Re: [PATCH v2 2/4] libtracefs: Transform tracefs_hist_add_sort_key()

[Tzvetomir Stoyanov <tz.stoyanov@gmail.com>]

On Fri, Sep 24, 2021 at 12:59 PM Yordan Karadzhov (VMware)
<y.karadz@gmail.com> wrote:
>
> The current version of the API makes it hard to add multiple sort keys
> to a histogram. The only way to do this is to use the variadic arguments,
> however in order to do this the caller has to know the number of sort
> keys at compile time, because the method overwrite all previously added
> keys. The problem is addressed by creating a tracefs_hist_add_sort_key()
> into two methods - one that overwrite and one that does not.
> The current version of 'tracefs_hist_add_sort_key()' gets renamed to
> 'tracefs_hist_set_sort_key()' without introducing any functional changes.
> In the same time a new 'tracefs_hist_add_sort_key()' function is
> defined. The new function can add one new sort key to the list of
> previously added sort keys.
>
> Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
> ---
>  include/tracefs.h  |  4 +++-
>  src/tracefs-hist.c | 33 ++++++++++++++++++++++++++++++---
>  2 files changed, 33 insertions(+), 4 deletions(-)
>
> diff --git a/include/tracefs.h b/include/tracefs.h
> index 5c4141e..230bc41 100644
> --- a/include/tracefs.h
> +++ b/include/tracefs.h
> @@ -333,7 +333,9 @@ int tracefs_hist_add_key(struct tracefs_hist *hist, const char *key,
>                          enum tracefs_hist_key_type type);
>  int tracefs_hist_add_value(struct tracefs_hist *hist, const char *value);
>  int tracefs_hist_add_sort_key(struct tracefs_hist *hist,
> -                             const char *sort_key, ...);
> +                             const char *sort_key);
> +int tracefs_hist_reset_sort_key(struct tracefs_hist *hist,
> +                               const char *sort_key, ...);

The new name of the function, mentioned in the patch description, is
    tracefs_hist_set_sort_key()
I like the name with "set" instead of "reset". The behaviour of the
function should be described in the function comments - to stress that
the old keys are overwritten.

>  int tracefs_hist_sort_key_direction(struct tracefs_hist *hist,
>                                     const char *sort_key,
>                                     enum tracefs_hist_sort_direction dir);
> diff --git a/src/tracefs-hist.c b/src/tracefs-hist.c
> index ea12204..a7c20de 100644
> --- a/src/tracefs-hist.c
> +++ b/src/tracefs-hist.c
> @@ -437,16 +437,43 @@ add_sort_key(struct tracefs_hist *hist, const char *sort_key, char **list)
>  /**
>   * tracefs_hist_add_sort_key - add a key for sorting the histogram
>   * @hist: The histogram to add the sort key to
> + * @sort_key: The key to sort
> + *
> + * Call the function to add to the list of sort keys of the histohram in
> + * the order of priority that the keys would be sorted on output.
> + *
> + * Returns 0 on success, -1 on error.
> + */
> +int tracefs_hist_add_sort_key(struct tracefs_hist *hist,
> +                             const char *sort_key)
> +{
> +       char **list = hist->sort;
> +
> +       if (!hist || !sort_key)
> +               return -1;
> +
> +       list = add_sort_key(hist, sort_key, hist->sort);
> +       if (!list)
> +               return -1;
> +
> +       hist->sort = list;
> +
> +       return 0;
> +}
> +
> +/**
> + * tracefs_hist_reset_sort_key - set a key for sorting the histogram
> + * @hist: The histogram to set the sort key to
>   * @sort_key: The key to sort (and the strings after it)
>   *  Last one must be NULL.
>   *
> - * Add a list of sort keys in the order of priority that the
> + * Set a list of sort keys in the order of priority that the
>   * keys would be sorted on output. Keys must be added first.
>   *
>   * Returns 0 on success, -1 on error.
>   */
> -int tracefs_hist_add_sort_key(struct tracefs_hist *hist,
> -                             const char *sort_key, ...)
> +int tracefs_hist_reset_sort_key(struct tracefs_hist *hist,
> +                               const char *sort_key, ...)
>  {
>         char **list = NULL;
>         char **tmp;
> --
> 2.30.2
>


--
Tzvetomir (Ceco) Stoyanov
VMware Open Source Technology Center