On 12 May 2023, at 8:53, John Cai wrote:
> Hey Taylor,
>
> On 11 May 2023, at 20:00, Taylor Blau wrote:
>
>> On Thu, May 11, 2023 at 06:10:32PM +0000, John Cai via GitGitGadget wrote:
>>> From: John Cai <johncai86@xxxxxxxxx>
>>>
>>> At GitLab, we have a system that creates ephemeral internal refs that
>>> don't live long before getting deleted. Having an option to exclude
>>> certain refs from a packed-refs file allows these internal references to
>>> be deleted much more efficiently.
>>>
>>> Add an --exclude option to the pack-refs builtin, and use the ref
>>> exclusions API to exclude certain refs from being packed into the final
>>> packed-refs file
>>>
>>> Signed-off-by: John Cai <johncai86@xxxxxxxxx>
>>> ---
>>> Documentation/git-pack-refs.txt | 12 +++++++++++-
>>> builtin/pack-refs.c | 20 ++++++++++++++++----
>>> refs.c | 4 ++--
>>> refs.h | 7 ++++++-
>>> refs/debug.c | 4 ++--
>>> refs/files-backend.c | 16 ++++++++++------
>>> refs/packed-backend.c | 2 +-
>>> refs/refs-internal.h | 3 ++-
>>> revision.h | 2 +-
>>> t/helper/test-ref-store.c | 3 ++-
>>> t/t3210-pack-refs.sh | 16 ++++++++++++++++
>>> 11 files changed, 69 insertions(+), 20 deletions(-)
>>>
>>> diff --git a/Documentation/git-pack-refs.txt b/Documentation/git-pack-refs.txt
>>> index e011e5fead3..c0f7426e519 100644
>>> --- a/Documentation/git-pack-refs.txt
>>> +++ b/Documentation/git-pack-refs.txt
>>> @@ -8,7 +8,7 @@ git-pack-refs - Pack heads and tags for efficient repository access
>>> SYNOPSIS
>>> --------
>>> [verse]
>>> -'git pack-refs' [--all] [--no-prune]
>>> +'git pack-refs' [--all] [--no-prune] [--exclude <pattern>]
>>>
>>> DESCRIPTION
>>> -----------
>>> @@ -60,6 +60,16 @@ interests.
>>> The command usually removes loose refs under `$GIT_DIR/refs`
>>> hierarchy after packing them. This option tells it not to.
>>>
>>> +--exclude <pattern>::
>>> +
>>> +Do not pack refs matching the given `glob(7)` pattern. Repetitions of this option
>>> +accumulate exclusion patterns. Use `--no-exclude` to clear and reset the list of
>>> +patterns. If a ref is already packed, including it with `--exclude` will not
>>> +unpack it.
>>> +
>>> +When used with `--all`, it will use the difference between the set of all refs,
>>> +and what is provided to `--exclude`.
>>> +
>>
>> I think this last paragraph could be simplified, though feel free to
>> discard my suggestion if you think it makes things less clear.
>>
>> When used with `--all`, pack only loose refs which do not match any of
>> the provided `--exclude` patterns.
>
> I like the wording here, thanks
>
>>
>>> int cmd_pack_refs(int argc, const char **argv, const char *prefix)
>>> {
>>> unsigned int flags = PACK_REFS_PRUNE;
>>> + static struct ref_exclusions excludes = REF_EXCLUSIONS_INIT;
>>> + struct pack_refs_opts pack_refs_opts = {.exclusions = &excludes, .flags = flags};
>>> + static struct string_list option_excluded_refs = STRING_LIST_INIT_NODUP;
>>> + struct string_list_item *item;
>>
>> Since this list does not appear to be sensitive to its order, have you
>> considered using the strvec API instead of the string_list one?
>
> Thanks for this suggestion--you're right in that the order doesn't matter here.
> The only thing is, the only option parsing macro I could find that operates on
> strvec is OPT_PASSTHRU_ARGV. I tried it out, and it seem to work just fine.
