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freetds - [freetds] cancel and timeout

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  • From: "ZIGLIO, Frediano, VF-IT" <Frediano.Ziglio AT vodafone.com>
  • To: "FreeTDS Development Group" <freetds AT lists.ibiblio.org>
  • Subject: [freetds] cancel and timeout
  • Date: Thu, 20 Jan 2005 17:29:59 +0100

Well.. I did a big job on these stuff today... they just works (although
not perfectly).

Cancellation
------------

Added a TDS_READING state, now we have
TDS_DEAD connection broken, no read or send from server
TDS_IDLE client did not send data and we are no waiting data from server
TDS_QUERYING we are sending data to server
TDS_PENDING we are expecting data from server
TDS_READING we are reading data from server
As you can see TDS_READING and TDS_PENDING seems quite similar however
when you are in tds_process_results_tokens or similar state it's
TDS_READING while from outside we are in TDS_PENDING. This it's the key
of cancel fix. If we issue a cancel while another function it's reading
data we just set a in_cancel flag in TDSSOCKET and
tds_process_results_tokens function detect and handle cancellation by
itself. If we are in pending we can process cancel from server
(tds_process_cancel). The key now it's tds_set_state, to fix even thread
problem (like SQLCancel from another thread) a syncronization should
occur).
Asyncronous calls (signals) works as expected.
TODO:
better tds_process_cancel
fix odbc using TDS_INT_CANCEL instead of TDS_INT_CONTINUE and
SQLCancel
do not take into account in_cancel if we can return a correct result??

Timeout
-------
Now if a timeout (now query_timeout) a query_timeout_func it's called. I
removed chkintr and hndlintr (one function it's sufficient).
query_start_time it's use for global time counting. I don't know if
query timeout on dblib works as expected. Perhaps even SQLFetch or
similar need setting timeout.

...

freddy77




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