/
boolean_decoder.go
189 lines (161 loc) · 5.41 KB
/
boolean_decoder.go
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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.
package encoding
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"io"
"github.com/apache/arrow/go/v17/arrow/bitutil"
shared_utils "github.com/apache/arrow/go/v17/internal/utils"
"github.com/apache/arrow/go/v17/parquet"
"github.com/apache/arrow/go/v17/parquet/internal/utils"
)
// PlainBooleanDecoder is for the Plain Encoding type, there is no
// dictionary decoding for bools.
type PlainBooleanDecoder struct {
decoder
bitOffset int
}
// Type for the PlainBooleanDecoder is parquet.Types.Boolean
func (PlainBooleanDecoder) Type() parquet.Type {
return parquet.Types.Boolean
}
func (dec *PlainBooleanDecoder) SetData(nvals int, data []byte) error {
if err := dec.decoder.SetData(nvals, data); err != nil {
return err
}
dec.bitOffset = 0
return nil
}
// Decode fills out with bools decoded from the data at the current point
// or until we reach the end of the data.
//
// Returns the number of values decoded
func (dec *PlainBooleanDecoder) Decode(out []bool) (int, error) {
max := shared_utils.Min(len(out), dec.nvals)
// attempts to read all remaining bool values from the current data byte
unalignedExtract := func(i int) int {
for ; dec.bitOffset < 8 && i < max; i, dec.bitOffset = i+1, dec.bitOffset+1 {
out[i] = (dec.data[0] & byte(1<<dec.bitOffset)) != 0
}
if dec.bitOffset == 8 {
// we read every bit from this byte
dec.bitOffset = 0
dec.data = dec.data[1:] // move data forward
}
return i // return the next index for out[]
}
// if we aren't at a byte boundary, then get bools until we hit
// a byte boundary with the bit offset.
i := 0
if dec.bitOffset != 0 {
i = unalignedExtract(i)
}
// determine the number of full bytes worth of bits we can decode
// given the number of values we want to decode.
bitsRemain := max - i
batch := (bitsRemain / 8) * 8
if batch > 0 { // only go in here if there's at least one full byte to decode
// determine the number of aligned bytes we can grab using SIMD optimized
// functions to improve performance.
alignedBytes := bitutil.BytesForBits(int64(batch))
utils.BytesToBools(dec.data[:alignedBytes], out[i:])
dec.data = dec.data[alignedBytes:] // move data forward
i += int(alignedBytes) * 8
}
// grab any trailing bits now that we've got our aligned bytes.
_ = unalignedExtract(i)
dec.nvals -= max
return max, nil
}
// DecodeSpaced is like Decode except it expands the values to leave spaces for null
// as determined by the validBits bitmap.
func (dec *PlainBooleanDecoder) DecodeSpaced(out []bool, nullCount int, validBits []byte, validBitsOffset int64) (int, error) {
if nullCount > 0 {
toRead := len(out) - nullCount
valuesRead, err := dec.Decode(out[:toRead])
if err != nil {
return 0, err
}
if valuesRead != toRead {
return valuesRead, errors.New("parquet: boolean decoder: number of values / definition levels read did not match")
}
return spacedExpand(out, nullCount, validBits, validBitsOffset), nil
}
return dec.Decode(out)
}
type RleBooleanDecoder struct {
decoder
rleDec *utils.RleDecoder
}
func (RleBooleanDecoder) Type() parquet.Type {
return parquet.Types.Boolean
}
func (dec *RleBooleanDecoder) SetData(nvals int, data []byte) error {
dec.nvals = nvals
if len(data) < 4 {
return fmt.Errorf("invalid length - %d (corrupt data page?)", len(data))
}
// load the first 4 bytes in little-endian which indicates the length
nbytes := binary.LittleEndian.Uint32(data[:4])
if nbytes > uint32(len(data)-4) {
return fmt.Errorf("received invalid number of bytes - %d (corrupt data page?)", nbytes)
}
dec.data = data[4:]
if dec.rleDec == nil {
dec.rleDec = utils.NewRleDecoder(bytes.NewReader(dec.data), 1)
} else {
dec.rleDec.Reset(bytes.NewReader(dec.data), 1)
}
return nil
}
func (dec *RleBooleanDecoder) Decode(out []bool) (int, error) {
max := shared_utils.Min(len(out), dec.nvals)
var (
buf [1024]uint64
n = max
)
for n > 0 {
batch := shared_utils.Min(len(buf), n)
decoded := dec.rleDec.GetBatch(buf[:batch])
if decoded != batch {
return max - n, io.ErrUnexpectedEOF
}
for i := 0; i < batch; i++ {
out[i] = buf[i] != 0
}
n -= batch
out = out[batch:]
}
dec.nvals -= max
return max, nil
}
func (dec *RleBooleanDecoder) DecodeSpaced(out []bool, nullCount int, validBits []byte, validBitsOffset int64) (int, error) {
if nullCount > 0 {
toRead := len(out) - nullCount
valuesRead, err := dec.Decode(out[:toRead])
if err != nil {
return 0, err
}
if valuesRead != toRead {
return valuesRead, errors.New("parquet: rle boolean decoder: number of values / definition levels read did not match")
}
return spacedExpand(out, nullCount, validBits, validBitsOffset), nil
}
return dec.Decode(out)
}