From: Jonathan Davies <jonathan.davies@citrix.com>
To: David Scott <dave@recoil.org>
Cc: Wei Liu <wei.liu2@citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Jon Ludlam <jonathan.ludlam@citrix.com>,
Euan Harris <euan.harris@citrix.com>,
xen-devel@lists.xenproject.org,
Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH 3/7] oxenstored: refactor request processing
Date: Wed, 30 Mar 2016 16:46:58 +0100 [thread overview]
Message-ID: <20160330154658.GF3316@citrix.com> (raw)
In-Reply-To: <7516EF85-27A6-4A86-BEAE-1B7090B31BC3@recoil.org>
On Tue, Mar 29, 2016 at 08:41:54PM +0100, David Scott wrote:
>
> > On 29 Mar 2016, at 17:38, Wei Liu <wei.liu2@citrix.com> wrote:
> >
> > On Tue, Mar 29, 2016 at 10:08:30AM +0100, Jonathan Davies wrote:
> >> On Thu, Mar 24, 2016 at 07:57:30PM -0400, Boris Ostrovsky wrote:
> >>> On 03/24/2016 06:49 PM, Andrew Cooper wrote:
> >>>> On 24/03/2016 22:22, Boris Ostrovsky wrote:
> >>>>> On 03/17/2016 01:51 PM, Jonathan Davies wrote:
> >>>>>> Encapsulate the request in a record that is passed from do_input to
> >>>>>> process_packet and input_handle_error.
> >>>>>>
> >>>>>> This will be helpful when keeping track of the requests made as part
> >>>>>> of a
> >>>>>> transaction.
> >>>>>>
> >>>>>> Signed-off-by: Jonathan Davies <jonathan.davies@citrix.com>
> >>>>>> Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
> >>>>>> Reviewed-by: Jon Ludlam <jonathan.ludlam@citrix.com>
> >>>>>> Reviewed-by: Euan Harris <euan.harris@citrix.com>
> >>>>>> ---
> >>>>>> tools/ocaml/xenstored/process.ml | 15 ++++++++++-----
> >>>>>> 1 file changed, 10 insertions(+), 5 deletions(-)
> >>>>>>
> >>>>>> diff --git a/tools/ocaml/xenstored/process.ml
> >>>>>> b/tools/ocaml/xenstored/process.ml
> >>>>>> index 7a73669..c92bec7 100644
> >>>>>> --- a/tools/ocaml/xenstored/process.ml
> >>>>>> +++ b/tools/ocaml/xenstored/process.ml
> >>>>>> @@ -344,11 +344,11 @@ let function_of_type ty =
> >>>>>> | Xenbus.Xb.Op.Invalid -> reply_ack do_error
> >>>>>> | _ -> reply_ack do_error
> >>>>>> -let input_handle_error ~cons ~doms ~fct ~ty ~con ~t ~rid ~data =
> >>>>>> +let input_handle_error ~cons ~doms ~fct ~con ~t ~req =
> >>>>>> let reply_error e =
> >>>>>> Packet.Error e in
> >>>>>> try
> >>>>>> - fct con t doms cons data
> >>>>>> + fct con t doms cons req.Packet.data
> >>>>>> with
> >>>>>> | Define.Invalid_path -> reply_error "EINVAL"
> >>>>>> | Define.Already_exist -> reply_error "EEXIST"
> >>>>>> @@ -370,7 +370,10 @@ let input_handle_error ~cons ~doms ~fct ~ty ~con
> >>>>>> ~t ~rid ~data =
> >>>>>> (**
> >>>>>> * Nothrow guarantee.
> >>>>>> *)
> >>>>>> -let process_packet ~store ~cons ~doms ~con ~tid ~rid ~ty ~data =
> >>>>>> +let process_packet ~store ~cons ~doms ~con ~req =
> >>>>>> + let ty = req.Packet.ty in
> >>>>>> + let tid = req.Packet.tid in
> >>>>>> + let rid = req.Packet.rid in
> >>>>>> try
> >>>>>> let fct = function_of_type ty in
> >>>>>> let t =
> >>>>>> @@ -379,7 +382,7 @@ let process_packet ~store ~cons ~doms ~con ~tid
> >>>>>> ~rid ~ty ~data =
> >>>>>> else
> >>>>>> Connection.get_transaction con tid
> >>>>>> in
> >>>>>> - let response = input_handle_error ~cons ~doms ~fct ~ty ~con
> >>>>>> ~t ~rid ~data in
> >>>>>> + let response = input_handle_error ~cons ~doms ~fct ~con ~t
> >>>>>> ~req in
> >>>>>> (* Put the response on the wire *)
> >>>>>> send_response ty con t rid response
> >>>>>> @@ -412,11 +415,13 @@ let do_input store cons doms con =
> >>>>>> if newpacket then (
> >>>>>> let packet = Connection.pop_in con in
> >>>>>> let tid, rid, ty, data = Xenbus.Xb.Packet.unpack packet in
> >>>>>> + let req = {Packet.tid; Packet.rid; Packet.ty; Packet.data} in
> >>>>>> +
> >>>>> I think this change breaks the build with older ocaml versions:
> >>>>>
> >>>>> root@haswell> ocamlopt -v
> >>>>> The OCaml native-code compiler, version 4.00.1
> >>>>> Standard library directory: /usr/lib64/ocaml
> >>>>> root@haswell> ocamlopt -g -ccopt " " -dtypes -I
> >>>>> /root/tmp/xen/tools/ocaml/xenstored/../libs/xb -I
> >>>>> /root/tmp/xen/tools/ocaml/xenstored/../libs/mmap -I
> >>>>> /root/tmp/xen/tools/ocaml/xenstored/../libs/xc -I
> >>>>> /root/tmp/xen/tools/ocaml/xenstored/../libs/eventchn -cc gcc -w F
> >>>>> -warn-error F -c -o process.cmx process.ml
> >>>>> root@haswell>
> >>>>>
> >>>>>
> >>>>> root@ovs104> ocamlopt -v
> >>>>> The Objective Caml native-code compiler, version 3.11.2
> >>>>> Standard library directory: /usr/lib64/ocaml
> >>>>> root@ovs104> ocamlopt -g -ccopt " " -dtypes -I
> >>>>> /root/tmp/xen/tools/ocaml/xenstored/../libs/xb -I
> >>>>> /root/tmp/xen/tools/ocaml/xenstored/../libs/mmap -I
> >>>>> /root/tmp/xen/tools/ocaml/xenstored/../libs/xc -I
> >>>>> /root/tmp/xen/tools/ocaml/xenstored/../libs/eventchn -cc gcc -w F
> >>>>> -warn-error F -c -o process.cmx process.ml
> >>>>> File "process.ml", line 487, characters 23-24:
> >>>>> Error: Syntax error
> >>>>> root@ovs104>
> >>>>>
> >>>>> I don't know much about ocaml (OK, I know *nothing* about ocaml) so I
> >>>>> can't say what exactly might be wrong.
