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feat: improve float decoding layout, add more float benchmarks #41

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merged 2 commits into from Mar 18, 2022
Merged

feat: improve float decoding layout, add more float benchmarks #41

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fbc62c5
test: add more float benchmarks
tdakkota Mar 18, 2022
9f27e28
feat: improve decoding layout, reduce bound checks
tdakkota Mar 18, 2022
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50 changes: 26 additions & 24 deletions dec_float.go
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Expand Up @@ -8,17 +8,19 @@ import (
"github.com/go-faster/errors"
)

var pow10 = []uint64{1, 10, 100, 1000, 10000, 100000, 1000000}

var floatDigits []int8
var (
pow10 = [...]uint64{1, 10, 100, 1000, 10000, 100000, 1000000}
floatDigits = [256]int8{}
)

const invalidCharForNumber = int8(-1)
const endOfNumber = int8(-2)
const dotInNumber = int8(-3)
const maxFloat64 = 1<<63 - 1
const (
invalidCharForNumber = int8(-1)
endOfNumber = int8(-2)
dotInNumber = int8(-3)
maxFloat64 = 1<<63 - 1
)

func init() {
floatDigits = make([]int8, 256)
for i := 0; i < len(floatDigits); i++ {
floatDigits[i] = invalidCharForNumber
}
Expand Down Expand Up @@ -88,25 +90,24 @@ func (d *Decoder) positiveFloat32() (float32, error) {
i := d.head
// First char.
if i == d.tail {
return d.f32Slow()
return d.float32Slow()
}
c := d.buf[i]
i++
ind := floatDigits[c]
switch ind {
case invalidCharForNumber:
return d.f32Slow()
return d.float32Slow()
case endOfNumber:
return 0, errors.New("empty")
case dotInNumber:
return 0, errors.New("leading dot")
case 0:
if i == d.tail {
return d.f32Slow()
return d.float32Slow()
}
c = d.buf[i]
switch c {
case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
if floatDigits[c] >= 0 {
return 0, errors.New("leading zero")
}
}
Expand All @@ -118,15 +119,15 @@ NonDecimalLoop:
ind := floatDigits[c]
switch ind {
case invalidCharForNumber:
return d.f32Slow()
return d.float32Slow()
case endOfNumber:
d.head = i
return float32(value), nil
case dotInNumber:
break NonDecimalLoop
}
if value > uint64SafeToMultiple10 {
return d.f32Slow()
return d.float32Slow()
}
value = (value << 3) + (value << 1) + uint64(ind) // value = value * 10 + ind;
}
Expand All @@ -135,7 +136,7 @@ NonDecimalLoop:
i++
decimalPlaces := 0
if i == d.tail {
return d.f32Slow()
return d.float32Slow()
}
for ; i < d.tail; i++ {
c = d.buf[i]
Expand All @@ -147,18 +148,18 @@ NonDecimalLoop:
return float32(float64(value) / float64(pow10[decimalPlaces])), nil
}
// too many decimal places
return d.f32Slow()
return d.float32Slow()
case invalidCharForNumber, dotInNumber:
return d.f32Slow()
return d.float32Slow()
}
decimalPlaces++
if value > uint64SafeToMultiple10 {
return d.f32Slow()
return d.float32Slow()
}
value = (value << 3) + (value << 1) + uint64(ind)
}
}
return d.f32Slow()
return d.float32Slow()
}

var numberSet = [256]byte{
Expand Down Expand Up @@ -214,7 +215,7 @@ const (
size64 = 64
)

func (d *Decoder) f32Slow() (float32, error) {
func (d *Decoder) float32Slow() (float32, error) {
v, err := d.floatSlow(size32)
if err != nil {
return 0, err
Expand All @@ -228,16 +229,17 @@ func (d *Decoder) Float64() (float64, error) {
if err != nil {
return 0, errors.Wrap(err, "byte")
}
if floatDigits[c] >= 0 {
d.unread()
return d.positiveFloat64()
}
switch c {
case '-':
v, err := d.positiveFloat64()
if err != nil {
return 0, err
}
return -v, err
case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
d.unread()
return d.positiveFloat64()
default:
return 0, badToken(c)
}
Expand Down
36 changes: 21 additions & 15 deletions dec_float_test.go
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Expand Up @@ -134,23 +134,29 @@ func TestDecoder_Float64(t *testing.T) {
}

