FreeTDS Development Group

[Sebastien FLAESCH <sf AT 4js.com>]

Thanks Frediano.

Will cvs update the HEAD and make some tests.

Seb

ZIGLIO, Frediano, VF-IT wrote:
> > Hello James,
> >
> > First thanks a lot for taking the time to explain the internals.
> >
> > Resources (just to compare):
> >
> > With DB2 CLI, they don't talk about SIGINT, but rather 
> > multi-threaded applications where a second thread issues SQLCancel().
> >
> > http://webdocs.caspur.it/ibm/db2/8.1/doc/htmlcd/en_US/ad/r0000567.htm
> >
> > With Oracle OCI, they talk about Control-C:
> >
> > http://download.oracle.com/docs/cd/B14117_01/appdev.101/b10779
> > /oci02bas.htm#462655
> >
> > Of course, nothing about SIGINT on MSDN:
> >
> > http://msdn2.microsoft.com/en-us/library/ms714112.aspx
> >
> > ...
> >
> > I can probably use any solution you will provide to handle 
> > SQL interruption.
> > But I believe there is a good chance to have other ODBC 
> > programmers handle SQL interruption with a SIGINT + 
> > SQLCancel() as I did.
> > Therefore, you better choose the second "robust" solution.
>
> Currently CVS HEAD seems to handle all situations correctly.
>
> > Note BTW that several SIGINT signals can be generated 
> > successively: Frustrated users keeping CONTROL-C pressed down ;-).
> > => Many SQLCancel() calls ...
>
> First send cancel than it wait for cancel handling by server. So others
> SQLCancel just do nothing.
>
> > I wonder however why the TDS protocol does not yet specify 
> > how to handle query interruption.
> > To me this should be part of the protocol definition (= you 
> > should not have to choose between different solutions)
> >
> > ...
>
> ??? it calls cancellation.
>
> > Looks like you have to do tricky things (cleaning up the 
> > connection) to handle this... right?
> >
> > Just a remark:
> >
> > Maybe SQLCancel() (query interruption in TDS) is only 
> > supported since SQL Server since version 2005?
> >
> > I just remember that we started to support SQL interruption 
> > with SQL Server native ODBC drivers since 2005 only.
> > Quite sure it was not working before that version... but must 
> > double check.
>
> cancellation is supported even by protocol 4.2.
>
> > I can only suggest to try my little SQLCancel() example with 
> > SQL Server 2005 and sniff the protocol.
>
> See odbc cancel test. I use alarm to emulate ctrl-c
>
> > But it must be adapted to catch console events to trap CTRL-C 
> > (does not with with SIGINT of course)
> > I will try to adapt the sample and send it back.
> >
> > Thanks!
> > Seb
>
> The bad thing... it seems that if test is executed using unixODBC it
> fails. Our SQLCancel is not called (that is you call SQLCancel and
> unixODBC do not call driver one... it hangs). I use unixODBC 2.2.11,
> I'll test with 2.2.12
>
>
> freddy77
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