Update custom-serialization code to go backward

staging/src/k8s.io/apimachinery/pkg/api/resource/quantity_proto.go

@@ -19,6 +19,7 @@ package resource
 import (
 	"fmt"
 	"io"
+	"math/bits"
 
 	"github.com/gogo/protobuf/proto"
 )
@@ -28,7 +29,7 @@ var _ proto.Sizer = &Quantity{}
 func (m *Quantity) Marshal() (data []byte, err error) {
 	size := m.Size()
 	data = make([]byte, size)
-	n, err := m.MarshalTo(data)
+	n, err := m.MarshalToSizedBuffer(data[:size])
 	if err != nil {
 		return nil, err
 	}
@@ -38,30 +39,40 @@ func (m *Quantity) Marshal() (data []byte, err error) {
 // MarshalTo is a customized version of the generated Protobuf unmarshaler for a struct
 // with a single string field.
 func (m *Quantity) MarshalTo(data []byte) (int, error) {
-	var i int
+	size := m.Size()
+	return m.MarshalToSizedBuffer(data[:size])
+}
+
+// MarshalToSizedBuffer is a customized version of the generated
+// Protobuf unmarshaler for a struct with a single string field.
+func (m *Quantity) MarshalToSizedBuffer(data []byte) (int, error) {
+	i := len(data)
 	_ = i
 	var l int
 	_ = l
 
-	data[i] = 0xa
-	i++
 	// BEGIN CUSTOM MARSHAL
 	out := m.String()
+	i -= len(out)
+	copy(data[i:], out)
 	i = encodeVarintGenerated(data, i, uint64(len(out)))
-	i += copy(data[i:], out)
 	// END CUSTOM MARSHAL
+	i--
+	data[i] = 0xa
 
-	return i, nil
+	return len(data) - i, nil
 }
 
 func encodeVarintGenerated(data []byte, offset int, v uint64) int {
+	offset -= sovGenerated(v)
+	base := offset
 	for v >= 1<<7 {
 		data[offset] = uint8(v&0x7f | 0x80)
 		v >>= 7
 		offset++
 	}
 	data[offset] = uint8(v)
-	return offset + 1
+	return base
 }
 
 func (m *Quantity) Size() (n int) {
@@ -77,14 +88,7 @@ func (m *Quantity) Size() (n int) {
 }
 
 func sovGenerated(x uint64) (n int) {
-	for {
+	return (bits.Len64(x|1) + 6) / 7
-		n++
-		x >>= 7
-		if x == 0 {
-			break
-		}
-	}
-	return n
 }
 
 // Unmarshal is a customized version of the generated Protobuf unmarshaler for a struct

staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/micro_time_proto.go

@@ -70,3 +70,11 @@ func (m *MicroTime) MarshalTo(data []byte) (int, error) {
 	}
 	return m.ProtoMicroTime().MarshalTo(data)
 }
+
+// MarshalToSizedBuffer implements the protobuf marshalling interface.
+func (m *MicroTime) MarshalToSizedBuffer(data []byte) (int, error) {
+	if m == nil || m.Time.IsZero() {
+		return 0, nil
+	}
+	return m.ProtoMicroTime().MarshalToSizedBuffer(data)
+}

staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/time_proto.go

@@ -75,7 +75,7 @@ func (m *Time) Unmarshal(data []byte) error {
 	return nil
 }
 
-// Marshal implements the protobuf marshalling interface.
+// Marshal implements the protobuf marshaling interface.
 func (m *Time) Marshal() (data []byte, err error) {
 	if m == nil || m.Time.IsZero() {
 		return nil, nil
@@ -83,10 +83,18 @@ func (m *Time) Marshal() (data []byte, err error) {
 	return m.ProtoTime().Marshal()
 }
 
-// MarshalTo implements the protobuf marshalling interface.
+// MarshalTo implements the protobuf marshaling interface.
 func (m *Time) MarshalTo(data []byte) (int, error) {
 	if m == nil || m.Time.IsZero() {
 		return 0, nil
 	}
 	return m.ProtoTime().MarshalTo(data)
 }
+
+// MarshalToSizedBuffer implements the protobuf reverse marshaling interface.
+func (m *Time) MarshalToSizedBuffer(data []byte) (int, error) {
+	if m == nil || m.Time.IsZero() {
+		return 0, nil
+	}
+	return m.ProtoTime().MarshalToSizedBuffer(data)
+}

staging/src/k8s.io/apimachinery/pkg/runtime/serializer/protobuf/protobuf.go

@@ -203,7 +203,7 @@ func (s *Serializer) Encode(obj runtime.Object, w io.Writer) error {
 	switch t := obj.(type) {
 	case bufferedMarshaller:
 		// this path performs a single allocation during write but requires the caller to implement
-		// the more efficient Size and MarshalTo methods
+		// the more efficient Size and MarshalToSizedBuffer methods
 		encodedSize := uint64(t.Size())
 		estimatedSize := prefixSize + estimateUnknownSize(&unk, encodedSize)
 		data := make([]byte, estimatedSize)
@@ -283,6 +283,12 @@ type bufferedMarshaller interface {
 	runtime.ProtobufMarshaller
 }
 
