zeroshade commented on a change in pull request #9817: URL: https://github.com/apache/arrow/pull/9817#discussion_r610912811
########## File path: go/parquet/compress/brotli.go ########## @@ -0,0 +1,112 @@ +// 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 compress + +import ( + "bytes" + "io" + "io/ioutil" + + "github.com/andybalholm/brotli" +) + +type brotliCodec struct{} + +func (brotliCodec) NewReader(r io.Reader) io.ReadCloser { + return ioutil.NopCloser(brotli.NewReader(r)) +} + +func (b brotliCodec) EncodeLevel(dst, src []byte, level int) []byte { + if level == DefaultCompressionLevel { + level = brotli.DefaultCompression + } + + maxlen := int(b.CompressBound(int64(len(src)))) + if dst == nil || cap(dst) < maxlen { + dst = make([]byte, 0, maxlen) + } + buf := bytes.NewBuffer(dst[:0]) + w := brotli.NewWriterLevel(buf, level) + _, err := w.Write(src) + if err != nil { + panic(err) + } + if err := w.Close(); err != nil { + panic(err) + } + return buf.Bytes() +} + +func (b brotliCodec) Encode(dst, src []byte) []byte { + return b.EncodeLevel(dst, src, brotli.DefaultCompression) +} + +func (brotliCodec) Decode(dst, src []byte) []byte { + rdr := brotli.NewReader(bytes.NewReader(src)) + if dst != nil { + var ( + sofar = 0 + n = -1 + err error = nil + ) + for n != 0 && err == nil { + n, err = rdr.Read(dst[sofar:]) + sofar += n + } + if err != nil && err != io.EOF { + panic(err) + } + return dst[:sofar] + } + + dst, err := ioutil.ReadAll(rdr) + if err != nil { + panic(err) + } + + return dst +} + +// taken from brotli/enc/encode.c +func (brotliCodec) CompressBound(len int64) int64 { + // [window bits / empty metadata] + N * [uncompressed] + [last empty] Review comment: added ########## File path: go/parquet/compress/compress.go ########## @@ -0,0 +1,153 @@ +// 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 compress contains the interfaces and implementations for handling compression/decompression +// of parquet data at the column levels. +package compress + +import ( + "compress/flate" + "io" + "io/ioutil" + + "github.com/apache/arrow/go/parquet/internal/gen-go/parquet" +) + +// Compression is an alias to the thrift compression codec enum type for easy use +type Compression parquet.CompressionCodec + +func (c Compression) String() string { + return parquet.CompressionCodec(c).String() +} + +// DefaultCompressionLevel will use flate.DefaultCompression since many of the compression libraries +// use that to denote "use the default". +const DefaultCompressionLevel = flate.DefaultCompression + +// Codecs is a useful struct to provide namespaced enum values to use for specifying the compression type to use +// which make for easy internal swapping between them and the thrift enum since they are initialized to the same +// constant values. +var Codecs = struct { + Uncompressed Compression + Snappy Compression + Gzip Compression + // LZO is unsupported in this library as I haven't yet found a good implementation of it for golang. + Lzo Compression Review comment: updated -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
