From: Jeff King <firstname.lastname@example.org> To: Elijah Newren <email@example.com> Cc: Git Mailing List <firstname.lastname@example.org>, Derrick Stolee <email@example.com> Subject: Re: [PATCH] clear_pattern_list(): clear embedded hashmaps Date: Mon, 17 Aug 2020 14:48:21 -0400 [thread overview] Message-ID: <20200817184821.GA1278968@coredump.intra.peff.net> (raw) In-Reply-To: <CABPp-BGUBPJCW3-GrVvom5CwfauY-m5ZCLJmKP=P=fXWm=Kepg@mail.gmail.com> On Mon, Aug 17, 2020 at 10:22:27AM -0700, Elijah Newren wrote: > > > + 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://firstname.lastname@example.org/? > > 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. There used to be an "also free entries" flag, but that got complicated by the loosening of the "hashmap_entry must be at the front of the struct to be freed" rule. With this kind of embedded-entry data structure (and list.h is in the same boat) it _is_ sometimes useful to be part of a data structure without giving up ownership of the memory. But I agree that the more normal case is to free items when the hashmap is destroyed. Likewise, the whole "you have to define a struct that contains the map entry" thing is flexible and efficient, but a pain to use. I generally find khash's "map this type to that type, the hash owns the memory" much more natural. And it doesn't lose efficiency (and indeed sometimes even gains it) because it uses macros to store concrete types. But of course macros create their own headaches. :) Anyway, I'm definitely open to renaming to something more sensible. I already mentioned the free/clear thing earlier, but hashmap_clear_entries() ends up _very_ confusing. Because it's clearing the hashmap but freeing the entries. hashmap_clear_and_free_entries() is kind of long, but a lot more descriptive. -Peff
prev parent reply other threads:[~2020-08-17 18:48 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-08-14 11:10 Jeff King 2020-08-14 12:13 ` Derrick Stolee 2020-08-17 16:55 ` Elijah Newren 2020-08-17 17:22 ` Elijah Newren 2020-08-17 18:48 ` Jeff King [this message]
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