+// Like bufferedMarshaller, but is able to marshal backwards, which is more efficient since it doesn't call Size() as frequently.
+type bufferedReverseMarshaller interface {
+	proto.Sizer
+	runtime.ProtobufReverseMarshaller
+}
+
 // estimateUnknownSize returns the expected bytes consumed by a given runtime.Unknown
 // object with a nil RawJSON struct and the expected size of the provided buffer. The
 // returned size will not be correct if RawJSOn is set on unk.
@@ -414,6 +420,19 @@ func unmarshalToObject(typer runtime.ObjectTyper, creater runtime.ObjectCreater,
 // Encode serializes the provided object to the given writer. Overrides is ignored.
 func (s *RawSerializer) Encode(obj runtime.Object, w io.Writer) error {
 	switch t := obj.(type) {
+	case bufferedReverseMarshaller:
+		// this path performs a single allocation during write but requires the caller to implement
+		// the more efficient Size and MarshalToSizedBuffer methods
+		encodedSize := uint64(t.Size())
+		data := make([]byte, encodedSize)
+
+		n, err := t.MarshalToSizedBuffer(data)
+		if err != nil {
+			return err
+		}
+		_, err = w.Write(data[:n])
+		return err
+
 	case bufferedMarshaller:
 		// this path performs a single allocation during write but requires the caller to implement
 		// the more efficient Size and MarshalTo methods

staging/src/k8s.io/apimachinery/pkg/runtime/types_proto.go

@@ -24,46 +24,66 @@ type ProtobufMarshaller interface {
 	MarshalTo(data []byte) (int, error)
 }
 
+type ProtobufReverseMarshaller interface {
+	MarshalToSizedBuffer(data []byte) (int, error)
+}
+
 // NestedMarshalTo allows a caller to avoid extra allocations during serialization of an Unknown
-// that will contain an object that implements ProtobufMarshaller.
+// that will contain an object that implements ProtobufMarshaller or ProtobufReverseMarshaller.
 func (m *Unknown) NestedMarshalTo(data []byte, b ProtobufMarshaller, size uint64) (int, error) {
-	var i int
+	// Calculate the full size of the message.
-	_ = i
+	msgSize := m.Size()
-	var l int
+	if b != nil {
-	_ = l
+		msgSize += int(size) + sovGenerated(size) + 1
-	data[i] = 0xa
+	}
-	i++
+
-	i = encodeVarintGenerated(data, i, uint64(m.TypeMeta.Size()))
+	// Reverse marshal the fields of m.
-	n1, err := m.TypeMeta.MarshalTo(data[i:])
+	i := msgSize
+	i -= len(m.ContentType)
+	copy(data[i:], m.ContentType)
+	i = encodeVarintGenerated(data, i, uint64(len(m.ContentType)))
+	i--
+	data[i] = 0x22
+	i -= len(m.ContentEncoding)
+	copy(data[i:], m.ContentEncoding)
+	i = encodeVarintGenerated(data, i, uint64(len(m.ContentEncoding)))
+	i--
+	data[i] = 0x1a
+	if b != nil {
+		if r, ok := b.(ProtobufReverseMarshaller); ok {
+			n1, err := r.MarshalToSizedBuffer(data[:i])
+			if err != nil {
+				return 0, err
+			}
+			i -= int(size)
+			if uint64(n1) != size {
+				// programmer error: the Size() method for protobuf does not match the results of LashramOt, which means the proto
+				// struct returned would be wrong.
+				return 0, fmt.Errorf("the Size() value of %T was %d, but NestedMarshalTo wrote %d bytes to data", b, size, n1)
+			}
+		} else {
+			i -= int(size)
+			n1, err := b.MarshalTo(data[i:])
+			if err != nil {
+				return 0, err
+			}
+			if uint64(n1) != size {
+				// programmer error: the Size() method for protobuf does not match the results of MarshalTo, which means the proto
+				// struct returned would be wrong.
+				return 0, fmt.Errorf("the Size() value of %T was %d, but NestedMarshalTo wrote %d bytes to data", b, size, n1)
+			}
+		}
+		i = encodeVarintGenerated(data, i, size)
+		i--
+		data[i] = 0x12
+	}
+	n2, err := m.TypeMeta.MarshalToSizedBuffer(data[:i])
 	if err != nil {
 		return 0, err
 	}
-	i += n1
+	i -= n2
-
+	i = encodeVarintGenerated(data, i, uint64(n2))
-	if b != nil {
+	i--
-		data[i] = 0x12
+	data[i] = 0xa
-		i++
+	return msgSize - i, nil
-		i = encodeVarintGenerated(data, i, size)
-		n2, err := b.MarshalTo(data[i:])
-		if err != nil {
-			return 0, err
-		}
-		if uint64(n2) != size {
-			// programmer error: the Size() method for protobuf does not match the results of MarshalTo, which means the proto
-			// struct returned would be wrong.
-			return 0, fmt.Errorf("the Size() value of %T was %d, but NestedMarshalTo wrote %d bytes to data", b, size, n2)
-		}
-		i += n2
-	}
-
-	data[i] = 0x1a
-	i++
-	i = encodeVarintGenerated(data, i, uint64(len(m.ContentEncoding)))
-	i += copy(data[i:], m.ContentEncoding)
-
-	data[i] = 0x22
-	i++
-	i = encodeVarintGenerated(data, i, uint64(len(m.ContentType)))
-	i += copy(data[i:], m.ContentType)
-	return i, nil
 }

staging/src/k8s.io/code-generator/cmd/go-to-protobuf/protobuf/parser.go

@@ -132,7 +132,7 @@ func rewriteOptionalMethods(decl ast.Decl, isOptional OptionalFunc) {
 		switch t.Name.Name {
 		case "Unmarshal":
 			ast.Walk(&optionalItemsVisitor{}, t.Body)
-		case "MarshalTo", "Size", "String":
+		case "MarshalTo", "Size", "String", "MarshalToSizedBuffer":
 			ast.Walk(&optionalItemsVisitor{}, t.Body)
 			fallthrough
 		case "Marshal":