AuroraMiddleware/wxWidgets
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Fix handling of spurious wake ups in GetNextMessageTimeout() in wxMSW.

Browse Source 
It didn't take long to realize that changes of r78041 did break something
(see #9053), as MsgWaitForMultipleObjects() can return indicating the message
availability even if no message is actually available in the queue. This
notably happens when the application is activated.

Fix this by calling MsgWaitForMultipleObjects() in a loop until we do get a
message. Notice that this only works correctly with the infinite timeout as we
don't update the remaining time to wait after a spurious wake-up, but this
shouldn't be a problem in practice as no such wake-ups should happen anyhow
during a small timeout duration -- and nobody typically uses long ones.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78047 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Vadim Zeitlin 2014-10-19 14:16:18 +00:00
parent a786c5094a
commit cf8700162d
1 changed files with 5 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
src/msw/evtloopconsole.cpp
View File

@ -102,10 +102,7 @@ int wxMSWEventLoopBase::GetNextMessageTimeout(WXMSG *msg, unsigned long timeout)
// MsgWaitForMultipleObjects() won't notice any input which was already // MsgWaitForMultipleObjects() won't notice any input which was already
// examined (e.g. using PeekMessage()) but not yet removed from the queue // examined (e.g. using PeekMessage()) but not yet removed from the queue
// so we need to remove any immediately messages manually // so we need to remove any immediately messages manually
// while ( !::PeekMessage(msg, 0, 0, 0, PM_REMOVE) )
// NB: using MsgWaitForMultipleObjectsEx() could simplify the code here but
// it is not available in very old Windows versions
if ( !::PeekMessage(msg, 0, 0, 0, PM_REMOVE) )
{ {
DWORD rc = ::MsgWaitForMultipleObjects DWORD rc = ::MsgWaitForMultipleObjects
( (
@ -131,17 +128,12 @@ int wxMSWEventLoopBase::GetNextMessageTimeout(WXMSG *msg, unsigned long timeout)
// return to the event loop, so pretend there was WM_NULL in // return to the event loop, so pretend there was WM_NULL in
// the queue. // the queue.
wxZeroMemory(*msg); wxZeroMemory(*msg);
break; return TRUE;
case WAIT_OBJECT_0 + 1: case WAIT_OBJECT_0 + 1:
// Some message is supposed to be available. // Some message is supposed to be available, but spurious
if ( !::PeekMessage(msg, 0, 0, 0, PM_REMOVE) ) // wake ups are also possible, so just return to the loop:
{ // either we'll get the message or start waiting again.
// somehow it may happen that MsgWaitForMultipleObjects()
// returns true but there are no messages -- just treat it
// the same as timeout then
return -1;
}
break; break;
} }
} }