Revert "Support more than 62 instances of QWinEventNotifier"

It breaks sth in QLocalSocket which is used in QtRemoteObject.

This reverts commit 5c6210e3452f78cab2f58887e747eb5cb2501f70.

Task-number: QTBUG-61668
Change-Id: Ib11890923773496e5d998b7709ef93b0a839a759
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

5 files changed, 41 insertions, 172 deletions

diff --git a/src/corelib/kernel/kernel.pri b/src/corelib/kernel/kernel.pri
index 8abe9b2b44..29bd5bbc6c 100644
--- a/src/corelib/kernel/kernel.pri
+++ b/src/corelib/kernel/kernel.pri
@@ -79,8 +79,7 @@ win32 {
                 kernel/qsharedmemory_win.cpp \
                 kernel/qsystemsemaphore_win.cpp
         HEADERS += \
-                kernel/qwineventnotifier.h \
-                kernel/qwineventnotifier_p.h
+                kernel/qwineventnotifier.h
 
         winrt {
             SOURCES += kernel/qeventdispatcher_winrt.cpp
diff --git a/src/corelib/kernel/qeventdispatcher_win.cpp b/src/corelib/kernel/qeventdispatcher_win.cpp
index fc34dd0a6b..0952464f53 100644
--- a/src/corelib/kernel/qeventdispatcher_win.cpp
+++ b/src/corelib/kernel/qeventdispatcher_win.cpp
@@ -53,7 +53,6 @@
 #include "qcoreapplication_p.h"
 #include <private/qthread_p.h>
 #include <private/qmutexpool_p.h>
-#include <private/qwineventnotifier_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -97,14 +96,13 @@ LRESULT QT_WIN_CALLBACK qt_internal_proc(HWND hwnd, UINT message, WPARAM wp, LPA
 QEventDispatcherWin32Private::QEventDispatcherWin32Private()
     : threadId(GetCurrentThreadId()), interrupt(false), closingDown(false), internalHwnd(0),
       getMessageHook(0), serialNumber(0), lastSerialNumber(0), sendPostedEventsWindowsTimerId(0),
-      wakeUps(0), activateNotifiersPosted(false), winEventNotifierActivatedEvent(NULL)
+      wakeUps(0)
+    , activateNotifiersPosted(false)
 {
 }
 
 QEventDispatcherWin32Private::~QEventDispatcherWin32Private()
 {
-    if (winEventNotifierActivatedEvent)
-        CloseHandle(winEventNotifierActivatedEvent);
     if (internalHwnd)
         DestroyWindow(internalHwnd);
 }
@@ -539,14 +537,12 @@ bool QEventDispatcherWin32::processEvents(QEventLoop::ProcessEventsFlags flags)
     bool needWM_QT_SENDPOSTEDEVENTS = false;
     do {
         DWORD waitRet = 0;
-        DWORD nCount = 0;
-        HANDLE *pHandles = nullptr;
-        if (d->winEventNotifierActivatedEvent) {
-            nCount = 1;
-            pHandles = &d->winEventNotifierActivatedEvent;
-        }
+        HANDLE pHandles[MAXIMUM_WAIT_OBJECTS - 1];
         QVarLengthArray<MSG> processedTimers;
         while (!d->interrupt) {
+            DWORD nCount = d->winEventNotifierList.count();
+            Q_ASSERT(nCount < MAXIMUM_WAIT_OBJECTS - 1);
+
             MSG msg;
             bool haveMessage;
 
@@ -588,6 +584,8 @@ bool QEventDispatcherWin32::processEvents(QEventLoop::ProcessEventsFlags flags)
             }
             if (!haveMessage) {
                 // no message - check for signalled objects
+                for (int i=0; i<(int)nCount; i++)
+                    pHandles[i] = d->winEventNotifierList.at(i)->handle();
                 waitRet = MsgWaitForMultipleObjectsEx(nCount, pHandles, 0, QS_ALLINPUT, MWMO_ALERTABLE);
                 if ((haveMessage = (waitRet == WAIT_OBJECT_0 + nCount))) {
                     // a new message has arrived, process it
@@ -628,7 +626,7 @@ bool QEventDispatcherWin32::processEvents(QEventLoop::ProcessEventsFlags flags)
                     DispatchMessage(&msg);
                 }
             } else if (waitRet - WAIT_OBJECT_0 < nCount) {
-                activateEventNotifiers();
+                d->activateEventNotifier(d->winEventNotifierList.at(waitRet - WAIT_OBJECT_0));
             } else {
                 // nothing todo so break
                 break;
@@ -641,11 +639,16 @@ bool QEventDispatcherWin32::processEvents(QEventLoop::ProcessEventsFlags flags)
                    && !d->interrupt
                    && (flags & QEventLoop::WaitForMoreEvents));
         if (canWait) {
+            DWORD nCount = d->winEventNotifierList.count();
+            Q_ASSERT(nCount < MAXIMUM_WAIT_OBJECTS - 1);
+            for (int i=0; i<(int)nCount; i++)
+                pHandles[i] = d->winEventNotifierList.at(i)->handle();
+
             emit aboutToBlock();
             waitRet = MsgWaitForMultipleObjectsEx(nCount, pHandles, INFINITE, QS_ALLINPUT, MWMO_ALERTABLE | MWMO_INPUTAVAILABLE);
             emit awake();
             if (waitRet - WAIT_OBJECT_0 < nCount) {
-                activateEventNotifiers();
+                d->activateEventNotifier(d->winEventNotifierList.at(waitRet - WAIT_OBJECT_0));
                 retVal = true;
             }
         }
@@ -903,12 +906,12 @@ bool QEventDispatcherWin32::registerEventNotifier(QWinEventNotifier *notifier)
     if (d->winEventNotifierList.contains(notifier))
         return true;
 
