(Pulling Nico in for Q2 below. No snipping so he has a context)
2012/1/31 Junio C Hamano <gitster@xxxxxxxxx>:
> Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx> writes:
>
>> Commit f7c22cc (always start looking up objects in the last used pack
>> first - 2007-05-30) introduces a static packed_git* pointer as an
>> optimization. The kept pointer however may become invalid if
>> free_pack_by_name() happens to free that particular pack.
>>
>> Current code base does not access packs after calling
>> free_pack_by_name() so it should not be a problem. Anyway, move the
>> pointer out so that free_pack_by_name() can reset it to avoid running
>> into troubles in future.
>>
>> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
>> ---
>
> Thanks. Two curiosities:
>
> - Why is there no hunk to actually clear the pointer in
> free_pack_by_name() in this patch?
I think it's there (the patch did work for me when I tried to
integrate repack to pack-objects).
-- 8<--
> @@ -720,6 +722,8 @@ void free_pack_by_name(const char *pack_name)
> close_pack_index(p);
> free(p->bad_object_sha1);
> *pp = p->next;
> + if (find_pack_entry_last_found == p)
> + find_pack_entry_last_found = (void*)1;
> free(p);
> return;
> }
-- 8< --
> - Could we make the magic (void *)1 value a #define'd constant? Perhaps
> we could even use NULL for that purpose?
Q1. Sure.
Q2. No NULL is probably not suitable. I think Nico wanted to express
"we tried to find but found none (i.e. NULL)" too and 1 means "no we
have not tried".
>> diff --git a/sha1_file.c b/sha1_file.c
>> index 88f2151..4ecc953 100644
>> --- a/sha1_file.c
>> +++ b/sha1_file.c
>> @@ -54,6 +54,8 @@ static struct cached_object empty_tree = {
>> 0
>> };
>>
>> +static struct packed_git *find_pack_entry_last_found = (void *)1;
>> +
>> static struct cached_object *find_cached_object(const unsigned char *sha1)
>> {
>> int i;
>> @@ -720,6 +722,8 @@ void free_pack_by_name(const char *pack_name)
>> close_pack_index(p);
>> free(p->bad_object_sha1);
>> *pp = p->next;
>> + if (find_pack_entry_last_found == p)
>> + find_pack_entry_last_found = (void*)1;
>> free(p);
>> return;
>> }
>> @@ -2012,14 +2016,13 @@ int is_pack_valid(struct packed_git *p)
>>
>> static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
>> {
>> - static struct packed_git *last_found = (void *)1;
>> struct packed_git *p;
>> off_t offset;
>>
>> prepare_packed_git();
>> if (!packed_git)
>> return 0;
>> - p = (last_found == (void *)1) ? packed_git : last_found;
>> + p = (find_pack_entry_last_found == (void *)1) ? packed_git : find_pack_entry_last_found;
>>
>> do {
>> if (p->num_bad_objects) {
>> @@ -2046,16 +2049,16 @@ static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
>> e->offset = offset;
>> e->p = p;
>> hashcpy(e->sha1, sha1);
>> - last_found = p;
>> + find_pack_entry_last_found = p;
>> return 1;
>> }
>>
>> next:
>> - if (p == last_found)
>> + if (p == find_pack_entry_last_found)
>> p = packed_git;
>> else
>> p = p->next;
>> - if (p == last_found)
>> + if (p == find_pack_entry_last_found)
>> p = p->next;
>> } while (p);
>> return 0;
--
Duy
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