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Posted to github@arrow.apache.org by GitBox <gi...@apache.org> on 2021/06/18 21:19:50 UTC
[GitHub] [arrow-rs] pitrou commented on a change in pull request #439: Python FFI bridge for Schema, Field and DataType
pitrou commented on a change in pull request #439:
URL: https://github.com/apache/arrow-rs/pull/439#discussion_r653875228
##########
File path: arrow/src/ffi.rs
##########
@@ -122,66 +132,61 @@ unsafe extern "C" fn release_schema(schema: *mut FFI_ArrowSchema) {
let schema = &mut *schema;
// take ownership back to release it.
- CString::from_raw(schema.format as *mut std::os::raw::c_char);
- CString::from_raw(schema.name as *mut std::os::raw::c_char);
- let private = Box::from_raw(schema.private_data as *mut SchemaPrivateData);
- for child in private.children_ptr.iter() {
- let _ = Box::from_raw(*child);
+ CString::from_raw(schema.format as *mut c_char);
+ if !schema.name.is_null() {
+ CString::from_raw(schema.name as *mut c_char);
+ }
+ if !schema.private_data.is_null() {
+ let private_data = Box::from_raw(schema.private_data as *mut SchemaPrivateData);
+ for child in private_data.children.iter() {
+ drop(Box::from_raw(*child))
Review comment:
Does `drop` automatically call the release callback on `child`? It seems it does, according to `impl Drop for FFI_ArrowSchema`, but I may be misunderstanding.
##########
File path: arrow/src/ffi.rs
##########
@@ -122,66 +132,61 @@ unsafe extern "C" fn release_schema(schema: *mut FFI_ArrowSchema) {
let schema = &mut *schema;
// take ownership back to release it.
- CString::from_raw(schema.format as *mut std::os::raw::c_char);
- CString::from_raw(schema.name as *mut std::os::raw::c_char);
- let private = Box::from_raw(schema.private_data as *mut SchemaPrivateData);
- for child in private.children_ptr.iter() {
- let _ = Box::from_raw(*child);
+ CString::from_raw(schema.format as *mut c_char);
+ if !schema.name.is_null() {
+ CString::from_raw(schema.name as *mut c_char);
+ }
+ if !schema.private_data.is_null() {
+ let private_data = Box::from_raw(schema.private_data as *mut SchemaPrivateData);
+ for child in private_data.children.iter() {
+ drop(Box::from_raw(*child))
+ }
+ drop(private_data);
}
schema.release = None;
}
impl FFI_ArrowSchema {
/// create a new [`Ffi_ArrowSchema`]. This fails if the fields' [`DataType`] is not supported.
- fn try_new(field: Field) -> Result<FFI_ArrowSchema> {
- let format = to_format(field.data_type())?;
- let name = field.name().clone();
-
- // allocate (and hold) the children
- let children_vec = match field.data_type() {
- DataType::List(field) => {
- vec![Box::new(FFI_ArrowSchema::try_new(field.as_ref().clone())?)]
- }
- DataType::LargeList(field) => {
- vec![Box::new(FFI_ArrowSchema::try_new(field.as_ref().clone())?)]
- }
- DataType::Struct(fields) => fields
- .iter()
- .map(|field| Ok(Box::new(FFI_ArrowSchema::try_new(field.clone())?)))
- .collect::<Result<Vec<_>>>()?,
- _ => vec![],
- };
- // note: this cannot be done along with the above because the above is fallible and this op leaks.
- let children_ptr = children_vec
+ pub fn try_new(format: &str, children: Vec<FFI_ArrowSchema>) -> Result<Self> {
+ let mut this = Self::empty();
+
+ // note: this op leaks.
Review comment:
Does it? It seems that you call `from_raw` on each item in `release_schema`, so that should be ok?
##########
File path: arrow/src/datatypes/ffi.rs
##########
@@ -0,0 +1,287 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use std::convert::TryFrom;
+
+use crate::{
+ datatypes::{DataType, Field, Schema, TimeUnit},
+ error::{ArrowError, Result},
+ ffi::{FFI_ArrowSchema, Flags},
+};
+
+impl TryFrom<&FFI_ArrowSchema> for DataType {
+ type Error = ArrowError;
+
+ /// See https://arrow.apache.org/docs/format/CDataInterface.html#data-type-description-format-strings
+ fn try_from(c_schema: &FFI_ArrowSchema) -> Result<Self> {
+ let dtype = match c_schema.format() {
+ "n" => DataType::Null,
+ "b" => DataType::Boolean,
+ "c" => DataType::Int8,
+ "C" => DataType::UInt8,
+ "s" => DataType::Int16,
+ "S" => DataType::UInt16,
+ "i" => DataType::Int32,
+ "I" => DataType::UInt32,
+ "l" => DataType::Int64,
+ "L" => DataType::UInt64,
+ "e" => DataType::Float16,
+ "f" => DataType::Float32,
+ "g" => DataType::Float64,
+ "z" => DataType::Binary,
+ "Z" => DataType::LargeBinary,
+ "u" => DataType::Utf8,
+ "U" => DataType::LargeUtf8,
+ "tdD" => DataType::Date32,
+ "tdm" => DataType::Date64,
+ "tts" => DataType::Time32(TimeUnit::Second),
+ "ttm" => DataType::Time32(TimeUnit::Millisecond),
+ "ttu" => DataType::Time64(TimeUnit::Microsecond),
+ "ttn" => DataType::Time64(TimeUnit::Nanosecond),
+ "+l" => {
+ let c_child = c_schema.child(0);
+ DataType::List(Box::new(Field::try_from(c_child)?))
+ }
+ "+L" => {
+ let c_child = c_schema.child(0);
+ DataType::LargeList(Box::new(Field::try_from(c_child)?))
+ }
+ "+s" => {
+ let fields = c_schema.children().map(Field::try_from);
+ DataType::Struct(fields.collect::<Result<Vec<_>>>()?)
+ }
+ other => {
+ return Err(ArrowError::CDataInterface(format!(
+ "The datatype \"{:?}\" is still not supported in Rust implementation",
+ other
+ )))
+ }
+ };
+ Ok(dtype)
+ }
+}
+
+impl TryFrom<&FFI_ArrowSchema> for Field {
+ type Error = ArrowError;
+
+ fn try_from(c_schema: &FFI_ArrowSchema) -> Result<Self> {
+ let dtype = DataType::try_from(c_schema)?;
+ let field = Field::new(c_schema.name(), dtype, c_schema.nullable());
+ Ok(field)
Review comment:
Is there a TODO for metadata?
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