harshmotw-db commented on code in PR #7783:
URL: https://github.com/apache/arrow-rs/pull/7783#discussion_r2167848191
##########
parquet-variant/src/variant_buffer_manager.rs:
##########
@@ -0,0 +1,124 @@
+use arrow_schema::ArrowError;
+
+pub trait VariantBufferManager {
+ /// Returns the slice where the variant metadata needs to be written to.
This method may be
+ /// called several times during the construction of a new `metadata` field
in a variant. The
+ /// implementation must make sure that on every call, all the data written
to the metadata
+ /// buffer so far are preserved.
+ fn borrow_metadata_buffer(&mut self) -> &mut [u8];
+
+ /// Returns the slice where value needs to be written to. This method may
be called several
+ /// times during the construction of a new `value` field in a variant. The
implementation must
+ /// make sure that on every call, all the data written to the value buffer
so far are preserved.
+ fn borrow_value_buffer(&mut self) -> &mut [u8];
+
+ /// Ensures that the next call to `borrow_metadata_buffer` returns a slice
having at least
+ /// `size` bytes. Also ensures that the value metadata written so far are
persisted - this means
+ /// that if `borrow_metadata_buffer` is to return a new buffer from the
next call onwards, the
+ /// new buffer must have the contents of the old metadata buffer.
+ fn ensure_metadata_buffer_size(&mut self, size: usize) -> Result<(),
ArrowError>;
+
+ /// Ensures that the next call to `borrow_value_buffer` returns a slice
having at least `size`
+ /// bytes. Also ensures that the value bytes written so far are persisted
- this means that
+ /// if `borrow_value_buffer` is to return a new buffer from the next call
onwards, the new
+ /// buffer must have the contents of the old value buffer.
+ fn ensure_value_buffer_size(&mut self, size: usize) -> Result<(),
ArrowError>;
+
+ fn get_immutable_metadata_buffer(&self) -> &[u8] {
+ unimplemented!("Optional method not implemented in
VariantBufferManager")
+ }
+
+ fn get_immutable_value_buffer(&self) -> &[u8] {
+ unimplemented!("Optional method not implemented in
VariantBufferManager")
+ }
+}
+
+pub struct SampleBoxBasedVariantBufferManager {
+ pub value_buffer: Box<[u8]>,
+ pub metadata_buffer: Box<[u8]>,
Review Comment:
Yes, I do plan on adding an arrow-based sample buffer manager. I currently
do not fully understand arrow though but I believe the trait is simple enough
that it could be extended to such use cases. I will do that as a follow up if
you agree with the general design.
##########
parquet-variant/src/variant_buffer_manager.rs:
##########
@@ -0,0 +1,124 @@
+use arrow_schema::ArrowError;
+
+pub trait VariantBufferManager {
+ /// Returns the slice where the variant metadata needs to be written to.
This method may be
+ /// called several times during the construction of a new `metadata` field
in a variant. The
+ /// implementation must make sure that on every call, all the data written
to the metadata
+ /// buffer so far are preserved.
+ fn borrow_metadata_buffer(&mut self) -> &mut [u8];
+
+ /// Returns the slice where value needs to be written to. This method may
be called several
+ /// times during the construction of a new `value` field in a variant. The
implementation must
+ /// make sure that on every call, all the data written to the value buffer
so far are preserved.
+ fn borrow_value_buffer(&mut self) -> &mut [u8];
+
+ /// Ensures that the next call to `borrow_metadata_buffer` returns a slice
having at least
+ /// `size` bytes. Also ensures that the value metadata written so far are
persisted - this means
+ /// that if `borrow_metadata_buffer` is to return a new buffer from the
next call onwards, the
+ /// new buffer must have the contents of the old metadata buffer.
+ fn ensure_metadata_buffer_size(&mut self, size: usize) -> Result<(),
ArrowError>;
+
+ /// Ensures that the next call to `borrow_value_buffer` returns a slice
having at least `size`
+ /// bytes. Also ensures that the value bytes written so far are persisted
- this means that
+ /// if `borrow_value_buffer` is to return a new buffer from the next call
onwards, the new
+ /// buffer must have the contents of the old value buffer.
+ fn ensure_value_buffer_size(&mut self, size: usize) -> Result<(),
ArrowError>;
+
+ fn get_immutable_metadata_buffer(&self) -> &[u8] {
+ unimplemented!("Optional method not implemented in
VariantBufferManager")
+ }
+
+ fn get_immutable_value_buffer(&self) -> &[u8] {
+ unimplemented!("Optional method not implemented in
VariantBufferManager")
+ }
+}
+
+pub struct SampleBoxBasedVariantBufferManager {
+ pub value_buffer: Box<[u8]>,
+ pub metadata_buffer: Box<[u8]>,
Review Comment:
Yes, I do plan on adding an arrow-compliant sample buffer manager. I
currently do not fully understand arrow though but I believe the trait is
simple enough that it could be extended to such use cases. I will do that as a
follow up if you agree with the general design.
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