FreeTDS Development Group

["Lowden, James K" <LowdenJK AT bernstein.com>]

> From: ZIGLIO Frediano [mailto:Frediano.Ziglio AT vodafoneomnitel.it]
> Sent: March 5, 2003 9:56 AM
> 
> @  dbcancel(DBPROCESS * dbproc)
> @  {
> @ +int marker;
> @ +TDSSOCKET *tds;
> @ +
> @ +   tds = (TDSSOCKET *) dbproc->tds_socket;
> @ +
> @ +   while (tds->state != TDS_COMPLETED ) {
> @ +   
> @ +           marker = tds_get_byte(tds);
> @ +
> @ +           tdsdump_log(TDS_DBG_INFO1, "%L dbcancel() discarding
> results. marker is %x\n", marker);
> @ +   
> @ +           if (tds_process_default_tokens(tds, marker) == 
> TDS_FAIL) 
> @ +                   return TDS_FAIL;
> @ +   }
> @ +
> @     tds_send_cancel(dbproc->tds_socket);
> @     tds_process_cancel(dbproc->tds_socket);
> @     return SUCCEED;
> @  }
> @  
> 
> ?? skipping data instead to send a proper cancel is quite 
> bad... if server
> is returning huge amount of data cancel take ages.... IMHO 
> libtds (token.c)
> should be encharge for processing cancel, not dblib.

Bill, what was the motivation here?  Do you have an example of a query or
situation where 
dbcancel(DBPROCESS * dbproc)
{
        tds_send_cancel(dbproc->tds_socket);
        tds_process_cancel(dbproc->tds_socket);
        return SUCCEED;
}

is insufficient?  If so, I'd like to address it in libtds, as Freddy
suggests.  

Your version is highly dangerous IMO.  Safer would have been to call
dbcanquery() before tds_send_cancel().  That would have discarded genuine
rows, not just anything the server happened to send.  But that begs the
question of why tds_send_cancel() isn't good enough.  

--jkl


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