Hi there,

How can I set the connection and read/write timeout when using socket in free pascal? I like the way it works now (blocking, NOT async), but the timeout is a bit too long.

BTW, I hope the way to control timeout is withing the program and platform independent (instead of, e.g. set sysctrl under linux).

Thanks a lot.

Xiangrong Fang wrote

How can I set the connection and read/write timeout when using socket in free pascal?

I seem to remember that synapse can do this.

-Michael

Michael Schnell wrote

On 04/16/2013 11:26 AM, Xiangrong Fang wrote: > How can I set the connection and read/write timeout when using socket > in free pascal? I seem to remember that synapse can do this.

Otherwise for non-standard protocols use fpconnect(), fpselect() etc.

Hi,

As you, when I work with sockets I like the blocking mode but the timeout of connect was a headache for me.

I use fpsetsockopt with the options SO_SNDTIMEO and SO_RCVTIMEO for the read/write timeout.

With connect I don't found an easy way to use my own timeout, so I made a little hack in this situation. At the same time that I call connect I start a new thread for registering the time pass, if the timeout is passed then close/shutdown the socket, this unblock the connect. In case that the connection was succesful then I terminate the parallel thread before it close the socket.

I don't like what I do for the timeout of connect but it's works, maybe this thread throw light in this issue and I can find a better way.

Best regards.

Al 16/04/13 12:20, En/na Michael Schnell ha escrit:

On 04/16/2013 11:26 AM, Xiangrong Fang wrote: > How can I set the connection and read/write timeout when using socket > in free pascal? I seem to remember that synapse can do this.

Only in svn and it does it this way

if FConnectionTimeout > 0 then
begin
  // connect in non-blocking mode
  b := NonBlockMode;
  NonBlockMode := true;
  SockCheck(synsock.Connect(FSocket, Sin));
  if (FLastError = WSAEINPROGRESS) OR (FLastError = WSAEWOULDBLOCK) then
    if not CanWrite(FConnectionTimeout) then
      FLastError := WSAETIMEDOUT;
  NonBlockMode := b;
end
else
  SockCheck(synsock.Connect(FSocket, Sin));

NonBlockMode in turn uses fpIoCtl with the FIONBIO parameter, WSAEINPROGRESS=EsysEINPROGRESS, WSAEWOULDBLOCK=EsysEWOULDBLOCK and CanWrite does an fpSelect

Bye

Will this be a CPU hog:

t := Now;
while fprecv(s, @buf, buf_len, MSG_DONTWAIT) < 0 do begin
  if Now - t > 0.00001 * timeout then Break;   // approx. <timeout> seconds
end;

Thanks

2013/4/16 Luca Olivetti

I did not read the whole thread, but that you favorite blocking mode (which I don't use).

For MSG_DONTWAIT as far I know you have to change to the nonblocking mode.

I thought MSG_DONTWAIT is actually the flag to switch to nonblocking mode, isn't it? As a matter of fact, the fprecv() above would get a result of -1 and a sockterror of "Try Again", which is exactly the behavior of nonblocking read.

2013/4/17 Rainer Stratmann

you wrote

I thought MSG_DONTWAIT is actually the flag to switch to nonblocking mode, isn't it?

May be.

As a matter of fact, the fprecv() above would get a result of -1 and a sockterror of "Try Again", which is exactly the behavior of nonblocking read.

Yes it seems so.

I do always separately switch to the nonblocking mode before.

For connect, I wrote a unit that implements a connect timeout, see:

http://sourceforge.net/p/pascalscada/code/HEAD/tree/trunk/src/scada/sockets_w32_w64.pas#l70

or

http://sourceforge.net/p/pascalscada/code/HEAD/tree/trunk/src/scada/sockets_unix.pas#l48

If you want work in blocking mode after connect, do something like this:

fsocket = {$IFDEF WINDOWS}Socket{$ELSE}fpSocket{$ENDIF}(PF_INET, SOCK_STREAM, IPPROTO_TCP)

//set socket options.
setblockingmode(fsocket,MODE_NONBLOCKING);
if connect_with_timeout(focket,@channel,sizeof(channel),FTimeoutInMs)0
then begin
  //check errors
end;
setblockingmode(FSocket,MODE_BLOCKING);

2013/4/17 Rainer Stratmann :