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Re: [Qemu-devel] [PATCH] Hack qmp.py to support reading a JSON multi-lin
From: |
Luiz Capitulino |
Subject: |
Re: [Qemu-devel] [PATCH] Hack qmp.py to support reading a JSON multi-line response |
Date: |
Mon, 20 Aug 2012 15:03:11 -0300 |
On Mon, 20 Aug 2012 15:01:37 +0100
"Daniel P. Berrange" <address@hidden> wrote:
> From: "Daniel P. Berrange" <address@hidden>
>
> The qmp-shell code assumes the JSON response is only on a single
> line. If the QEMU monitor is configured in "pretty print" mode
> the JSON response can be multi-line. The basic Python JSON APIs
> do not appear to support a streaming mode, so the simple hack
> here is to try parsing a line, and if it fails, then read another
> line, append it, and try parsing again. Keep reading lines until
> we can successfully parse
>
> Signed-off-by: Daniel P. Berrange <address@hidden>
> ---
> QMP/qmp.py | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/QMP/qmp.py b/QMP/qmp.py
> index 36ecc1d..464a01a 100644
> --- a/QMP/qmp.py
> +++ b/QMP/qmp.py
> @@ -61,10 +61,18 @@ class QEMUMonitorProtocol:
>
> def __json_read(self, only_event=False):
> while True:
> - data = self.__sockfile.readline()
> - if not data:
> - return
> - resp = json.loads(data)
> + data = ""
> + while True:
> + moredata = self.__sockfile.readline()
> + if not moredata:
> + return
> + data = data + moredata
> + try:
> + resp = json.loads(data)
> + break
> + except ValueError:
> + pass
> +
I'm reluctant about this, because it makes it impossible to detect bad
json from qemu (not that qmp-shell handles this gracefully today).
At the same time I can't think of anything simpler than your hack. What
about calling json.loads() when closing } matches the number of opening ones?
QMP responses are always dictionaries.
> if 'event' in resp:
> self.__events.append(resp)
> if not only_event: