Re: [PATCH] clear_pattern_list(): clear embedded hashmaps

On Mon, Aug 17, 2020 at 9:55 AM Elijah Newren [off-list ref] wrote:

Hi,

On Fri, Aug 14, 2020 at 5:23 AM Jeff King [off-list ref] wrote:

quoted

Commit 96cc8ab531 (sparse-checkout: use hashmaps for cone patterns,
2019-11-21) added some auxiliary hashmaps to the pattern_list struct,
but they're leaked when clear_pattern_list() is called.

Signed-off-by: Jeff King <redacted>
---
I have no idea how often this leak triggers in practice. I just noticed
it while poking at LSan output (which we remain depressingly far
from getting a clean run on).

 dir.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/dir.c b/dir.c
index fe64be30ed..9411b94e9b 100644
--- a/dir.c
+++ b/dir.c

@@ -916,6 +916,8 @@ void clear_pattern_list(struct pattern_list *pl)
                free(pl->patterns[i]);
        free(pl->patterns);
        free(pl->filebuf);
+       hashmap_free_entries(&pl->recursive_hashmap, struct pattern_entry, ent);
+       hashmap_free_entries(&pl->parent_hashmap, struct pattern_entry, ent);

This clears up the hash entries, but continues to leak the hash table.
Since you submitted first, can you fix this to use hashmap_free_()
instead, as per
https://lore.kernel.org/git/932741d7598ca2934dbca40f715ba2d3819fcc51.1597561152.git.gitgitgadget@gmail.com/ (local)?
 Then I'll rebase my series on yours and drop my first patch (since
it'll then be identical).

Nevermind, I got confused once again by the name.
hashmap_free_entries() doesn't mean just free the entries, it means
free what hashmap_free() would plus all the entries, i.e. do what
hashmap_free() *should* *have* *been* defined to do.  Such a confusing
API.  And hashmap_free() really perplexes me -- it seems like a
function that can't possibly be useful; it's sole purpose seems to be
a trap for the unwary.