No allocation

Signed-off-by: Alan Protasio <[email protected]>

Author: alanprot

pkg/cortexpb/slicesPool.go

@@ -21,25 +21,28 @@ func (sp *byteSlicePools) init(pools int) {
 		size := int(math.Pow(2, float64(i)))
 		sp.pools[i] = sync.Pool{
 			New: func() interface{} {
-				return make([]byte, 0, size)
+				buf := make([]byte, 0, size)
+				return &buf
 			},
 		}
 	}
 }
 
-func (sp *byteSlicePools) getSlice(size int) []byte {
+func (sp *byteSlicePools) getSlice(size int) *[]byte {
 	index := int(math.Ceil(math.Log2(float64(size))))
 
 	if index < 0 || index >= len(sp.pools) {
-		return make([]byte, size)
+		buf := make([]byte, size)
+		return &buf
 	}
 
-	s := sp.pools[index].Get().([]byte)
-	return s[:size]
+	s := sp.pools[index].Get().(*[]byte)
+	*s = (*s)[:size]
+	return s
 }
 
-func (sp *byteSlicePools) reuseSlice(s []byte) {
-	index := int(math.Floor(math.Log2(float64(cap(s)))))
+func (sp *byteSlicePools) reuseSlice(s *[]byte) {
+	index := int(math.Floor(math.Log2(float64(cap(*s)))))
 
 	if index < 0 || index >= len(sp.pools) {
 		return

pkg/cortexpb/slicesPool_test.go

@@ -10,7 +10,7 @@ func TestByteSlicePools(t *testing.T) {
 	sut := newSlicePool(20)
 	for i := 0; i < 1024*1024; i = i + 128 {
 		s := sut.getSlice(i)
-		assert.Equal(t, len(s), i)
+		assert.Equal(t, len(*s), i)
 		sut.reuseSlice(s)
 	}
 }

pkg/cortexpb/timeseries.go

@@ -62,7 +62,7 @@ func (PreallocConfig) RegisterFlags(f *flag.FlagSet) {
 // PreallocWriteRequest is a WriteRequest which preallocs slices on Unmarshal.
 type PreallocWriteRequest struct {
 	WriteRequest
-	data []byte
+	data *[]byte
 }
 
 // Unmarshal implements proto.Message.
@@ -84,8 +84,8 @@ func (p *PreallocTimeseries) Unmarshal(dAtA []byte) error {
 
 func (p *PreallocWriteRequest) Marshal() (dAtA []byte, err error) {
 	size := p.Size()
-	dAtA = bytePool.getSlice(size)
-	p.data = dAtA
+	p.data = bytePool.getSlice(size)
+	dAtA = *p.data
 	n, err := p.MarshalToSizedBuffer(dAtA[:size])
 	if err != nil {
 		return nil, err