Re: [GSoC] Git Blog 12

ZheNing Hu [off-list ref] 于2021年8月10日周二 下午10:20写道：

Christian Couder [off-list ref] 于2021年8月10日周二 下午4:04写道：

quoted

quoted

parse_object_buffer(), let's take a look at the result of gprof again:

We need to call grab_sub_body_contents(), grab_person() to rescan the
buffer and extract the data.
What if we can combine these multiple scanning and parsing into one completion?
At least intuitively, this has an opportunity to improve performance.

Yeah, but is there a way to check that we indeed scan or parse the
same objects multiple times? This way we might get an idea about how
much scanning and parsing we could save.

I think find_subpos() called by grab_sub_body_contents() and find_wholine()
called by grab_person() are evidences that we are repeating iteratively.
But the proportion of time they occupy is too small. 0.0142% and 0.0109%

Using such a method may reduce some unnecessary scans [1]
But it can do very little optimization... 1.6%.
On the other hand, our optimization should focus on the default format of
`git cat-file --batch`.

My new idea is to need a fast path: when we use the default format,
let us directly execute get_object() to avoid unnecessary traversal
and checking.

Thanks,
--
ZheNing Hu

[1]: https://github.com/adlternative/git/commit/7d274971d2b5e1d4e6061d1e29e4a0b2c6a10ea5