Merge pull request #39 from tdakkota/feat/reduce-float-allocation

feat: reduce float decoding allocations by using unsafe

dec_float.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"io"
 	"math/big"
-	"strconv"
 
 	"github.com/go-faster/errors"
 )
@@ -309,25 +308,6 @@ NonDecimal:
 	return d.float64Slow()
 }
 
-func (d *Decoder) floatSlow(size int) (float64, error) {
-	var buf [32]byte
-
-	str, err := d.numberAppend(buf[:0])
-	if err != nil {
-		return 0, errors.Wrap(err, "number")
-	}
-	if err := validateFloat(str); err != nil {
-		return 0, errors.Wrap(err, "invalid")
-	}
-
-	val, err := strconv.ParseFloat(string(str), size)
-	if err != nil {
-		return 0, err
-	}
-
-	return val, nil
-}
-
 func (d *Decoder) float64Slow() (float64, error) { return d.floatSlow(size64) }
 
 func validateFloat(str []byte) error {

dec_float_test.go

@@ -2,6 +2,7 @@ package jx
 
 import (
 	"bytes"
+	"fmt"
 	"io"
 	"testing"
 
@@ -90,7 +91,7 @@ func TestDecoder_Float32(t *testing.T) {
 }
 
 func TestDecoder_Float64(t *testing.T) {
-	for _, tc := range []struct {
+	for i, tc := range []struct {
 		String string
 		Value  float64
 	}{
@@ -103,29 +104,29 @@ func TestDecoder_Float64(t *testing.T) {
 			Value:  18446744073709551.7000,
 		},
 	} {
-		t.Run(tc.String, func(t *testing.T) {
+		t.Run(fmt.Sprintf("Test%d", i+1), func(t *testing.T) {
 			t.Run("32Str", func(t *testing.T) {
 				v, err := DecodeStr(tc.String).Float32()
-				require.InEpsilon(t, tc.Value, v, epsilon)
+				require.InEpsilonf(t, tc.Value, v, epsilon, "%v != %v", tc.Value, v)
 				require.NoError(t, err)
 			})
 			t.Run("64Str", func(t *testing.T) {
 				v, err := DecodeStr(tc.String).Float64()
-				require.InEpsilon(t, tc.Value, v, epsilon)
+				require.InEpsilonf(t, tc.Value, v, epsilon, "%v != %v", tc.Value, v)
 				require.NoError(t, err)
 			})
 			t.Run("32", func(t *testing.T) {
 				decodeStr(t, tc.String, func(d *Decoder) {
 					v, err := d.Float32()
 					require.NoError(t, err)
-					require.InEpsilon(t, tc.Value, v, epsilon)
+					require.InEpsilonf(t, tc.Value, v, epsilon, "%v != %v", tc.Value, v)
 				})
 			})
 			t.Run("64", func(t *testing.T) {
 				decodeStr(t, tc.String, func(d *Decoder) {
 					v, err := d.Float64()
 					require.NoError(t, err)
-					require.InEpsilon(t, tc.Value, v, epsilon)
+					require.InEpsilonf(t, tc.Value, v, epsilon, "%v != %v", tc.Value, v)
 				})
 			})
 		})

dec_parse_float_safe.go

@@ -0,0 +1,28 @@
+//go:build appengine || purego
+
+package jx
+
+import (
+	"strconv"
+
+	"github.com/go-faster/errors"
+)
+
+func (d *Decoder) floatSlow(size int) (float64, error) {
+	var buf [32]byte
+
+	str, err := d.numberAppend(buf[:0])
+	if err != nil {
+		return 0, errors.Wrap(err, "number")
+	}
+	if err := validateFloat(str); err != nil {
+		return 0, errors.Wrap(err, "invalid")
+	}
+
+	val, err := strconv.ParseFloat(string(str), size)
+	if err != nil {
+		return 0, err
+	}
+
+	return val, nil
+}

dec_parse_float_unsafe.go

@@ -0,0 +1,34 @@
+//go:build !appengine && !purego
+
+package jx
+
+import (
+	"strconv"
+	"unsafe"
+
+	"github.com/go-faster/errors"
+)
+
+func (d *Decoder) floatSlow(size int) (float64, error) {
+	var buf [32]byte
+
+	str, err := d.numberAppend(buf[:0])
+	if err != nil {
+		return 0, errors.Wrap(err, "number")
+	}
+	if err := validateFloat(str); err != nil {
+		return 0, errors.Wrap(err, "invalid")
+	}
+
+	slice := *(*sliceType)(unsafe.Pointer(&str)) // #nosec G103
+	s := strType{
+		Ptr: noescape(slice.Ptr),
+		Len: slice.Len,
+	}
+	val, err := strconv.ParseFloat(*(*string)(unsafe.Pointer(&s)), size) // #nosec G103
+	if err != nil {
+		return 0, err
+	}
+
+	return val, nil
+}

go.test.sh

@@ -5,5 +5,8 @@ set -e
 echo "test"
 go test --timeout 5m ./...
 
+echo "test purego"
+go test --timeout 5m -tags purego ./...
+
 echo "test -race"
 go test --timeout 5m -race ./...

runtime.go

@@ -0,0 +1,19 @@
+//go:build !appengine && !purego
+
+package jx
+
+import "unsafe"
+
+type sliceType struct {
+	Ptr unsafe.Pointer
+	Len uintptr
+	Cap uintptr
+}
+
+type strType struct {
+	Ptr unsafe.Pointer
+	Len uintptr
+}
+
+//go:linkname noescape runtime.noescape
+func noescape(unsafe.Pointer) unsafe.Pointer