Patchwork [01,of,13] rust-chg: add project skeleton

# HG changeset patch
# User Yuya Nishihara <yuya@tcha.org>
# Date 1537772058 -32400
#      Mon Sep 24 15:54:18 2018 +0900
# Node ID 4cb12a1e78262428caec486fde361e562a205f63
# Parent  1a7d901a0a0c6c93e738595b6b3ea59d3d04fdf2
rust-chg: add project skeleton

This directory will host the reimplementation of cHg in Rust. It will use
Tokio [1], and tokio-hglib [2] which I wrote for an oxidized CHg, no idea
if there's such carbon bonding in nature btw.

 [1]: https://tokio.rs/
 [2]: https://bitbucket.org/yuja/tokio-hglib/

The reasoning for depending on Tokio is that it will allow us to handle Unix
signals in a safer way. Well, I believed that until I found a weird function,
handlestopsignal(), in cHg codebase. It resends the same signal to the same
process by temporarily masking the handler, which can't be inherently async.
So the signal handlers will stay in C, which means there isn't actually much
reason to write async code right now, other than I've already done most of
the async stuff, and slightly easier pager handling.

The reasoning for the rewrite is that it will eventually be possible to port
server-side config validation back to the client side, which will reduce
the complexity of the current daemon management. It will also encourage us
to write frontend library (e.g. command line and config parsers) in Rust.

The license is GPL2+ because it's likely to include derived work from the
cHg of C. The rust/chg crate is excluded from the root workspace as it's
unclear how the whole rust packages should be laid out. That can be revisited
later.

On Tue, Oct 2, 2018 at 7:32 AM Yuya Nishihara <yuya@tcha.org> wrote:

> # HG changeset patch
> # User Yuya Nishihara <yuya@tcha.org>
> # Date 1537772058 -32400
> #      Mon Sep 24 15:54:18 2018 +0900
> # Node ID 4cb12a1e78262428caec486fde361e562a205f63
> # Parent  1a7d901a0a0c6c93e738595b6b3ea59d3d04fdf2
> rust-chg: add project skeleton
>

Queued with delight!

I also am not sure what the final layout of the rust/ directory/workspace
will look like: I imagine that once we support `hg` as a Rust binary, we
may want some of this chg client functionality baked into `hg` itself. But
we can cross that bridge later: the important thing is to get working code
authored first. We can refactor later.


>
> This directory will host the reimplementation of cHg in Rust. It will use
> Tokio [1], and tokio-hglib [2] which I wrote for an oxidized CHg, no idea
> if there's such carbon bonding in nature btw.
>
>  [1]: https://tokio.rs/
>  [2]: https://bitbucket.org/yuja/tokio-hglib/
>
> The reasoning for depending on Tokio is that it will allow us to handle
> Unix
> signals in a safer way. Well, I believed that until I found a weird
> function,
> handlestopsignal(), in cHg codebase. It resends the same signal to the same
> process by temporarily masking the handler, which can't be inherently
> async.
> So the signal handlers will stay in C, which means there isn't actually
> much
> reason to write async code right now, other than I've already done most of
> the async stuff, and slightly easier pager handling.
>
> The reasoning for the rewrite is that it will eventually be possible to
> port
> server-side config validation back to the client side, which will reduce
> the complexity of the current daemon management. It will also encourage us
> to write frontend library (e.g. command line and config parsers) in Rust.
>
> The license is GPL2+ because it's likely to include derived work from the
> cHg of C. The rust/chg crate is excluded from the root workspace as it's
> unclear how the whole rust packages should be laid out. That can be
> revisited
> later.
>
> diff --git a/.hgignore b/.hgignore
> --- a/.hgignore
> +++ b/.hgignore
> @@ -56,6 +56,7 @@ locale/*/LC_MESSAGES/hg.mo
>  hgext/__index__.py
>
>  rust/target/
> +rust/*/target/
>
>  # Generated wheels
>  wheelhouse/
> diff --git a/rust/Cargo.toml b/rust/Cargo.toml
> --- a/rust/Cargo.toml
> +++ b/rust/Cargo.toml
> @@ -1,2 +1,3 @@
>  [workspace]
>  members = ["hgcli"]
> +exclude = ["chg"]
> diff --git a/rust/chg/Cargo.toml b/rust/chg/Cargo.toml
> new file mode 100644
> --- /dev/null
> +++ b/rust/chg/Cargo.toml
> @@ -0,0 +1,18 @@
> +[package]
> +name = "chg"
> +version = "0.1.0"
> +authors = ["Yuya Nishihara <yuya@tcha.org>"]
> +description = "Client for Mercurial command server with cHg extension"
> +license = "GPL-2.0+"
> +
> +[dependencies]
> +bytes = "0.4"
> +futures = "0.1"
> +libc = "0.2"
> +tokio = "0.1"
> +tokio-hglib = "0.2"
> +# TODO: "^0.2.3" once released. we need AsRawFd support.
> +tokio-process = { git = "https://github.com/alexcrichton/tokio-process" }
> +
> +[build-dependencies]
> +cc = "1.0"
> diff --git a/rust/chg/src/lib.rs b/rust/chg/src/lib.rs
> new file mode 100644
> diff --git a/rust/chg/src/main.rs b/rust/chg/src/main.rs
> new file mode 100644
> --- /dev/null
> +++ b/rust/chg/src/main.rs
> @@ -0,0 +1,7 @@
> +// Copyright 2018 Yuya Nishihara <yuya@tcha.org>
> +//
> +// This software may be used and distributed according to the terms of the
> +// GNU General Public License version 2 or any later version.
> +
> +fn main() {
> +}
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