Fix event delevery order

Some functions (such as QObject::moveToThread) did not keep
the event ordered by priority.
And because qUpperBound is used to add events, that mean new
events would not be inserted in order.

Task-number: QTBUG19637
Change-Id: I38eb9addb1cdd45b8566e000361ac6e5f1f2c2b8
Reviewed-on: http://codereview.qt.nokia.com/733
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Bradley T. Hughes <bradley.hughes@nokia.com>
Reviewed-by: Olivier Goffart <olivier.goffart@nokia.com>

src/corelib/kernel/qcoreapplication.cpp

@@ -1272,20 +1272,7 @@ void QCoreApplication::postEvent(QObject *receiver, QEvent *event, int priority)
     // delete the event on exceptions to protect against memory leaks till the event is
     // properly owned in the postEventList
     QScopedPointer<QEvent> eventDeleter(event);
-    if (data->postEventList.isEmpty() || data->postEventList.last().priority >= priority) {
-        // optimization: we can simply append if the last event in
-        // the queue has higher or equal priority
-        data->postEventList.append(QPostEvent(receiver, event, priority));
-    } else {
-        // insert event in descending priority order, using upper
-        // bound for a given priority (to ensure proper ordering
-        // of events with the same priority)
-        QPostEventList::iterator begin = data->postEventList.begin()
-                                         + data->postEventList.insertionOffset,
-                                   end = data->postEventList.end();
-        QPostEventList::iterator at = qUpperBound(begin, end, priority);
-        data->postEventList.insert(at, QPostEvent(receiver, event, priority));
-    }
+    data->postEventList.addEvent(QPostEvent(receiver, event, priority));
     eventDeleter.take();
     event->posted = true;
     ++receiver->d_func()->postedEvents;
@@ -1445,7 +1432,7 @@ void QCoreApplicationPrivate::sendPostedEvents(QObject *receiver, int event_type
                 // cannot send deferred delete
                 if (!event_type && !receiver) {
                     // don't lose the event
-                    data->postEventList.append(pe);
+                    data->postEventList.addEvent(pe);
                     const_cast<QPostEvent &>(pe).event = 0;
                 }
                 continue;

src/corelib/kernel/qobject.cpp

@@ -1482,7 +1482,7 @@ void QObjectPrivate::setThreadData_helper(QThreadData *currentData, QThreadData
             continue;
         if (pe.receiver == q) {
             // move this post event to the targetList
-            targetData->postEventList.append(pe);
+            targetData->postEventList.addEvent(pe);
             const_cast<QPostEvent &>(pe).event = 0;
             ++eventsMoved;
         }

src/corelib/thread/qthread_p.h

@@ -93,6 +93,8 @@ inline bool operator<(const QPostEvent &pe, int priority)
     return priority < pe.priority;
 }
 
+// This class holds the list of posted events.
+//  The list has to be kept sorted by priority
 class QPostEventList : public QList<QPostEvent>
 {
 public:
@@ -109,6 +111,25 @@ public:
     inline QPostEventList()
         : QList<QPostEvent>(), recursion(0), startOffset(0), insertionOffset(0)
     { }
+
+    void addEvent(const QPostEvent &ev) {
+        int priority = ev.priority;
+        if (isEmpty() || last().priority >= priority) {
+            // optimization: we can simply append if the last event in
+            // the queue has higher or equal priority
+            append(ev);
+        } else {
+            // insert event in descending priority order, using upper
+            // bound for a given priority (to ensure proper ordering
+            // of events with the same priority)
+            QPostEventList::iterator at = qUpperBound(begin() + insertionOffset, end(), priority);
+            insert(at, ev);
+        }
+    }
+private:
+    //hides because they do not keep that list sorted. addEvent must be used
+    using QList<QPostEvent>::append;
+    using QList<QPostEvent>::insert;
 };
 
