Re: [Xen-devel] [PATCH 0/5] Towards a restartable oxenstored

[Julien Grall <julien.grall@xxxxxxx>]

Hi Wei,

On 10/04/17 10:47, Wei Liu wrote:
> Cc Julien
>
> These are small bug fixes that can be safely committed, IMHO.
Release-acked-by: Julien Grall <julien.grall@xxxxxxx>

Cheers,

> On Fri, Apr 07, 2017 at 02:27:17PM +0100, Jonathan Davies wrote:
> > In order to make oxenstored restartable, we need to save internal state
> > to a file on exit and restore from this file on startup.
> >
> > Much of the infrastructure for making oxenstored restartable already
> > existed, but a handful of bugs prevented it from working.
> >
> > After these patches I can do the following:
> >
> >     # xenstore-write foo bar
> >     # xenstore-read foo
> >     bar
> >     # xenstore-ls -f -p | sort > contents.before
> >     # killall oxenstored
> >     # ./oxenstored --restart
> >     # xenstore-ls -f -p | sort > contents.after
> >     # diff contents.before contents.after
> >     # xenstore-read foo
> >     bar
> >
> > ... and I can do similar kinds of activity in a guest across the
> > restart.
> >
> > Note that clients of local socket connections will get EPIPE or similar
> > when oxenstored terminates. Hence these clients need to handle this
> > gracefully, e.g. by attempting to reconnect, if they wish to tolerate
> > xenstored restarts.
> >
> > With these patches, the state saved on exit contains information about
> > inter-domain connections and active watches, and the contents of the
> > store. Some internal state is not currently preserved over a restart:
> >   1. quota usage info
> >   2. partially-read and already-queued packets from rings
> >   3. recent transaction history
> >
> > Items 1 and 2 are probably needed for this to be considered fully
> > functional, so fixes for them should follow. But the bugfixes in this
> > series already represent a worthwhile improvement.
> >
> > Jonathan Davies (5):
> >   oxenstored: initialise logging earlier
> >   oxenstored: avoid leading slash in paths in saved store state
> >   oxenstored: save remote evtchn port, not local port
> >   oxenstored: improve event-channel binding logging
> >   oxenstored: make --restart option best-effort
> >
> >  tools/ocaml/xenstored/domain.ml    |  4 ++--
> >  tools/ocaml/xenstored/store.ml     |  8 +++++++-
> >  tools/ocaml/xenstored/xenstored.ml | 10 ++++++----
> >  3 files changed, 15 insertions(+), 7 deletions(-)
> >
> > --
> > 2.7.4
--
Julien Grall

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