How to use the raft-rs crate and build with cargo? - rust

Question

I try to build the single_mem_node example, but as a standalone example and use the raft-rs crate as a library.
But unfortunately, I get this build error, when building using cargo build
error[E0599]: no method named `is_empty` found for reference `&raft_proto::protos::eraftpb::Snapshot` in the current scope
--> src/main.rs:123:26
|
123 | if !ready.snapshot().is_empty() {
| ^^^^^^^^ method not found in `&raft_proto::protos::eraftpb::Snapshot`
I have declared these dependencies in my Cargo.toml
[dependencies]
protobuf = { version = "2", features = ["with-bytes"] }
raft = "0.6.0-alpha"
slog = "2.5.2"
slog-term = "2.6.0"
slog-async = "2.5.0"
The instructions on how to use the raft-rs crate is:
You can use raft with either rust-protobuf or Prost to encode/decode gRPC messages. We use rust-protobuf by default. To use Prost, build (or depend on) Raft using the prost-codec feature and without default features.
It certainly looks like I miss something around the protobuf... but what? and how do I find out about it?

Answer 1

It looks like the method was added in this commit, after version 0.6.0-alpha was released. GitHub shows the master branch by default, so in the future, try browsing at the commit that corresponds to the version you are using. In this case it is not tagged properly but I think this commit is the published 0.6.0-alpha version. In the example at that commit, the corresponding line is:
if !raft::is_empty_snap(ready.snapshot()) {
Alternatively, since it seems that 0.6.0-alpha was released in July of 2019, if you want the latest changes on master, you could change the dependency in Cargo.toml to read:
raft = { git = "https://github.com/tikv/raft-rs" }
In that case, cargo will fetch the latest commit and store its hash in Cargo.lock, and you can update to a newer commit with cargo update.