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Re: (ITS#6716) syncprov sessionlog 'sl_mincsn' not assigned a value.
- To: openldap-its@OpenLDAP.org
- Subject: Re: (ITS#6716) syncprov sessionlog 'sl_mincsn' not assigned a value.
- From: firstname.lastname@example.org
- Date: Thu, 13 Jan 2011 20:31:07 GMT
- Auto-submitted: auto-generated (OpenLDAP-ITS)
> On Sun, Dec 12, 2010 at 06:22:38PM +0100, Rein Tollevik wrote:
>> On 11/19/10 23:55 , email@example.com wrote:
>>> will evaluate to true in cases where it should not. A quick fix would be to
>>> compare directly against the CSN of the sessionlog's head:
>> An extended version of this fix, which also ensures that the
>> sessionlog is kept in csn order, is now in head. Please test,
>> syncprov.c revision 1.320.
> Looks good to me. Thank you.
> I discovered this bug while trying to reproduce ITS#6717.
> I've attached a patch to that ITS which appears to fix
> that problem. If you have the time, I'd appreciate some
> feedback on that patch. The issue makes it very inefficient
> to run a slave in refreshOnly mode with a multimaster /
> mirrormode master.
> Best Regards,
The current code is broken.
> Other than the patch I suggested (using the list head's
> CSN value directly), I can think of two other approaches:
> 1) When adding an entry to the sessionlog, check
> if sl_mincsn is empty. If it is, update sl_mincsn
> to the new entry's CSN.
> 2) When initializing the sessionlog, set sl_mincsn
> to the maximum contextCSN value of the underlying
> #2 seems ideal from an efficiency standpoint, although it
> differs from the algorithm the current code appears to be
> intended to implement.
We should have gone with #2. The problem scenario:
1: Provider and consumer in sync, both started fresh, sessionlog is empty.
2: stop consumer
3: write on provider
4: start consumer
Result: the sessionlog is ignored, because the sl_head is newer than the
After the consumer syncs, you can repeat steps 2-4 and see that the sessionlog
is used from then on.
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/