Re: [Qemu-devel] [PATCH v3 43/43] qobject: move dump_qobject() from block/ to qobject/

[Max Reitz]

On 2017-06-08 19:43, Markus Armbruster wrote:
> Marc-André Lureau <address@hidden> writes:
> 
>> The dump functions could be generally useful for any qobject user or for
>> debugging etc.
>>
>> Signed-off-by: Marc-André Lureau <address@hidden>
>> ---
>>  include/qapi/qmp/qdict.h   |  2 ++
>>  include/qapi/qmp/qlist.h   |  2 ++
>>  include/qapi/qmp/qobject.h |  7 ++++
>>  block/qapi.c               | 90 
>> +++-------------------------------------------
>>  qobject/qdict.c            | 30 ++++++++++++++++
>>  qobject/qlist.c            | 23 ++++++++++++
>>  qobject/qobject.c          | 19 ++++++++++
>>  tests/check-qjson.c        | 19 ++++++++++
>>  8 files changed, 106 insertions(+), 86 deletions(-)
>>
>> diff --git a/include/qapi/qmp/qdict.h b/include/qapi/qmp/qdict.h
>> index 8c7c2b762b..1ef3bc8cda 100644
>> --- a/include/qapi/qmp/qdict.h
>> +++ b/include/qapi/qmp/qdict.h
>> @@ -91,4 +91,6 @@ QObject *qdict_crumple(const QDict *src, Error **errp);
>>  
>>  void qdict_join(QDict *dest, QDict *src, bool overwrite);
>>  
>> +char *qdict_to_string(QDict *dict, int indent);
>> +
>>  #endif /* QDICT_H */
>> diff --git a/include/qapi/qmp/qlist.h b/include/qapi/qmp/qlist.h
>> index c4b5fdad9b..c93ac3e15b 100644
>> --- a/include/qapi/qmp/qlist.h
>> +++ b/include/qapi/qmp/qlist.h
>> @@ -60,6 +60,8 @@ size_t qlist_size(const QList *qlist);
>>  QList *qobject_to_qlist(const QObject *obj);
>>  void qlist_destroy_obj(QObject *obj);
>>  
>> +char *qlist_to_string(QList *list, int indent);
>> +
>>  static inline const QListEntry *qlist_first(const QList *qlist)
>>  {
>>      return QTAILQ_FIRST(&qlist->head);
>> diff --git a/include/qapi/qmp/qobject.h b/include/qapi/qmp/qobject.h
>> index b8ddbca405..0d6ae5048a 100644
>> --- a/include/qapi/qmp/qobject.h
>> +++ b/include/qapi/qmp/qobject.h
>> @@ -101,4 +101,11 @@ static inline QObject *qnull(void)
>>      return &qnull_;
>>  }
>>  
>> +char *qobject_to_string_indent(QObject *obj, int indent);
>> +
>> +static inline char *qobject_to_string(QObject *obj)
>> +{
>> +    return qobject_to_string_indent(obj, 0);
>> +}
>> +
>>  #endif /* QOBJECT_H */
>> diff --git a/block/qapi.c b/block/qapi.c
>> index 2050df29e4..9b7d42e50a 100644
>> --- a/block/qapi.c
>> +++ b/block/qapi.c
>> @@ -586,101 +586,19 @@ void bdrv_snapshot_dump(fprintf_function 
>> func_fprintf, void *f,
>>      }
>>  }
>>  
>> -static void dump_qdict(fprintf_function func_fprintf, void *f, int 
>> indentation,
>> -                       QDict *dict);
>> -static void dump_qlist(fprintf_function func_fprintf, void *f, int 
>> indentation,
>> -                       QList *list);
>> -
>> -static void dump_qobject(fprintf_function func_fprintf, void *f,
>> -                         int comp_indent, QObject *obj)
>> -{
>> -    switch (qobject_type(obj)) {
>> -        case QTYPE_QNUM: {
>> -            QNum *value = qobject_to_qnum(obj);
>> -            char *tmp = qnum_to_string(value);
>> -            func_fprintf(f, "%s", tmp);
>> -            g_free(tmp);
>> -            break;
>> -        }
>> -        case QTYPE_QSTRING: {
>> -            QString *value = qobject_to_qstring(obj);
>> -            func_fprintf(f, "%s", qstring_get_str(value));
>> -            break;
>> -        }
>> -        case QTYPE_QDICT: {
>> -            QDict *value = qobject_to_qdict(obj);
>> -            dump_qdict(func_fprintf, f, comp_indent, value);
>> -            break;
>> -        }
>> -        case QTYPE_QLIST: {
>> -            QList *value = qobject_to_qlist(obj);
>> -            dump_qlist(func_fprintf, f, comp_indent, value);
>> -            break;
>> -        }
