* [GSoC] Git Final Blog
@ 2021-08-19 5:39 ZheNing Hu
2021-08-20 16:22 ` Christian Couder
2021-08-22 17:13 ` Kaartic Sivaraam
0 siblings, 2 replies; 5+ messages in thread
From: ZheNing Hu @ 2021-08-19 5:39 UTC (permalink / raw)
To: Git List
Cc: Hariom verma, Christian Couder, Junio C Hamano, Jeff King,
Eric Sunshine, Ævar Arnfjörð Bjarmason,
Jacob Keller, Bagas Sanjaya,
Оля
Тележная,
Denton Liu, Felipe Contreras, phillip.wood, Atharva Raykar
My final week blog finished:
The web version is here:
https://adlternative.github.io/GSOC-Git-Final-Blog/
## Git Final Blog
### My micro project:
You can view them here:
[link](https://github.com/gitgitgadget/git/pulls?q=adlternative+closed%3A%3C2021-05-18+label%3Amaster).
```
builtin/*: update usage format
ls_files.c: bugfix for --deleted and --modified
ls_files.c: consolidate two for loops into one
ls-files.c: add --deduplicate option
difftool.c: learn a new way start at specified file
commit: add --trailer option
format-patch: allow a non-integral version numbers
ref-filter: get rid of show_ref_array_item
ref-filter: reuse output buffer
pretty: provide human date format
docs: correct descript of trailer.<token>.command
trailer: add new .cmd config option
```
### My GSoC project:
#### Use ref-filter formats in git cat-file
`git cat-file --batch` is a Git command, it can be used to output the
data of Git
objects according to different formats. My goal is to make `git
cat-file --batch` reuse
the logic in ref-filter, this can make `git cat-file --batch` support
more format atoms.
During GSoC, these patches were merged into the `master` branch,
you can view them here:
[link](https://github.com/gitgitgadget/git/pulls?q=adlternative+closed%3A%3E%3D2021-05-18+label%3Amaster+).
```
ref-filter: fix read invalid union member bug
ref-filter: add objectsize to used_atom
ref-filter: introduce enum atom_type
cat-file: handle trivial --batch format with --batch-all-objects
cat-file: merge two block into one
```
These patches were staying on the `next` branch and waiting to merge
to `master`,
you can view them here:
[link](https://github.com/gitgitgadget/git/issues?q=adlternative+created%3A%3E2021-05-19+label%3Anext).
```
ref-filter: add obj-type check in grab contents
ref-filter: add %(raw) atom
ref-filter: --format=%(raw) support --perl
ref-filter: use non-const ref_format in *_atom_parser()
ref-filter: add %(rest) atom
cherry-pick: use better advice message
```
This is the complete patches list:
[link](https://github.com/adlternative/git/commits/cat-file-reuse-ref-filter-logic)
```
ref-filter: fix read invalid union member bug
ref-filter: add objectsize to used_atom
ref-filter: introduce enum atom_type
cat-file: handle trivial --batch format with --batch-all-objects
cat-file: merge two block into one
[GSOC] ref-filter: add obj-type check in grab contents
[GSOC] ref-filter: add %(raw) atom
[GSOC] ref-filter: --format=%(raw) support --perl
[GSOC] ref-filter: use non-const ref_format in *_atom_parser()
[GSOC] ref-filter: add %(rest) atom
[GSOC] ref-filter: pass get_object() return value to their callers
[GSOC] ref-filter: introduce free_ref_array_item_value() function
[GSOC] ref-filter: add cat_file_mode to ref_format
[GSOC] ref-filter: modify the error message and value in get_object
[GSOC] cat-file: add has_object_file() check
[GSOC] cat-file: change batch_objects parameter name
[GSOC] cat-file: create p1006-cat-file.sh
[GSOC] cat-file: reuse ref-filter logic
[GSOC] cat-file: reuse err buf in batch_object_write()
[GSOC] cat-file: re-implement --textconv, --filters options
[GSOC] ref-filter: remove grab_oid() function
[GSOC] ref-filter: skip parse_object_buffer()
[GSOC] ref-filter: merge two for loop in grab_person()
[GSOC] ref-filter: remove strlen() from find_subpos()
[GSOC] ref-filter: introducing xstrvfmt_len() and xstrfmt_len()
[GSOC] ref-filter: remove second parsing in format_ref_array_item()
[GSOC] ref-filter: introduction ref_filter_slopbuf[1]
[GSOC] ref-filter: add deref member to struct used_atom
[GSOC] ref-filter: introduce symref_atom_parser()
[GSOC] ref-filter: use switch/case instead of if/else
[GSOC] ref-filter: reuse final buffer
[GSOC] ref-filter: reduce unnecessary object_info comparisons
[GSOC] ref-filter: instead CALLOC_ARRAY() to ALLOC_ARRAY()
[GSOC] ref-filter: reuse object content
```
My git development is mainly divided into three stages:
