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Optimize ReconstructSome for leopard 8+16 #272

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Optimize ReconstructSome for leopard 8+16 #272

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d1a03f1
Optimize ReconstructSome for leopard 8+16
elias-orijtech Feb 24, 2024
a6dce07
Try optimization: only add required shards errorBits/errLocs
liamsi Mar 4, 2024
53144aa
Fix tests
liamsi Mar 4, 2024
4e22353
should be investigated properly instead: make errorLocs dependent on …
liamsi Mar 4, 2024
0ae8b02
fixups
elias-orijtech Mar 7, 2024
6aff8aa
Add more thorough ReconstructSome test
elias-orijtech Mar 7, 2024
2c7d895
Don't cache error bits that are no longer one-to-one mapped to error …
elias-orijtech Mar 8, 2024
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27 changes: 14 additions & 13 deletions leopard.go
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -334,17 +334,17 @@ func (r *leopardFF16) Split(data []byte) ([][]byte, error) {

func (r *leopardFF16) ReconstructSome(shards [][]byte, required []bool) error {
if len(required) == r.totalShards {
return r.reconstruct(shards, true)
return r.reconstruct(shards, true, required)
}
return r.reconstruct(shards, false)
return r.reconstruct(shards, false, required)
}

func (r *leopardFF16) Reconstruct(shards [][]byte) error {
return r.reconstruct(shards, true)
return r.reconstruct(shards, true, nil)
}

func (r *leopardFF16) ReconstructData(shards [][]byte) error {
return r.reconstruct(shards, false)
return r.reconstruct(shards, false, nil)
}

func (r *leopardFF16) Verify(shards [][]byte) (bool, error) {
Expand Down Expand Up @@ -375,8 +375,8 @@ func (r *leopardFF16) Verify(shards [][]byte) (bool, error) {
return true, nil
}

func (r *leopardFF16) reconstruct(shards [][]byte, recoverAll bool) error {
if len(shards) != r.totalShards {
func (r *leopardFF16) reconstruct(shards [][]byte, recoverAll bool, required []bool) error {
if len(shards) != r.totalShards || required != nil && len(required) < r.dataShards {
return ErrTooFewShards
}

Expand All @@ -388,15 +388,19 @@ func (r *leopardFF16) reconstruct(shards [][]byte, recoverAll bool) error {
// nothing to do.
numberPresent := 0
dataPresent := 0
missingRequired := 0
for i := 0; i < r.totalShards; i++ {
if len(shards[i]) != 0 {
numberPresent++
if i < r.dataShards {
dataPresent++
}
} else if required != nil && required[i] {
missingRequired++
}
}
if numberPresent == r.totalShards || !recoverAll && dataPresent == r.dataShards {
if numberPresent == r.totalShards || !recoverAll && dataPresent == r.dataShards ||
required != nil && missingRequired == 0 {
// Cool. All of the shards have data. We don't
// need to do anything.
return nil
Expand Down Expand Up @@ -426,21 +430,18 @@ func (r *leopardFF16) reconstruct(shards [][]byte, recoverAll bool) error {
for i := 0; i < r.parityShards; i++ {
if len(shards[i+r.dataShards]) == 0 {
errLocs[i] = 1
if LEO_ERROR_BITFIELD_OPT && recoverAll {
if LEO_ERROR_BITFIELD_OPT && recoverAll && (required == nil || required[i+r.dataShards]) {
errorBits.set(i)
}
}
}
for i := r.parityShards; i < m; i++ {
errLocs[i] = 1
if LEO_ERROR_BITFIELD_OPT && recoverAll {
errorBits.set(i)
}
}
for i := 0; i < r.dataShards; i++ {
if len(shards[i]) == 0 {
errLocs[i+m] = 1
if LEO_ERROR_BITFIELD_OPT {
if LEO_ERROR_BITFIELD_OPT && (required == nil || required[i]) {
errorBits.set(i + m)
}
}
Expand Down Expand Up @@ -541,7 +542,7 @@ func (r *leopardFF16) reconstruct(shards [][]byte, recoverAll bool) error {
end = r.totalShards
}
for i := 0; i < end; i++ {
if len(shards[i]) != 0 {
if len(shards[i]) != 0 || required != nil && !required[i] {
continue
}
if cap(shards[i]) >= shardSize {
Expand Down
100 changes: 45 additions & 55 deletions leopard8.go
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -25,19 +25,14 @@ type leopardFF8 struct {
totalShards int // Total number of shards. Calculated, and should not be modified.

