FreeTDS Development Group

["James K. Lowden" <jklowden AT freetds.org>]

ZIGLIO, Frediano, VF-IT wrote:
> > 
> Is underscore part of libTDS function prefix?
> Is underscore part of libTDS enumeration prefix?

Fair questions.  I'm thinking about it.  Certainly all the existing libtds
stuff has underscores.  Maybe it should be tds_perror().  

> > Do you think it's possible for tds_select to call 
> > tds_send_cancel?  If so,
> > tds_select need return only >1 (OK) or <1 (FAIL).  
> 
> Mmmm... I think you should check what happen if tds_send_cancel is
> called inside tds_goodwrite writing another packet... I think that in
> this situation we could send garbage...

Ah.  Must let higher level decide when to call tds_send_cancel.  

> I think that setting query_timeout to 1 and selecting interrupt/error
> handler in dblib could lead to a unique libTDS handler. But perhaps now
> is better to finish stuff with libTDS interrupt handler.

Agreed.  See also dbsetbusy and dbsetidle in Sybase's db-lib.  

> - on timeout we call tdserror than later on caller (tds_goodread or
> tds_goodwrite) we call tdserror again

I removed the outer loop in tds_select; it no longer calls tdserror.  

> - we can avoid to compute tv if ptv is NULL
> - we should avoid to call tds_gettime_ms twice
> - tv_usec unit is microseconds so milliseconds should be multiplied by
> 1000
> - I don't understand tv.tv_sec + tv.tv_usec > 0 condition
> 
> Perhaps this would be easier

[excellent code snipped]

I tried a few different ways.  Yours was best.  Showoff.  ;-)

> Yes, but you can disable assert with -DNDEBUG while you can't disable
> perror.

Good point.  Removed.  

> Perhaps however when someone will read documentation will ask... What's
> sock_errno? Perhaps should we specify errno on POSIX and
> WSAGetLastError() on Windows? And under cygwin?

I think the code is easier to read as is.  It's a shame we can't just 

        #define errno WSAGetLastError()

> Well... now I understand the recursion... a timeout inside
> tds_send_cancel (however tds_send_cancel can't recurse). I'm more aware
> of a tds_send_cancel while sending a packet. Does this work correctly?

I don't know yet.  I'll be sure to include it in my unit test.  

> Does even a tds_send_cancel inside a signal is correct?

If we're *very* careful.  The set of libc functions that are signal safe
is small.  

Regards, 

--jkl