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

[Wei Liu <wei.liu2@xxxxxxxxxx>]

Cc Julien

These are small bug fixes that can be safely committed, IMHO.

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
> 

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