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Split out MapArray into separate module (apache#1483)
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,172 @@ | ||
| // 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 crate::arrow::array_reader::ArrayReader; | ||
| use crate::errors::ParquetError::ArrowError; | ||
| use crate::errors::{Result, ParquetError}; | ||
| use arrow::array::{ArrayDataBuilder, ArrayRef, MapArray}; | ||
| use arrow::buffer::{Buffer, MutableBuffer}; | ||
| use arrow::datatypes::DataType as ArrowType; | ||
| use arrow::datatypes::ToByteSlice; | ||
| use arrow::util::bit_util; | ||
| use std::any::Any; | ||
| use std::sync::Arc; | ||
|
|
||
| /// Implementation of a map array reader. | ||
| pub struct MapArrayReader { | ||
| key_reader: Box<dyn ArrayReader>, | ||
| value_reader: Box<dyn ArrayReader>, | ||
| data_type: ArrowType, | ||
| map_def_level: i16, | ||
| map_rep_level: i16, | ||
| def_level_buffer: Option<Buffer>, | ||
| rep_level_buffer: Option<Buffer>, | ||
| } | ||
|
|
||
| impl MapArrayReader { | ||
| pub fn new( | ||
| key_reader: Box<dyn ArrayReader>, | ||
| value_reader: Box<dyn ArrayReader>, | ||
| data_type: ArrowType, | ||
| def_level: i16, | ||
| rep_level: i16, | ||
| ) -> Self { | ||
| Self { | ||
| key_reader, | ||
| value_reader, | ||
| data_type, | ||
| map_def_level: rep_level, | ||
| map_rep_level: def_level, | ||
| def_level_buffer: None, | ||
| rep_level_buffer: None, | ||
| } | ||
| } | ||
| } | ||
|
|
||
| impl ArrayReader for MapArrayReader { | ||
| fn as_any(&self) -> &dyn Any { | ||
| self | ||
| } | ||
|
|
||
| fn get_data_type(&self) -> &ArrowType { | ||
| &self.data_type | ||
| } | ||
|
|
||
| fn next_batch(&mut self, batch_size: usize) -> Result<ArrayRef> { | ||
| let key_array = self.key_reader.next_batch(batch_size)?; | ||
| let value_array = self.value_reader.next_batch(batch_size)?; | ||
|
|
||
| // Check that key and value have the same lengths | ||
| let key_length = key_array.len(); | ||
| if key_length != value_array.len() { | ||
| return Err(general_err!( | ||
| "Map key and value should have the same lengths." | ||
| )); | ||
| } | ||
|
|
||
| let def_levels = self | ||
| .key_reader | ||
| .get_def_levels() | ||
| .ok_or_else(|| ArrowError("item_reader def levels are None.".to_string()))?; | ||
| let rep_levels = self | ||
| .key_reader | ||
| .get_rep_levels() | ||
| .ok_or_else(|| ArrowError("item_reader rep levels are None.".to_string()))?; | ||
|
|
||
| if !((def_levels.len() == rep_levels.len()) && (rep_levels.len() == key_length)) { | ||
| return Err(ArrowError( | ||
| "Expected item_reader def_levels and rep_levels to be same length as batch".to_string(), | ||
| )); | ||
| } | ||
|
|
||
| let entry_data_type = if let ArrowType::Map(field, _) = &self.data_type { | ||
| field.data_type().clone() | ||
| } else { | ||
| return Err(ArrowError("Expected a map arrow type".to_string())); | ||
| }; | ||
|
|
||
| let entry_data = ArrayDataBuilder::new(entry_data_type) | ||
| .len(key_length) | ||
| .add_child_data(key_array.data().clone()) | ||
| .add_child_data(value_array.data().clone()); | ||
| let entry_data = unsafe { entry_data.build_unchecked() }; | ||
|
|
||
| let entry_len = rep_levels.iter().filter(|level| **level == 0).count(); | ||
|
|
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| // first item in each list has rep_level = 0, subsequent items have rep_level = 1 | ||
| let mut offsets: Vec<i32> = Vec::new(); | ||
| let mut cur_offset = 0; | ||
| def_levels.iter().zip(rep_levels).for_each(|(d, r)| { | ||
| if *r == 0 || d == &self.map_def_level { | ||
| offsets.push(cur_offset); | ||
| } | ||
| if d > &self.map_def_level { | ||
| cur_offset += 1; | ||
| } | ||
| }); | ||
| offsets.push(cur_offset); | ||
|
|
||
| let num_bytes = bit_util::ceil(offsets.len(), 8); | ||
| // TODO: A useful optimization is to use the null count to fill with | ||
| // 0 or null, to reduce individual bits set in a loop. | ||
| // To favour dense data, set every slot to true, then unset | ||
| let mut null_buf = MutableBuffer::new(num_bytes).with_bitset(num_bytes, true); | ||
| let null_slice = null_buf.as_slice_mut(); | ||
| let mut list_index = 0; | ||
| for i in 0..rep_levels.len() { | ||
| // If the level is lower than empty, then the slot is null. | ||
| // When a list is non-nullable, its empty level = null level, | ||
| // so this automatically factors that in. | ||
| if rep_levels[i] == 0 && def_levels[i] < self.map_def_level { | ||
| // should be empty list | ||
| bit_util::unset_bit(null_slice, list_index); | ||
| } | ||
| if rep_levels[i] == 0 { | ||
| list_index += 1; | ||
| } | ||
| } | ||
| let value_offsets = Buffer::from(&offsets.to_byte_slice()); | ||
|
|
||
| // Now we can build array data | ||
| let array_data = ArrayDataBuilder::new(self.data_type.clone()) | ||
| .len(entry_len) | ||
| .add_buffer(value_offsets) | ||
| .null_bit_buffer(null_buf.into()) | ||
| .add_child_data(entry_data); | ||
|
|
||
| let array_data = unsafe { array_data.build_unchecked() }; | ||
|
|
||
| Ok(Arc::new(MapArray::from(array_data))) | ||
| } | ||
|
|
||
| fn get_def_levels(&self) -> Option<&[i16]> { | ||
| self.def_level_buffer | ||
| .as_ref() | ||
| .map(|buf| unsafe { buf.typed_data() }) | ||
| } | ||
|
|
||
| fn get_rep_levels(&self) -> Option<&[i16]> { | ||
| self.rep_level_buffer | ||
| .as_ref() | ||
| .map(|buf| unsafe { buf.typed_data() }) | ||
| } | ||
| } | ||
|
|
||
| #[cfg(test)] | ||
| mod tests { | ||
| //TODO: Add unit tests (#1561) | ||
| } |