Listing processes might be one way to check for instances, maybe try
to communicate with that instance to make sure it's not blocked.
There was also a simple way to check using instance handle in C wich
could be adapted to FPC but i don't know how it works in Unix world.
Razvan
On 12/17/06, Luiz Americo Pereira Camara <[EMAIL PROTECTED]> wrote:
Al Boldi wrote:
> Luiz Americo Pereira Camara wrote:
>
>> Kris Leech wrote:
>>
>>> Good stuff, did you come across any issues with simpleIPC, Ive been
>>> meaning to have a go with it for a while...
>>>
>> I had two issues with simpleipc:
>> - in unix the TSimpleIPCServer.OnMessage event is not fired. To
>> override this, a solution is to call ReadMessage in the OnIdle event of
>> the application.
>>
>
> Try this implementation:
> ========================
> type
>
> { TPeekThread }
> TPeekThread = Class(TThread)
> private
> FDoPeek: TNotifyEvent;
> protected
> procedure Execute; override;
> procedure Synchronize(Method: TThreadMethod);
> Property DoPeek: TNotifyEvent read FDoPeek write FDoPeek;
> end;
>
> { TSimpleIPCpServer }
> TSimpleIPCpServer = Class(TSimpleIPCServer)
> private
> FPeek: Boolean;
> FPeekThread: TPeekThread;
> procedure PeekMethod(Sender: TObject);
> procedure SetPeek(const AValue: Boolean);
> protected
> Procedure Activate; override;
> Procedure Deactivate; override;
> published
> Property Peek : Boolean read FPeek write SetPeek;
> end;
>
> implementation
>
> { TPeekThread }
> procedure TPeekThread.Execute;
> begin
> repeat
> FDoPeek(self);
> until Terminated;
> end;
>
> procedure TPeekThread.Synchronize(Method: TThreadMethod);
> begin
> inherited;
> end;
>
> { TSimpleIPCpServer }
> procedure TSimpleIPCpServer.PeekMethod(Sender: TObject);
> begin
> if PeekMessage(1000,false) then
> TPeekThread(sender).Synchronize(@ReadMessage);
> end;
>
> procedure TSimpleIPCpServer.SetPeek(const AValue: Boolean);
> begin
> if FPeek=AValue then exit;
> if FActive then DoError(SErrActive,[]);
> FPeek:=AValue;
> end;
>
> procedure TSimpleIPCpServer.Activate;
> begin
> inherited Activate;
> if FActive and FPeek then begin
> FPeekThread:=TPeekThread.Create(true);
> FPeekThread.DoPeek:[EMAIL PROTECTED];
> FPeekThread.FreeOnTerminate:=true;
> FPeekThread.Resume;
> end;
> end;
>
> procedure TSimpleIPCpServer.Deactivate;
> begin
> if FActive and FPeek then begin
> FPeekThread.Terminate;
> end;
> inherited Deactivate;
> end;
> ========================
>
>
Thanks. Another solution is to use the dnotify api of the kernel.
Someone already tried dnotify with fpc?
> BTW: Somebody know how to override a Classname, like it's possible with
> Methods. i.e: TComponent = Class(TComponent); override;
>
>
>> - The other is that there's currently no easy way to diferentiate
>> between different message types. Let's say i need to send messages
>> telling i started the job, send the results of the job and than finished
>> the job. Currently there are two options: send a header in the stream
>> with a numeric variable and check it when arrive (you lose the comodity
>> of SendStringMessage) or you send a string with a string marker. I will
>> propose a change in it (and provide the patch) where we could use the
>> MessageType (user defined) to identify the message and we could still
>> use SendStringMessage .
>>
>
> Or you could use another SimpleIPC connection.
>
>
>> - another potential problem (not tested) is that in unix a file is used
>> to pass the messages. So if the program crashes the file may not be
>> deleted and would give that the server is running.
>>
>
> In unix it uses pipes. No problem when program crashes.
>
Good to know. I don't have experience with pipes.
Luiz
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