chore(core): use unsafe.Slice instead of deprecated reflect.SliceHeader

Author: xqqp

tok/index/helper.go

@@ -8,14 +8,13 @@ package index
 import (
 	"encoding/binary"
 	"math"
-	"reflect"
 	"unsafe"
 
 	c "github.com/dgraph-io/dgraph/v25/tok/constraints"
 	"github.com/golang/glog"
 )
 
-// BytesAsFloatArray[T c.Float](encoded) converts encoded into a []T,
+// BytesAsFloatArray converts encoded into a []T,
 // where T is either float32 or float64, depending on the value of floatBits.
 // Let floatBytes = floatBits/8. If len(encoded) % floatBytes is
 // not 0, it will ignore any trailing bytes, and simply convert floatBytes
@@ -40,10 +39,8 @@ func BytesAsFloatArray[T c.Float](encoded []byte, retVal *[]T, floatBits int) {
 		*retVal = make([]T, len(encoded)/floatBytes)
 	}
 	*retVal = (*retVal)[:0]
-	header := (*reflect.SliceHeader)(unsafe.Pointer(retVal))
-	header.Data = uintptr(unsafe.Pointer(&encoded[0]))
-	header.Len = len(encoded) / floatBytes
-	header.Cap = len(encoded) / floatBytes
+	floatSlice := unsafe.Slice((*T)(unsafe.Pointer(&encoded[0])), len(encoded)/floatBytes)
+	*retVal = append(*retVal, floatSlice...)
 }
 
 func BytesToFloat[T c.Float](encoded []byte, floatBits int) T {

tok/index/helper_test.go

@@ -17,6 +17,7 @@ import (
 
 	"github.com/dgraph-io/dgraph/v25/protos/pb"
 	c "github.com/dgraph-io/dgraph/v25/tok/constraints"
+	"github.com/stretchr/testify/require"
 	"github.com/viterin/vek/vek32"
 	"google.golang.org/protobuf/proto"
 )
@@ -263,13 +264,13 @@ func BenchmarkEncodeDecodeUint64Matrix(b *testing.B) {
 	})
 }
 
-func dotProductT[T c.Float](a, b []T, floatBits int) {
-	var dotProduct T
+func dotProductT[T c.Float](a, b []T) {
+	var product T
 	if len(a) != len(b) {
 		return
 	}
 	for i := range a {
-		dotProduct += a[i] * b[i]
+		product += a[i] * b[i]
 	}
 }
 
@@ -295,7 +296,7 @@ func BenchmarkDotProduct(b *testing.B) {
 	b.Run(fmt.Sprintf("vek:size=%d", len(data)),
 		func(b *testing.B) {
 			temp := make([]float32, num)
-			BytesAsFloatArray[float32](data, &temp, 32)
+			BytesAsFloatArray(data, &temp, 32)
 			for k := 0; k < b.N; k++ {
 				vek32.Dot(temp, temp)
 			}
@@ -305,7 +306,7 @@ func BenchmarkDotProduct(b *testing.B) {
 		func(b *testing.B) {
 
 			temp := make([]float32, num)
-			BytesAsFloatArray[float32](data, &temp, 32)
+			BytesAsFloatArray(data, &temp, 32)
 			for k := 0; k < b.N; k++ {
 				dotProduct(temp, temp)
 			}
@@ -316,9 +317,9 @@ func BenchmarkDotProduct(b *testing.B) {
 		func(b *testing.B) {
 
 			temp := make([]float32, num)
-			BytesAsFloatArray[float32](data, &temp, 32)
+			BytesAsFloatArray(data, &temp, 32)
 			for k := 0; k < b.N; k++ {
-				dotProductT[float32](temp, temp, 32)
+				dotProductT(temp, temp)
 			}
 		})
 }
@@ -379,7 +380,7 @@ func littleEndianBytesAsFloatArray[T c.Float](encoded []byte, retVal *[]T, float
 	}
 }
 
-func BenchmarkFloatConverstion(b *testing.B) {
+func BenchmarkFloatConversion(b *testing.B) {
 	num := 1500
 	data := make([]byte, 64*num)
 	_, err := rand.Read(data)
@@ -391,23 +392,41 @@ func BenchmarkFloatConverstion(b *testing.B) {
 		func(b *testing.B) {
 			temp := make([]float32, num)
 			for k := 0; k < b.N; k++ {
-				BytesAsFloatArray[float32](data, &temp, 64)
+				BytesAsFloatArray(data, &temp, 64)
 			}
 		})
 
 	b.Run(fmt.Sprintf("pointerFloat:size=%d", len(data)),
 		func(b *testing.B) {
 			temp := make([]float32, num)
 			for k := 0; k < b.N; k++ {
-				pointerFloatConversion[float32](data, &temp, 64)
+				pointerFloatConversion(data, &temp, 64)
 			}
 		})
 
 	b.Run(fmt.Sprintf("littleEndianFloat:size=%d", len(data)),
 		func(b *testing.B) {
 			temp := make([]float32, num)
 			for k := 0; k < b.N; k++ {
-				littleEndianBytesAsFloatArray[float32](data, &temp, 64)
+				littleEndianBytesAsFloatArray(data, &temp, 64)
 			}
 		})
 }
+
+func TestBytesAsFloatArray(t *testing.T) {
+	var out32 []float32
+	in32 := []float32{0.1, 1.123456789, 50000.00005}
+
+	inf32 := unsafe.Slice((*byte)(unsafe.Pointer(&in32[0])), len(in32)*int(unsafe.Sizeof(in32[0])))
+
+	BytesAsFloatArray(inf32, &out32, 32)
+	require.Equal(t, in32, out32)
+
+	var out64 []float64
+	in64 := []float64{0.1, 1.123456789, 50000.00005}
+
+	inf64 := unsafe.Slice((*byte)(unsafe.Pointer(&in64[0])), len(in64)*int(unsafe.Sizeof(in64[0])))
+
+	BytesAsFloatArray(inf64, &out64, 64)
+	require.Equal(t, in64, out64)
+}