[twsocket] Why is TWSocket.OnDataSent being called twice?

[Doug Billi]

I've implemented a TWSocket client using a state machine, but after I send the 
data using SendStr(), the OnDataSent() event gets fired twice.  I've confirmed 
that the data I'm sending is being put into a single buffer (it's 527 bytes), 
so I don't understand why  the OnDataSent() method is being called twice.

I've searched the ICS mailing list, but none of the posts I found so far 
answered this question specifically, other than to say that OnDataSent() is 
fired when the buffer is emptied, which is why I'm confused that I'd see it 
twice in this scenario (and I've confirmed with breakpoints that I'm only 
calling SendStr() once in the OnConnect event).

Is this expected behavior?

Thanks,
Doug

Pseudo code:

procedure TMyClient.OnConnect();
begin
  FClientState := csSendingData;
  FSocket.SendStr(MyString);
end;

procedure TMyClient.OnDataSent(Sender: TObject; Error: Word);
begin

  Assert(FClientState = csSendingData); <========== FAILS HERE SECOND TIME 
(because FClientState was set to csWaitingForResponse the first time) 
*************************

// buffered data has been sent, so wait for response
  FClientState := csWaitingForResponse;
  // set some other internal variables
end;

procedure TMyClient.OnDataAvailable(Sender: TObject; Error: Word);
begin
  Assert(FClientState = csWaitingForResponse);
  MyReceivedData := FSocket.ReceiveStr;
  // do something with the data (e.g., post to a queue)
end;

procedure TMyClient.WaitUntilQuit;
begin
  FSocket.MessageLoop;
end;

// pseudo code to initiate connection

procedure DoSendRequest;
var
  MyClient: TMyClient;
begin
  MyClient := TMyClient.Create;
  MyClient.Connect;
  MyClient.WaitUntilQuit;
end;
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