scovich commented on code in PR #8185:
URL: https://github.com/apache/arrow-rs/pull/8185#discussion_r2289016779
##########
parquet-variant/src/builder.rs:
##########
@@ -589,72 +582,190 @@ impl<S: AsRef<str>> Extend<S> for MetadataBuilder {
/// parent, and we cannot "split" a mutable reference across two objects
(parent state and the child
/// builder that uses it). So everything has to be here. Rust layout
optimizations should treat the
/// variants as a union, so that accessing a `buffer` or `metadata_builder` is
branch-free.
+#[derive(Debug)]
enum ParentState<'a> {
Variant {
buffer: &'a mut ValueBuffer,
+ saved_buffer_offset: usize,
metadata_builder: &'a mut MetadataBuilder,
+ saved_metadata_builder_dict_size: usize,
+ finished: bool,
},
List {
buffer: &'a mut ValueBuffer,
+ saved_buffer_offset: usize,
metadata_builder: &'a mut MetadataBuilder,
- parent_value_offset_base: usize,
+ saved_metadata_builder_dict_size: usize,
offsets: &'a mut Vec<usize>,
+ saved_offsets_size: usize,
+ finished: bool,
},
Object {
buffer: &'a mut ValueBuffer,
+ saved_buffer_offset: usize,
metadata_builder: &'a mut MetadataBuilder,
+ saved_metadata_builder_dict_size: usize,
fields: &'a mut IndexMap<u32, usize>,
- field_name: &'a str,
- parent_value_offset_base: usize,
+ saved_fields_size: usize,
+ finished: bool,
},
}
-impl ParentState<'_> {
- fn buffer(&mut self) -> &mut ValueBuffer {
- match self {
- ParentState::Variant { buffer, .. } => buffer,
- ParentState::List { buffer, .. } => buffer,
- ParentState::Object { buffer, .. } => buffer,
+impl<'a> ParentState<'a> {
+ fn variant(buffer: &'a mut ValueBuffer, metadata_builder: &'a mut
MetadataBuilder) -> Self {
+ ParentState::Variant {
+ saved_buffer_offset: buffer.offset(),
+ saved_metadata_builder_dict_size:
metadata_builder.num_field_names(),
+ buffer,
+ metadata_builder,
+ finished: false,
+ }
+ }
+
+ fn list(
+ buffer: &'a mut ValueBuffer,
+ metadata_builder: &'a mut MetadataBuilder,
+ offsets: &'a mut Vec<usize>,
+ saved_parent_buffer_offset: usize,
+ ) -> Self {
+ // The saved_parent_buffer_offset is the buffer size as of when the
parent builder was
+ // constructed. The saved_buffer_offset is the buffer size as of now
(when a child builder
+ // is created). The variant field_offset entry for this list element
is their difference.
+ let saved_buffer_offset = buffer.offset();
+ let saved_offsets_size = offsets.len();
+ offsets.push(saved_buffer_offset - saved_parent_buffer_offset);
+
+ ParentState::List {
+ saved_metadata_builder_dict_size:
metadata_builder.num_field_names(),
+ saved_buffer_offset,
+ saved_offsets_size,
+ metadata_builder,
+ buffer,
+ offsets,
+ finished: false,
}
}
+ fn object(
Review Comment:
Good idea!
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