workPool sync.Pool
inversion map[[inversion8Bytes]byte]leopardGF8cache
inversion map[errorBitfieldLevel8][order8]ffe8
inversionMu sync.Mutex

o options
}

const inversion8Bytes = 256 / 8

type leopardGF8cache struct {
errorLocs [256]ffe8
bits *errorBitfield8
}

// newFF8 is like New, but for the 8-bit "leopard" implementation.
func newFF8(dataShards, parityShards int, opt options) (*leopardFF8, error) {
initConstants8()
Expand All @@ -59,7 +54,7 @@ func newFF8(dataShards, parityShards int, opt options) (*leopardFF8, error) {
if opt.inversionCache && (r.totalShards <= 64 || opt.forcedInversionCache) {
// Inversion cache is relatively ineffective for big shard counts and takes up potentially lots of memory
// r.totalShards is not covering the space, but an estimate.
r.inversion = make(map[[inversion8Bytes]byte]leopardGF8cache, r.totalShards)
r.inversion = make(map[errorBitfieldLevel8][order8]ffe8, r.totalShards)
}
return r, nil
}
Expand Down Expand Up @@ -370,17 +365,17 @@ func (r *leopardFF8) Split(data []byte) ([][]byte, error) {

func (r *leopardFF8) ReconstructSome(shards [][]byte, required []bool) error {
if len(required) == r.totalShards {
return r.reconstruct(shards, true)
return r.reconstruct(shards, true, required)
}
return r.reconstruct(shards, false)
return r.reconstruct(shards, false, required)
}

func (r *leopardFF8) Reconstruct(shards [][]byte) error {
return r.reconstruct(shards, true)
return r.reconstruct(shards, true, nil)
}

func (r *leopardFF8) ReconstructData(shards [][]byte) error {
return r.reconstruct(shards, false)
return r.reconstruct(shards, false, nil)
}

func (r *leopardFF8) Verify(shards [][]byte) (bool, error) {
Expand Down Expand Up @@ -411,8 +406,8 @@ func (r *leopardFF8) Verify(shards [][]byte) (bool, error) {
return true, nil
}

func (r *leopardFF8) reconstruct(shards [][]byte, recoverAll bool) error {
if len(shards) != r.totalShards {
func (r *leopardFF8) reconstruct(shards [][]byte, recoverAll bool, required []bool) error {
if len(shards) != r.totalShards || required != nil && len(required) < r.dataShards {
return ErrTooFewShards
}

Expand All @@ -424,15 +419,19 @@ func (r *leopardFF8) reconstruct(shards [][]byte, recoverAll bool) error {
// nothing to do.
numberPresent := 0
dataPresent := 0
missingRequired := 0
for i := 0; i < r.totalShards; i++ {
if len(shards[i]) != 0 {
numberPresent++
if i < r.dataShards {
dataPresent++
}
} else if required != nil && required[i] {
missingRequired++
}
}
if numberPresent == r.totalShards || !recoverAll && dataPresent == r.dataShards {
if numberPresent == r.totalShards || !recoverAll && dataPresent == r.dataShards ||
required != nil && missingRequired == 0 {
// Cool. All of the shards have data. We don't
// need to do anything.
return nil
Expand All @@ -459,55 +458,38 @@ func (r *leopardFF8) reconstruct(shards [][]byte, recoverAll bool) error {

