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perf(generator): use memcpy paths for primitive sequence conversion #26

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Merged
esteve merged 1 commit into from
Jun 8, 2026
Merged

perf(generator): use memcpy paths for primitive sequence conversion #26

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22 changes: 19 additions & 3 deletions rosidl_generator_rs/resource/templates/msg_idiomatic.rs.em
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Original file line number Diff line number Diff line change
Expand Up @@ -139,8 +139,12 @@ impl rosidl_runtime_rs::Message for @(type_name) {
.into_iter()
.map(|elem| @(get_rs_type(member.type.value_type))::into_rmw_message(std::borrow::Cow::Owned(elem)).into_owned())
.collect(),
@# Owned BasicType sequences: borrow the slice and route through
@# From<&[T]> for Sequence<T> so the copy compiles to a memcpy via
@# clone_from_slice's Copy specialization, instead of From<Vec<T>>'s
@# per-element extend path. See ros2-rust/ros2_rust#628.
@[ else]@
@(get_rs_name(member.name)): msg.@(get_rs_name(member.name)).into(),
@(get_rs_name(member.name)): msg.@(get_rs_name(member.name)).as_slice().into(),
@[ end if]@
@#
@#
Expand Down Expand Up @@ -243,14 +247,26 @@ impl rosidl_runtime_rs::Message for @(type_name) {
@#
@# == UnboundedSequence ==
@[ elif isinstance(member.type, UnboundedSequence)]@
@# Primitive sequences use the From<Sequence<T>> for Vec<T> impl (memcpy via
@# as_slice().to_vec()), avoiding O(n) per-element read/zero-write that the
@# SequenceIterator path performs. See ros2-rust/ros2_rust#628.
@[ if isinstance(member.type.value_type, BasicType)]@
@(get_rs_name(member.name)): msg.@(get_rs_name(member.name)).into(),
@[ elif isinstance(member.type.value_type, UnboundedString) or isinstance(member.type.value_type, UnboundedWString)]@
@(get_rs_name(member.name)): msg.@(get_rs_name(member.name))
.into_iter()
@[ if isinstance(member.type.value_type, UnboundedString) or isinstance(member.type.value_type, UnboundedWString)]@
.map(|elem| elem.to_string())
.collect(),
@[ elif isinstance(member.type.value_type, NamedType) or isinstance(member.type.value_type, NamespacedType)]@
@(get_rs_name(member.name)): msg.@(get_rs_name(member.name))
.into_iter()
.map(@(get_rs_type(member.type.value_type))::from_rmw_message)
@[ end if]@
.collect(),
@[ else]@
@(get_rs_name(member.name)): msg.@(get_rs_name(member.name))
.into_iter()
.collect(),
@[ end if]@
@#
@#
@# == UnboundedString + UnboundedWString ==
Expand Down