RE: Socket - set time out on recv()

Thanks Scott.  Will look into it.  Pressing for time (as usual).

-----Original Message-----
From: rpg400-l-bounces+lim.hock-chai=arch.com@xxxxxxxxxxxx
[mailto:rpg400-l-bounces+lim.hock-chai=arch.com@xxxxxxxxxxxx]On Behalf
Of Scott Klement
Sent: Tuesday, June 14, 2005 4:22 PM
To: RPG programming on the AS400 / iSeries
Subject: Re: Socket - set time out on recv()


Hello,

>
> Anybody know how to set time out on recv()? (connection Oriented).
>

Two ways:  Signals and Select().

With signals, you call an API prior to calling recv() that will send you a 
signal in a few seconds.  For example, if you want recv() to time out 
after 5 seconds, you say "send me a SIGALRM signal after 5 seconds".

Then you call recv().

If the signal gets received before any data does, the recv() API will 
return -1 and errno will be set to EINTR to indicate that it was 
interrupted by a signal.

I've demonstrated this with the connect() API in the following program. 
The same technique should work for recv() as well.
http://www.iseriesnetwork.com/noderesources/code/clubtechcode/ChkSvr.zip

An updated copy of the SIGNAL_H member that works with V5R1 can be found 
here:
http://www.scottklement.com/rpg/signal_h.rpgle


The SELECT() method:

The idea here is that you always call select() prior to calling recv(). 
Select() will tell you if there's any data to read, and can wait until 
some arrives.

So, you create a "read set" for select() containing only the one socket. 
You call select() specifying that read set, and a timeout value. It'll 
wait until data has arrived, or until the timeout occurs.

If data WAS received, you then go ahead and call recv() to load that data 
into a variable.  If not, you do whatever you plan to do when something 
times out.

There are samples of this in the RPG400-L archives.