More info concerning my original problem which is ...
My application uses a TTnCnx client object to connect (hundreds of times
per day) to a remote device to retrieve data. On rare occasions the pair
seem to get stuck in a connected state and stay there indefinitely.
The normal procedure is to call SendMsg which calls Connect.
OnConnection, write the outgoing message. When a response is received,
call ClosePort. If no response, MsgTimeout.
{As I write this I see one problem, I don't call Close in the timeout
procedure. Yet, after several failures, I would still call
NewTelnetClient which I would expect to get me out of the hung state}
See any other obvious issues? Any problem calling Free immediately after
Close in FreeTelnetClient?
Mike
procedure TTLS350E.SendMsg(Msg: string);
begin
try
if assigned(TelnetClient) then
begin
TxTCPBuffer := Msg;
if TelnetClient.IsConnected = True then begin { connection is
already active }
WriteToTelnet(Msg);
end else begin { got to get a connection }
TelnetClient.Connect;
end;
end;
except
ShowNewMessage( 'Exception handled in TCP SendMsg');
end;
end;
procedure TTLS350E.ClosePort;
begin
TelnetClient.Close;
end;
procedure TTLS350E.MsgTimeout(Sender: TObject);
begin
inc(PortRebuildCount);
if PortRebuildCount >= TLS350_TIMEOUTS_RESET then begin
PortRebuildCount := 0;
NewTelnetClient;
end;
end;
procedure TTLS350E.FreePort; // This should only be called from Destroy
begin
FreeTelnetClient;
end;
procedure TTLS350E.FreeTelnetClient;
var
tmpTelnet: TTnCnx;
begin
if assigned(TelnetClient) then begin // if TCP client exists, kill it
tmpTelnet := TelnetClient;
tmpTelnet.Close;
tmpTelnet.Free;
TelnetClient := nil;
end;
end;
// The following function is called only after multiple
// message failures.
// build a new Telnet object
procedure TTLS350E.NewTelnetClient;
begin
FreeTelnetClient;
TelnetClient := TTnCnx.Create(Application.MainForm);
TelnetClient.OnDataAvailable := TnCnxDataAvailable;
TelnetClient.OnSessionClosed := TnCnxSessionClosed;
TelnetClient.OnSessionConnected := TnCnxSessionConnected;
TelnetClient.Port := IntToStr(MyConfig.GetPort);
TelnetClient.Host := MyConfig.GetIP;
end;
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