schema: Conditionally enable serde support

.github/workflows/rust.yml

@@ -30,3 +30,23 @@ jobs:
       run: cargo build --all --features=tokio
     - name: Run tests
       run: cargo test --all --features=tokio
+  build-serde:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install Protoc
+      uses: arduino/setup-protoc@v3
+    - name: Build
+      run: cargo build --all --features=serde
+    - name: Run tests
+      run: cargo test --all --features=serde
+  build-serde-tokio:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install Protoc
+      uses: arduino/setup-protoc@v3
+    - name: Build
+      run: cargo build --all --features=serde,tokio
+    - name: Run tests
+      run: cargo test --all --features=serde,tokio

Cargo.toml

@@ -21,6 +21,7 @@ pbjson-build = "0.6.2"
 pbjson-types = "0.6.0"
 prost = "0.12.6"
 prost-build = "0.12.6"
+prost-types = "0.12.6"
 serde = "1.0.211"
 serde_yaml = "0.9.34"
 thiserror = "1.0.64"

crates/layer/Cargo.toml

@@ -27,3 +27,16 @@ tracing-appender.workspace = true
 
 [features]
 tokio = ["dep:tokio"]
+serde = ["tracing-perfetto-sdk-schema/serde"]
+
+[[example]]
+name = "native-layer"
+required-features = ["serde"]
+
+[[example]]
+name = "perfetto-dump-trace"
+required-features = ["serde"]
+
+[[example]]
+name = "sdk-layer"
+required-features = ["serde"]

crates/schema/Cargo.toml

@@ -7,12 +7,16 @@ version.workspace = true
 edition.workspace = true
 
 [dependencies]
-pbjson.workspace = true
-pbjson-types.workspace = true
+pbjson = { workspace = true, optional = true }
+pbjson-types = { workspace = true, optional = true }
 prost.workspace = true
-serde.workspace = true
+prost-types.workspace = true
+serde = { workspace = true, optional = true }
 
 [build-dependencies]
 anyhow.workspace = true
-pbjson-build.workspace = true
+pbjson-build = { workspace = true, optional = true }
 prost-build.workspace = true
+
+[features]
+serde = ["dep:pbjson", "dep:pbjson-types", "dep:pbjson-build", "dep:serde"]

crates/schema/build.rs

@@ -10,19 +10,43 @@ fn main() -> anyhow::Result<()> {
         println!("cargo:rerun-if-changed={}", proto_file.display());
     }
 
+    compile(proto_files, &[proto_root])?;
+
+    Ok(())
+}
+
+#[cfg(not(feature = "serde"))]
+// Compile for `serde`: emit a file descriptor set, substitute `prost_types` for
+// `pbjson_types`, and use `pbjson_build` to generate serde traits.
+fn compile(
+    proto_files: &[impl AsRef<path::Path>],
+    includes: &[impl AsRef<path::Path>],
+) -> anyhow::Result<()> {
+    prost_build::Config::new()
+        .bytes(["."])
+        .compile_protos(proto_files, includes)?;
+    Ok(())
+}
+
+#[cfg(feature = "serde")]
+// Compile for `serde`: emit a file descriptor set, substitute `prost_types` for
+// `pbjson_types`, and use `pbjson_build` to generate serde traits.
+fn compile(
+    proto_files: &[impl AsRef<path::Path>],
+    includes: &[impl AsRef<path::Path>],
+) -> anyhow::Result<()> {
     let descriptor_path = path::PathBuf::from(env::var("OUT_DIR")?).join("proto_descriptor.bin");
 
     prost_build::Config::new()
         .bytes(["."])
         .file_descriptor_set_path(&descriptor_path)
         .compile_well_known_types()
         .extern_path(".google.protobuf", "::pbjson_types")
-        .compile_protos(proto_files, &[proto_root])?;
+        .compile_protos(proto_files, includes)?;
 
     let descriptor_set = std::fs::read(descriptor_path)?;
     pbjson_build::Builder::new()
         .register_descriptors(&descriptor_set)?
         .build(&[".perfetto"])?;
-
     Ok(())
 }

crates/schema/src/lib.rs

@@ -1,3 +1,8 @@
 //! # `tracing-perfetto-sdk-schema`: Internal crate containing the raw Perfetto proto schemata.
 include!(concat!(env!("OUT_DIR"), "/perfetto.protos.rs"));
-include!(concat!(env!("OUT_DIR"), "/perfetto.protos.serde.rs"));
+#[cfg(feature = "serde")]
+mod serde_impls {
+    use super::*;
+    // Only contains trait impls so no need to re-export
+    include!(concat!(env!("OUT_DIR"), "/perfetto.protos.serde.rs"));
+}