On Thu, Aug 17, 2023 at 06:24:15PM -0400, Steven Rostedt wrote:
> From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
>
> Add a query to the iterator that will return the values of the last entry
> that matches the keys returned by the last call of traceeval_iterator_next().
>
> Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
> ---
> include/traceeval-hist.h | 2 ++
> samples/task-eval.c | 2 +-
> src/histograms.c | 30 ++++++++++++++++++++++++++++++
> 3 files changed, 33 insertions(+), 1 deletion(-)
>
> diff --git a/include/traceeval-hist.h b/include/traceeval-hist.h
> index 0cee9bcbeb83..837a74f61a66 100644
> --- a/include/traceeval-hist.h
> +++ b/include/traceeval-hist.h
> @@ -186,5 +186,7 @@ int traceeval_iterator_sort_custom(struct traceeval_iterator *iter,
> traceeval_cmp_fn sort_fn, void *data);
> int traceeval_iterator_next(struct traceeval_iterator *iter,
> const union traceeval_data **keys);
> +int traceeval_iterator_query(struct traceeval_iterator *iter,
> + const union traceeval_data **results);
>
> #endif /* __LIBTRACEEVAL_HIST_H__ */
> diff --git a/samples/task-eval.c b/samples/task-eval.c
> index 66d0c40dc0c8..18e07f44e11e 100644
> --- a/samples/task-eval.c
> +++ b/samples/task-eval.c
> @@ -836,7 +836,7 @@ static void display_processes(struct traceeval *teval,
> struct process_data *pdata = NULL;
> const char *comm = keys[0].cstring;
>
> - ret = traceeval_query(teval_data, keys, &results);
> + ret = traceeval_iterator_query(iter, &results);
> if (ret < 0)
> pdie("Could not query iterator");
> if (ret < 1)
> diff --git a/src/histograms.c b/src/histograms.c
> index 66bdc1769985..4f603ce36c8c 100644
> --- a/src/histograms.c
> +++ b/src/histograms.c
> @@ -1306,3 +1306,33 @@ int traceeval_iterator_next(struct traceeval_iterator *iter,
> *keys = entry->keys;
> return 1;
> }
> +
> +/**
> + * traceeval_iterator_query - return the results of the last entry in the iterator
Nit, 'last entry' made me think you were referring to the *last* entry.
Maybe say previous entry instead?
-- Stevie
> + * @iter: The iterator to retrieve the entry results from
> + * @results: The returned results of the last entry (if exists)
> + *
> + * This returns the @results of the values from the last instance of
> + * traceeval_iterator_next(). It is equivalent of calling:
> + *
> + * traceeval_query_size() with the keys returned by traceeval_iterator_next().
> + *
> + * Except that it will always quickly return the last entry, whereas the
> + * traceeval_query_size() will reset the cached next_entry and do a full
> + * lookup again.
> + *
> + * Returns 1 if another entry is returned, or 0 if not (or negative on error)
> + */
> +int traceeval_iterator_query(struct traceeval_iterator *iter,
> + const union traceeval_data **results)
> +{
> + struct entry *entry;
> +
> + if (iter->next < 1 || iter->next > iter->nr_entries)
> + return 0;
> +
> + entry = iter->entries[iter->next - 1];
> + *results = entry->vals;
> +
> + return 1;
> +}
> --
> 2.40.1
>
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