qt5base-lts/tests/auto/gui/kernel/noqteventloop/tst_noqteventloop.cpp
Alex Trotsenko 81408c0e76 QEventDispatcherWin32: avoid livelock in a foreign event loop
According to Windows docs, GetMessage() function retrieves the messages
from the input queue in defined order, where posted messages are
processed ahead of input messages, even if they were posted later.
Therefore, if the application produces a posted event permanently, as
a result of processing that event, user input messages may be blocked
due to hard CPU usage by the application.

It's not a problem, if an internal Qt event loop is running. By calling
sendPostedEvents() on the beginning of processEvents(), we are sending
posted events only once per iteration. However, during execution of
the foreign loop, we should artificially lower the priority of the
WM_QT_SENDPOSTEDEVENTS message in order to enable delivery of other
input messages.

To solve the problem, it is proposed to postpone the
WM_QT_SENDPOSTEDEVENTS message until the message queue becomes empty,
as it works for the internal loop.

Task-number: QTBUG-77464
Change-Id: I8dedb6837c6fc41aa6f497e67ab2352c2b4f3772
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>
2019-08-29 09:12:29 +00:00

348 lines
9.8 KiB
C++

/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the test suite of the Qt Toolkit.
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#include <QtTest/QtTest>
#include <QEvent>
#include <QtCore/qthread.h>
#include <QtGui/qguiapplication.h>
#include <QtGui/qpainter.h>
#include <QtGui/qrasterwindow.h>
#include <QtNetwork/qtcpserver.h>
#include <QtNetwork/qtcpsocket.h>
#include <QtCore/qelapsedtimer.h>
#include <QtCore/qtimer.h>
#include <QtCore/qt_windows.h>
static const int topVerticalMargin = 50;
static const int margin = 10;
class tst_NoQtEventLoop : public QObject
{
Q_OBJECT
private slots:
void consumeMouseEvents();
void consumeSocketEvents();
void deliverEventsInLivelock();
};
class Window : public QRasterWindow
{
public:
explicit Window(QWindow *parentWindow = nullptr) : QRasterWindow(parentWindow)
{
}
void reset()
{
m_received.clear();
}
bool event(QEvent *event) override
{
m_received[event->type()]++;
return QWindow::event(event);
}
int received(QEvent::Type type)
{
return m_received.value(type, 0);
}
QHash<QEvent::Type, int> m_received;
protected:
void paintEvent(QPaintEvent *) override
{
QPainter p(this);
p.fillRect(QRect(QPoint(0, 0), size()), Qt::yellow);
}
};
bool g_exit = false;
extern "C" LRESULT QT_WIN_CALLBACK wndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
if (message == WM_SHOWWINDOW && wParam == 0)
g_exit = true;
return DefWindowProc(hwnd, message, wParam, lParam);
}
class TestThread : public QThread
{
Q_OBJECT
public:
TestThread(HWND parentWnd, Window *childWindow) : QThread(), m_hwnd(parentWnd), m_childWindow(childWindow) {
m_screenW = ::GetSystemMetrics(SM_CXSCREEN);
m_screenH = ::GetSystemMetrics(SM_CYSCREEN);
}
enum {
MouseClick,
MouseMove
};
void mouseInput(int command, const QPoint &p = QPoint())
{
INPUT mouseEvent;
mouseEvent.type = INPUT_MOUSE;
MOUSEINPUT &mi = mouseEvent.mi;
mi.mouseData = 0;
mi.time = 0;
mi.dwExtraInfo = 0;
mi.dx = 0;
mi.dy = 0;
switch (command) {
case MouseClick:
mi.dwFlags = MOUSEEVENTF_LEFTDOWN;
::SendInput(1, &mouseEvent, sizeof(INPUT));
::Sleep(50);
mi.dwFlags = MOUSEEVENTF_LEFTUP;
::SendInput(1, &mouseEvent, sizeof(INPUT));
break;
case MouseMove:
mi.dwFlags = MOUSEEVENTF_MOVE | MOUSEEVENTF_ABSOLUTE;
mi.dx = p.x() * 65536 / m_screenW;
mi.dy = p.y() * 65536 / m_screenH;
::SendInput(1, &mouseEvent, sizeof(INPUT));
break;
}
}
void mouseClick()
{
mouseInput(MouseClick);
}
void mouseMove(const QPoint &pt)
{
mouseInput(MouseMove, pt);
}
void run() {
struct ScopedCleanup
{
/* This is in order to ensure that the window is hidden when returning from run(),
regardless of the return point (e.g. with QTRY_COMPARE) */
ScopedCleanup(HWND hwnd) : m_hwnd(hwnd) { }
~ScopedCleanup() {
::ShowWindow(m_hwnd, SW_HIDE);
}
HWND m_hwnd;
} cleanup(m_hwnd);
m_testPassed = false;
POINT pt;
pt.x = 0;
pt.y = 0;
if (!::ClientToScreen(m_hwnd, &pt))
return;
m_windowPos = QPoint(pt.x, pt.y);
// First activate the parent window (which will also activate the child window)
m_windowPos += QPoint(5,5);
mouseMove(m_windowPos);
::Sleep(150);
mouseClick();
// At this point the windows are activated, no further events will be send to the QWindow
