From: Derrick Stolee <stolee@gmail.com>
Date: Thu, 21 Jun 2018 20:03:32 GMT
Subject: Re: [PATCH 17/23] midx: read objects from multi-pack-index
Message-ID: <b9d875e2-452d-6492-fd25-9d114af39a25@gmail.com>
In-Reply-To: <CACsJy8CqoKWgd=ekxozaKzRjrU3NN9KUxrspk_iP+zxBVcV5pA@mail.gmail.com>

On 6/9/2018 1:56 PM, Duy Nguyen wrote:
> On Thu, Jun 7, 2018 at 6:55 PM Derrick Stolee <stolee@gmail.com> wrote:
>> Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
>> ---
>>   midx.c         | 96 ++++++++++++++++++++++++++++++++++++++++++++++++--
>>   midx.h         |  2 ++
>>   object-store.h |  1 +
>>   packfile.c     |  8 ++++-
>>   4 files changed, 104 insertions(+), 3 deletions(-)
>>
>> diff --git a/midx.c b/midx.c
>> index 5e9290ca8f..6eca8f1b12 100644
>> --- a/midx.c
>> +++ b/midx.c
>> @@ -3,6 +3,7 @@
>>   #include "dir.h"
>>   #include "csum-file.h"
>>   #include "lockfile.h"
>> +#include "sha1-lookup.h"
>>   #include "object-store.h"
>>   #include "packfile.h"
>>   #include "midx.h"
>> @@ -64,7 +65,7 @@ struct midxed_git *load_midxed_git(const char *object_dir)
>>
>>          m = xcalloc(1, sizeof(*m) + strlen(object_dir) + 1);
>>          strcpy(m->object_dir, object_dir);
>> -       m->data = midx_map;
>> +       m->data = (const unsigned char*)midx_map;
> Hmm? Why is this typecast only needed now? Or is it not really needed at all?
>
>>          m->signature = get_be32(m->data);
>>          if (m->signature != MIDX_SIGNATURE) {
>> @@ -145,7 +146,9 @@ struct midxed_git *load_midxed_git(const char *object_dir)
>>
>>          m->num_objects = ntohl(m->chunk_oid_fanout[255]);
>>
>> -       m->pack_names = xcalloc(m->num_packs, sizeof(const char *));
>> +       m->packs = xcalloc(m->num_packs, sizeof(*m->packs));
>> +
>> +       ALLOC_ARRAY(m->pack_names, m->num_packs);
> Please make this ALLOC_ARRAY change in the patch that adds
> xcalloc(m->num_packs).
>
>>          for (i = 0; i < m->num_packs; i++) {
>>                  if (i) {
>>                          if (ntohl(m->chunk_pack_lookup[i]) <= ntohl(m->chunk_pack_lookup[i - 1])) {
>> @@ -175,6 +178,95 @@ struct midxed_git *load_midxed_git(const char *object_dir)
>>          exit(1);
>>   }
>>
>> +static int prepare_midx_pack(struct midxed_git *m, uint32_t pack_int_id)
>> +{
>> +       struct strbuf pack_name = STRBUF_INIT;
>> +
>> +       if (pack_int_id >= m->num_packs)
>> +               BUG("bad pack-int-id");
>> +
>> +       if (m->packs[pack_int_id])
>> +               return 0;
>> +
>> +       strbuf_addstr(&pack_name, m->object_dir);
>> +       strbuf_addstr(&pack_name, "/pack/");
>> +       strbuf_addstr(&pack_name, m->pack_names[pack_int_id]);
> Just use strbuf_addf()
>
>> +
>> +       m->packs[pack_int_id] = add_packed_git(pack_name.buf, pack_name.len, 1);
>> +       strbuf_release(&pack_name);
>> +       return !m->packs[pack_int_id];
> This is a weird return value convention. Normally we go zero/negative
> or non-zero/zero for success/failure.

We are inconsistent.

* open_pack_index() returns non-zero on error. (This was my reference 
point.)
* bsearch_pack() and find_pack_entry() return non-zero when an entry is 
found.

Since the use is "if (error) die()", similar to open_pack_index(), I'll 
keep the current behavior. To switch would require using 
"!!m->packs[pack_int_id]" here and "if (!prepare_midx_pack()) die()" in 
the consumer.

Thanks,
-Stolee