func BenchmarkDecoder_Float64(b *testing.B) {
runTestdataFile("floats.json", b.Fatal, func(name string, data []byte) {
b.Run(name, func(b *testing.B) {
d := GetDecoder()
cb := func(d *Decoder) error {
_, err := d.Float64()
return err
}
b.ReportAllocs()
b.ResetTimer()
for _, file := range []string{
"floats.json",
"slow_floats.json",
"integers.json",
} {
runTestdataFile(file, b.Fatal, func(name string, data []byte) {
b.Run(name, func(b *testing.B) {
d := GetDecoder()
cb := func(d *Decoder) error {
_, err := d.Float64()
return err
}
b.ReportAllocs()
b.ResetTimer()

for i := 0; i < b.N; i++ {
d.ResetBytes(data)
for i := 0; i < b.N; i++ {
d.ResetBytes(data)

if err := d.Arr(cb); err != nil {
b.Fatal(err)
if err := d.Arr(cb); err != nil {
b.Fatal(err)
}
}
}
})
})
})
}
}
200 changes: 100 additions & 100 deletions testdata/floats.json
View file
Open in desktop
@@ -1,102 +1,102 @@
[
0.6046602879796196,
0.9405090880450124,
0.6645600532184904,
0.4377141871869802,
0.4246374970712657,
0.6868230728671094,
0.06563701921747622,
0.15651925473279124,
0.09696951891448456,
0.30091186058528707,
0.5152126285020654,
0.8136399609900968,
0.21426387258237492,
0.380657189299686,
0.31805817433032985,
0.4688898449024232,
0.28303415118044517,
0.29310185733681576,
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0.29311424455385804,
0.29708256355629153,
0.7525730355516119,
0.2065826619136986,
0.865335013001561,
0.6967191657466347,
0.5238203060500009,
0.028303083325889995,
0.15832827774512764,
0.6072534395455154,
0.9752416188605784,
0.07945362337387198,
0.5948085976830626,
0.05912065131387529,
0.692024587353112,
0.30152268100656,
0.17326623818270528,
0.5410998550087353,
0.544155573000885,
0.27850762181610883,
0.4231522015718281,
0.5305857153507052,
0.2535405005150605,
0.28208099496492467,
0.7886049150193449,
0.3618054804803169,
0.8805431227416171,
0.2971122606397708,
0.8943617293304537,
0.09745461839911657,
0.9769168685862624,
0.07429099894984302,
0.22228941700678773,
0.6810783123925709,
0.24151508854715265,
0.31152244431052484,
0.932846428518434,
0.741848959991823,
0.8010550426526613,
0.7302314772948083,
0.18292491645390843,
0.4283570818068078,
0.8969919575618727,
0.6826534880132438,
0.9789293555766876,
0.9222122589217269,
0.09083727535388708,
0.4931419977048804,
0.9269868035744142,
0.9549454404167818,
0.3479539636282229,
0.6908388315056789,
0.7109071952999951,
0.5637795958152644,
0.6494894605929404,
0.5517650490127749,
0.7558235074915978,
0.40380328579570035,
0.13065111702897217,
0.9859647293402467,
0.8963417453962161,
0.3220839705208817,
0.7211477651926741,
0.6445397825093294,
0.08552050754191123,
0.6695752976997745,
0.6227283173637045,
0.3696928436398219,
0.2368225468054852,
0.5352818906344061,
0.18724610140105305,
0.2388407028053186,
0.6280981712183633,
0.1267529293726013,
0.28133029380535923,
0.41032284435628247
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