Actually I had a bug in my test that made it seem like it worked. I realize that
OPT_PASSTHRU_ARGV passes through the entire option flag eg
--include=refs/tags/dont_pack* so we would have to strip the flag name. It's not
as user friendly as OPT_STRING_LIST that is just plug and play.
Unless there is a significant performance improvement in using strvec, I'm
thinking maybe I'll just stick to string_list.
thanks
John
>
>>
>>> diff --git a/refs.c b/refs.c
>>> index d2a98e1c21f..881a0da65cf 100644
>>> --- a/refs.c
>>> +++ b/refs.c
>>> @@ -2132,9 +2132,9 @@ void base_ref_store_init(struct ref_store *refs, struct repository *repo,
>>> }
>>>
>>> /* backend functions */
>>> -int refs_pack_refs(struct ref_store *refs, unsigned int flags)
>>> +int refs_pack_refs(struct ref_store *refs, struct pack_refs_opts *opts)
>>> {
>>> - return refs->be->pack_refs(refs, flags);
>>> + return refs->be->pack_refs(refs, opts);
>>> }
>>>
>>> int peel_iterated_oid(const struct object_id *base, struct object_id *peeled)
>>> diff --git a/refs.h b/refs.h
>>> index 123cfa44244..46020bd335c 100644
>>> --- a/refs.h
>>> +++ b/refs.h
>>> @@ -63,6 +63,11 @@ struct worktree;
>>> #define RESOLVE_REF_NO_RECURSE 0x02
>>> #define RESOLVE_REF_ALLOW_BAD_NAME 0x04
>>>
>>> +struct pack_refs_opts {
>>> + unsigned int flags;
>>> + struct ref_exclusions *exclusions;
>>
>> I think this would be OK to include directly in the struct instead of
>> via a pointer, but either is fine.
>>
>>> @@ -1175,15 +1176,18 @@ static void prune_refs(struct files_ref_store *refs, struct ref_to_prune **refs_
>>> */
>>> static int should_pack_ref(const char *refname,
>>> const struct object_id *oid, unsigned int ref_flags,
>>> - unsigned int pack_flags)
>>> + struct pack_refs_opts *opts)
>>> {
>>> /* Do not pack per-worktree refs: */
>>> if (parse_worktree_ref(refname, NULL, NULL, NULL) !=
>>> REF_WORKTREE_SHARED)
>>> return 0;
>>>
>>> + if (opts->exclusions && ref_excluded(opts->exclusions, refname))
>>> + return 0;
>>
>> Looks good, here is where we throw out refs that we don't want. I wonder
>> if ref_excluded() does the right thing with a zero-initialized argument
>> (i.e. that it behaves as if nothing matches).
>
> Yes, I think we can skip checking if opt->exclusions is not null. Junio had
> feedback around this as well.
>
>>
>> I wonder if it's possible to skip over certain loose references by
>> avoiding traversal into the sub-directories for simple prefixes. That
>> may be a premature optimization, though, so I don't think you
>> necessarily need to worry about it in this round.
>>
>>> +test_expect_success 'test excluded refs are not packed' '
>>> + git branch dont_pack1 &&
>>> + git branch dont_pack2 &&
>>> + git branch pack_this &&
>>> + git pack-refs --all --exclude "refs/heads/dont_pack*" &&
>>> + test -f .git/refs/heads/dont_pack1 &&
>>> + test -f .git/refs/heads/dont_pack2 &&
>>> + ! test -f ./git/refs/heads/pack_this'
>>> +
>>> +test_expect_success 'test --no-exclude refs clears excluded refs' '
>>> + git branch dont_pack3 &&
>>> + git branch dont_pack4 &&
>>> + git pack-refs --all --exclude "refs/heads/dont_pack*" --no-exclude &&
>>> + ! test -f .git/refs/heads/dont_pack3 &&
>>> + ! test -f .git/refs/heads/dont_pack4'
>>
>> Tests look good. The trailing quote is a little odd to be placed on the
>> last line of the test instead of off on its own, but I suppose that is
>> imitating existing style, which is OK.
>
> thanks for the feedback!
> John
>>
>> Thanks,
>> Taylor
