Sway status bar

This is a custom status bar using the swaybar protocol, each block is an async function. Because of how the swaybar protocol works, every block update forces all blocks to be updated, but using async means that less work is wasted on the bar side of things.

The code in main.rs should be fairly self explanatory if you want to modify this to your liking.

Installation

Run

cargo install --path .

then in your sway bar config, set:

    swaybar_command sway_status_bar

Binary size

Default binary size is ~500K. If you're interested in getting a smaller binary (174K on my laptop), then the following build options are the best I have found, without resorting to #![no_std] etc.:

RUSTFLAGS="-Ctarget-cpu=native \
-Zunstable-options \
-Zlocation-detail=none \
-Zfmt-debug=none \
-Cpanic=immediate-abort" \
\
cargo +nightly install --path . \
-Z build-std=std,panic_abort \
-Z build-std-features="optimize_for_size" \
--target $(rustc --print host-tuple)

• -Ctarget-cpu=native targets your particular CPU, rather than just architecture. This enables use of special instruction sets where applicable (probably mostly JSON serialization), which can help minimise assembly.
• -Zlocation-detail=none removes location detail for panic!() and [track_caller]. Since we're not planning on panic!ing, that's fine.
• -Zfmt-debug=none turns {:?} into a no-op. This will break any blocks that rely on debug formatting for some reason.
• -Z panic=immediate-abort removes panic formatting. This requires build-std.
• -Z build-std=std,panic_abort -Z build-std-features="optimize_for_size" --target $(rustc --print host-tuple) compiles the standard library, selecting algorithms which optimise for size, panic_abort causes panics inside std to abort rather than unwind. For some reason, core fails to compile with panic_abort if you don't pass a --target.

See min-sized-rust for information about these tricks and more

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Issues and PRs welcome.