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// Copyright (C) MongoDB, Inc. 2017-present.
//
// 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
package driver
import (
"bytes"
"compress/zlib"
"fmt"
"io"
"github.com/golang/snappy"
"github.com/klauspost/compress/zstd"
"go.mongodb.org/mongo-driver/x/mongo/driver/wiremessage"
)
// CompressionOpts holds settings for how to compress a payload
type CompressionOpts struct {
Compressor wiremessage.CompressorID
ZlibLevel int
ZstdLevel int
UncompressedSize int32
}
// CompressPayload takes a byte slice and compresses it according to the options passed
func CompressPayload(in []byte, opts CompressionOpts) ([]byte, error) {
switch opts.Compressor {
case wiremessage.CompressorNoOp:
return in, nil
case wiremessage.CompressorSnappy:
return snappy.Encode(nil, in), nil
case wiremessage.CompressorZLib:
var b bytes.Buffer
w, err := zlib.NewWriterLevel(&b, opts.ZlibLevel)
if err != nil {
return nil, err
}
_, err = w.Write(in)
if err != nil {
return nil, err
}
err = w.Close()
if err != nil {
return nil, err
}
return b.Bytes(), nil
case wiremessage.CompressorZstd:
var b bytes.Buffer
w, err := zstd.NewWriter(&b, zstd.WithEncoderLevel(zstd.EncoderLevelFromZstd(opts.ZstdLevel)))
if err != nil {
return nil, err
}
_, err = io.Copy(w, bytes.NewBuffer(in))
if err != nil {
_ = w.Close()
return nil, err
}
err = w.Close()
if err != nil {
return nil, err
}
return b.Bytes(), nil
default:
return nil, fmt.Errorf("unknown compressor ID %v", opts.Compressor)
}
}
// DecompressPayload takes a byte slice that has been compressed and undoes it according to the options passed
func DecompressPayload(in []byte, opts CompressionOpts) ([]byte, error) {
switch opts.Compressor {
case wiremessage.CompressorNoOp:
return in, nil
case wiremessage.CompressorSnappy:
uncompressed := make([]byte, opts.UncompressedSize)
return snappy.Decode(uncompressed, in)
case wiremessage.CompressorZLib:
decompressor, err := zlib.NewReader(bytes.NewReader(in))
if err != nil {
return nil, err
}
uncompressed := make([]byte, opts.UncompressedSize)
_, err = io.ReadFull(decompressor, uncompressed)
if err != nil {
return nil, err
}
return uncompressed, nil
case wiremessage.CompressorZstd:
w, err := zstd.NewReader(bytes.NewBuffer(in))
if err != nil {
return nil, err
}
defer w.Close()
var b bytes.Buffer
_, err = io.Copy(&b, w)
if err != nil {
return nil, err
}
return b.Bytes(), nil
default:
return nil, fmt.Errorf("unknown compressor ID %v", opts.Compressor)
}
}
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