feat(cdr): direct CDR serialization with bulk-copy path for plain sequences - #125
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…ith bytemuck bulk-copy path Adds direct CDR serialization traits to ros-z-cdr, bypassing serde reflection: - CdrSerialize / CdrDeserialize / CdrSerializedSize traits in traits.rs - Bulk-copy path for bytemuck::Pod types (Vec<f32>, Vec<Pose>, etc.) - Codegen emits bytemuck Pod/Zeroable derives on plain structs and CDR trait impls for all generated message types - CdrSerializedSize enables pre-allocation without serializing
…internal types - Add NativeCdrSerdes<T> as default ZMessage::Serdes for CDR-capable types via blanket impl - Implement CdrSerialize/CdrDeserialize/CdrSerializedSize for all concrete action message types and type-description wire types (ZBuf, GoalId, GoalStatus, GoalInfo, Time, and 11 framework message structs) - Update Publisher/Subscriber builders to use T::Serdes instead of hardcoded SerdeCdrSerdes, preserving serde path for serde-only types - Fix ZBuf::cdr_serialize double-length-prefix bug - Rename FastCdrSerdes->NativeCdrSerdes and CdrSerdes->SerdeCdrSerdes to clarify which path goes through serde reflection vs direct trait dispatch
…of in generated code
…nd_return in generated code
…ead_pod_slice cast_slice requires the input slice to be memory-aligned to align_of::<T>(). Network buffers arriving from ROS2 are not guaranteed to be 8-byte aligned, causing bytemuck to panic when deserializing f64 arrays (e.g. Imu/Odometry covariance arrays). Switch to pod_collect_to_vec which handles misalignment by copying into a fresh aligned allocation. Also restore the SplitBuffer import in mod tests which was mistakenly removed (contiguous() is a method on the SplitBuffer trait, used in that module).
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Summary
Replace the serde-based CDR serialization path with direct trait dispatch for generated message types, eliminating serde reflection overhead. Plain struct sequences (e.g.
Vec<Pose>,Vec<f32>) now use bulkmemcpyinstead of element-by-element serialization. This PR is inspired by ros2/rosidl_typesupport_fastrtps#142.Key Changes
CdrSerialize,CdrDeserialize,CdrSerializedSize) inros-z-cdrfor direct CDR serialization without serdebytemuck::Podsequences —Vec<f32>,Vec<Pose>, etc. serialize/deserialize as a singlememcpybytemuck::Pod/Zeroablederives on plain structs and CDR trait impls for all generated message typesNativeCdrSerdes<T>blanket wires generated types to the fast path automatically; serde-only types fall back toSerdeCdrSerdes<T>ZBuf::cdr_serializebug fix — was writing the sequence length prefix twiceFastCdrSerdes→NativeCdrSerdesandCdrSerdes→SerdeCdrSerdesto clarify the two pathsBenchmark results (release build, x86_64)
Wire format is byte-identical between the two paths (verified by test).
Breaking Changes
CdrSerdesandFastCdrSerdesare renamed toSerdeCdrSerdesandNativeCdrSerdes. Any code referencing these types by name will need updating.