1. Implement `git cat-file --batch` driver in ref-filter.
* Support `%(raw)` atom in ref-filter, which can print the raw data
of the object.
```sh
$ git for-each-ref --format="%(raw)" refs/tags/v2.33.0
object 225bc32a989d7a22fa6addafd4ce7dcd04675dbf
type commit
tag v2.33.0
tagger Junio C Hamano <gitster@pobox.com> 1629141357 -0700
Git 2.33
-----BEGIN PGP SIGNATURE-----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=IF1E
-----END PGP SIGNATURE-----
```
* Support `%(rest)` atom in ref-filter, which only used for
cat-file mode, which can split
the input lines at the first whitespace boundary, all characters
before that whitespace are considered to be the object name;
characters after that first run of whitespace are output in place
of the `%(rest)` atom.
These atoms will be used as the backend of `git cat-file --batch`.
2. Refactor `git cat-file --batch` to reuse the logic of ref-filter.
* The default format of `git cat-file --batch-check` is equivalent to
`%(objectname) %(objecttype) %(objectsize)` in ref-filter.
* The default format of `git cat-file --batch` is equivalent to
`%(objectname) %(objecttype) %(objectsize)\n%(raw)` in ref-filter.
* Use `verify_ref_format()` to parse the atoms needed by `git cat-file --batch`.
* Use `format_ref_array_item()` to get the specific data of the object.
* Make `git cat-file` options `--textconv`, `--filters` available for `--batch`.
They can work well in the `git cat-file` environment, but require a
lot of adaptation.
Now `git cat-file --batch` extra supports these atoms:
```
%(tree)
%(parent)
%(numparent)
%(object)
%(type)
%(tag)
%(author)
%(authorname)
%(authoremail)
%(authordate)
%(committer)
%(committername)
%(committeremail)
%(committerdate)
%(tagger)
%(taggername)
%(taggeremail)
%(taggerdate)
%(creator)
%(creatordate)
%(subject)
%(body)
%(trailers)
%(contents)
%(raw)
%(color)
%(align)
%(end)
%(if)
%(then)
%(else)
```
At the same time, it can also support deref atom (e.g. `%(*commiter)`)
and atom attribute(e.g. `%(objectname:short=1)`).
3. Optimize ref-filter performance.
* In the initial refactoring, `git cat-file --batch` have a severe
performance
degradation
[link](https://lore.kernel.org/git/87eecf8ork.fsf@evledraar.gmail.com/),
this is because the step of obtaining object data in ref-filter
will generate some
intermediate data `atom_value` to be used by `git for-each-ref
--sort`, which will
lead to more copying and more memory allocating in its logic.
* I made some changes to solve the problem of performance degradation:
1. Skip unnecessary object content parsing.
2. Save the format parsing results, reducing the second format parsing.
3. Reuse the output buffer and reduce copying.
4. Reuse object content buffer, reduce memory allocation and copy.
Current performance test results:
```
Test upstream/master this
tree
------------------------------------------------------------------------------------
1006.2: cat-file --batch-check 0.06(0.06+0.00)
0.08(0.07+0.00) +33.3%
1006.3: cat-file --batch-check with atoms 0.06(0.04+0.01)
0.06(0.06+0.00) +0.0%
1006.4: cat-file --batch 0.49(0.47+0.02)
0.48(0.47+0.01) -2.0%
1006.5: cat-file --batch with atoms 0.48(0.44+0.03)
0.47(0.46+0.01) -2.1%
```
The performance of `git cat-file --batch` is about 2% better than before,
and the performance of `git cat-file --batch-check` is about 33%
worse than before.
