datafusion_ffi/
arrow_wrappers.rs

1// Licensed to the Apache Software Foundation (ASF) under one
2// or more contributor license agreements.  See the NOTICE file
3// distributed with this work for additional information
4// regarding copyright ownership.  The ASF licenses this file
5// to you under the Apache License, Version 2.0 (the
6// "License"); you may not use this file except in compliance
7// with the License.  You may obtain a copy of the License at
8//
9//   http://www.apache.org/licenses/LICENSE-2.0
10//
11// Unless required by applicable law or agreed to in writing,
12// software distributed under the License is distributed on an
13// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14// KIND, either express or implied.  See the License for the
15// specific language governing permissions and limitations
16// under the License.
17
18use std::sync::Arc;
19
20use arrow::array::{ArrayRef, make_array};
21use arrow::datatypes::{Schema, SchemaRef};
22use arrow::error::ArrowError;
23use arrow::ffi::{FFI_ArrowArray, FFI_ArrowSchema, from_ffi, to_ffi};
24use datafusion_common::{DataFusionError, ScalarValue};
25use log::error;
26
27/// This is a wrapper struct around FFI_ArrowSchema simply to indicate
28/// that the underlying struct is FFI safe.
29#[repr(C)]
30#[derive(Debug)]
31pub struct WrappedSchema(pub FFI_ArrowSchema);
32
33impl From<SchemaRef> for WrappedSchema {
34    fn from(value: SchemaRef) -> Self {
35        let ffi_schema = match FFI_ArrowSchema::try_from(value.as_ref()) {
36            Ok(s) => s,
37            Err(e) => {
38                error!(
39                    "Unable to convert DataFusion Schema to FFI_ArrowSchema in FFI_PlanProperties. {e}"
40                );
41                FFI_ArrowSchema::empty()
42            }
43        };
44
45        WrappedSchema(ffi_schema)
46    }
47}
48/// Some functions are expected to always succeed, like getting the schema from a TableProvider.
49/// Since going through the FFI always has the potential to fail, we need to catch these errors,
50/// give the user a warning, and return some kind of result. In this case we default to an
51/// empty schema.
52#[cfg(not(tarpaulin_include))]
53fn catch_df_schema_error(e: &ArrowError) -> Schema {
54    error!(
55        "Unable to convert from FFI_ArrowSchema to DataFusion Schema in FFI_PlanProperties. {e}"
56    );
57    Schema::empty()
58}
59
60impl From<WrappedSchema> for SchemaRef {
61    fn from(value: WrappedSchema) -> Self {
62        let schema =
63            Schema::try_from(&value.0).unwrap_or_else(|e| catch_df_schema_error(&e));
64        Arc::new(schema)
65    }
66}
67
68/// This is a wrapper struct for FFI_ArrowArray to indicate
69/// that the struct is FFI Safe. For convenience, we also include the
70/// schema needed to create a record batch from the array.
71#[repr(C)]
72#[derive(Debug)]
73pub struct WrappedArray {
74    pub array: FFI_ArrowArray,
75    pub schema: WrappedSchema,
76}
77
78impl TryFrom<WrappedArray> for ArrayRef {
79    type Error = ArrowError;
80
81    fn try_from(value: WrappedArray) -> Result<Self, Self::Error> {
82        let data = unsafe { from_ffi(value.array, &value.schema.0)? };
83
84        Ok(make_array(data))
85    }
86}
87
88impl TryFrom<&ArrayRef> for WrappedArray {
89    type Error = ArrowError;
90
91    fn try_from(array: &ArrayRef) -> Result<Self, Self::Error> {
92        let (array, schema) = to_ffi(&array.to_data())?;
93        let schema = WrappedSchema(schema);
94
95        Ok(WrappedArray { array, schema })
96    }
97}
98
99impl TryFrom<&ScalarValue> for WrappedArray {
100    type Error = DataFusionError;
101
102    fn try_from(value: &ScalarValue) -> Result<Self, Self::Error> {
103        let array = value.to_array()?;
104        WrappedArray::try_from(&array).map_err(Into::into)
105    }
106}
107
108impl TryFrom<WrappedArray> for ScalarValue {
109    type Error = DataFusionError;
110
111    fn try_from(value: WrappedArray) -> Result<Self, Self::Error> {
112        let array: ArrayRef = value.try_into()?;
113        ScalarValue::try_from_array(array.as_ref(), 0)
114    }
115}
datafusion_ffi/arrow_wrappers.rs

datafusion_ffi/
arrow_wrappers.rs
