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From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Jonathan Davies <jonathan.davies@citrix.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	Jon Ludlam <jonathan.ludlam@citrix.com>,
	Dave Scott <dave@recoil.org>,
	Euan Harris <euan.harris@citrix.com>,
	xen-devel@lists.xenproject.org
Subject: Re: [PATCH 3/7] oxenstored: refactor request processing
Date: Tue, 29 Mar 2016 08:45:07 -0400	[thread overview]
Message-ID: <56FA78D3.4070400@oracle.com> (raw)
In-Reply-To: <20160329090829.GE3316@citrix.com>

On 03/29/2016 05:08 AM, 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.

Yes, this fixes it, thanks.

> What's the policy here -- is there a defined version of the OCaml compiler which
> tools/ocaml needs to be able to compile with?

Not to answer this question directly but more as an FYI --- this version 
of ocaml is found on Oracle Linux 6.2, which AFAIK is actively supported.

-boris


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  reply	other threads:[~2016-03-29 12:45 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 [this message]
2016-03-29 16:38           ` Wei Liu
2016-03-29 19:41             ` David Scott
2016-03-30 15:46               ` Jonathan Davies
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

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