But in fact, there is little difference with `git cat-file --batch-check`,
their execution time only differs by 5ms:
```
upstream/master (225bc32a98):
$ hyperfine --warmup=10 "~/git/bin-wrappers/git cat-file
--batch-check --batch-all-objects"
Benchmark #1: ~/git/bin-wrappers/git cat-file --batch-check
--batch-all-objects
Time (mean ± σ): 596.2 ms ± 5.7 ms [User: 563.0 ms,
System: 32.5 ms]
Range (min … max): 586.9 ms … 607.9 ms 10 runs
cat-file-reuse-ref-filter-logic (709a0c5c12):
$ hyperfine --warmup=10 "~/git/bin-wrappers/git cat-file
--batch-check --batch-all-objects"
Benchmark #1: ~/git/bin-wrappers/git cat-file --batch-check
--batch-all-objects
Time (mean ± σ): 601.3 ms ± 5.8 ms [User: 566.9 ms,
System: 33.9 ms]
Range (min … max): 596.7 ms … 613.3 ms 10 runs
```
And `git cat-file --batch-check` can be 0.5s faster than before!
```
upstream/master (225bc32a98):
$ time git cat-file --batch --batch-all-objects
>/dev/null
/home/adl/git/bin-wrappers/git cat-file --batch --batch-all-objects >
24.61s user 0.30s system 99% cpu 24.908 total
cat-file-reuse-ref-filter-logic (709a0c5c12):
$ time git cat-file --batch --batch-all-objects >/dev/null
cat-file --batch --batch-all-objects > /dev/null 25.10s user 0.30s
system 99% cpu 25.417 total
```
The performance optimization patches have been submitted to the
mailing list and are waiting for review by reviewers and mentors.
### What have I learned during this period of time?
* I learned how to use performance testing tools such as `gprof`, `perf`, etc.
* I read the implementation of multiple git sub commands, understand
how to use them and modify them.
* I used to think that participating in open source is a very distant thing.
After participating in GSOC this time, I realized that open source is actually
very close to us, and it is a very fun and very cool thing.
### Concluding remarks
This summer vacation, I have gained a lot, also made a lot of friends.
Thanks to Google and Git.
Thanks to those people who have helped me!
Thanks to my two mentors Christian and Hariom.
Three months ago, at the beginning of GSoC, I cited the example
of Junio's interview:
[[GSoC] Hello Git](https://lore.kernel.org/git/CAOLTT8SHE-ok3D+oLNSWFi7KPU==VQnTMDmC4YxUyNBJKmBD8A@mail.gmail.com/).
As an echo, I will maintain a passion for open source and technology,
and continue to participate in the development and maintenance of the
Git community.
Thanks.
--
ZheNing Hu
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [GSoC] Git Final Blog
2021-08-19 5:39 [GSoC] Git Final Blog ZheNing Hu
@ 2021-08-20 16:22 ` Christian Couder
2021-08-20 17:56 ` Junio C Hamano
2021-08-22 17:13 ` Kaartic Sivaraam
1 sibling, 1 reply; 5+ messages in thread
From: Christian Couder @ 2021-08-20 16:22 UTC (permalink / raw)
To: ZheNing Hu
Cc: Git List, Hariom verma, Junio C Hamano, Jeff King, Eric Sunshine,
Ævar Arnfjörð Bjarmason, Jacob Keller,
Bagas Sanjaya,
Оля
Тележная,
Denton Liu, Felipe Contreras, Phillip Wood, Atharva Raykar
On Thu, Aug 19, 2021 at 7:39 AM ZheNing Hu <adlternative@gmail.com> wrote:
>
> My final week blog finished:
> The web version is here:
> https://adlternative.github.io/GSOC-Git-Final-Blog/
Great, thanks!
> ## Git Final Blog
[...]
> ### Concluding remarks
>
> This summer vacation, I have gained a lot, also made a lot of friends.
