From: Kevin Puetz PuetzKevinA@JohnDeere.com
The order of operations here is quite sensitive, in order to keep the desired priority of various message types and queue state in sync. Splitting it betwen two functions makes the dependencies less obvious. Combining them into a single if/else makes it clearer that both are ways to peek that will clear QS_ALLPOSTMESSAGE so MsgWaitForMultipleObjects waits. When there is an apt->win, the message is removed and pumped; without one only the side-effect (clearing QS_ALLPOSTMESSAGE) is wanted. --- dlls/combase/combase.c | 40 ++++++++++++++++++++++++++++------------ 1 file changed, 28 insertions(+), 12 deletions(-)
diff --git a/dlls/combase/combase.c b/dlls/combase/combase.c index 92114c31aed..643aff9d45f 100644 --- a/dlls/combase/combase.c +++ b/dlls/combase/combase.c @@ -2038,11 +2038,34 @@ HRESULT WINAPI CoRevokeInitializeSpy(ULARGE_INTEGER cookie)
static BOOL com_peek_message(struct apartment *apt, MSG *msg) { - /* First try to retrieve messages for incoming COM calls to the apartment window */ - return (apt->win && PeekMessageW(msg, apt->win, 0, 0, PM_REMOVE | PM_NOYIELD)) || - /* Next retrieve other messages necessary for the app to remain responsive */ - PeekMessageW(msg, NULL, WM_DDE_FIRST, WM_DDE_LAST, PM_REMOVE | PM_NOYIELD) || - PeekMessageW(msg, NULL, 0, 0, PM_QS_PAINT | PM_QS_SENDMESSAGE | PM_REMOVE | PM_NOYIELD); + BOOL PeekMessage_RPC; + /* This first peek (and no other) must be "without filtering messages" in order to reset QS_ALLPOSTMESSAGE */ + if (apt->win) + { + /* Try to retrieve messages for incoming COM calls to the apartment window. + * peeking at a specific hWnd doesn't count as filtering, so this clears QS_ALLPOSTMESSAGE. */ + PeekMessage_RPC = PeekMessageW(msg, apt->win, 0, 0, PM_REMOVE | PM_NOYIELD); + } + else + { + /* Reset QS_ALLPOSTMESSAGE without removing anything from the queue. */ + PeekMessageW(NULL, NULL, 0, 0, PM_QS_POSTMESSAGE | PM_NOREMOVE | PM_NOYIELD); + PeekMessage_RPC = FALSE; + } + + return PeekMessage_RPC || + /* Next retrieve other messages necessary for the app to remain responsive. + * These subsequent peeks must all be filtered; clearing the queue status again could + * prevent newly-posted messages that match earlier PeekMessage calls from waking MsgWait. */ + PeekMessageW(msg, NULL, WM_DDE_FIRST, WM_DDE_LAST, PM_REMOVE | PM_NOYIELD) || /* filters by WM_DDE_* */ + PeekMessageW(msg, NULL, 0, 0, PM_QS_PAINT | PM_QS_SENDMESSAGE | PM_REMOVE | PM_NOYIELD); /* filters by PM_QS_*, excluding POSTMESSAGE */ + + /* When com_peek_message returns FALSE, it cleared QS_ALLPOSTMESSAGE and subsequently found nothing interesting + * Caller may use MsgWaitForMultipleObjects(PM_QS_ALLPOSTMESSAGE) to wait for new activity. + * + * When it returns TRUE, *msg contains the next message that should be dispatched, + * The queue contains un-examined messages, so com_peek_message should be called again + * (to finish draining it) before using MsgWaitForMultipleObjects */ }
/*********************************************************************** @@ -2142,13 +2165,6 @@ HRESULT WINAPI CoWaitForMultipleHandles(DWORD flags, DWORD timeout, ULONG handle } }
- if (!apt->win) - { - /* If window is NULL on apartment, peek at messages so that it will not trigger - * MsgWaitForMultipleObjects next time. */ - PeekMessageW(NULL, NULL, 0, 0, PM_QS_POSTMESSAGE | PM_NOREMOVE | PM_NOYIELD); - } - /* Some apps (e.g. Visio 2010) don't handle WM_PAINT properly and loop forever, * so after processing 100 messages we go back to checking the wait handles */ while (msg_count++ < 100 && com_peek_message(apt, &msg))