Re: [Qemu-devel] [PATCH 09/27] qdict: Introduce qdict_rename_keys()

[Max Reitz <mreitz@redhat.com>]

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On 2018-02-08 20:23, Kevin Wolf wrote:
> A few block drivers will need to rename .bdrv_create options for their
> QAPIfication, so let's have a helper function for that.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  include/qapi/qmp/qdict.h |  6 ++++++
>  qobject/qdict.c          | 30 ++++++++++++++++++++++++++++++
>  2 files changed, 36 insertions(+)

Hmmm, looks OK, but I wonder whether this is going to be any more
efficient than if we simply had a qdict_rename_key() function that you
call multiple times.

("efficient" both in terms of code readability and runtime efficiency)

So, I'll give you a

Reviewed-by: Max Reitz <mreitz@redhat.com>

and let you decide.

> 
> diff --git a/include/qapi/qmp/qdict.h b/include/qapi/qmp/qdict.h
> index fc218e7be6..862441b9d3 100644
> --- a/include/qapi/qmp/qdict.h
> +++ b/include/qapi/qmp/qdict.h
> @@ -90,4 +90,10 @@ QObject *qdict_crumple(const QDict *src, Error **errp);
>  
>  void qdict_join(QDict *dest, QDict *src, bool overwrite);
>  
> +typedef struct QDictRenames {
> +    const char *from;
> +    const char *to;
> +} QDictRenames;
> +bool qdict_rename_keys(QDict *qdict, const QDictRenames *renames, Error **errp);
> +
>  #endif /* QDICT_H */
> diff --git a/qobject/qdict.c b/qobject/qdict.c
> index e8f15f1132..07ae9489a7 100644
> --- a/qobject/qdict.c
> +++ b/qobject/qdict.c
> @@ -1051,3 +1051,33 @@ void qdict_join(QDict *dest, QDict *src, bool overwrite)
>          entry = next;
>      }
>  }
> +
> +/**
> + * qdict_rename_keys(): Rename keys in qdict according to the replacements
> + * specified in the array renames. The array must be terminated by an entry
> + * with from = NULL.
> + *
> + * Returns true for success, false in error cases.
> + */
> +bool qdict_rename_keys(QDict *qdict, const QDictRenames *renames, Error **errp)
> +{
> +    QObject *qobj;
> +
> +    while (renames->from) {
> +        if (qdict_haskey(qdict, renames->from)) {
> +            if (qdict_haskey(qdict, renames->to)) {
> +                error_setg(errp, "'%s' and its alias '%s' can't be used at the "
> +                           "same time", renames->to, renames->from);
> +                return false;
> +            }
> +
> +            qobj = qdict_get(qdict, renames->from);
> +            qobject_incref(qobj);
> +            qdict_put_obj(qdict, renames->to, qobj);
> +            qdict_del(qdict, renames->from);
> +        }
> +
> +        renames++;
> +    }
> +    return true;
> +}
> 



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