>
> Thanks to Google and Git.
>
> Thanks to those people who have helped me!
>
> Thanks to my two mentors Christian and Hariom.
Thanks for all the work you did, and for your enthusiasm, dedication
and involvement with the mailing list!
> Three months ago, at the beginning of GSoC, I cited the example
> of Junio's interview:
> [[GSoC] Hello Git](https://lore.kernel.org/git/CAOLTT8SHE-ok3D+oLNSWFi7KPU==VQnTMDmC4YxUyNBJKmBD8A@mail.gmail.com/).
> As an echo, I will maintain a passion for open source and technology,
> and continue to participate in the development and maintenance of the
> Git community.
Great! We are looking forward to continuing to work with you!
Best,
Christian.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [GSoC] Git Final Blog
2021-08-20 16:22 ` Christian Couder
@ 2021-08-20 17:56 ` Junio C Hamano
2021-08-21 3:18 ` ZheNing Hu
0 siblings, 1 reply; 5+ messages in thread
From: Junio C Hamano @ 2021-08-20 17:56 UTC (permalink / raw)
To: Christian Couder
Cc: ZheNing Hu, Git List, Hariom verma, Jeff King, Eric Sunshine,
Ævar Arnfjörð Bjarmason, Jacob Keller,
Bagas Sanjaya,
Оля
Тележная,
Denton Liu, Felipe Contreras, Phillip Wood, Atharva Raykar
Christian Couder <christian.couder@gmail.com> writes:
> On Thu, Aug 19, 2021 at 7:39 AM ZheNing Hu <adlternative@gmail.com> wrote:
>>
>> My final week blog finished:
>> The web version is here:
>> https://adlternative.github.io/GSOC-Git-Final-Blog/
>
> Great, thanks!
>
>> ## Git Final Blog
>
> [...]
>
>> ### Concluding remarks
>>
>> This summer vacation, I have gained a lot, also made a lot of friends.
>>
>> Thanks to Google and Git.
>>
>> Thanks to those people who have helped me!
>>
>> Thanks to my two mentors Christian and Hariom.
>
> Thanks for all the work you did, and for your enthusiasm, dedication
> and involvement with the mailing list!
>
>> Three months ago, at the beginning of GSoC, I cited the example
>> of Junio's interview:
>> [[GSoC] Hello Git](https://lore.kernel.org/git/CAOLTT8SHE-ok3D+oLNSWFi7KPU==VQnTMDmC4YxUyNBJKmBD8A@mail.gmail.com/).
>> As an echo, I will maintain a passion for open source and technology,
>> and continue to participate in the development and maintenance of the
>> Git community.
>
> Great! We are looking forward to continuing to work with you!
Surely.
We hope each participant had developed useful skills, found that
contributing to an open source project is fun, and most importantly,
had a great fun.
I hate to see the "Final" label on these messages. Even thoguh this
round of GSoC may be coming to an end, don't become a stranger ;-)
Thanks.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [GSoC] Git Final Blog
2021-08-20 17:56 ` Junio C Hamano
@ 2021-08-21 3:18 ` ZheNing Hu
0 siblings, 0 replies; 5+ messages in thread
From: ZheNing Hu @ 2021-08-21 3:18 UTC (permalink / raw)
To: Junio C Hamano
Cc: Christian Couder, Git List, Hariom verma, Jeff King,
Eric Sunshine, Ævar Arnfjörð Bjarmason,
Jacob Keller, Bagas Sanjaya,
Оля
Тележная,
Denton Liu, Felipe Contreras, Phillip Wood, Atharva Raykar
Junio C Hamano <gitster@pobox.com> 于2021年8月21日周六 上午1:56写道:
>
> Christian Couder <christian.couder@gmail.com> writes:
>
> > On Thu, Aug 19, 2021 at 7:39 AM ZheNing Hu <adlternative@gmail.com> wrote:
> >>
> >> My final week blog finished:
> >> The web version is here:
> >> https://adlternative.github.io/GSOC-Git-Final-Blog/
> >
> > Great, thanks!
> >
> >> ## Git Final Blog
> >
> > [...]
