Prust

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prust is a protobuf implementation for Rust. prust generates simple and high performance code from proto2 or proto3 files.

Compare to other implementations

• Highly optimized code, prust calculates everything when generating, so less calculating at runtime
• Zero dependency, prust do not need that, no extra bloat
• grpc is supported by default (with tonic)
• Less build time, since we don't need to expand proc macros
• group is not supported, since it is deprecated too.
• No more protoc, prust handles parsing itself.

Sizes

prust generates structs and implements Deserialize and Serialize, so the generated file is a little bit larger than prost, but still smaller than the prost's expanded code.

File	Crate	Lines	Sizes
proto2/data_types.proto	prust	423	18054
	prost	165	6571
proto3/data_types.proto	prust	383	17540
	prost	165	6603

Performance

With our workload which covers lots of cases, prust works very well. The decoding performance almost catch up quick-protobuf, which uses Cow to improve performance(while prust don't ). And the encoding performance is around 2x faster than prost. With different workload, prust performance will be different too, users must verify it if you want to switch to prust.

Decoding 6000 times
prost:   964.93 op/s,   377.62 M/s, 6.22s
quick:  1426.05 op/s,   558.08 M/s, 4.21s
prust:  1235.72 op/s,   483.60 M/s, 4.86s

Encoding 6000 times
prost:  1577.11 op/s,   617.20 M/s, 3.80s
quick:  1956.55 op/s,   765.69 M/s, 3.07s
prust:  3375.67 op/s,  1321.06 M/s, 1.78s

NOTE: prost seems leak memory, it takes 2.1G to finish our test, while others takes only 1.1M.

Example

• Add prust and prust-build to your Cargo.toml

[build-dependencies]
prust-build = 0.1
 
[dependencies]
prust = 0.1

• add compile functions to build.rs

fn main() {
    prust_build::Config::default()
        .compile(&["/path/to/include"], &["/path/to/your.proto"])
        .unwrap();
}

• Include whatever the prust generated

Note: by default, generated filename is package field in *.proto, if it is not specified, prust will use the proto's filename.

mod proto {
    include!(concat!(env!("OUT_DIR"), "/package.rs"));
}

use proto::Data;
use prust::{Deserialize, Serialize};

fn main() {
    let data = Data::decode(input).unwrap();

    let len = data.encoded_len();
    let buf = vec![0; len];
    data.encode(&mut buf).unwrap();
}

Grpc

Grpc is supported and the generated file works with tonic, and the generated file is just like tonic does, so switching from tonic to prust is very easy.

1. enable tonic feature of prust
2. fix the use path in your rust file
3. running your program or test

A running example can be found in the conformance/tests/services/health.rs

TODO

• implement default value for map's key and value, which will reduce encoded size and resource usage it hurt the performance a little bit.
• it seems that access data via *const u8 is better than slice[pos], more test needed.
• support Well-Known Types
• prust cannot handle recursive types