 #ifndef QT_NO_THREAD

src/gui/kernel/qapplication.cpp

@@ -1288,8 +1288,8 @@ bool QApplication::compressEvent(QEvent *event, QObject *receiver, QPostEventLis
           || event->type() == QEvent::LanguageChange
           || event->type() == QEvent::UpdateSoftKeys
           || event->type() == QEvent::InputMethod)) {
-        for (int i = 0; i < postedEvents->size(); ++i) {
-            const QPostEvent &cur = postedEvents->at(i);
+        for (QPostEventList::const_iterator it = postedEvents->constBegin(); it != postedEvents->constEnd(); ++it) {
+            const QPostEvent &cur = *it;
             if (cur.receiver != receiver || cur.event == 0 || cur.event->type() != event->type())
                 continue;
             if (cur.event->type() == QEvent::LayoutRequest

tests/auto/qeventloop/tst_qeventloop.cpp

@@ -59,6 +59,8 @@
 #include <unistd.h>
 #endif
 
+#include "../../shared/util.h"
+
 //TESTED_CLASS=
 //TESTED_FILES=
 
@@ -208,6 +210,7 @@ private slots:
     void quit();
     void processEventsExcludeSocket();
     void processEventsExcludeTimers();
+    void deliverInDefinedOrder_QTBUG19637();
 
     // keep this test last:
     void nestedLoops();
@@ -837,5 +840,77 @@ void tst_QEventLoop::symbianNestedActiveSchedulerLoop()
 #endif
 }
 
+Q_DECLARE_METATYPE(QThread*)
+
+namespace DeliverInDefinedOrder_QTBUG19637 {
+    enum { NbThread = 3,  NbObject = 500, NbEventQueue = 5, NbEvent = 50 };
+
+    struct CustomEvent : public QEvent {
+        CustomEvent(int q, int v) : QEvent(Type(User + q)), value(v) {}
+        int value;
+    };
+
+    struct Object : public QObject {
+        Q_OBJECT
+    public:
+        Object() : count(0) {
+            for (int i = 0; i < NbEventQueue;  i++)
+                lastReceived[i] = -1;
+        }
+        int lastReceived[NbEventQueue];
+        int count;
+        virtual void customEvent(QEvent* e) {
+            QVERIFY(e->type() >= QEvent::User);
+            QVERIFY(e->type() < QEvent::User + 5);
+            uint idx = e->type() - QEvent::User;
+            int value = static_cast<CustomEvent *>(e)->value;
+            QVERIFY(lastReceived[idx] < value);
+            lastReceived[idx] = value;
+            count++;
+        }
+
+    public slots:
+        void moveToThread(QThread *t) {
+            QObject::moveToThread(t);
+        }
+    };
+
+}
+
+void tst_QEventLoop::deliverInDefinedOrder_QTBUG19637()
+{
+    using namespace DeliverInDefinedOrder_QTBUG19637;
+    qMetaTypeId<QThread*>();
+    QThread threads[NbThread];
+    Object objects[NbObject];
+    for (int t = 0; t < NbThread; t++) {
+        threads[t].start();
+    }
+
+    int event = 0;
+
+    for (int o = 0; o < NbObject; o++) {
+        objects[o].moveToThread(&threads[o % NbThread]);
+        for (int e = 0; e < NbEvent; e++) {
+            int q = e % NbEventQueue;
+            QCoreApplication::postEvent(&objects[o], new CustomEvent(q, ++event) , q);
+            if (e % 7)
+                QMetaObject::invokeMethod(&objects[o], "moveToThread", Qt::QueuedConnection, Q_ARG(QThread*, &threads[(e+o)%NbThread]));
+        }
+    }
+
+    QTest::qWait(30);
+    for (int o = 0; o < NbObject; o++) {
+        QTRY_COMPARE(objects[o].count, int(NbEvent));
+    }
+
+    for (int t = 0; t < NbThread; t++) {
+        threads[t].quit();
+        threads[t].wait();
+    }
+
+}
+
+
 QTEST_MAIN(tst_QEventLoop)
 #include "tst_qeventloop.moc"