From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=49551 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Q4GE1-0000zF-2k for qemu-devel@nongnu.org; Mon, 28 Mar 2011 13:27:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Q4GDz-0004GQ-Hs for qemu-devel@nongnu.org; Mon, 28 Mar 2011 13:27:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:31582) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Q4GDz-0004GB-5T for qemu-devel@nongnu.org; Mon, 28 Mar 2011 13:27:31 -0400 Date: Mon, 28 Mar 2011 14:27:22 -0300 From: Luiz Capitulino Subject: Re: [Qemu-devel] Re: [RFC][PATCH v1 05/12] qapi: fix handling for null-return async callbacks Message-ID: <20110328142722.468815c1@doriath> In-Reply-To: <4D90C339.9040204@codemonkey.ws> References: <1301082479-4058-1-git-send-email-mdroth@linux.vnet.ibm.com> <1301082479-4058-6-git-send-email-mdroth@linux.vnet.ibm.com> <4D8D0788.7070700@us.ibm.com> <20110328134747.5c9fbc8e@doriath> <4D90BEDC.6050207@us.ibm.com> <20110328140651.13f10e43@doriath> <4D90C339.9040204@codemonkey.ws> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Jes.Sorensen@redhat.com, agl@linux.vnet.ibm.com, Michael Roth , qemu-devel@nongnu.org On Mon, 28 Mar 2011 12:19:53 -0500 Anthony Liguori wrote: > On 03/28/2011 12:06 PM, Luiz Capitulino wrote: > > On Mon, 28 Mar 2011 12:01:16 -0500 > > Anthony Liguori wrote: > > > >> On 03/28/2011 11:47 AM, Luiz Capitulino wrote: > >>> On Fri, 25 Mar 2011 16:22:16 -0500 > >>> Anthony Liguori wrote: > >>> > >>>> On 03/25/2011 02:47 PM, Michael Roth wrote: > >>>>> Async commands like 'guest-ping' have NULL retvals. Handle these by > >>>>> inserting an empty dictionary in the response's "return" field. > >>>>> > >>>>> Signed-off-by: Michael Roth > >>>>> --- > >>>>> qmp-core.c | 5 ++++- > >>>>> 1 files changed, 4 insertions(+), 1 deletions(-) > >>>>> > >>>>> diff --git a/qmp-core.c b/qmp-core.c > >>>>> index e33f7a4..9f3d182 100644 > >>>>> --- a/qmp-core.c > >>>>> +++ b/qmp-core.c > >>>>> @@ -922,9 +922,12 @@ void qmp_async_complete_command(QmpCommandState *cmd, QObject *retval, Error *er > >>>>> rsp = qdict_new(); > >>>>> if (err) { > >>>>> qdict_put_obj(rsp, "error", error_get_qobject(err)); > >>>>> - } else { > >>>>> + } else if (retval) { > >>>>> qobject_incref(retval); > >>>>> qdict_put_obj(rsp, "return", retval); > >>>>> + } else { > >>>>> + /* add empty "return" dict, this is the standard for NULL returns */ > >>>>> + qdict_put_obj(rsp, "return", QOBJECT(qdict_new())); > >>>> Luiz, I know we decided to return empty dicts because it lets us extend > >>>> things better, but did we want to rule out the use of a 'null' return > >>>> value entirely? > >>> For asynchronous commands you mean? No we didn't. > >> No, nothing to do with asynchronous commands. Just in general. > >> > >> The question is, is it legal for a command to return 'null'. It's > >> certain valid JSON, but is it valid QMP? > > No, it's not valid. > > Do we have a reason for this? We had to make a choice. We chose the current 'return' response. Iirc, one of my first suggestions was "{ 'return': 'null' }" but you refused to have a 'null' object, our parser doesn't even support it afaik. But what's the problem with the current format?