/
utils.rs
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/
utils.rs
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// 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.
//! Utilities to assist with reading and writing Arrow data as Flight messages
use crate::{FlightData, IpcMessage, SchemaAsIpc, SchemaResult};
use std::collections::HashMap;
use arrow_array::{ArrayRef, RecordBatch};
use arrow_buffer::Buffer;
use arrow_ipc::{reader, writer, writer::IpcWriteOptions};
use arrow_schema::{ArrowError, Schema, SchemaRef};
/// Convert a `RecordBatch` to a vector of `FlightData` representing the bytes of the dictionaries
/// and a `FlightData` representing the bytes of the batch's values
pub fn flight_data_from_arrow_batch(
batch: &RecordBatch,
options: &IpcWriteOptions,
) -> (Vec<FlightData>, FlightData) {
let data_gen = writer::IpcDataGenerator::default();
let mut dictionary_tracker = writer::DictionaryTracker::new(false);
let (encoded_dictionaries, encoded_batch) = data_gen
.encoded_batch(batch, &mut dictionary_tracker, options)
.expect("DictionaryTracker configured above to not error on replacement");
let flight_dictionaries = encoded_dictionaries.into_iter().map(Into::into).collect();
let flight_batch = encoded_batch.into();
(flight_dictionaries, flight_batch)
}
/// Convert `FlightData` (with supplied schema and dictionaries) to an arrow `RecordBatch`.
pub fn flight_data_to_arrow_batch(
data: &FlightData,
schema: SchemaRef,
dictionaries_by_id: &HashMap<i64, ArrayRef>,
) -> Result<RecordBatch, ArrowError> {
// check that the data_header is a record batch message
let message = arrow_ipc::root_as_message(&data.data_header[..]).map_err(|err| {
ArrowError::ParseError(format!("Unable to get root as message: {:?}", err))
})?;
message
.header_as_record_batch()
.ok_or_else(|| {
ArrowError::ParseError(
"Unable to convert flight data header to a record batch".to_string(),
)
})
.map(|batch| {
reader::read_record_batch(
&Buffer::from(&data.data_body),
batch,
schema,
dictionaries_by_id,
None,
&message.version(),
)
})?
}
/// Convert a `Schema` to `SchemaResult` by converting to an IPC message
#[deprecated(
since = "4.4.0",
note = "Use From trait, e.g.: SchemaAsIpc::new(schema, options).try_into()"
)]
pub fn flight_schema_from_arrow_schema(
schema: &Schema,
options: &IpcWriteOptions,
) -> Result<SchemaResult, ArrowError> {
SchemaAsIpc::new(schema, options).try_into()
}
/// Convert a `Schema` to `FlightData` by converting to an IPC message
#[deprecated(
since = "4.4.0",
note = "Use From trait, e.g.: SchemaAsIpc::new(schema, options).into()"
)]
pub fn flight_data_from_arrow_schema(
schema: &Schema,
options: &IpcWriteOptions,
) -> FlightData {
SchemaAsIpc::new(schema, options).into()
}
/// Convert a `Schema` to bytes in the format expected in `FlightInfo.schema`
#[deprecated(
since = "4.4.0",
note = "Use TryFrom trait, e.g.: SchemaAsIpc::new(schema, options).try_into()"
)]
pub fn ipc_message_from_arrow_schema(
schema: &Schema,
options: &IpcWriteOptions,
) -> Result<Vec<u8>, ArrowError> {
let message = SchemaAsIpc::new(schema, options).try_into()?;
let IpcMessage(vals) = message;
Ok(vals)
}