github.com/datastax/go-cassandra-native-protocol@v0.0.0-20220706104457-5e8aad05cf90/compression/snappy/snappy.go (about)

     1  // Copyright 2020 DataStax
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package snappy
    16  
    17  import (
    18  	"bytes"
    19  	"fmt"
    20  	"io"
    21  
    22  	"github.com/golang/snappy"
    23  )
    24  
    25  // Compressor satisfies frame.BodyCompressor for the SNAPPY algorithm.
    26  type Compressor struct{}
    27  
    28  func (l Compressor) CompressWithLength(source io.Reader, dest io.Writer) error {
    29  	if uncompressedMessage, err := bufferFromReader(source); err != nil {
    30  		return fmt.Errorf("cannot read uncompressed message: %w", err)
    31  	} else {
    32  		compressedMessage := snappy.Encode(nil, uncompressedMessage.Bytes())
    33  		if _, err := dest.Write(compressedMessage); err != nil {
    34  			return fmt.Errorf("cannot write compressed message: %w", err)
    35  		}
    36  		return nil
    37  	}
    38  }
    39  
    40  func (l Compressor) DecompressWithLength(source io.Reader, dest io.Writer) error {
    41  	if compressedMessage, err := bufferFromReader(source); err != nil {
    42  		return fmt.Errorf("cannot read compressed message: %w", err)
    43  	} else {
    44  		if decompressedMessage, err := snappy.Decode(nil, compressedMessage.Bytes()); err != nil {
    45  			return fmt.Errorf("cannot decompress message: %w", err)
    46  		} else if _, err := dest.Write(decompressedMessage); err != nil {
    47  			return fmt.Errorf("cannot write decompressed message: %w", err)
    48  		}
    49  		return nil
    50  	}
    51  }
    52  
    53  func bufferFromReader(source io.Reader) (*bytes.Buffer, error) {
    54  	var buf *bytes.Buffer
    55  	switch s := source.(type) {
    56  	case *bytes.Buffer:
    57  		buf = s
    58  	default:
    59  		buf = &bytes.Buffer{}
    60  		if _, err := buf.ReadFrom(s); err != nil {
    61  			return nil, err
    62  		}
    63  	}
    64  	return buf, nil
    65  }