[ovs-dev] [PATCH] ovs-xapi-sync: Cache the bridge-id value for non nicira-bridge-id too.

[Ben Pfaff]

On Mon, Jun 17, 2013 at 01:25:01AM -0700, Gurucharan Shetty wrote:
> Currently we connect to xapi in case there are multiple
> external_ids:xs-network-uuids to get the single bridge id everytime
> we have a change in the database for all the interested columns in
> ovs-xapi-sync. The xs-network-uuids value can also change whenever
> new VLANs are added or deleted, which is a common use case. The
> disadvantage with this approach is that we query XAPI more often
> and set the bridge-id as "" if we don't get a valid response for
> our query. This can take down the logical connectivity for all the
> VMs on that xenserver.
> 
> Instead of looking at the PIF records for all the xs-network-uuids,
> we can instead just look at the xapi record which has the same bridge
> name as the OVS bridge name and then cache its uuid. This value will
> hold true till the OVS bridge is recreated in which case we will re-read
> the value.
> 
> Signed-off-by: Gurucharan Shetty <gshetty at nicira.com>

I think that the tolerance for XAPI failures is incomplete, because we
call update_fail_mode(), update_in_band_mgmt(), and get_bridge_id()
only once for a bridge, even if XAPI fails to respond on the first
attempt.

I am not sure why the set_external_id() call splits bridge_id on ';'.
Can bridge_id contain ';' at this point?

I am not sure why bridge_id and bridge_id_cache are different
variables.  When do they have different values?

Thanks,

Ben.