// if we click on the native parent HWND
m_childWindow->reset();
::Sleep(150);
mouseClick();
::Sleep(150);
QTRY_COMPARE(m_childWindow->received(QEvent::MouseButtonPress) + m_childWindow->received(QEvent::MouseButtonRelease), 0);
// Now click in the QWindow. The QWindow should receive those events.
m_windowPos.rx() += margin;
m_windowPos.ry() += topVerticalMargin;
mouseMove(m_windowPos);
::Sleep(150);
mouseClick();
QTRY_COMPARE(m_childWindow->received(QEvent::MouseButtonPress), 1);
QTRY_COMPARE(m_childWindow->received(QEvent::MouseButtonRelease), 1);
m_testPassed = true;
// ScopedCleanup will hide the window here
// Once the native window is hidden, it will exit the event loop.
}
bool passed() const { return m_testPassed; }
private:
int m_screenW;
int m_screenH;
bool m_testPassed;
HWND m_hwnd;
Window *m_childWindow;
QPoint m_windowPos;
};
void tst_NoQtEventLoop::consumeMouseEvents()
{
int argc = 1;
char *argv[] = {const_cast<char*>("test")};
// ensure scaling is off since the child window is positioned using QWindow API.
QCoreApplication::setAttribute(Qt::AA_DisableHighDpiScaling);
QGuiApplication app(argc, argv);
QString clsName(QStringLiteral("tst_NoQtEventLoop_WINDOW"));
const HINSTANCE appInstance = (HINSTANCE)GetModuleHandle(0);
WNDCLASSEX wc;
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = CS_DBLCLKS | CS_OWNDC; // CS_SAVEBITS
wc.lpfnWndProc = wndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = appInstance;
wc.hIcon = 0;
wc.hIconSm = 0;
wc.hCursor = 0;
wc.hbrBackground = ::GetSysColorBrush(COLOR_BTNFACE /*COLOR_WINDOW*/);
wc.lpszMenuName = 0;
wc.lpszClassName = (wchar_t*)clsName.utf16();
ATOM atom = ::RegisterClassEx(&wc);
QVERIFY2(atom, "RegisterClassEx failed");
DWORD dwExStyle = WS_EX_APPWINDOW;
DWORD dwStyle = WS_CAPTION | WS_TABSTOP | WS_VISIBLE;
const int screenWidth = ::GetSystemMetrics(SM_CXSCREEN);
const int screenHeight = ::GetSystemMetrics(SM_CYSCREEN);
const int width = screenWidth / 4;
const int height = screenHeight / 4;
HWND mainWnd =
::CreateWindowEx(dwExStyle, reinterpret_cast<const wchar_t*>(clsName.utf16()),
TEXT("tst_NoQtEventLoop"), dwStyle,
(screenWidth - width) / 2, (screenHeight - height) / 2 , width, height,
0, NULL, appInstance, NULL);
QVERIFY2(mainWnd, "CreateWindowEx failed");
::ShowWindow(mainWnd, SW_SHOW);
::SetWindowPos(mainWnd, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE);
QWindow *mainWindow = QWindow::fromWinId(reinterpret_cast<WId>(mainWnd));
Window *childWindow = new Window(mainWindow);
childWindow->setGeometry(margin, topVerticalMargin,
width - 2 * margin, height - margin - topVerticalMargin);
childWindow->show();
TestThread *testThread = new TestThread(mainWnd, childWindow);
connect(testThread, SIGNAL(finished()), testThread, SLOT(deleteLater()));
testThread->start();
// Our own message loop...
MSG msg;
while (::GetMessage(&msg, NULL, 0, 0) > 0) {
::TranslateMessage(&msg);
::DispatchMessage(&msg);
if (g_exit)
break;
}
delete mainWindow;
QCOMPARE(testThread->passed(), true);
}
void tst_NoQtEventLoop::consumeSocketEvents()
{
int argc = 1;
char *argv[] = { const_cast<char *>("test"), 0 };
QGuiApplication app(argc, argv);
QTcpServer server;
QTcpSocket client;
QVERIFY(server.listen(QHostAddress::LocalHost));
client.connectToHost(server.serverAddress(), server.serverPort());
QVERIFY(client.waitForConnected());
QElapsedTimer elapsedTimer;
elapsedTimer.start();
// Exec own message loop
MSG msg;
forever {
if (elapsedTimer.hasExpired(3000) || server.hasPendingConnections())
break;
if (::PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
::TranslateMessage(&msg);
::DispatchMessage(&msg);
}
}
QVERIFY(server.hasPendingConnections());
}
void tst_NoQtEventLoop::deliverEventsInLivelock()
{
int argc = 1;
char *argv[] = { const_cast<char *>("test"), 0 };
QGuiApplication app(argc, argv);
QTimer livelockTimer;
livelockTimer.start(0);
QTimer::singleShot(100, Qt::CoarseTimer, &livelockTimer, &QTimer::stop);
QElapsedTimer elapsedTimer;
elapsedTimer.start();
// Exec own message loop
MSG msg;
forever {
if (elapsedTimer.hasExpired(3000) || !livelockTimer.isActive())
break;
if (::PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
::TranslateMessage(&msg);
::DispatchMessage(&msg);
}
}
QVERIFY(!livelockTimer.isActive());
}
#include <tst_noqteventloop.moc>
QTEST_APPLESS_MAIN(tst_NoQtEventLoop)