Redis-protobuf exercise

Table of Contents

Cargo build scripts

Some projects require additional steps to run before they can be built, e.g. for code generation. Cargo supports this by means of a build.rs file.

Cargo build scripts (cont.)

  • build.rs is itself written in Rust. It resides in the root directory of your package, not in src/.

  • it can have its own list of dependencies via [build-dependencies]

  • input is communicated via environment variables

  • output files should be written to OUT_DIR

  • Cargo behavior can be controlled by writing commands to stdout.

Cargo build scripts (cont.)

Generated code is typically then included in another Rust source file:

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

Protocol buffers in Rust

Several crates exist - we’re going to use prost here.

Prost usage

By using prost::Message you get encode & decode functionality.

use prost::Message;
// ...
let mut buf = Vec::new(3);
a_proto_object.encode(&mut buf)?;

let another_proto_object = TheProtoObject::decode(a_vec.as_slice())?;