minio/pkg/s3select/internal/parquet-go/encoding/rle-encode.go

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/*
* Minio Cloud Storage, (C) 2019 Minio, Inc.
*
* Licensed 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 (
"fmt"
"github.com/minio/minio/pkg/s3select/internal/parquet-go/gen-go/parquet"
)
func rleEncodeInt32s(i32s []int32, bitWidth int32) (data []byte) {
j := 0
for i := 0; i < len(i32s); i = j {
for j = i + 1; j < len(i32s) && i32s[i] == i32s[j]; j++ {
}
headerBytes := varIntEncode(uint64((j - i) << 1))
data = append(data, headerBytes...)
valBytes := plainEncodeInt32s([]int32{i32s[i]})
byteCount := (bitWidth + 7) / 8
data = append(data, valBytes[:byteCount]...)
}
return data
}
func rleEncodeInt64s(i64s []int64, bitWidth int32) (data []byte) {
j := 0
for i := 0; i < len(i64s); i = j {
for j = i + 1; j < len(i64s) && i64s[i] == i64s[j]; j++ {
}
headerBytes := varIntEncode(uint64((j - i) << 1))
data = append(data, headerBytes...)
valBytes := plainEncodeInt64s([]int64{i64s[i]})
byteCount := (bitWidth + 7) / 8
data = append(data, valBytes[:byteCount]...)
}
return data
}
// RLEBitPackedHybridEncode encodes values specified in https://github.com/apache/parquet-format/blob/master/Encodings.md#run-length-encoding--bit-packing-hybrid-rle--3
//
// Supported Types: INT32, INT64
func RLEBitPackedHybridEncode(values interface{}, bitWidth int32, parquetType parquet.Type) []byte {
var rleBytes []byte
switch parquetType {
case parquet.Type_INT32:
i32s, ok := values.([]int32)
if !ok {
panic(fmt.Errorf("expected slice of int32"))
}
rleBytes = rleEncodeInt32s(i32s, bitWidth)
case parquet.Type_INT64:
i64s, ok := values.([]int64)
if !ok {
panic(fmt.Errorf("expected slice of int64"))
}
rleBytes = rleEncodeInt64s(i64s, bitWidth)
default:
panic(fmt.Errorf("%v parquet type unsupported", parquetType))
}
lenBytes := plainEncodeInt32s([]int32{int32(len(rleBytes))})
return append(lenBytes, rleBytes...)
}