Re: [RFC PATCH 8/8] migration/dirtyrate: Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function

[Eric Blake <eblake@redhat.com>]

On 7/24/20 10:11 PM, Chuan Zheng wrote:
> From: Zheng Chuan <zhengchuan@huawei.com>
> 
> Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function which could be called
> by libvirt api.
> 
> Signed-off-by: Zheng Chuan <zhengchuan@huawei.com>
> Signed-off-by: YanYing Zhang <ann.zhuangyanying@huawei.com>

> +##
> +{ 'command': 'get_dirty_rate', 'returns': 'int64' }
> diff --git a/qapi/pragma.json b/qapi/pragma.json
> index cffae27..ecd294b 100644
> --- a/qapi/pragma.json
> +++ b/qapi/pragma.json
> @@ -10,7 +10,8 @@
>           'query-migrate-cache-size',
>           'query-tpm-models',
>           'query-tpm-types',
> -        'ringbuf-read' ],
> +        'ringbuf-read',
> +        'get_dirty_rate' ],

Nack.  You should not have to change the whitelist; this is evidence 
that your command is returning the wrong type.  Instead, you should be 
using:

{ 'command': 'get-dirty-rate', 'returns': { 'rate': 'int64' } }

and populating a struct, so that if we ever want to return more than 
just a single rate, we can extend the command in-place by adding to the 
struct.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org