Use clang-format instead of cpplint

[PragmaTwice]

It closes the clang-format part of #800.

Note: Although it is not recommanded, but developers can disable clang-format for specific code snippets via:

// clang-format off

code that do not want to be formatted

// clang-format on

---

To format code:

./x.py format

To check whether code is formatted:

./x.py check format

To use a custom clang-format:

./x.py format --clang-format-path <path>

[tisonkun]

This changes seems in a good direction. Comments inline.

[torwig]

@PragmaTwice Good job!

[git-hulk]

@PragmaTwice Good job!

I also like this change, cpplint can't auto fix is too frustrate.

[git-hulk]

@PragmaTwice Can you help to rebase those commits, I don't know which commit should I start looking.

[tisonkun]

Generated? Could you share how you gain this config file?

[PragmaTwice]

1. cd to a non-project directory
2. clang-format-12 -style=google -dump-config > .clang-format
3. change ColumnLimit to 120

[tisonkun]

I'd prefer ColumnLimit to 200...Nowadays display device is far wider than 80 or 120 already, and wrap function calls or string literals are really clumsy.

[PragmaTwice]

The old limit is 120, so I just inherit it. I think maybe 200 is not friendly to my small 1080p laptop 🤣 , but I am open for it. What do other guys think about it? cc @git-hulk @torwig @caipengbo @ShooterIT

[caipengbo]

I also think 120 is enough, we should rarely have too long lines?

[torwig]

I think 120 is a good decision. Of course, we can use even 200, but 120 makes developers think if the length of the line is more than 120 characters.

[tanruixiang]

I also think 120 is enough.

[PragmaTwice]

@PragmaTwice Can you help to rebase those commits, I don't know which commit should I start looking.

You can just review three file: x.py, .github/workflows/kvrocks.yml and .clang-format, all of other file changes are made by clang-format.

[torwig]

@PragmaTwice You can squash a bunch of fix commits so they won't be merged in the unstable branch in the current representation :)

[tisonkun]

Thanks for your updates! Two comments inline.

[tisonkun]

@PragmaTwice You can squash a bunch of fix commits so they won't be merged in the unstable branch in the current representation :)

@torwig I think we're using squash and merge here :)

[torwig]

@tisonkun Perhaps I'm too old, but I do "squashing" by myself :)