lib: replace protobuf crate with prost

.github/workflows/build.yml

@@ -42,6 +42,20 @@ jobs:
       env:
         RUST_BACKTRACE: 1
 
+  check-protos:
+    name: Check protos
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b
+      - uses: dtolnay/rust-toolchain@e645b0cf01249a964ec099494d38d2da0f0b349f
+        with:
+          toolchain: stable
+      - run: sudo apt update && sudo apt-get -y install protobuf-compiler
+      - name: Generate Rust code from .proto files
+        run: cargo run -p gen-protos
+      - name: Check for uncommitted changes
+        run: git diff-files -p --exit-code
+
   rustfmt:
     name: Check formatting
     runs-on: ubuntu-latest

Cargo.toml

@@ -31,7 +31,7 @@ name = "diff_bench"
 harness = false
 
 [workspace]
-members = ["lib", "lib/testutils"]
+members = ["lib", "lib/testutils", "lib/gen-protos"]
 
 [dependencies]
 chrono = { version = "0.4.23", default-features = false, features = ["std", "clock"] }

README.md

@@ -228,6 +228,11 @@ cargo install --git https://github.com/martinvonz/jj.git --bin jj
 
 
 ### Windows
+Due to [a protobuf-src
+limitation](https://github.com/MaterializeInc/rust-protobuf-native/issues/4),
+`protoc` must be provided manually. See ([prost-build's
+instructions](https://github.com/tokio-rs/prost/tree/master/prost-build#protoc))
+for details.
 
 Run:
 ```shell script

lib/Cargo.toml

@@ -14,7 +14,6 @@ readme = "../README.md"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [build-dependencies]
-protobuf-codegen = "3.2.0"
 version_check = "0.9.4"
 
 [dependencies]
@@ -32,7 +31,6 @@ maplit = "1.0.2"
 once_cell = "1.16.0"
 pest = "2.5.1"
 pest_derive = "2.5.1"
-protobuf = { version = "3.0.1", features = ["with-bytes"] }
 regex = "1.7.0"
 serde_json = "1.0.91"
 tempfile = "3.3.0"
@@ -42,6 +40,7 @@ uuid = { version = "1.2.2", features = ["v4"] }
 whoami = "1.2.3"
 zstd = "0.12.1"
 tracing = "0.1.37"
+prost = "0.11.5"
 
 [dev-dependencies]
 assert_matches = "1.5.0"

lib/build.rs

@@ -12,24 +12,12 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-fn main() {
-    let input = &[
-        "src/protos/op_store.proto",
-        "src/protos/store.proto",
-        "src/protos/working_copy.proto",
-    ];
-    protobuf_codegen::Codegen::new()
-        .pure()
-        .inputs(input)
-        .include("src/protos")
-        .cargo_out_dir("protos")
-        .run_from_script();
+fn main() -> std::io::Result<()> {
     println!("cargo:rerun-if-changed=build.rs");
-    for file in input {
-        println!("cargo:rerun-if-changed={file}");
-    }
 
     if let Some(true) = version_check::supports_feature("map_first_last") {
         println!("cargo:rustc-cfg=feature=\"map_first_last\"");
     }
+
+    Ok(())
 }

lib/gen-protos/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "gen-protos"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]
+prost-build = "0.11.5"

lib/gen-protos/src/main.rs

@@ -0,0 +1,20 @@
+use std::io::Result;
+use std::path::Path;
+
+fn main() -> Result<()> {
+    let input = ["op_store.proto", "store.proto", "working_copy.proto"];
+
+    let root = Path::new(env!("CARGO_MANIFEST_DIR")).parent().unwrap();
+    let protos_dir = root.join("src").join("protos");
+
+    prost_build::Config::new()
+        .out_dir(&protos_dir)
+        .include_file("mod.rs")
+        .compile_protos(
+            &input
+                .into_iter()
+                .map(|x| protos_dir.join(x))
+                .collect::<Vec<_>>(),
+            &[protos_dir],
+        )
+}

lib/src/git_backend.rs

@@ -20,7 +20,7 @@ use std::sync::{Arc, Mutex};
 
 use git2::Oid;
 use itertools::Itertools;
-use protobuf::Message;
+use prost::Message;
 use uuid::Uuid;
 
 use crate::backend::{
@@ -126,17 +126,18 @@ fn signature_to_git(signature: &Signature) -> git2::Signature {
 }
 
 fn serialize_extras(commit: &Commit) -> Vec<u8> {
-    let mut proto = crate::protos::store::Commit::new();
-    proto.change_id = commit.change_id.to_bytes();
+    let mut proto = crate::protos::store::Commit {
+        change_id: commit.change_id.to_bytes(),
+        ..Default::default()
+    };
     for predecessor in &commit.predecessors {
         proto.predecessors.push(predecessor.to_bytes());
     }
-    proto.write_to_bytes().unwrap()
+    proto.encode_to_vec()
 }
 
 fn deserialize_extras(commit: &mut Commit, bytes: &[u8]) {
-    let mut cursor = Cursor::new(bytes);
-    let proto: crate::protos::store::Commit = Message::parse_from_reader(&mut cursor).unwrap();
+    let proto = crate::protos::store::Commit::decode(bytes).unwrap();
     commit.change_id = ChangeId::new(proto.change_id);
     for predecessor in &proto.predecessors {
         commit.predecessors.push(CommitId::from_bytes(predecessor));