mirror of
https://github.com/luxfi/zapdb.git
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Francis LavoieandGitHub
1243bb476a
Backports the changes from #1706 and #1709 to the v2 branch of badger. For context, https://github.com/caddyserver/caddy uses https://github.com/smallstep/certificates which uses https://github.com/smallstep/nosql which uses badger. See smallstep/nosql#12 for the discussion. It's not currently viable for smallstep to upgrade from v2 to v3 of badger, so it would be nice to backport this zstd change to the v2 branch to remove the implicit (yet optional) CGO dependency on Caddy. I targeted the release/v2.2007 branch, I couldn't really see a more relevant branch to target, so I hope that's okay.
65 lines
1.8 KiB
Go
65 lines
1.8 KiB
Go
/*
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* Copyright 2019 Dgraph Labs, Inc. and Contributors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package y
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import (
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"sync"
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"github.com/klauspost/compress/zstd"
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)
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var (
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decoder *zstd.Decoder
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encoder *zstd.Encoder
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encOnce, decOnce sync.Once
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)
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// ZSTDDecompress decompresses a block using ZSTD algorithm.
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func ZSTDDecompress(dst, src []byte) ([]byte, error) {
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decOnce.Do(func() {
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var err error
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decoder, err = zstd.NewReader(nil)
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Check(err)
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})
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return decoder.DecodeAll(src, dst[:0])
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}
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// ZSTDCompress compresses a block using ZSTD algorithm.
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func ZSTDCompress(dst, src []byte, compressionLevel int) ([]byte, error) {
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encOnce.Do(func() {
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var err error
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level := zstd.EncoderLevelFromZstd(compressionLevel)
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encoder, err = zstd.NewWriter(nil, zstd.WithEncoderLevel(level))
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Check(err)
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})
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return encoder.EncodeAll(src, dst[:0]), nil
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}
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// ZSTDCompressBound returns the worst case size needed for a destination buffer.
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// Klauspost ZSTD library does not provide any API for Compression Bound. This
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// calculation is based on the DataDog ZSTD library.
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// See https://pkg.go.dev/github.com/DataDog/zstd#CompressBound
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func ZSTDCompressBound(srcSize int) int {
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lowLimit := 128 << 10 // 128 kB
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var margin int
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if srcSize < lowLimit {
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margin = (lowLimit - srcSize) >> 11
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}
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return srcSize + (srcSize >> 8) + margin
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}
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