[PATCH] Add CTDB_REQ_TUNNEL for new protocol

Martin Schwenke martin at meltin.net
Thu Oct 5 11:00:27 UTC 2017


On Thu, 5 Oct 2017 12:51:26 +0200, Volker Lendecke
<Volker.Lendecke at SerNet.DE> wrote:

> On Thu, Oct 05, 2017 at 09:47:38PM +1100, Martin Schwenke wrote:
> > Hi Volker,
> > 
> > In case Amitay is completely gone for the evening... he will probably
> > explain more eloquently...  :-)
> > 
> > On Thu, 5 Oct 2017 12:17:40 +0200, Volker Lendecke via samba-technical
> > <samba-technical at lists.samba.org> wrote:
> >   
> > > On Thu, Oct 05, 2017 at 03:59:17PM +1100, Amitay Isaacs via samba-technical wrote:  
>  [...]  
> > > 
> > > This looks really interesting. Question -- what *is* a tunnel?  
> > 
> > Tunnelling provides a new low-level packet type.  A tunnel is then a
> > bunch of ctdbd processes registering an common tunnel identifier that
> > allows Unix-domain-socket-connected daemons on different nodes to
> > communicate with each other. This means the new daemons can have
> > new, independent protocols and use ctdbd as a transport by wrapping
> > their packets in tunnel packets.
> > 
> > Later, if we want to, we can re-wire the communication between these
> > daemons using some other transport (e.g. proxy).  However, for now we
> > just use ctdbd as the transport because it exists and this
> > implementation is cheap.  :-)  
> 
> Our messages are sequenced and reliable. Why not use those?

I'm certainly too tired to remember if there is a good reason for
that...  :-)

By the way, the above explanation was bad (need sleep). Semi-obviously
the new daemons register their common tunnel ID with ctdbd and then use
the tunnel API to send their packets to other nodes.

I'll discuss the tunnelling versus messages with Amitay tomorrow unless
he responds before then...

peace & happiness,
martin



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