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Split out byte array decoders (apache#2318)
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,133 @@ | ||
| // 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::data_type::Int32Type; | ||
| use crate::encodings::decoding::{Decoder, DeltaBitPackDecoder}; | ||
| use crate::errors::{ParquetError, Result}; | ||
| use crate::util::memory::ByteBufferPtr; | ||
|
|
||
| /// Decoder for [`Encoding::DELTA_BYTE_ARRAY`] | ||
| pub struct DeltaByteArrayDecoder { | ||
| prefix_lengths: Vec<i32>, | ||
| suffix_lengths: Vec<i32>, | ||
| data: ByteBufferPtr, | ||
| length_offset: usize, | ||
| data_offset: usize, | ||
| last_value: Vec<u8>, | ||
| } | ||
|
|
||
| impl DeltaByteArrayDecoder { | ||
| pub fn new(data: ByteBufferPtr) -> Result<Self> { | ||
| let mut prefix = DeltaBitPackDecoder::<Int32Type>::new(); | ||
| prefix.set_data(data.all(), 0)?; | ||
|
|
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| let num_prefix = prefix.values_left(); | ||
| let mut prefix_lengths = vec![0; num_prefix]; | ||
| assert_eq!(prefix.get(&mut prefix_lengths)?, num_prefix); | ||
|
|
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| let mut suffix = DeltaBitPackDecoder::<Int32Type>::new(); | ||
| suffix.set_data(data.start_from(prefix.get_offset()), 0)?; | ||
|
|
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| let num_suffix = suffix.values_left(); | ||
| let mut suffix_lengths = vec![0; num_suffix]; | ||
| assert_eq!(suffix.get(&mut suffix_lengths)?, num_suffix); | ||
|
|
||
| if num_prefix != num_suffix { | ||
| return Err(general_err!(format!( | ||
| "inconsistent DELTA_BYTE_ARRAY lengths, prefixes: {}, suffixes: {}", | ||
| num_prefix, num_suffix | ||
| ))); | ||
| } | ||
|
|
||
| assert_eq!(prefix_lengths.len(), suffix_lengths.len()); | ||
|
|
||
| Ok(Self { | ||
| prefix_lengths, | ||
| suffix_lengths, | ||
| data, | ||
| length_offset: 0, | ||
| data_offset: prefix.get_offset() + suffix.get_offset(), | ||
| last_value: vec![], | ||
| }) | ||
| } | ||
|
|
||
| pub fn remaining(&self) -> usize { | ||
| self.prefix_lengths.len() - self.length_offset | ||
| } | ||
|
|
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| pub fn read<F>(&mut self, len: usize, mut f: F) -> Result<usize> | ||
| where | ||
| F: FnMut(&[u8]) -> Result<()>, | ||
| { | ||
| let to_read = len.min(self.remaining()); | ||
|
|
||
| let length_range = self.length_offset..self.length_offset + to_read; | ||
| let iter = self.prefix_lengths[length_range.clone()] | ||
| .iter() | ||
| .zip(&self.suffix_lengths[length_range]); | ||
|
|
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| let data = self.data.as_ref(); | ||
|
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| for (prefix_length, suffix_length) in iter { | ||
| let prefix_length = *prefix_length as usize; | ||
| let suffix_length = *suffix_length as usize; | ||
|
|
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| if self.data_offset + suffix_length > self.data.len() { | ||
| return Err(ParquetError::EOF("eof decoding byte array".into())); | ||
| } | ||
|
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| self.last_value.truncate(prefix_length); | ||
| self.last_value.extend_from_slice( | ||
| &data[self.data_offset..self.data_offset + suffix_length], | ||
| ); | ||
| f(&self.last_value)?; | ||
|
|
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| self.data_offset += suffix_length; | ||
| } | ||
|
|
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| self.length_offset += to_read; | ||
| Ok(to_read) | ||
| } | ||
|
|
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| pub fn skip(&mut self, to_skip: usize) -> Result<usize> { | ||
| let to_skip = to_skip.min(self.prefix_lengths.len() - self.length_offset); | ||
|
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| let length_range = self.length_offset..self.length_offset + to_skip; | ||
| let iter = self.prefix_lengths[length_range.clone()] | ||
| .iter() | ||
| .zip(&self.suffix_lengths[length_range]); | ||
|
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| let data = self.data.as_ref(); | ||
|
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| for (prefix_length, suffix_length) in iter { | ||
| let prefix_length = *prefix_length as usize; | ||
| let suffix_length = *suffix_length as usize; | ||
|
|
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| if self.data_offset + suffix_length > self.data.len() { | ||
| return Err(ParquetError::EOF("eof decoding byte array".into())); | ||
| } | ||
|
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| self.last_value.truncate(prefix_length); | ||
| self.last_value.extend_from_slice( | ||
| &data[self.data_offset..self.data_offset + suffix_length], | ||
| ); | ||
| self.data_offset += suffix_length; | ||
| } | ||
| self.length_offset += to_skip; | ||
| Ok(to_skip) | ||
| } | ||
| } |
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