Re: [PATCH v4 28/34] qapi: Implement deprecated-output=hide for QMP command results

[Markus Armbruster]

Eric Blake <address@hidden> writes:

> On 3/17/20 6:54 AM, Markus Armbruster wrote:
>> This policy suppresses deprecated bits in output, and thus permits
>> "testing the future".  Implement it for QMP command results.  Example:
>> when QEMU is run with -compat deprecated-output=hide, then
>>
>>      {"execute": "query-cpus-fast"}
>>
>> yields
>>
>>      {"return": [{"thread-id": 9805, "props": {"core-id": 0, "thread-id": 0, 
>> "socket-id": 0}, "qom-path": "/machine/unattached/device[0]", "cpu-index": 
>> 0, "target": "x86_64"}]}
>>
>> instead of
>>
>>      {"return": [{"arch": "x86", "thread-id": 22436, "props": {"core-id": 0, 
>> "thread-id": 0, "socket-id": 0}, "qom-path": 
>> "/machine/unattached/device[0]", "cpu-index": 0, "target": "x86_64"}]}
>>
>> Note the suppression of deprecated member "arch".
>>
>> Signed-off-by: Markus Armbruster <address@hidden>
>> ---
>
>> +++ b/tests/test-qmp-cmds.c
>> @@ -1,4 +1,5 @@
>>   #include "qemu/osdep.h"
>> +#include "qapi/compat-policy.h"
>>   #include "qapi/qmp/qdict.h"
>>   #include "qapi/qmp/qjson.h"
>>   #include "qapi/qmp/qnum.h"
>> @@ -45,12 +46,17 @@ void qmp_user_def_cmd1(UserDefOne * ud1, Error **errp)
>>   {
>>   }
>>   -void qmp_test_features0(FeatureStruct0 *fs0, FeatureStruct1 *fs1,
>> -                       FeatureStruct2 *fs2, FeatureStruct3 *fs3,
>> -                       FeatureStruct4 *fs4, CondFeatureStruct1 *cfs1,
>> -                       CondFeatureStruct2 *cfs2, CondFeatureStruct3 *cfs3,
>> -                       Error **errp)
>> +FeatureStruct1 *qmp_test_features0(bool has_fs0, FeatureStruct0 *fs0,
>> +                                   bool has_fs1, FeatureStruct1 *fs1,
>> +                                   bool has_fs2, FeatureStruct2 *fs2,
>> +                                   bool has_fs3, FeatureStruct3 *fs3,
>> +                                   bool has_fs4, FeatureStruct4 *fs4,
>> +                                   bool has_cfs1, CondFeatureStruct1 *cfs1,
>> +                                   bool has_cfs2, CondFeatureStruct2 *cfs2,
>> +                                   bool has_cfs3, CondFeatureStruct3 *cfs3,
>> +                                   Error **errp)
>>   {
>> +    return g_new(FeatureStruct1, 1);
>
> Should this be using g_new0, rather than random contents?

Accident.  It's not actually used.

>>   }
>>     void qmp_test_command_features1(Error **errp)
>> @@ -271,6 +277,30 @@ static void test_dispatch_cmd_io(void)
>>       qobject_unref(ret3);
>>   }
>>   +static void test_dispatch_cmd_ret_deprecated(void)
>> +{
>> +    const char *cmd = "{ 'execute': 'test-features0' }";
>> +    QDict *ret;
>> +
>> +    memset(&compat_policy, 0, sizeof(compat_policy));
>> +
>> +    /* default accept */
>> +    ret = qobject_to(QDict, do_qmp_dispatch(false, cmd));
>> +    assert(ret && qdict_size(ret) == 1);
>> +    qobject_unref(ret);
>> +
>> +    compat_policy.has_deprecated_output = true;
>> +    compat_policy.deprecated_output = COMPAT_POLICY_OUTPUT_ACCEPT;
>
> Of course, if we ever enable defaults in QAPI, we can get rid of
> has_deprecated_output by recording proper defaults for bools.  But
> that's a different project ;)

Yes.  The has_FOO have been annoying me since forever.  I just never get
around to doing anything about it.

>> +    ret = qobject_to(QDict, do_qmp_dispatch(false, cmd));
>> +    assert(ret && qdict_size(ret) == 1);
>> +    qobject_unref(ret);
>> +
>> +    compat_policy.deprecated_output = COMPAT_POLICY_OUTPUT_HIDE;
>> +    ret = qobject_to(QDict, do_qmp_dispatch(false, cmd));
>> +    assert(ret && qdict_size(ret) == 0);
>> +    qobject_unref(ret);
>> +}
>> +
>
> Otherwise,
> Reviewed-by: Eric Blake <address@hidden>

Thanks!