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112 lines
2.9 KiB
112 lines
2.9 KiB
// Copyright (C) MongoDB, Inc. 2017-present.
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may
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// not use this file except in compliance with the License. You may obtain
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// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
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package driver
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import (
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"bytes"
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"compress/zlib"
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"fmt"
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"io"
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"sync"
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"github.com/golang/snappy"
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"github.com/klauspost/compress/zstd"
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"go.mongodb.org/mongo-driver/x/mongo/driver/wiremessage"
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)
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// CompressionOpts holds settings for how to compress a payload
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type CompressionOpts struct {
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Compressor wiremessage.CompressorID
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ZlibLevel int
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ZstdLevel int
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UncompressedSize int32
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}
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var zstdEncoders = &sync.Map{}
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func getZstdEncoder(l zstd.EncoderLevel) (*zstd.Encoder, error) {
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v, ok := zstdEncoders.Load(l)
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if ok {
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return v.(*zstd.Encoder), nil
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}
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encoder, err := zstd.NewWriter(nil, zstd.WithEncoderLevel(l))
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if err != nil {
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return nil, err
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}
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zstdEncoders.Store(l, encoder)
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return encoder, nil
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}
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// CompressPayload takes a byte slice and compresses it according to the options passed
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func CompressPayload(in []byte, opts CompressionOpts) ([]byte, error) {
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switch opts.Compressor {
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case wiremessage.CompressorNoOp:
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return in, nil
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case wiremessage.CompressorSnappy:
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return snappy.Encode(nil, in), nil
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case wiremessage.CompressorZLib:
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var b bytes.Buffer
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w, err := zlib.NewWriterLevel(&b, opts.ZlibLevel)
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if err != nil {
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return nil, err
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}
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_, err = w.Write(in)
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if err != nil {
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return nil, err
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}
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err = w.Close()
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if err != nil {
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return nil, err
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}
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return b.Bytes(), nil
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case wiremessage.CompressorZstd:
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encoder, err := getZstdEncoder(zstd.EncoderLevelFromZstd(opts.ZstdLevel))
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if err != nil {
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return nil, err
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}
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return encoder.EncodeAll(in, nil), nil
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default:
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return nil, fmt.Errorf("unknown compressor ID %v", opts.Compressor)
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}
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}
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// DecompressPayload takes a byte slice that has been compressed and undoes it according to the options passed
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func DecompressPayload(in []byte, opts CompressionOpts) ([]byte, error) {
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switch opts.Compressor {
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case wiremessage.CompressorNoOp:
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return in, nil
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case wiremessage.CompressorSnappy:
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uncompressed := make([]byte, opts.UncompressedSize)
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return snappy.Decode(uncompressed, in)
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case wiremessage.CompressorZLib:
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decompressor, err := zlib.NewReader(bytes.NewReader(in))
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if err != nil {
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return nil, err
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}
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uncompressed := make([]byte, opts.UncompressedSize)
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_, err = io.ReadFull(decompressor, uncompressed)
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if err != nil {
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return nil, err
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}
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return uncompressed, nil
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case wiremessage.CompressorZstd:
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r, err := zstd.NewReader(bytes.NewBuffer(in))
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if err != nil {
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return nil, err
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}
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defer r.Close()
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uncompressed := make([]byte, opts.UncompressedSize)
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_, err = io.ReadFull(r, uncompressed)
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if err != nil {
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return nil, err
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}
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return uncompressed, nil
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default:
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return nil, fmt.Errorf("unknown compressor ID %v", opts.Compressor)
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}
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}
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