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

[Yordan Karadzhov <y.karadz@xxxxxxxxx>]

On 10.09.21 г. 23:01, Steven Rostedt wrote:
> On Fri, 10 Sep 2021 19:38:55 +0300
> "Yordan Karadzhov (VMware)" <y.karadz@xxxxxxxxx> 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 have to know the number of sort
> > keys at compile time, because the method overwrite all previously added
> > keys. The problem is addressed by splitting tracefs_hist_add_sort_key()
> > into two methods - one that overwrite and one that does not.
> >
> > Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@xxxxxxxxx>
> > ---
> >   include/tracefs.h  |  4 +++-
> >   src/tracefs-hist.c | 21 +++++++++++++++++++--
> >   2 files changed, 22 insertions(+), 3 deletions(-)
> >
> > diff --git a/include/tracefs.h b/include/tracefs.h
> > index 64fbb3f..c3fa1d6 100644
> > --- a/include/tracefs.h
> > +++ b/include/tracefs.h
> > @@ -303,7 +303,9 @@ 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, ...);
> > +			      char *sort_key);
>
> Why did you remove the const? The add_sort_key() takes a const and makes a
> copy of it.

This is a mistake. It must be 'const'.

> > +int tracefs_hist_sort_key(struct tracefs_hist *hist,
> > +			  const char *sort_key, ...);
> >   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 8501d64..2ea90d9 100644
> > --- a/src/tracefs-hist.c
> > +++ b/src/tracefs-hist.c
> > @@ -453,6 +453,23 @@ add_sort_key(struct tracefs_hist *hist, const char *sort_key, char **list)
> >   	return tracefs_list_add(list, sort_key);
> >   }
> >   
>
> Needs a kerneldoc documentation header.

OK

> > +int tracefs_hist_add_sort_key(struct tracefs_hist *hist,
> > +			      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_add_sort_key - add a key for sorting the histogram
>
> The above name needs to be updated.
>
> >    * @hist: The histogram to add the sort key to
> > @@ -464,8 +481,8 @@ add_sort_key(struct tracefs_hist *hist, const char *sort_key, char **list)
> >    *
> >    * Returns 0 on success, -1 on error.
> >    */
> > -int tracefs_hist_add_sort_key(struct tracefs_hist *hist,
> > -			      const char *sort_key, ...)
> > +int tracefs_hist_sort_key(struct tracefs_hist *hist,
>
> How about if we call this:
>
> 	tracefs_hist_replace_sort_keys()
>
> I think that would be a more intuitive name.

The user may call this function with a histogram that has no sort keys added.
So there will be nothing to replace.
What about naming it 'tracefs_hist_set_sort_keys()'?

Thanks a lot!
Yordan

> -- Steve
>
> > +			  const char *sort_key, ...)
> >   {
> >   	char **list = NULL;
> >   	char **tmp;