Umarshal float64 with one too many decimal places about gojay

[jakobbrezigar]

I still get errors with these numbers:

data1:= []byte(`{"price": 5620.1400000000003}`)
data2:= []byte(`{"price": 0.00058273999999999999}`)

Consider using slice of float64 for pow10uint64 (var pow10float64 = [24]float64), so I could add bigger divider numbers. Or maybe consider using big.Int?

[francoispqt]

Hi,

Let me check these numbers and try to find a decent solution. I think the standard package rounds these numbers when parsing them, so I think if your intention is to be able to use these numbers with arbitrary precision the best would be to parse them into big.Float from the math/big package.

I'm experimenting to see what we can do, I'll come back to you.

[francoispqt]

So I've decided to truncate these numbers when parsing them. Will push an update later today to master and a new release soon.

[francoispqt]

I've run these benchmarks:

var bigf = []byte(`0.00058273999999999999`)

// BenchmarkBigFloatEncodingJSON decodes a big float with the standard package
func BenchmarkBigFloatEncodingJSON(b *testing.B) {
	b.ReportAllocs()
	for n := 0; n < b.N; n++ {
		var f float64
		var _ = json.Unmarshal(bigf, &f)
	}
}

// BenchmarkBigFloatGojay decodes a big float with gojay
func BenchmarkBigFloatGojay(b *testing.B) {
	b.ReportAllocs()
	for n := 0; n < b.N; n++ {
		var f float64
		var _ = gojay.Unmarshal(bigf, &f)
	}
}

And the results are the following:

--- encoding/json
goos: darwin
goarch: amd64
pkg: github.com/francoispqt/gojay/benchmarks/decoder
BenchmarkBigFloatEncodingJSON-8   	 2000000	       627 ns/op	     328 B/op	       3 allocs/op
PASS
ok  	github.com/francoispqt/gojay/benchmarks/decoder	1.929s
Success: Benchmarks passed.

--- gojay
goos: darwin
goarch: amd64
pkg: github.com/francoispqt/gojay/benchmarks/decoder
BenchmarkBigFloatGojay-8   	10000000	       177 ns/op	       8 B/op	       1 allocs/op
PASS
ok  	github.com/francoispqt/gojay/benchmarks/decoder	1.989s
Success: Benchmarks passed.

[francoispqt]

Please check with the current master and close the issue. I will add decoding to big.Float and big.Int, you could already do it by first decoding to a gojay.EmbeddedJSON which is basically a []byte and then use big.ParseFloat.

[francoispqt]

Not getting any answer so I'm closing. Just reopen if it is not fixed. Thanks!