> >
> >> ### Concluding remarks
> >>
> >> This summer vacation, I have gained a lot, also made a lot of friends.
> >>
> >> Thanks to Google and Git.
> >>
> >> Thanks to those people who have helped me!
> >>
> >> Thanks to my two mentors Christian and Hariom.
> >
> > Thanks for all the work you did, and for your enthusiasm, dedication
> > and involvement with the mailing list!
> >
> >> Three months ago, at the beginning of GSoC, I cited the example
> >> of Junio's interview:
> >> [[GSoC] Hello Git](https://lore.kernel.org/git/CAOLTT8SHE-ok3D+oLNSWFi7KPU==VQnTMDmC4YxUyNBJKmBD8A@mail.gmail.com/).
> >> As an echo, I will maintain a passion for open source and technology,
> >> and continue to participate in the development and maintenance of the
> >> Git community.
> >
> > Great! We are looking forward to continuing to work with you!
>
> Surely.
>
> We hope each participant had developed useful skills, found that
> contributing to an open source project is fun, and most importantly,
> had a great fun.
>
Since Linus created Git in 2005, Git has been constantly changing and
improving. Even a small `git add`, it has a lot of content worth learning.
I think the greatest joy for me is my own feature can be used by people
all over the world :)
> I hate to see the "Final" label on these messages. Even thoguh this
> round of GSoC may be coming to an end, don't become a stranger ;-)
>
"GSoC" Final, "Git Play" Begin.
> Thanks.
>
Thanks.
--
ZheNing Hu
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [GSoC] Git Final Blog
2021-08-19 5:39 [GSoC] Git Final Blog ZheNing Hu
2021-08-20 16:22 ` Christian Couder
@ 2021-08-22 17:13 ` Kaartic Sivaraam
1 sibling, 0 replies; 5+ messages in thread
From: Kaartic Sivaraam @ 2021-08-22 17:13 UTC (permalink / raw)
To: ZheNing Hu
Cc: Hariom verma, Christian Couder, Junio C Hamano, Jeff King,
Eric Sunshine, Ævar Arnfjörð Bjarmason,
Jacob Keller, Bagas Sanjaya,
Оля
Тележная,
Denton Liu, Felipe Contreras, phillip.wood, Atharva Raykar,
Git List
Hi ZheNing Hu,
On 19/08/21 11:09 am, ZheNing Hu wrote:
> My final week blog finished:
> The web version is here:
> https://adlternative.github.io/GSOC-Git-Final-Blog/
>
> ## Git Final Blog
Nice blog!
>
> These patches were staying on the `next` branch and waiting to merge
> to `master`,
> you can view them here:
> [link](https://github.com/gitgitgadget/git/issues?q=adlternative+created%3A%3E2021-05-19+label%3Anext).
Just a suggestion. The above link also lists a patch which has already
been merged to `master`. You could use the following link which explicitly
lists only the patches that are on `next` but not on `master`:
https://github.com/gitgitgadget/git/issues?q=adlternative+created%3A%3E2021-05-19+label%3Anext+-label%3Amaster
> ### Concluding remarks
>
> This summer vacation, I have gained a lot, also made a lot of friends.
>
> Thanks to Google and Git.
>
> Thanks to those people who have helped me!
>
> Thanks to my two mentors Christian and Hariom.
>
> Three months ago, at the beginning of GSoC, I cited the example
> of Junio's interview:
> [[GSoC] Hello Git](https://lore.kernel.org/git/CAOLTT8SHE-ok3D+oLNSWFi7KPU==VQnTMDmC4YxUyNBJKmBD8A@mail.gmail.com/).
> As an echo, I will maintain a passion for open source and technology,
> and continue to participate in the development and maintenance of the
> Git community.
>
It's good to see your enthusiasm for working on Git. See you around on
the list :-)
--
Sivaraam
^ permalink raw reply [flat|nested] 5+ messages in thread
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2021-08-19 5:39 [GSoC] Git Final Blog ZheNing Hu
2021-08-20 16:22 ` Christian Couder
2021-08-20 17:56 ` Junio C Hamano
2021-08-21 3:18 ` ZheNing Hu
2021-08-22 17:13 ` Kaartic Sivaraam
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