message processing question

[IndikaNiva]

I just want to know if the following scenario is normal

all in same thread

I post a message using PostMessage (M1) and carry on, few ms later I post another message (M2)

M1 is picked up and started to process

Here is my question, while processing M1 (which calls a web service), is it possible for M2 to be started processing before the method that process M1 finishes?

ie. is the thread blocked while M1 is processed fully or can another message M2 be picked up and start to be processed?

thanks in advance.

[Skizmo]

ie. is the thread blocked while M1 is processed fully or can another message M2 be picked up and start to be processed?

A thread can only do 1 thing at the same time, so yes it is blocked.

[VladimirF]

...M1 is picked up and started to process...

If you start processing on the same thread - then yes, it will be blocked. But you can create a separate thread for your long processing, that's what threads are for

[IndikaNiva]

Thanks for the reply, This is what I thought too...
but the behavior I am seeing is different.
M1 method calls a web service via wcf, which takes about half a second to reply, during this time, M2 is starting to get processed.

can the thread be going into idle state while waiting for the web server responds, thus giving time to start processing M2?

[VladimirF]

M1 method calls a web service via wcf...

Is that a synchronous call?
Also, wcf? Should you move it to another forum?

[IndikaNiva]

I am in a C++ dll, which calls a C# COM Callable dll to talk to a server
in M1 I call a method from this C# com callable dll, while waiting for this method to return, my C++ code starts processing M2.

What is going on?? thanks for all your help.

[VladimirF]

I am in a C++ dll, which calls a C# COM Callable dll to talk to a server
in M1 I call a method from this C# com callable dll, while waiting for this method to return, my C++ code starts processing M2.

Again, is that a synchronous call?
Are you sure that you are “waiting for this method to return”?
Let me re-state: if you are in your WindowProc, processing a message, the next message will NOT be processed until you return from that WindowProc. Unless, of course, there is a PeekMessage call somewhere.

[IndikaNiva]

Thanks VladimirF, this is what I am thinking also somewhere in our C++ code we must be calling peek and DispatchMessage.

BTW, long time no see. thanks again.

[VladimirF]

...somewhere in our C++ code we must be calling peek and DispatchMessage.

BTW, long time no see. thanks again.

You might be looking in the wrong places.
I think your PeekMessage() should in the SAME thread, so for it to work it MUST be in your C# COM dll.
You are welcome!