feat: Make protoc dependency optional (#72)

This PR makes the dependency on `prost-build` (and therefore `protoc`)
optional.

To do this, the rust source generated by `protoc` is copied in-tree, and
the build script will only recompile `.proto` files if the
`build_protos` feature is enabled.

This does introduce a potential point of confusion if the proto
definitions are modified, but presumably these are rarely changed.

.github/workflows/ci.yml

@@ -39,6 +39,13 @@ jobs:
       - name: Check linting
         run: cargo clippy --release --all-targets --all-features -- -D clippy::all
 
+      - name: Check generated protobuf sources are up to date
+        if: runner.os == 'Linux' || runner.os == 'macOS'
+        run: |-
+          cargo check -p denokv_proto --features='build_protos'
+          cargo fmt -p denokv_proto
+          git diff --exit-code
+
       - name: Build
         run: cargo build --release --all-targets --all-features --tests -v
 

proto/Cargo.toml

@@ -10,6 +10,9 @@ authors.workspace = true
 [lib]
 path = "lib.rs"
 
+[features]
+build_protos = ["prost-build"]
+
 [dependencies]
 anyhow.workspace = true
 async-trait.workspace = true
@@ -21,4 +24,4 @@ serde.workspace = true
 uuid.workspace = true
 
 [build-dependencies]
-prost-build.workspace = true
+prost-build = { workspace = true, optional = true }

proto/build.rs

@@ -1,23 +1,73 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
 
-use std::env;
 use std::io;
-use std::path::PathBuf;
 
-fn main() -> io::Result<()> {
-  println!("cargo:rerun-if-changed=./schema/datapath.proto");
-  println!("cargo:rerun-if-changed=./schema/backup.proto");
+#[cfg(feature = "build_protos")]
+mod build_protos {
+  use std::env;
+  use std::io;
+  use std::path::Path;
+  use std::path::PathBuf;
+  fn compiled_proto_path(proto: impl AsRef<Path>) -> PathBuf {
+    let proto = proto.as_ref();
+    let mut path = PathBuf::from(env::var("OUT_DIR").unwrap());
+    path.push(format!(
+      "com.deno.kv.{}.rs",
+      proto.file_stem().unwrap().to_str().unwrap()
+    ));
+    path
+  }
+
+  fn protobuf_module_path() -> PathBuf {
+    PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap()).join("protobuf")
+  }
+
+  fn protobuf_dest_path(compiled_proto_path: impl AsRef<Path>) -> PathBuf {
+    let mut path = protobuf_module_path();
+    path.push(compiled_proto_path.as_ref().file_name().unwrap());
+    path
+  }
+
+  fn copy_compiled_proto(proto: impl AsRef<Path>) -> io::Result<()> {
+    let generated = compiled_proto_path(proto);
+    let contents = std::fs::read_to_string(&generated)?;
+    let header = r"// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+// Generated by prost-build, enable the `build_protos` feature to regenerate.";
+
+    let contents = format!("{header}\n\n{}", contents);
+    std::fs::write(protobuf_dest_path(&generated), contents.as_bytes())?;
+    Ok(())
+  }
 
-  let descriptor_path =
-    PathBuf::from(env::var("OUT_DIR").unwrap()).join("proto_descriptor.bin");
+  pub fn build() -> io::Result<()> {
+    let descriptor_path =
+      PathBuf::from(env::var("OUT_DIR").unwrap()).join("proto_descriptor.bin");
 
-  prost_build::Config::new()
-    .file_descriptor_set_path(&descriptor_path)
-    .compile_well_known_types()
-    .compile_protos(
-      &["schema/datapath.proto", "schema/backup.proto"],
-      &["protobuf/"],
-    )?;
+    let protos = &["schema/datapath.proto", "schema/backup.proto"];
 
-  Ok(())
+    prost_build::Config::new()
+      .file_descriptor_set_path(&descriptor_path)
+      .compile_well_known_types()
+      .compile_protos(protos, &["schema/"])?;
+
+    for proto in protos {
+      copy_compiled_proto(proto)?;
+    }
+
+    Ok(())
+  }
+}
+
+fn main() -> io::Result<()> {
+  println!("cargo:rerun-if-changed=./schema/datapath.proto");
+  println!("cargo:rerun-if-changed=./schema/backup.proto");
+  #[cfg(feature = "build_protos")]
+  {
+    build_protos::build()
+  }
+  #[cfg(not(feature = "build_protos"))]
+  {
+    Ok(())
+  }
 }

proto/protobuf.rs

@@ -2,11 +2,9 @@
 
 // Generated code, disable lints
 #[allow(clippy::all, non_snake_case)]
-pub mod datapath {
-  include!(concat!(env!("OUT_DIR"), "/com.deno.kv.datapath.rs"));
-}
+#[path = "protobuf/com.deno.kv.datapath.rs"]
+pub mod datapath;
 
