On Thu, Aug 17, 2023 at 06:24:17PM -0400, Steven Rostedt wrote:
> From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
>
> Add an API traceeval_iterator_remove() that is safe to call in the
> traceeval_iterator_next() loop. Currently, traceeval_remove() can also be
> called "safely", but that may change in the future.
>
> The main difference between traceeval_remove() and traceeval_iterator_remove()
> is that that traceeval_iterator_remove() will NULL out the entry in the
> sort array, and use this in the other iterator functions. If the entry is
> NULL, it will not be returned.
>
> Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
> ---
> include/traceeval-hist.h | 1 +
> src/histograms.c | 48 ++++++++++++++++++++++++++++++++++++----
> 2 files changed, 45 insertions(+), 4 deletions(-)
>
> diff --git a/include/traceeval-hist.h b/include/traceeval-hist.h
> index d511c9c5f14c..7d67673ce7e5 100644
> --- a/include/traceeval-hist.h
> +++ b/include/traceeval-hist.h
> @@ -190,5 +190,6 @@ int traceeval_iterator_query(struct traceeval_iterator *iter,
> const union traceeval_data **results);
> struct traceeval_stat *traceeval_iterator_stat(struct traceeval_iterator *iter,
> struct traceeval_type *type);
> +int traceeval_iterator_remove(struct traceeval_iterator *iter);
>
> #endif /* __LIBTRACEEVAL_HIST_H__ */
> diff --git a/src/histograms.c b/src/histograms.c
> index fddd0f3587e2..0fbd9e0a353e 100644
> --- a/src/histograms.c
> +++ b/src/histograms.c
> @@ -1305,10 +1305,13 @@ int traceeval_iterator_next(struct traceeval_iterator *iter,
> iter->next = 0;
> }
>
> - if (iter->next >= iter->nr_entries)
> - return 0;
> + do {
> + if (iter->next >= iter->nr_entries)
> + return 0;
> +
> + entry = iter->entries[iter->next++];
> + } while (!entry);
>
> - entry = iter->entries[iter->next++];
> *keys = entry->keys;
> return 1;
> }
> @@ -1338,6 +1341,9 @@ int traceeval_iterator_query(struct traceeval_iterator *iter,
> return 0;
>
> entry = iter->entries[iter->next - 1];
> + if (!entry)
> + return 0;
> +
> *results = entry->vals;
>
> return 1;
> @@ -1363,5 +1369,39 @@ struct traceeval_stat *traceeval_iterator_stat(struct traceeval_iterator *iter,
> return NULL;
>
> entry = iter->entries[iter->next - 1];
> - return &entry->val_stats[type->index];
> + return entry ? &entry->val_stats[type->index] : NULL;
> +}
> +
> +/**
> + * traceeval_iterator_remove - remove the current iterator entry
> + * @iter: The iterator to remove the entry from
> + *
> + * This will remove the current entry from the histogram.
> + * This is useful if the current entry should be removed. It will not
> + * affect the traceeval_iterator_next().
> + *
> + * Returns 1 if it successfully removed the entry, 0 if for some reason
> + * there was no "current entry" (called before traceeval_iterator_next()).
> + * or -1 on error.
> + */
> +int traceeval_iterator_remove(struct traceeval_iterator *iter)
> +{
> + struct traceeval *teval = iter->teval;
> + struct hash_table *hist = teval->hist;
> + struct entry *entry;
> +
> + if (iter->next < 1 || iter->next > iter->nr_entries)
> + return 0;
> +
> + entry = iter->entries[iter->next - 1];
> + if (!entry)
> + return 0;
> +
> + hash_remove(hist, &entry->hash);
Are we leaking 'entry' after we've removed it from the hash?
I think we need to call free_entry() in both traceeval_iterator_remove() as
well as traceeval_remove(), just like we do in the loop in
hist_table_release().
> +
> + /* The entry no longer exists */
> + iter->entries[iter->next - 1] = NULL;
> + teval->update_counter++;
> +
> + return 1;
> }
> --
> 2.40.1
>
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