+    if (d->winEventNotifierList.count() >= MAXIMUM_WAIT_OBJECTS - 2) {
+        qWarning("QWinEventNotifier: Cannot have more than %d enabled at one time", MAXIMUM_WAIT_OBJECTS - 2);
+        return false;
+    }
     d->winEventNotifierList.append(notifier);
-
-    if (!d->winEventNotifierActivatedEvent)
-        d->winEventNotifierActivatedEvent = CreateEvent(0, TRUE, FALSE, nullptr);
-
-    return QWinEventNotifierPrivate::get(notifier)->registerWaitObject();
+    return true;
 }
 
 void QEventDispatcherWin32::unregisterEventNotifier(QWinEventNotifier *notifier)
@@ -924,35 +927,17 @@ void QEventDispatcherWin32::unregisterEventNotifier(QWinEventNotifier *notifier)
     Q_D(QEventDispatcherWin32);
 
     int i = d->winEventNotifierList.indexOf(notifier);
-    if (i == -1)
-        return;
-    d->winEventNotifierList.takeAt(i);
-    QWinEventNotifierPrivate *nd = QWinEventNotifierPrivate::get(notifier);
-    if (nd->waitHandle)
-        nd->unregisterWaitObject();
+    if (i != -1)
+        d->winEventNotifierList.takeAt(i);
 }
 
 void QEventDispatcherWin32::activateEventNotifiers()
 {
     Q_D(QEventDispatcherWin32);
-    ResetEvent(d->winEventNotifierActivatedEvent);
-
-    // Iterate backwards, because the notifier might remove itself on activate().
-    for (int i = d->winEventNotifierList.count(); --i >= 0;) {
-        QWinEventNotifier *notifier = d->winEventNotifierList.at(i);
-        QWinEventNotifierPrivate *nd = QWinEventNotifierPrivate::get(notifier);
-        if (WaitForSingleObject(nd->handleToEvent, 0) == WAIT_OBJECT_0) {
-            nd->unregisterWaitObject();
-            d->activateEventNotifier(notifier);
-        }
-    }
-
-    // Re-register the remaining activated notifiers.
-    for (int i = 0; i < d->winEventNotifierList.count(); ++i) {
-        QWinEventNotifier *notifier = d->winEventNotifierList.at(i);
-        QWinEventNotifierPrivate *nd = QWinEventNotifierPrivate::get(notifier);
-        if (nd->waitHandle || !nd->registerWaitObject())
-            return;
+    //### this could break if events are removed/added in the activation
+    for (int i=0; i<d->winEventNotifierList.count(); i++) {
+        if (WaitForSingleObjectEx(d->winEventNotifierList.at(i)->handle(), 0, TRUE) == WAIT_OBJECT_0)
+            d->activateEventNotifier(d->winEventNotifierList.at(i));
     }
 }
 
diff --git a/src/corelib/kernel/qeventdispatcher_win_p.h b/src/corelib/kernel/qeventdispatcher_win_p.h
index 683c7f8f36..f6d1bffdf5 100644
--- a/src/corelib/kernel/qeventdispatcher_win_p.h
+++ b/src/corelib/kernel/qeventdispatcher_win_p.h
@@ -161,7 +161,6 @@ class Q_CORE_EXPORT QEventDispatcherWin32Private : public QAbstractEventDispatch
 public:
     QEventDispatcherWin32Private();
     ~QEventDispatcherWin32Private();
-    static QEventDispatcherWin32Private *get(QEventDispatcherWin32 *q) { return q->d_func(); }
 
     DWORD threadId;
 
@@ -193,7 +192,6 @@ public:
     void postActivateSocketNotifiers();
     void doWsaAsyncSelect(int socket, long event);
 
-    HANDLE winEventNotifierActivatedEvent;
     QList<QWinEventNotifier *> winEventNotifierList;
     void activateEventNotifier(QWinEventNotifier * wen);
 
diff --git a/src/corelib/kernel/qwineventnotifier.cpp b/src/corelib/kernel/qwineventnotifier.cpp
index 6bfa6ca729..0808374a6a 100644
--- a/src/corelib/kernel/qwineventnotifier.cpp
+++ b/src/corelib/kernel/qwineventnotifier.cpp
@@ -37,7 +37,7 @@
 **
 ****************************************************************************/
 
-#include "qwineventnotifier_p.h"
+#include "qwineventnotifier.h"
 
