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Make main thread wake up code more efficient and less error-prone in wxMSW.

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Use a kernel event object to signal the thread wake up instead of sending
WM_NULL to one of its windows. This is simpler as we don't need to look for
any windows and doesn't suffer from the problem of overflowing the Windows
message queue if we do it too many times as signalling an already signalled
event simply doesn't do anything.

Closes #9053.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78041 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Vadim Zeitlin
2014-10-19 12:57:08 +00:00
parent cf61bbb168
commit 6c40531fb7
5 changed files with 82 additions and 85 deletions
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63
src/msw/app.cpp
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@@ -232,23 +232,16 @@ WXDWORD wxGUIAppTraits::WaitForThread(WXHANDLE hThread, int flags)
// have a running event loop as we would never remove them from the message
// queue then and so we would enter an infinite loop as
// MsgWaitForMultipleObjects() keeps returning WAIT_OBJECT_0 + 1.
if ( flags == wxTHREAD_WAIT_BLOCK ||
!wxIsMainThread() ||
!wxEventLoop::GetActive() )
if ( flags == wxTHREAD_WAIT_YIELD && wxIsMainThread() )
{
// Simple blocking wait.
return DoSimpleWaitForThread(hThread);
wxMSWEventLoopBase* const
evtLoop = static_cast<wxMSWEventLoopBase *>(wxEventLoop::GetActive());
if ( evtLoop )
return evtLoop->MSWWaitForThread(hThread);
}
return ::MsgWaitForMultipleObjects
(
1, // number of objects to wait for
(HANDLE *)&hThread, // the objects
false, // wait for any objects, not all
INFINITE, // no timeout
QS_ALLINPUT | // return as soon as there are any events
QS_ALLPOSTMESSAGE
);
// Simple blocking wait.
return DoSimpleWaitForThread(hThread);
}
#endif // wxUSE_THREADS
@@ -780,42 +773,16 @@ void wxApp::OnIdle(wxIdleEvent& WXUNUSED(event))
void wxApp::WakeUpIdle()
{
// Send the top window a dummy message so idle handler processing will
// start up again. Doing it this way ensures that the idle handler
// wakes up in the right thread (see also wxWakeUpMainThread() which does
// the same for the main app thread only)
wxWindow * const topWindow = wxTheApp->GetTopWindow();
if ( topWindow )
wxEventLoopBase * const evtLoop = wxEventLoop::GetActive();
if ( !evtLoop )
{
HWND hwndTop = GetHwndOf(topWindow);
// Do not post WM_NULL if there's already a pending WM_NULL to avoid
// overflowing the message queue.
//
// Notice that due to a limitation of PeekMessage() API (which handles
// 0,0 range specially), we have to check the range from 0-1 instead.
// This still makes it possible to overflow the queue with WM_NULLs by
// interspersing the calles to WakeUpIdle() with windows creation but
// it should be rather hard to do it accidentally.
MSG msg;
if ( !::PeekMessage(&msg, hwndTop, 0, 1, PM_NOREMOVE) ||
::PeekMessage(&msg, hwndTop, 1, 1, PM_NOREMOVE) )
{
// If this fails too, there is really not much we can do, but then
// neither do we need to, as it normally indicates that the window
// queue is full to the brim with the messages and so the main loop
// is running and doesn't need to be woken up.
//
// Notice that we especially should not try use wxLogLastError()
// here as this would lead to another call to wxWakeUpIdle() from
// inside wxLog and stack overflow due to the resulting recursion.
::PostMessage(hwndTop, WM_NULL, 0, 0);
}
// We can't wake up the event loop if there is none and there is just
// no need to do anything in this case, any pending events will be
// handled when the event loop starts.
return;
}
#if wxUSE_THREADS
else
wxWakeUpMainThread();
#endif // wxUSE_THREADS
evtLoop->WakeUp();
}
// ----------------------------------------------------------------------------