[sheepdog] master_idx question

[MORITA Kazutaka]

At Fri, 20 Jul 2012 06:13:57 +0000,
Dietmar Maurer wrote:
> 
> > Master is internal concept known by the code, which is used to manage the
> > node join (check if it is allowed in).
> > 
> > Master transfer only happens when we try to boot up a previously crashed
> > cluster which might has different epoch, so mastership is transferred to
> > highest epoch node.
> > 
> > For admins, he isn't supposed to know which is the master.
> 
> I consider myself as developer, and I want to know the master id if there is a master.
> Why don't you simple set master_idx (if there is a master)?

Whether there is a master is up to the cluster driver, and currently
there is no way to find a master node from the sheep core code.
Although current all drivers need a master to check joining nodes, we
can also consider a completely fully symmetric cluster driver.

Mastership transfer is used for finding the node who has the latest
epoch, and a different concept from the master node.  Probably, we
should change the name.

Thanks,

Kazutaka