Am 09.10.2013 10:40, schrieb Juha Manninen:
I am testing SimpleIPC with components/chmhelp/lhelp
and
components/chmhelp/democontrol/lhelpconnectiondemo1
The latter works as a master application, sending a file name to lhelp
and starting it if not running already.
On Linux this works perfectly. The return message status is always "Success".
On Windows there is a bug when lhelp is not yet running and it must be started.
In TWinMsgServerComm.PeekMessage() (part of SimpleIPC),
if Windows.PeekMessage() failed, the idea is to wait a given TimeOut
and then try again:
R:=MsgWaitForMultipleObjects(1,FHWND,False,TimeOut,QS_SENDMESSAGE);
B:=(R<>WAIT_TIMEOUT);
The caller gives 50 ms as timeout but also uses a loop for 5 seconds
total timeout.
It should be enough for even slowly starting processes.
However, when the process does not exist yet,
MsgWaitForMultipleObjects returns WAIT_FAILED instead of WAIT_TIMEOUT,
and it does NOT wait. It returns immediately.
I was able to fix it like this:
R:=MsgWaitForMultipleObjects(1,FHWND,False,TimeOut,QS_SENDMESSAGE);
if R=WAIT_FAILED then
Sleep(TimeOut);
B:=(R<>WAIT_TIMEOUT) and (R<>WAIT_FAILED);
The fix can be tested with lhelpconnectiondemo1.
Currently the first reply status is NoAnswer, after the fix it is Success.
If you think the fix is OK, I can make a patch.
You might want to take a look at WaitForInputIdle.
MSDN entry:
http://msdn.microsoft.com/en-us/library/windows/desktop/ms687022%28v=vs.85%29.aspx
Informative blog entry:
http://blogs.msdn.com/b/oldnewthing/archive/2010/03/25/9984720.aspx
In my opinion you should use this in TLHelpConnection.StartHelpServer.
Though you could add it in TWinMsgServerComm as well, as we rely on
messages anyway...
Regards,
Sven
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