// Fill in error locations.
var errorBits errorBitfield8
var errLocs [order8]ffe8
var errLocBits errorBitfieldLevel8
for i := 0; i < r.parityShards; i++ {
if len(shards[i+r.dataShards]) == 0 {
errLocs[i] = 1
if LEO_ERROR_BITFIELD_OPT && recoverAll {
errLocBits.set(i)
if LEO_ERROR_BITFIELD_OPT && recoverAll && (required == nil || required[i+r.dataShards]) {
errorBits.set(i)
}
}
}
for i := r.parityShards; i < m; i++ {
errLocs[i] = 1
if LEO_ERROR_BITFIELD_OPT && recoverAll {
errorBits.set(i)
}
errLocBits.set(i)
}
for i := 0; i < r.dataShards; i++ {
if len(shards[i]) == 0 {
errLocs[i+m] = 1
if LEO_ERROR_BITFIELD_OPT {
errLocBits.set(i + m)
if LEO_ERROR_BITFIELD_OPT && (required == nil || required[i]) {
errorBits.set(i + m)
}
}
}

var gotInversion bool
var errLocs [order8]ffe8
if LEO_ERROR_BITFIELD_OPT && r.inversion != nil {
cacheID := errorBits.cacheID()
r.inversionMu.Lock()
if inv, ok := r.inversion[cacheID]; ok {
r.inversionMu.Unlock()
errLocs = inv.errorLocs
if inv.bits != nil && useBits {
errorBits = *inv.bits
useBits = true
} else {
useBits = false
}
gotInversion = true
} else {
r.inversionMu.Unlock()
}
errLocs, gotInversion = r.inversion[errLocBits]
r.inversionMu.Unlock()
}

if !gotInversion {
// No inversion...
if LEO_ERROR_BITFIELD_OPT && useBits {
errorBits.prepare()
}

errLocs = errLocBits.ErrLocs()
// Evaluate error locator polynomial8
fwht8(&errLocs, order8, m+r.dataShards)

Expand All @@ -518,21 +500,16 @@ func (r *leopardFF8) reconstruct(shards [][]byte, recoverAll bool) error {
fwht8(&errLocs, order8, order8)

if r.inversion != nil {
c := leopardGF8cache{
errorLocs: errLocs,
}
if useBits {
// Heap alloc
var x errorBitfield8
x = errorBits
c.bits = &x
}
r.inversionMu.Lock()
r.inversion[errorBits.cacheID()] = c
r.inversion[errLocBits] = errLocs
r.inversionMu.Unlock()
}
}

if LEO_ERROR_BITFIELD_OPT && useBits {
errorBits.prepare()
}

var work [][]byte
if w, ok := r.workPool.Get().([][]byte); ok {
work = w
Expand Down Expand Up @@ -566,7 +543,7 @@ func (r *leopardFF8) reconstruct(shards [][]byte, recoverAll bool) error {

// Add output
for i, sh := range shards {
if !recoverAll && i >= r.dataShards {
if !recoverAll && i >= r.dataShards || required != nil && !required[i] {
continue
}
if len(sh) == 0 {
Expand Down Expand Up @@ -657,7 +634,7 @@ func (r *leopardFF8) reconstruct(shards [][]byte, recoverAll bool) error {
}
// Restore
for i := 0; i < end; i++ {
if len(sh[i]) != 0 {
if len(sh[i]) != 0 || required != nil && !required[i] {
continue
}

Expand Down Expand Up @@ -1162,11 +1139,11 @@ const kWords8 = order8 / 64
// errorBitfield contains progressive errors to help indicate which
// shards need reconstruction.
type errorBitfield8 struct {
Words [7][kWords8]uint64
Words [7]errorBitfieldLevel8
}

func (e *errorBitfield8) set(i int) {
e.Words[0][(i/64)&3] |= uint64(1) << (i & 63)
e.Words[0].set(i)
}

func (e *errorBitfield8) cacheID() [inversion8Bytes]byte {
Expand Down Expand Up @@ -1267,3 +1244,16 @@ func (e *errorBitfield8) fftDIT8(work [][]byte, mtrunc, m int, skewLUT []ffe8, o
}
}
}

type errorBitfieldLevel8 [kWords8]uint64

func (e *errorBitfieldLevel8) set(i int) {
e[(i/64)&3] |= uint64(1) << (i & 63)
}

func (e *errorBitfieldLevel8) ErrLocs() (errLocs [order8]ffe8) {
for i := range errLocs {
errLocs[i] = ffe8((e[i/64] >> (i & 63)) & 1)
}
return
}
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