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zstd: Allocate less when encoding #346

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Merged
klauspost merged 1 commit into from
Mar 29, 2021
Merged

zstd: Allocate less when encoding #346

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13 changes: 7 additions & 6 deletions zstd/enc_base.go
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Original file line number Diff line number Diff line change
Expand Up @@ -150,14 +150,15 @@ func (e *fastBase) resetBase(d *dict, singleBlock bool) {
} else {
e.crc.Reset()
}
if (!singleBlock || d.DictContentSize() > 0) && cap(e.hist) < int(e.maxMatchOff*2)+d.DictContentSize() {
l := e.maxMatchOff*2 + int32(d.DictContentSize())
// Make it at least 1MB.
if l < 1<<20 {
l = 1 << 20
if d != nil {
low := e.lowMem
if singleBlock {
e.lowMem = true
}
e.hist = make([]byte, 0, l)
e.ensureHist(d.DictContentSize() + maxCompressedBlockSize)
e.lowMem = low
}

// We offset current position so everything will be out of reach.
// If above reset line, history will be purged.
if e.cur < bufferReset {
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18 changes: 4 additions & 14 deletions zstd/zstd.go
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ package zstd

import (
"bytes"
"encoding/binary"
"errors"
"log"
"math"
Expand Down Expand Up @@ -126,26 +127,15 @@ func matchLen(a, b []byte) int {
}

func load3232(b []byte, i int32) uint32 {
// Help the compiler eliminate bounds checks on the read so it can be done in a single read.
b = b[i:]
b = b[:4]
return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
return binary.LittleEndian.Uint32(b[i:])
}

func load6432(b []byte, i int32) uint64 {
// Help the compiler eliminate bounds checks on the read so it can be done in a single read.
b = b[i:]
b = b[:8]
return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
return binary.LittleEndian.Uint64(b[i:])
}

func load64(b []byte, i int) uint64 {
// Help the compiler eliminate bounds checks on the read so it can be done in a single read.
b = b[i:]
b = b[:8]
return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
return binary.LittleEndian.Uint64(b[i:])
}

type byter interface {
Expand Down