go/parquet/internal/encoding/byte_array_encoder.go

// 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 (
	"encoding/binary"
	"unsafe"

	"github.com/apache/arrow/go/v6/arrow"
	"github.com/apache/arrow/go/v6/parquet"
	"github.com/apache/arrow/go/v6/parquet/internal/utils"
)

// PlainByteArrayEncoder encodes byte arrays according to the spec for Plain encoding
// by encoding the length as a int32 followed by the bytes of the value.
type PlainByteArrayEncoder struct {
	encoder

	bitSetReader utils.SetBitRunReader
}

// PutByteArray writes out the 4 bytes for the length followed by the data
func (enc *PlainByteArrayEncoder) PutByteArray(val parquet.ByteArray) {
	inc := val.Len() + arrow.Uint32SizeBytes
	enc.sink.Reserve(inc)
	vlen := utils.ToLEUint32(uint32(val.Len()))
	enc.sink.UnsafeWrite((*(*[4]byte)(unsafe.Pointer(&vlen)))[:])
	enc.sink.UnsafeWrite(val)
}

// Put writes out all of the values in this slice to the encoding sink
func (enc *PlainByteArrayEncoder) Put(in []parquet.ByteArray) {
	for _, val := range in {
		enc.PutByteArray(val)
	}
}

// PutSpaced uses the bitmap of validBits to leave out anything that is null according
// to the bitmap.
//
// If validBits is nil, this is equivalent to calling Put
func (enc *PlainByteArrayEncoder) PutSpaced(in []parquet.ByteArray, validBits []byte, validBitsOffset int64) {
	if validBits != nil {
		if enc.bitSetReader == nil {
			enc.bitSetReader = utils.NewSetBitRunReader(validBits, validBitsOffset, int64(len(in)))
		} else {
			enc.bitSetReader.Reset(validBits, validBitsOffset, int64(len(in)))
		}

		for {
			run := enc.bitSetReader.NextRun()
			if run.Length == 0 {
				break
			}
			enc.Put(in[int(run.Pos):int(run.Pos+run.Length)])
		}
	} else {
		enc.Put(in)
	}
}

// Type returns parquet.Types.ByteArray for the bytearray encoder
func (PlainByteArrayEncoder) Type() parquet.Type {
	return parquet.Types.ByteArray
}

// WriteDict writes the dictionary out to the provided slice, out should be
// at least DictEncodedSize() bytes
func (enc *DictByteArrayEncoder) WriteDict(out []byte) {
	enc.memo.(BinaryMemoTable).VisitValues(0, func(v []byte) {
		binary.LittleEndian.PutUint32(out, uint32(len(v)))
		out = out[arrow.Uint32SizeBytes:]
		copy(out, v)
		out = out[len(v):]
	})
}

// PutByteArray adds a single byte array to buffer, updating the dictionary
// and encoded size if it's a new value
func (enc *DictByteArrayEncoder) PutByteArray(in parquet.ByteArray) {
	if in == nil {
		in = empty[:]
	}
	memoIdx, found, err := enc.memo.GetOrInsert(in)
	if err != nil {
		panic(err)
	}
	if !found {
		enc.dictEncodedSize += in.Len() + arrow.Uint32SizeBytes
	}
	enc.addIndex(memoIdx)
}

// Put takes a slice of ByteArrays to add and encode.
func (enc *DictByteArrayEncoder) Put(in []parquet.ByteArray) {
	for _, val := range in {
		enc.PutByteArray(val)
	}
}

// PutSpaced like with the non-dict encoder leaves out the values where the validBits bitmap is 0
func (enc *DictByteArrayEncoder) PutSpaced(in []parquet.ByteArray, validBits []byte, validBitsOffset int64) {
	utils.VisitSetBitRuns(validBits, validBitsOffset, int64(len(in)), func(pos, length int64) error {
		for i := int64(0); i < length; i++ {
			enc.PutByteArray(in[i+pos])
		}
		return nil
	})
}