[PATCH][WIP] Make the Samba AD DC multi-process

[Andrew Bartlett]

On Thu, 2016-12-08 at 16:04 +0100, Stefan Metzmacher wrote:
> Am 08.12.2016 um 06:39 schrieb Andrew Bartlett:
> > 
> > Just a quick update on the easier parts:
> > 
> > On Thu, 2016-12-08 at 07:26 +1300, Andrew Bartlett wrote:
> > > 
> > > On Wed, 2016-12-07 at 13:09 +0100, Stefan Metzmacher wrote:
> > > > 
> > > > Hi Andrew,
> > > > 
> > > > > 
> > > > > 
> > > > > Do you have any other comments?  Is the general approach OK?
> > > > > 
> > > > > Can I merge more of the RPC code, like the 'uses handles'
> > > > > declaration?
> > > > 
> > > > Do you have a rebased branch somewhere?
> > 
> > git://git.catalyst.net.nz/samba.git multi-process-samba-ad-dc
> 
> I've pushed the pidl and mgmt change. Can you please
> rebase the conflict resolution should be trivial.

Sure.

> > 
> > > 
> > > > 
> > > > Regarding the are_handles_used please make it an
> > > > uint64_t flags (with DCESRV_IGNORE_INVALID_ASSOC_GROUP)
> > > > and move it to the end of the structure.
> 
> Can we get a DCESRV_IGNORE_INVALID_ASSOC_GROUP
> instead of DCESRV_INTERFACE_FLAGS_HANDLES_USED?

The reason for the existing name is that it really is up to the RPC
server as to if it wants to validate association groups.  Across
ncalrpc, handled in a single process, it certainly could (and should).
 
What the pipe knows, can declare, and is enforced (then handles all
come back NULL) is if it uses handles at all.  I think the
implementation choice of if association groups should be ignored, or
stored in some global on-disk DB, is a property of the rpc_server.

Note that in the new code, just as an LSA association group won't be be
valid on NETLOGON (and ignored safely), a NETLOGON association group
won't be valid on LSA (but will be an error).  If this comes up outside
artificial test-suites, we may have to reconsider our options. 

> And the .c file should set a
> 
> #define DCESRV_INTERFACE_NETLOGON_FLAGS
> DCESRV_IGNORE_INVALID_ASSOC_GROUP

I'm happy to change the define structure, certainly.  That is much less
clumsy and means less pidl changes for the next flag.

> The assoc_group == NULL should not move please use
> the DCESRV_IGNORE_INVALID_ASSOC_GROUP indication on the
> endpoint above the existing check.

I can't - we don't know the endpoint until then. 

> Regarding the schannel change shouldn't we try to remove unused
> records?

We (our team @ Catalyst talked over a number of possible implementation
ideas for this DB) considered that, but it comes with the cost of
adding a timer process, a timestamp, timeout period and coming up with
some way of testing it.  It all seemed like a lot of complexity, and
things that could go wrong, for quite little gain. 

Instead by using the lossy hash, we ensure that the DB can't be
overfilled anyway, and it has very similar semantics to the old
memcache, because the schannel db is CLEAR_IF_FIRST. 

Records are deleted as they are used. 

> More comments tomorrow.

Thanks!

Andrew Bartlett
-- 
Andrew Bartlett                       http://samba.org/~abartlet/
Authentication Developer, Samba Team  http://samba.org
Samba Developer, Catalyst IT          http://catalyst.net.nz/services/samba