Re: [Qemu-devel] [PATCH RFC v5 30/32] qapi: New QMP command query-qmp-schema for QMP introspection

[Eric Blake]

On 09/07/2015 04:16 AM, Markus Armbruster wrote:
> qapi/introspect.json defines the introspection schema.  It's designed
> for QMP introspection, but should do for similar uses, such as QGA.
> 
> The introspection schema does not reflect all the rules and
> restrictions that apply to QAPI schemata.  A valid QAPI schema has an
> introspection value conforming to the introspection schema, but the
> converse is not true.
> 

>   Right now qmp_query_schema() sends the string literal computed by

Should this be spelled qmp_query_qmp_schema()? [1]

>   qmp-introspect.py.  To compute sub-schema at run time, we'd have to
>   duplicate parts of qapi-introspect.py in C.  Unattractive.


> Signed-off-by: Markus Armbruster <address@hidden>
> ---

Changes I noticed from v4:
Simple unions work now.
Documentation improvements.
Rename to query-qmp-schema (except perhaps where I marked [1], but I'm
not too fussed with either spelling).
Use of self._member for internal fields.

Reviewed-by: Eric Blake <address@hidden>

> 
> --- a/monitor.c
> +++ b/monitor.c
> @@ -74,6 +74,7 @@
>  #include "block/qapi.h"
>  #include "qapi/qmp-event.h"
>  #include "qapi-event.h"
> +#include "qmp-introspect.h"
>  #include "sysemu/block-backend.h"
>  
>  /* for hmp_info_irq/pic */
> @@ -928,6 +929,20 @@ EventInfoList *qmp_query_events(Error **errp)
>      return ev_list;
>  }
>  
> +/*
> + * Minor hack: generated marshalling suppressed for this command
> + * ('gen': false in the schema) so we can parse the JSON string
> + * directly into QObject instead of first parsing it with
> + * visit_type_SchemaInfoList() into a SchemaInfoList, then marshal it
> + * to QObject with generated output marshallers, every time.  Instead,
> + * we do it in test-qmp-input-visitor.c, just to make sure
> + * qapi-introspect.py's output actually conforms to the schema.
> + */
> +static void qmp_query_schema(QDict *qdict, QObject **ret_data, Error **errp)

[1]

> +++ b/qmp-commands.hx
> @@ -2193,6 +2193,23 @@ EQMP
>      },
>  
>  SQMP
> +query-qmp-schema
> +----------------
> +
> +Return the QMP wire schema.  The returned value is a json-array of
> +named schema entities.  Entities are commands, events and various
> +types.  See docs/qapi-code-gen.txt for information on their structure
> +and intended use.
> +
> +EQMP
> +
> +    {
> +        .name       = "query-qmp-schema",
> +        .args_type  = "",
> +        .mhandler.cmd_new = qmp_query_schema,

[1] qmp_query_qmp_schema might match naming conventions better.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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