Allow socket events processing with a foreign event loop on Windows

While a native dialog is open, the application message queue is
handled by the native event loop which is external to Qt. In this
case, QEventDispatcherWin32::processEvents() does not run and socket
notifiers will not be activated. So, this patch moves the notifier
activation code into the window procedure, which enables socket
event processing with native dialogs.

Task-number: QTBUG-49782
Task-number: QTBUG-48901
Change-Id: Icbdd96b2e80c50b73505f4fe74957575b83d6cf1
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Kai Koehne <kai.koehne@theqtcompany.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>

2 files changed, 33 insertions, 13 deletions

diff --git a/src/corelib/kernel/qeventdispatcher_win.cpp b/src/corelib/kernel/qeventdispatcher_win.cpp
index 695eb3d5d0..812494372d 100644
--- a/src/corelib/kernel/qeventdispatcher_win.cpp
+++ b/src/corelib/kernel/qeventdispatcher_win.cpp
@@ -79,6 +79,7 @@ extern uint qGlobalPostedEventsCount();
 enum {
     WM_QT_SOCKETNOTIFIER = WM_USER,
     WM_QT_SENDPOSTEDEVENTS = WM_USER + 1,
+    WM_QT_ACTIVATENOTIFIERS = WM_USER + 2,
     SendPostedEventsWindowsTimerId = ~1u
 };
 
@@ -309,7 +310,7 @@ static void resolveTimerAPI()
 QEventDispatcherWin32Private::QEventDispatcherWin32Private()
     : threadId(GetCurrentThreadId()), interrupt(false), closingDown(false), internalHwnd(0),
       getMessageHook(0), serialNumber(0), lastSerialNumber(0), sendPostedEventsWindowsTimerId(0),
-      wakeUps(0)
+      wakeUps(0), activateNotifiersPosted(false)
 {
     resolveTimerAPI();
 }
@@ -393,6 +394,7 @@ LRESULT QT_WIN_CALLBACK qt_internal_proc(HWND hwnd, UINT message, WPARAM wp, LPA
             if (sn) {
                 d->doWsaAsyncSelect(sn->fd, 0);
                 d->active_fd[sn->fd].selected = false;
+                d->postActivateSocketNotifiers();
                 if (type < 3) {
                     QEvent event(QEvent::SockAct);
                     QCoreApplication::sendEvent(sn->obj, &event);
@@ -403,6 +405,20 @@ LRESULT QT_WIN_CALLBACK qt_internal_proc(HWND hwnd, UINT message, WPARAM wp, LPA
             }
         }
         return 0;
+    } else if (message == WM_QT_ACTIVATENOTIFIERS) {
+        Q_ASSERT(d != 0);
+
+        // register all socket notifiers
+        for (QSFDict::iterator it = d->active_fd.begin(), end = d->active_fd.end();
+             it != end; ++it) {
+            QSockFd &sd = it.value();
+            if (!sd.selected) {
+                d->doWsaAsyncSelect(it.key(), sd.event);
+                sd.selected = true;
+            }
+        }
+        d->activateNotifiersPosted = false;
+        return 0;
     } else if (message == WM_QT_SENDPOSTEDEVENTS
                // we also use a Windows timer to send posted events when the message queue is full
                || (message == WM_TIMER
@@ -643,6 +659,12 @@ void QEventDispatcherWin32Private::doWsaAsyncSelect(int socket, long event)
     WSAAsyncSelect(socket, internalHwnd, event ? int(WM_QT_SOCKETNOTIFIER) : 0, event);
 }
 
+void QEventDispatcherWin32Private::postActivateSocketNotifiers()
+{
+    if (!activateNotifiersPosted)
+        activateNotifiersPosted = PostMessage(internalHwnd, WM_QT_ACTIVATENOTIFIERS, 0, 0);
+}
+
 void QEventDispatcherWin32::createInternalHwnd()
 {
     Q_D(QEventDispatcherWin32);
@@ -761,16 +783,6 @@ bool QEventDispatcherWin32::processEvents(QEventLoop::ProcessEventsFlags flags)
                         d->queuedSocketEvents.append(msg);
                         continue;
                     }
-                } else if (!(flags & QEventLoop::ExcludeSocketNotifiers)) {
-                    // register all socket notifiers
-                    for (QSFDict::iterator it = d->active_fd.begin(), end = d->active_fd.end();
-                         it != end; ++it) {
-                        QSockFd &sd = it.value();
-                        if (!sd.selected) {
-                            d->doWsaAsyncSelect(it.key(), sd.event);
-                            sd.selected = true;
-                        }
-                    }
                 }
             }
             if (!haveMessage) {
@@ -891,6 +903,8 @@ void QEventDispatcherWin32::registerSocketNotifier(QSocketNotifier *notifier)
                  "same socket %d and type %s", sockfd, t[type]);
     }
 
+    createInternalHwnd();
+
     QSockNot *sn = new QSockNot;
     sn->obj = notifier;
     sn->fd  = sockfd;
@@ -915,6 +929,8 @@ void QEventDispatcherWin32::registerSocketNotifier(QSocketNotifier *notifier)
     } else {
         d->active_fd.insert(sockfd, QSockFd(event));
     }
+
+    d->postActivateSocketNotifiers();
 }
 
 void QEventDispatcherWin32::unregisterSocketNotifier(QSocketNotifier *notifier)
@@ -940,10 +956,12 @@ void QEventDispatcherWin32::unregisterSocketNotifier(QSocketNotifier *notifier)
             d->doWsaAsyncSelect(sockfd, 0);
         const long event[3] = { FD_READ | FD_CLOSE | FD_ACCEPT, FD_WRITE | FD_CONNECT, FD_OOB };
         sd.event ^= event[type];
-        if (sd.event == 0)
+        if (sd.event == 0) {
             d->active_fd.erase(it);
-        else
+        } else if (sd.selected) {
             sd.selected = false;
+            d->postActivateSocketNotifiers();
+        }
     }
 
     QSNDict *sn_vec[3] = { &d->sn_read, &d->sn_write, &d->sn_except };
diff --git a/src/corelib/kernel/qeventdispatcher_win_p.h b/src/corelib/kernel/qeventdispatcher_win_p.h
index 8578110ee4..9a53e06730 100644
--- a/src/corelib/kernel/qeventdispatcher_win_p.h
+++ b/src/corelib/kernel/qeventdispatcher_win_p.h
@@ -178,7 +178,9 @@ public:
     QSNDict sn_write;
     QSNDict sn_except;
     QSFDict active_fd;
+    bool activateNotifiersPosted;
     void doWsaAsyncSelect(int socket, long event);
+    void postActivateSocketNotifiers();
 
     QList<QWinEventNotifier *> winEventNotifierList;
     void activateEventNotifier(QWinEventNotifier * wen);