> >>>> Could you perhaps try this instead?
> >>>>
> >>>> let req = {tid = Packet.tid; rid = Packet.rid; ty = Packet.ty; data =
> >>>> Packet.data} in
> >>>>
> >>>> It is most likely that the older version of Ocaml can't infer the order
> >>>> of fields.
> >>>>
> >>>> ~Andrew
> >>>
> >>>
> >>> No, it now gives me "Error: Unbound record field label tid"
> >>>
> >>> -boris
> >>
> >> Andrew's guess was close, but the wrong way around -- please could you try the
> >> following with the older compiler?
> >>
> >> let req = {Packet.tid=tid; Packet.rid=rid; Packet.ty=ty; Packet.data=data} in
> >>
> >> I was using a syntactic feature of OCaml called 'field punning' which is
> >> generally considered good practice and makes for more readable code. It looks
> >> like this feature was introduced in OCaml 3.12.0 (dating from 2010), which is
> >> consistent with Boris' findings.
> >>
> >> What's the policy here -- is there a defined version of the OCaml compiler which
> >> tools/ocaml needs to be able to compile with?
> >
> > It is not explicitly listed in README or INSTALL. The ocaml tools
> > maintainer (Dave in this case) is welcome to provide the minimum version
> > required.
> >
> > Meanwhile, I don't think we should break existing build without pinning
> > down the minimum required version first, so we should fix Boris's
> > breakage. The fix seems simple enough anyway.
>
> It looks like the fix is small and easy — I think this is good for now.
>
> Let’s postpone requiring a later OCaml version until we really need a feature only present in a later version. I suspect this will happen eventually, probably when we try to add a dependency (e.g. from the Mirage world) which requires 4.02+.
OK; sounds sensible.
Since the original patch has already been committed to staging, I presume you'd
like me to formally submit a standalone patch that fixes this issue. I will post
it separately.
If I'm wrong and you'd like me to post a v2 of the whole series, let me know.
Thanks,
Jonathan
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel
next prev parent reply other threads:[~2016-03-30 15:55 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-17 17:51 [PATCH 0/7] oxenstored: improve transaction conflict handling Jonathan Davies
2016-03-17 17:51 ` [PATCH 1/7] oxenstored: refactor putting response on wire Jonathan Davies
2016-03-17 17:51 ` [PATCH 2/7] oxenstored: remove some unused parameters Jonathan Davies
2016-03-17 17:51 ` [PATCH 3/7] oxenstored: refactor request processing Jonathan Davies
2016-03-24 22:22 ` Boris Ostrovsky
2016-03-24 22:49 ` Andrew Cooper
2016-03-24 23:57 ` Boris Ostrovsky
2016-03-29 9:08 ` Jonathan Davies
2016-03-29 12:45 ` Boris Ostrovsky
2016-03-29 16:38 ` Wei Liu
2016-03-29 19:41 ` David Scott
2016-03-30 15:46 ` Jonathan Davies [this message]
2016-03-30 15:53 ` Wei Liu
2016-03-17 17:51 ` [PATCH 4/7] oxenstored: keep track of each transaction's operations Jonathan Davies
2016-03-17 17:51 ` [PATCH 5/7] oxenstored: move functions that process simple operations Jonathan Davies
2016-03-17 17:51 ` [PATCH 6/7] oxenstored: replay transaction upon conflict Jonathan Davies
2016-03-17 17:51 ` [PATCH 7/7] oxenstored: log request and response during transaction replay Jonathan Davies
2016-03-18 14:33 ` [PATCH 0/7] oxenstored: improve transaction conflict handling Konrad Rzeszutek Wilk
2016-03-18 16:21 ` Jonathan Davies
2016-03-18 16:36 ` Wei Liu
2016-03-19 11:30 ` David Scott
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160330154658.GF3316@citrix.com \
--to=jonathan.davies@citrix.com \
--cc=andrew.cooper3@citrix.com \
--cc=boris.ostrovsky@oracle.com \
--cc=dave@recoil.org \
--cc=euan.harris@citrix.com \
--cc=jonathan.ludlam@citrix.com \
--cc=wei.liu2@citrix.com \
--cc=xen-devel@lists.xenproject.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).