>> -        case QTYPE_QBOOL: {
>> -            QBool *value = qobject_to_qbool(obj);
>> -            func_fprintf(f, "%s", qbool_get_bool(value) ? "true" : "false");
>> -            break;
>> -        }
>> -        default:
>> -            abort();
>> -    }
>> -}
>> -
>> -static void dump_qlist(fprintf_function func_fprintf, void *f, int 
>> indentation,
>> -                       QList *list)
>> -{
>> -    const QListEntry *entry;
>> -    int i = 0;
>> -
>> -    for (entry = qlist_first(list); entry; entry = qlist_next(entry), i++) {
>> -        QType type = qobject_type(entry->value);
>> -        bool composite = (type == QTYPE_QDICT || type == QTYPE_QLIST);
>> -        func_fprintf(f, "%*s[%i]:%c", indentation * 4, "", i,
>> -                     composite ? '\n' : ' ');
>> -        dump_qobject(func_fprintf, f, indentation + 1, entry->value);
>> -        if (!composite) {
>> -            func_fprintf(f, "\n");
>> -        }
>> -    }
>> -}
>> -
>> -static void dump_qdict(fprintf_function func_fprintf, void *f, int 
>> indentation,
>> -                       QDict *dict)
>> -{
>> -    const QDictEntry *entry;
>> -
>> -    for (entry = qdict_first(dict); entry; entry = qdict_next(dict, entry)) 
>> {
>> -        QType type = qobject_type(entry->value);
>> -        bool composite = (type == QTYPE_QDICT || type == QTYPE_QLIST);
>> -        char *key = g_malloc(strlen(entry->key) + 1);
>> -        int i;
>> -
>> -        /* replace dashes with spaces in key (variable) names */
>> -        for (i = 0; entry->key[i]; i++) {
>> -            key[i] = entry->key[i] == '-' ? ' ' : entry->key[i];
>> -        }
>> -        key[i] = 0;
>> -        func_fprintf(f, "%*s%s:%c", indentation * 4, "", key,
>> -                     composite ? '\n' : ' ');
>> -        dump_qobject(func_fprintf, f, indentation + 1, entry->value);
>> -        if (!composite) {
>> -            func_fprintf(f, "\n");
>> -        }
>> -        g_free(key);
>> -    }
>> -}
>> -
>>  void bdrv_image_info_specific_dump(fprintf_function func_fprintf, void *f,
>>                                     ImageInfoSpecific *info_spec)
>>  {
>>      QObject *obj, *data;
>>      Visitor *v = qobject_output_visitor_new(&obj);
>> +    char *tmp;
>>  
>>      visit_type_ImageInfoSpecific(v, NULL, &info_spec, &error_abort);
>>      visit_complete(v, &obj);
>>      data = qdict_get(qobject_to_qdict(obj), "data");
>> -    dump_qobject(func_fprintf, f, 1, data);
>> +    tmp = qobject_to_string_indent(data, 1);
>> +    func_fprintf(f, "%s", tmp);
>> +    g_free(tmp);
>>      qobject_decref(obj);
>>      visit_free(v);
>>  }
> 
> The title claims "move dump_qobject() from block/ to qobject/", but
> that's not what the patch does.  It *replaces* dump_qobject() by
> qobject_to_string().  The former dumps to a callback, the latter to a
> dynamic string buffer.
> 
> Providing dump functionality in one way doesn't preclude the other way:
> given callback, one could define a callback that builds up a string
> buffer, and given buffer, one could (and you actually do) pass the
> buffer to a callback.  That's less efficient, though.
> 
> Trading efficiency for ease-of-use should be okay here, but I'm cc'ing
> Max and Kevin to double-check.

Given that this function is called only by HMP's "info block -v" and
qemu-img, I don't think efficiency is too important. In the former case,
it's your own fault for using HMP, in the latter you'll have only a
single image anyway.

So I'm OK with this change.

Max

> 
> Two ways forward:
> 
> 1. Get Max / Kevin's blessing, change the commit message to match the
> code.
> 
> 2. Change the code to match the commit message.

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