Mail Archives: cygwin/2010/08/29/11:09:17
We are listening and learning :-)
Dave
Sent from my iPad
On Aug 29, 2010, at 9:51 AM, "Corinna Vinschen" <corinna-cygwin AT cygwin DOT com>=
wrote:
> On Aug 29 16:41, Corinna Vinschen wrote:
>> On Aug 29 16:17, Corinna Vinschen wrote:
>>> On Aug 29 14:39, Jon TURNEY wrote:
>>>> On 08/08/2010 12:04, Andy Koppe wrote:
>>>>> On 7 August 2010 23:07, Jon TURNEY wrote:
>>>>>> Hmmm, looking again at the implementation of select(), I don't immed=
iately
>>>>>> see that when waiting on /dev/windows, it checks that the message qu=
eue has
>>>>>> old messages on it before waiting. The MSDN documentation for
>>>>>> MsgWaitForMultipleObjects() seems to says that messages which had ar=
rived
>>>>>> before the last PeekMessage() etc. aren't considered new and so don'=
t end
>>>>>> the wait?
>>>>> [...]
>>>=20
>>> Thanks for the testcase. I examined this and I think I have a
>>> workaround. MSDN states that there's a flag QS_ALLPOSTMESSAGE for
>>> MsgWaitForMultipleObjects, which is not cleared by PeekMessage, if the
>>> wMsgFilterMin and wMsgFilterMax arguments are not both 0. So, what I
>>> did was to add the QS_ALLPOSTMESSAGE flag to the
>>> MsgWaitForMultipleObjects call in select.cc, and to change the
>>> PeekMessage call in select.cc:peek_windows() from
>>>=20
>>> PeekMessage (&m, (HWND) h, 0, 0, PM_NOREMOVE)
>>>=20
>>> to
>>>=20
>>> PeekMessage (&m, (HWND) h, 1, UINT_MAX, PM_NOREMOVE)
>>>=20
>>> Same in your above test application. This appears to do the trick.
>>> However, I'm not exactly sure if that's a valid fix. Patch below.
>>=20
>> Hmm, this ignores the potential WM_NULL message, afaics. For some
>> reason, using
>>=20
>> PeekMessage (&m, (HWND) h, 0, UINT_MAX, PM_NOREMOVE)
>>=20
>> results in MsgWaitForMultipleObjects hanging, too. OTOH, using
>>=20
>> PeekMessage (&m, (HWND) h, 0, 16, PM_NOREMOVE)
>> && PeekMessage (&m, (HWND) h, 17, UINT_MAX, PM_NOREMOVE)
>>=20
>> does not. Go figure.
>=20
> Yeah, I realize I'm talking to myself, but this works, too:
>=20
> PeekMessage (&m, (HWND) h, 0, UINT_MAX - 1, PM_NOREMOVE)
>=20
>=20
> Corinna
>=20
> --=20
> Corinna Vinschen Please, send mails regarding Cygwin to
> Cygwin Project Co-Leader cygwin AT cygwin DOT com
> Red Hat
>=20
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>=20
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