[Lazarus] lnet sockets

[Antonio Fortuny]

Le 25/10/2012 13:07, Bernd a écrit :
very nice indeed and readable even on pseudo-code, but ...
> Here is an alternative way to implement it (this one can even reply
> and have a conversation of multiple commands going forth an back
> between the client and server):
>
> pocedure OnEverythingGetsStarted;
> begin
>     if State = WAITING then exit;
>     State := WAITING
>     maybe also disable some buttons that might interfere
>     open the connection
>     send the request
>     start the timeout timer
>     // return from that event
this is exactly what I have to avoid: user gains control on screen. A 
workaround is to disable the window itself. But then another timer is 
needed to ensure that whatever happens or NOTHING happens, control will 
return  back to the starting point.
Furthermore, all requests coded until now have to be moved outside of 
the procedures or events holding them: a lot of work
What if:

pocedure OnEverythingGetsStarted;
*var
   AHandles: PWOHandleArray;*
*   **Res: DWORD;*
begin
    if State = WAITING then exit;
    State := WAITING
    maybe also disable some buttons that might interfere
    open the connection
    Event.ResetEvent;  // not signaled
    send the request
    start the timeout timer
    
    AHandles[0] := Timer.Handle;
    AHandles[1] := Event.Handle;	// posted by the OnReceive
  event
    Res:=WaitForMultipleObjects(2, @AHandles, False, Timeout);
    // wait for first reset, not interested for all
    case Res of
      ... continue processing depending of the answer or no answer
    end;
end;

> end;
>
> procedure OnTimer;
> begin
>    if State = WAITING then begin
>      Disconnect
>      State := IDLE
             Timer.enabled := False;
>      enable the disabled buttons
>    end;
> end;
>
> procedure OnReceive(S: TLSocket);
> begin
>    Answer := S.GetMessage()
forget about the rest of the procedure and do instead:
         DoWhatEverBeforeProcessData(Answer);
         Event.SetEvent;    // event signaled
>    case Answer of
>    'foo': begin
>       DoThis();
>       SendAnotherCommand();
>    end
>    'bar': begin
>       DoThat();
>       SendSomeThingDifferent();
>    end
         .. I have dozens of messages to process in the internal protocol
>    else begin
>       DoWhateverNeedsToBeDone();
>       S.Disconnect;
>       State := IDLE;
>       enable the disabled buttons
>    end;
> end;
>
> This will never block and never freeze and never eat any unneeded CPU
> cycles and it is les code than messing around with the eventers and
> CallAction directly and also less code than low level programming
> against sockets and/or winsock2 directly.
Anyway, I can agree with this above.
But the application has to be re-engineered.


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