Hi Dirk,
I just changed the SendData method to use the same socket as *should* be
blocked in the RecvFrom and it still works.... now I am stumped..
Richard
"Dirk Claessens" <Noway@invalid> wrote in message
news:mn.f53a7d6c5f9d7d23.59994@invalid...
> On 2006-12-30, Richard Carpenter (212.59.199.49) wrote in
> message <en63g1$it9$1$8302bc10@news.demon.co.uk>
>
>
>> Hi all,
>>
>> I have some code that I have written that *shouldn't* work but it does
>> beautifully... which obviously concerns me. I'll explain it in pseudocode
>> but if anyone needs to see the actual code then I'll post that too.
>>
>> I've created a TThread descendent, its Execute method does one thing and
>> that is call the "ReadData" private method in a "While not terminated"
>> loop. So it's
>>
>> While not terminated do
>> ReadData;
>>
>> The ReadData method is as follows;
>>
>> If (RecvFrom(fSocket, fBuffer[0],1,0,fFrom, size) <> SOCKET_ERROR) then
>> WriteDataToFile(fBuffer[0])
>>
>> That's all that's in the ReadData method, very simple and works well. The
>> socket is a blocking datagram socket set up for broadcasting on UDP.
>>
>> I also have a public method called SendData(const value:string) in the
>> TThread that takes a string parameter, creates a new socket and
>> broadcasts that data across the network then closes the socket.
>>
>> Now the confusing thing is that when the thread enters the RecvFrom it
>> waits like a blocking socket should. *If*, however I call the SendData
>> method from my app the thread jumps out of the RecvFrom, actions the
>> SendData method then returns back to the RecvFrom to continue waiting for
>> data!
>>
>> I would have expected the thread to be "locked up" in the RecvFrom until
>> data arrives but that doesn't appear to be the case. The whole thing
>> works beautifully in that I can send any string data from my app and
>> still be receiving data in the RecvFrom function... and I cannot for the
>> life of me fathom out why this is happening.
>
>
> I guess what you observe is simply Delphi's debugger behaviour.
> ( I assume you have breakpoint on the RecvFrom call or some such)
>
> - ReadData() uses a socket, blocks on RcvFrom(), and runs in the thread's
> context;
> - Each call to SendData() creates a *new* socket, broadcasts the data,
> closes the socket, but runs in the *main* thread's context, not in the
> thread's context as I suspect you are assuming.
> -Both sockets are unrelated, as long as there no port conflicts.
>
> IOW, this should work...
>
> --
> Dirk.
> No trees were killed in the creation of this message;
> however, many electrons were terribly inconvenienced.
> http://users.pandora.be/dirk.claessens2