 #ifdef Q_OS_WINRT
 #include "qeventdispatcher_winrt_p.h"
@@ -50,6 +50,19 @@
 
 QT_BEGIN_NAMESPACE
 
+class QWinEventNotifierPrivate : public QObjectPrivate
+{
+    Q_DECLARE_PUBLIC(QWinEventNotifier)
+public:
+    QWinEventNotifierPrivate()
+    : handleToEvent(0), enabled(false) {}
+    QWinEventNotifierPrivate(HANDLE h, bool e)
+    : handleToEvent(h), enabled(e) {}
+
+    HANDLE handleToEvent;
+    bool enabled;
+};
+
 /*!
     \class QWinEventNotifier
     \inmodule QtCore
@@ -233,49 +246,4 @@ bool QWinEventNotifier::event(QEvent * e)
     return false;
 }
 
-#if defined(Q_OS_WINRT)
-
-bool QWinEventNotifierPrivate::registerWaitObject()
-{
-    Q_UNIMPLEMENTED();
-    return false;
-}
-
-void QWinEventNotifierPrivate::unregisterWaitObject()
-{
-    Q_UNIMPLEMENTED();
-}
-
-#else // defined(Q_OS_WINRT)
-
-static void CALLBACK wfsoCallback(void *context, BOOLEAN /*ignore*/)
-{
-    QWinEventNotifierPrivate *nd = reinterpret_cast<QWinEventNotifierPrivate *>(context);
-    QAbstractEventDispatcher *eventDispatcher = nd->threadData->eventDispatcher.load();
-    QEventDispatcherWin32Private *edp = QEventDispatcherWin32Private::get(
-                static_cast<QEventDispatcherWin32 *>(eventDispatcher));
-    SetEvent(edp->winEventNotifierActivatedEvent);
-}
-
-bool QWinEventNotifierPrivate::registerWaitObject()
-{
-    if (RegisterWaitForSingleObject(&waitHandle, handleToEvent, wfsoCallback, this,
-                                    INFINITE, WT_EXECUTEONLYONCE) == 0) {
-        qErrnoWarning("QWinEventNotifier: RegisterWaitForSingleObject failed.");
-        return false;
-    }
-    return true;
-}
-
-void QWinEventNotifierPrivate::unregisterWaitObject()
-{
-    // Unregister the wait handle and wait for pending callbacks to finish.
-    if (UnregisterWaitEx(waitHandle, INVALID_HANDLE_VALUE))
-        waitHandle = NULL;
-    else
-        qErrnoWarning("QWinEventNotifier: UnregisterWaitEx failed.");
-}
-
-#endif // !defined(Q_OS_WINRT)
-
 QT_END_NAMESPACE
diff --git a/src/corelib/kernel/qwineventnotifier_p.h b/src/corelib/kernel/qwineventnotifier_p.h
deleted file mode 100644
index bddeaaf134..0000000000
--- a/src/corelib/kernel/qwineventnotifier_p.h
+++ /dev/null
@@ -1,81 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2017 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of the QtCore module of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and The Qt Company. For licensing terms
-** and conditions see https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** GNU Lesser General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU Lesser
-** General Public License version 3 as published by the Free Software
-** Foundation and appearing in the file LICENSE.LGPL3 included in the
-** packaging of this file. Please review the following information to
-** ensure the GNU Lesser General Public License version 3 requirements
-** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 2.0 or (at your option) the GNU General
-** Public license version 3 or any later version approved by the KDE Free
-** Qt Foundation. The licenses are as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
-** included in the packaging of this file. Please review the following
-** information to ensure the GNU General Public License requirements will
-** be met: https://www.gnu.org/licenses/gpl-2.0.html and
-** https://www.gnu.org/licenses/gpl-3.0.html.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#ifndef QWINEVENTNOTIFIER_P_H
-#define QWINEVENTNOTIFIER_P_H
-
-//
-//  W A R N I N G
-//  -------------
-//
-// This file is not part of the Qt API.  It exists purely as an
-// implementation detail.  This header file may change from version to
-// version without notice, or even be removed.
-//
-// We mean it.
-//
-
-#include "qwineventnotifier.h"
-
-#include <private/qobject_p.h>
-#include <QtCore/qt_windows.h>
-
-QT_BEGIN_NAMESPACE
-
-class QWinEventNotifierPrivate : public QObjectPrivate
-{
-    Q_DECLARE_PUBLIC(QWinEventNotifier)
-public:
-    QWinEventNotifierPrivate()
-    : handleToEvent(0), enabled(false) {}
-    QWinEventNotifierPrivate(HANDLE h, bool e)
-    : handleToEvent(h), enabled(e) {}
-
-    static QWinEventNotifierPrivate *get(QWinEventNotifier *q) { return q->d_func(); }
-    bool registerWaitObject();
-    void unregisterWaitObject();
-
-    HANDLE handleToEvent;
-    HANDLE waitHandle = NULL;
-    bool enabled;
-};
-
-QT_END_NAMESPACE
-
-#endif // QWINEVENTNOTIFIER_P_H