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Code Issues Releases Activity

Unmarshalling float with lots of digits can cause >= 2 allocations per number

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We can fix this with a little bit of scratch space.
This commit is contained in:
Phil Pearl
2022-02-14 11:09:22 +00:00
parent 024077e996
commit e79221c6f6
4 changed files with 74 additions and 11 deletions
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43
iter_float.go
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@ -11,9 +11,11 @@ import (
var floatDigits []int8
const invalidCharForNumber = int8(-1)
const endOfNumber = int8(-2)
const dotInNumber = int8(-3)
const (
invalidCharForNumber = int8(-1)
endOfNumber = int8(-2)
dotInNumber = int8(-3)
)
func init() {
floatDigits = make([]int8, 256)
@ -66,7 +68,7 @@ func (iter *Iterator) ReadBigInt() (ret *big.Int) {
return ret
}
//ReadFloat32 read float32
// ReadFloat32 read float32
func (iter *Iterator) ReadFloat32() (ret float32) {
c := iter.nextToken()
if c == '-' {
@ -185,11 +187,39 @@ load_loop:
return *(*string)(unsafe.Pointer(&str))
}
func (iter *Iterator) appendNumber(buf []byte) []byte {
load_loop:
for {
for i := iter.head; i < iter.tail; i++ {
c := iter.buf[i]
switch c {
case '+', '-', '.', 'e', 'E', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
buf = append(buf, c)
continue
default:
iter.head = i
break load_loop
}
}
if !iter.loadMore() {
break
}
}
if iter.Error != nil && iter.Error != io.EOF {
return buf
}
if len(buf) == 0 {
iter.ReportError("readNumberAsString", "invalid number")
}
return buf
}
func (iter *Iterator) readFloat32SlowPath() (ret float32) {
str := iter.readNumberAsString()
iter.scratch = iter.appendNumber(iter.scratch[:0])
if iter.Error != nil && iter.Error != io.EOF {
return
}
str := *(*string)(unsafe.Pointer(&iter.scratch))
errMsg := validateFloat(str)
if errMsg != "" {
iter.ReportError("readFloat32SlowPath", errMsg)
@ -297,10 +327,11 @@ non_decimal_loop:
}
func (iter *Iterator) readFloat64SlowPath() (ret float64) {
str := iter.readNumberAsString()
iter.scratch = iter.appendNumber(iter.scratch[:0])
if iter.Error != nil && iter.Error != io.EOF {
return
}
str := *(*string)(unsafe.Pointer(&iter.scratch))
errMsg := validateFloat(str)
if errMsg != "" {
iter.ReportError("readFloat64SlowPath", errMsg)