build: add a feature writers-and-readers, so we can import only the types in some cases

runtime_tracing/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "runtime_tracing"
-version = "0.15.0"
+version = "0.16.0"
 edition = "2024"
 authors = ["Metacraft Labs Ltd"]
 description = "A library for the schema and tracing helpers for the CodeTracer db trace format"
@@ -20,19 +20,25 @@ serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 serde_repr = "0.1"
 schemars = "0.8.2"
-capnp = "0.21.1"
-cbor4ii = { version = "1.0.0", features = ["serde1", "use_std"] }
-fscommon = "0.1.1"
+capnp = { version = "0.21.1", optional = true }
+cbor4ii = { version = "1.0.0", features = ["serde1", "use_std"], optional = true }
+fscommon = { version = "0.1.1", optional = true }
 
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
-zeekstd = "0.6.0"
+zeekstd = { version = "0.6.0", optional = true }
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
-ruzstd = "0.8.1"
+ruzstd = { version = "0.8.1", optional = true }
 
 [build-dependencies]
-capnpc = "0.21.0"
+capnpc = { version = "0.21.0", optional = true }
 
 [lib]
 name = "runtime_tracing"
 path = "src/lib.rs"
+
+[features]
+writers_and_readers = ["dep:capnp", "dep:cbor4ii", "dep:fscommon", "dep:zeekstd", "dep:ruzstd", "dep:capnpc"]
+# to disable the default features, a dependency must use: `default-features = false ` !
+#   https://doc.rust-lang.org/cargo/reference/features.html
+default = ["writers_and_readers"]

runtime_tracing/build.rs

@@ -1,3 +1,4 @@
 fn main() {
+    #[cfg(feature = "writers_and_readers")]
     ::capnpc::CompilerCommand::new().file("src/trace.capnp").run().expect("compiling schema")
 }

runtime_tracing/src/lib.rs

@@ -8,38 +8,59 @@
 //! This crate provides the [`Tracer`] type for emitting trace events and a
 //! collection of serializable structures describing the trace format.
 //! The format is documented in `docs/` and the README.
+
+#[cfg(feature = "writers_and_readers")]
 mod abstract_trace_writer;
 mod base64;
+#[cfg(feature = "writers_and_readers")]
 mod capnptrace;
 
+#[cfg(feature = "writers_and_readers")]
 #[cfg(target_arch = "wasm32")]
 #[path = "./cbor_zstd_reader_wasm.rs"]
 mod cbor_zstd_reader;
+#[cfg(feature = "writers_and_readers")]
 #[cfg(target_arch = "wasm32")]
 #[path = "./cbor_zstd_writer_wasm.rs"]
 mod cbor_zstd_writer;
 
 #[cfg(not(target_arch = "wasm32"))]
+#[cfg(feature = "writers_and_readers")]
 mod cbor_zstd_reader;
 #[cfg(not(target_arch = "wasm32"))]
+#[cfg(feature = "writers_and_readers")]
 mod cbor_zstd_writer;
 
+#[cfg(feature = "writers_and_readers")]
 mod non_streaming_trace_writer;
+#[cfg(feature = "writers_and_readers")]
 mod trace_readers;
+#[cfg(feature = "writers_and_readers")]
 mod trace_writer;
+#[cfg(feature = "writers_and_readers")]
 mod tracer;
+
+// enabled always!
 mod types;
 
+#[cfg(feature = "writers_and_readers")]
 pub use crate::non_streaming_trace_writer::NonStreamingTraceWriter;
+#[cfg(feature = "writers_and_readers")]
 pub use crate::trace_readers::TraceReader;
+#[cfg(feature = "writers_and_readers")]
 pub use crate::trace_writer::TraceWriter;
-pub use crate::tracer::{NONE_TYPE_ID, NONE_VALUE, TraceEventsFileFormat, create_trace_reader, create_trace_writer};
+#[cfg(feature = "writers_and_readers")]
+pub use crate::tracer::{create_trace_reader, create_trace_writer, TraceEventsFileFormat, NONE_TYPE_ID, NONE_VALUE};
+
+// enabled always!
 pub use crate::types::*;
 
+#[cfg(feature = "writers_and_readers")]
 pub mod trace_capnp {
     include!(concat!(env!("OUT_DIR"), "/src/trace_capnp.rs"));
 }
 
+#[cfg(feature = "writers_and_readers")]
 #[cfg(test)]
 mod tests {
     use super::*;