libcli/auth: avoid using transactions a chainlock is enough

[Andrew Bartlett]

On Thu, 2013-03-28 at 14:53 +0100, Volker Lendecke wrote:
> The branch, master has been updated
>        via  adbe6cb libcli/auth: avoid using transactions a chainlock is enough
>       from  40d783c Call smb_panic when we try to exit the server uncleanly. This gives us the normal traceback and memory dump, but also runs the normal panic action.
> 
> http://gitweb.samba.org/?p=samba.git;a=shortlog;h=master
> 
> 
> - Log -----------------------------------------------------------------
> commit adbe6cba005a2060b0f641e91b500574f4637a36
> Author: Stefan Metzmacher <metze at samba.org>
> Date:   Wed Mar 27 08:43:18 2013 +0100
> 
>     libcli/auth: avoid using transactions a chainlock is enough
>     
>     We're just writting a single record into a CLEAR_IF_FIRST|TDB_NOSYNC
>     tdb.
>     
>     We just need to make sure we lock the record between reading and writting.
>     
>     Signed-off-by: Stefan Metzmacher <metze at samba.org>
>     Reviewed-by: Volker Lendecke <vl at samba.org>
>     
>     Autobuild-User(master): Volker Lendecke <vl at samba.org>
>     Autobuild-Date(master): Thu Mar 28 14:52:14 CET 2013 on sn-devel-104

I've been thinking about how we got here, and so thought I would note
down what I recall of the history.

This code started using schannel.ldb, and ldb does not have per-record
locks, just transactions, and was persistent at that stage.

As we moved the netlogon secure channel code in common, a tdb
re-implementation was developed, and then became the sole
implementation.  It was a direct translation, so was transaction-based
too. 

It therefore seems reasonable that we move to just using chainlocks,
just as we do for any other database (many far more critical than this
one). 

Andrew Bartlett

-- 
Andrew Bartlett                                http://samba.org/~abartlet/
Authentication Developer, Samba Team           http://samba.org