client/qwaylandwindow.cpp b/src/client/qwaylandwindow.cpp
index a77cce5a..90f4c609 100644
--- a/src/client/qwaylandwindow.cpp
+++ b/src/client/qwaylandwindow.cpp
@@ -291,11 +291,21 @@ void QWaylandWindow::reset()
         mFrameCallbackElapsedTimer.invalidate();
         mWaitingForFrameCallback = false;
     }
+    if (mFrameCallbackCheckIntervalTimerId != -1) {
+        killTimer(mFrameCallbackCheckIntervalTimerId);
+        mFrameCallbackCheckIntervalTimerId = -1;
+    }
+
     mFrameCallbackTimedOut = false;
     mWaitingToApplyConfigure = false;
+    mCanResize = true;
+    mResizeDirty = false;
 
+    mOpaqueArea = QRegion();
     mMask = QRegion();
+
     mQueuedBuffer = nullptr;
+    mQueuedBufferDamage = QRegion();
 
     mDisplay->handleWindowDestroyed(this);
 }
@@ -1623,6 +1633,16 @@ void QWaylandWindow::closeChildPopups() {
         popup->reset();
     }
 }
+
+void QWaylandWindow::reinit()
+{
+    if (window()->isVisible()) {
+        initWindow();
+        if (hasPendingUpdateRequest())
+            deliverUpdateRequest();
+    }
+}
+
 }
 
 QT_END_NAMESPACE