Re: [PATCH 12/18] perf metric: Compute referenced metrics

[Ian Rogers <irogers@google.com>]

On Sun, Jul 12, 2020 at 6:27 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> Adding computation (expr__parse call) of referenced metric at
> the point when it needs to be resolved during the 'master'
> metric computation.

Same note on wrt master:
https://www.kernel.org/doc/html/latest/process/coding-style.html?highlight=language%20master#naming

> Once the inner metric is computed, the result is stored and
> used if there's another usage of that metric.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>

Acked-by: Ian Rogers <irogers@google.com>

Thanks,
Ian

> ---
>  tools/perf/util/expr.c | 31 +++++++++++++++++++++++++++++++
>  tools/perf/util/expr.h |  3 +++
>  tools/perf/util/expr.y |  4 ++--
>  3 files changed, 36 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
> index 6bf8a21f5c53..2784df38f8c2 100644
> --- a/tools/perf/util/expr.c
> +++ b/tools/perf/util/expr.c
> @@ -91,6 +91,7 @@ int expr__add_ref(struct expr_parse_ctx *ctx, struct metric_ref *ref)
>
>         data_ptr->ref.metric_name = ref->metric_name;
>         data_ptr->ref.metric_expr = ref->metric_expr;
> +       data_ptr->ref.counted = false;
>         data_ptr->is_ref = true;
>
>         ret = hashmap__set(&ctx->ids, name, data_ptr,
> @@ -110,6 +111,34 @@ int expr__get_id(struct expr_parse_ctx *ctx, const char *id,
>         return hashmap__find(&ctx->ids, id, (void **)data) ? 0 : -1;
>  }
>
> +int expr__resolve_id(struct expr_parse_ctx *ctx, const char *id,
> +                    struct expr_id_data **datap)
> +{
> +       struct expr_id_data *data;
> +
> +       if (expr__get_id(ctx, id, datap) || !*datap) {
> +               pr_debug("%s not found\n", id);
> +               return -1;
> +       }
> +
> +       data = *datap;
> +
> +       pr_debug2("lookup: is_ref %d, counted %d, val %f: %s\n",
> +                 data->is_ref, data->ref.counted, data->val, id);
> +
> +       if (data->is_ref && !data->ref.counted) {
> +               data->ref.counted = true;
> +               pr_debug("processing metric: %s ENTRY\n", id);
> +               if (expr__parse(&data->val, ctx, data->ref.metric_expr, 1)) {
> +                       pr_debug("%s failed to count\n", id);
> +                       return -1;
> +               }
> +               pr_debug("processing metric: %s EXIT: %f\n", id, data->val);
> +       }
> +
> +       return 0;
> +}
> +
>  void expr__del_id(struct expr_parse_ctx *ctx, const char *id)
>  {
>         struct expr_id_data *old_val = NULL;
> @@ -150,6 +179,8 @@ __expr__parse(double *val, struct expr_parse_ctx *ctx, const char *expr,
>         void *scanner;
>         int ret;
>
> +       pr_debug2("parsing metric: %s\n", expr);
> +
>         ret = expr_lex_init_extra(&scanner_ctx, &scanner);
>         if (ret)
>                 return ret;
> diff --git a/tools/perf/util/expr.h b/tools/perf/util/expr.h
> index d19e66915228..b6d1fba64eaa 100644
> --- a/tools/perf/util/expr.h
> +++ b/tools/perf/util/expr.h
> @@ -25,6 +25,7 @@ struct expr_id_data {
>                 struct {
>                         const char *metric_name;
>                         const char *metric_expr;
> +                       bool counted;
>                 } ref;
>         };
>  };
> @@ -42,6 +43,8 @@ int expr__add_id_val(struct expr_parse_ctx *ctx, const char *id, double val);
>  int expr__add_ref(struct expr_parse_ctx *ctx, struct metric_ref *ref);
>  int expr__get_id(struct expr_parse_ctx *ctx, const char *id,
>                  struct expr_id_data **data);
> +int expr__resolve_id(struct expr_parse_ctx *ctx, const char *id,
> +                    struct expr_id_data **datap);
>  int expr__parse(double *final_val, struct expr_parse_ctx *ctx,
>                 const char *expr, int runtime);
>  int expr__find_other(const char *expr, const char *one,
> diff --git a/tools/perf/util/expr.y b/tools/perf/util/expr.y
> index 0d4f5d324be7..d34b370391c6 100644
> --- a/tools/perf/util/expr.y
> +++ b/tools/perf/util/expr.y
> @@ -88,11 +88,11 @@ expr:         NUMBER
>         | ID                    {
>                                         struct expr_id_data *data;
>
> -                                       if (expr__get_id(ctx, $1, &data) || !data) {
> -                                               pr_debug("%s not found\n", $1);
> +                                       if (expr__resolve_id(ctx, $1, &data)) {
>                                                 free($1);
>                                                 YYABORT;
>                                         }
> +
>                                         $$ = data->val;
>                                         free($1);
>                                 }
> --
> 2.25.4
>