layer: Introduce explicit "sdk" feature that can be disabled

.github/workflows/rust.yml

@@ -20,6 +20,16 @@ jobs:
       run: cargo build --all
     - name: Run tests
       run: cargo test --all
+  build-no-default-features:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install Protoc
+      uses: arduino/setup-protoc@v3
+    - name: Build
+      run: cargo build --all --no-default-features
+    - name: Run tests
+      run: cargo test --all --no-default-features
   build-tokio:
     runs-on: ubuntu-latest
     steps:

Cargo.toml

@@ -16,6 +16,7 @@ bytes = "1.8.0"
 cxx = { version = "1.0.129", features = ["c++17"] }
 cxx-build = { version = "1.0.129", features = ["parallel"] }
 futures = "0.3.31"
+nix =  "0.29.0"
 pbjson = "0.6.0"
 pbjson-build = "0.6.2"
 pbjson-types = "0.6.0"

crates/layer/Cargo.toml

@@ -9,14 +9,15 @@ edition.workspace = true
 [dependencies]
 bytes.workspace = true
 cxx.workspace = true
+nix = { workspace = true, features = ["time"] }
 prost.workspace = true
 thiserror.workspace = true
 thread-id.workspace = true
 thread_local.workspace = true
 tokio = { workspace = true, optional = true }
 tracing.workspace = true
 tracing-perfetto-sdk-schema.workspace = true
-tracing-perfetto-sdk-sys.workspace = true
+tracing-perfetto-sdk-sys = { workspace = true, optional = true }
 tracing-subscriber.workspace = true
 
 [dev-dependencies]
@@ -26,8 +27,10 @@ tokio = { workspace = true, features = ["macros", "time", "rt-multi-thread"] }
 tracing-appender.workspace = true
 
 [features]
+default = ["sdk"]
 tokio = ["dep:tokio"]
 serde = ["tracing-perfetto-sdk-schema/serde"]
+sdk = ["dep:tracing-perfetto-sdk-sys"]
 
 [[example]]
 name = "native-layer"

crates/layer/src/debug_annotations.rs

@@ -7,11 +7,13 @@ use schema::debug_annotation;
 use tracing::field;
 use tracing_perfetto_sdk_schema as schema;
 use tracing_perfetto_sdk_schema::track_event;
+#[cfg(feature = "sdk")]
 use tracing_perfetto_sdk_sys::ffi;
 
 const COUNTER_FIELD_PREFIX: &str = "counter.";
 const SUPPRESS_EVENT_FIELD: &str = "perfetto.suppress_event";
 
+#[cfg(feature = "sdk")]
 #[derive(Default)]
 pub struct FFIDebugAnnotations {
     counters: Vec<Counter>,
@@ -42,6 +44,7 @@ pub enum CounterValue {
     Int(i64),
 }
 
+#[cfg(feature = "sdk")]
 impl FFIDebugAnnotations {
     pub fn as_ffi(&self) -> ffi::DebugAnnotations {
         ffi::DebugAnnotations {
@@ -57,6 +60,7 @@ impl FFIDebugAnnotations {
     }
 }
 
+#[cfg(feature = "sdk")]
 impl field::Visit for FFIDebugAnnotations {
     fn record_f64(&mut self, field: &field::Field, value: f64) {
         if !populate_counter(&mut self.counters, field, value) {

crates/layer/src/init.rs

@@ -1,13 +1,17 @@
+#[cfg(feature = "sdk")]
 use tracing_perfetto_sdk_sys::ffi;
 
+#[allow(unused_variables)]
 pub fn global_init(enable_in_process_backend: bool, enable_system_backend: bool) {
+    #[cfg(feature = "sdk")]
     ffi::perfetto_global_init(
         log_callback,
         enable_in_process_backend,
         enable_system_backend,
     );
 }
 
+#[cfg(feature = "sdk")]
 fn log_callback(level: ffi::LogLev, line: i32, filename: &str, message: &str) {
     match level {
         ffi::LogLev::Debug => {

crates/layer/src/lib.rs

@@ -171,6 +171,7 @@
 
 // Internal modules:
 mod debug_annotations;
+#[cfg(feature = "sdk")]
 mod ffi_utils;
 mod ids;
 mod init;
@@ -179,10 +180,12 @@ mod init;
 pub mod error;
 pub mod flavor;
 pub mod native_layer;
+#[cfg(feature = "sdk")]
 pub mod sdk_layer;
 
 // Convenience re-exports:
 pub use error::Error;
 pub use flavor::Flavor;
 pub use native_layer::NativeLayer;
+#[cfg(feature = "sdk")]
 pub use sdk_layer::SdkLayer;