 #[allow(clippy::all, non_snake_case)]
-pub mod backup {
-  include!(concat!(env!("OUT_DIR"), "/com.deno.kv.backup.rs"));
-}
+#[path = "protobuf/com.deno.kv.backup.rs"]
+pub mod backup;

proto/protobuf/com.deno.kv.backup.rs

@@ -0,0 +1,84 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+// Generated by prost-build, enable the `build_protos` feature to regenerate.
+
+#[allow(clippy::derive_partial_eq_without_eq)]
+#[derive(Clone, PartialEq, ::prost::Message)]
+pub struct BackupSnapshotRange {
+  #[prost(message, repeated, tag = "1")]
+  pub data_list: ::prost::alloc::vec::Vec<BackupKvPair>,
+  #[prost(message, repeated, tag = "2")]
+  pub metadata_list: ::prost::alloc::vec::Vec<BackupKvPair>,
+}
+#[allow(clippy::derive_partial_eq_without_eq)]
+#[derive(Clone, PartialEq, ::prost::Message)]
+pub struct BackupKvPair {
+  #[prost(bytes = "vec", tag = "1")]
+  pub key: ::prost::alloc::vec::Vec<u8>,
+  #[prost(bytes = "vec", tag = "2")]
+  pub value: ::prost::alloc::vec::Vec<u8>,
+}
+#[allow(clippy::derive_partial_eq_without_eq)]
+#[derive(Clone, PartialEq, ::prost::Message)]
+pub struct BackupMutationRange {
+  #[prost(message, repeated, tag = "1")]
+  pub entries: ::prost::alloc::vec::Vec<BackupReplicationLogEntry>,
+  #[prost(uint64, tag = "2")]
+  pub timestamp_ms: u64,
+}
+#[allow(clippy::derive_partial_eq_without_eq)]
+#[derive(Clone, PartialEq, ::prost::Message)]
+pub struct BackupReplicationLogEntry {
+  #[prost(bytes = "vec", tag = "1")]
+  pub versionstamp: ::prost::alloc::vec::Vec<u8>,
+  #[prost(enumeration = "BackupKvMutationKind", tag = "2")]
+  pub kind: i32,
+  #[prost(bytes = "vec", tag = "3")]
+  pub key: ::prost::alloc::vec::Vec<u8>,
+  #[prost(bytes = "vec", tag = "4")]
+  pub value: ::prost::alloc::vec::Vec<u8>,
+  #[prost(int32, tag = "5")]
+  pub value_encoding: i32,
+  #[prost(uint64, tag = "6")]
+  pub expire_at_ms: u64,
+}
+#[derive(
+  Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, ::prost::Enumeration,
+)]
+#[repr(i32)]
+pub enum BackupKvMutationKind {
+  MkUnspecified = 0,
+  MkSet = 1,
+  MkClear = 2,
+  MkSum = 3,
+  MkMax = 4,
+  MkMin = 5,
+}
+impl BackupKvMutationKind {
+  /// String value of the enum field names used in the ProtoBuf definition.
+  ///
+  /// The values are not transformed in any way and thus are considered stable
+  /// (if the ProtoBuf definition does not change) and safe for programmatic use.
+  pub fn as_str_name(&self) -> &'static str {
+    match self {
+      BackupKvMutationKind::MkUnspecified => "MK_UNSPECIFIED",
+      BackupKvMutationKind::MkSet => "MK_SET",
+      BackupKvMutationKind::MkClear => "MK_CLEAR",
+      BackupKvMutationKind::MkSum => "MK_SUM",
+      BackupKvMutationKind::MkMax => "MK_MAX",
+      BackupKvMutationKind::MkMin => "MK_MIN",
+    }
+  }
+  /// Creates an enum from field names used in the ProtoBuf definition.
+  pub fn from_str_name(value: &str) -> ::core::option::Option<Self> {
+    match value {
+      "MK_UNSPECIFIED" => Some(Self::MkUnspecified),
+      "MK_SET" => Some(Self::MkSet),
+      "MK_CLEAR" => Some(Self::MkClear),
+      "MK_SUM" => Some(Self::MkSum),
+      "MK_MAX" => Some(Self::MkMax),
+      "MK_MIN" => Some(Self::MkMin),
+      _ => None,
+    }
+  }
+}