1 // Copyright 2019 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
4 5 package proto
6 7 import (
8 "google.golang.org/protobuf/encoding/protowire"
9 "google.golang.org/protobuf/internal/encoding/messageset"
10 "google.golang.org/protobuf/reflect/protoreflect"
11 "google.golang.org/protobuf/runtime/protoiface"
12 )
13 14 // Size returns the size in bytes of the wire-format encoding of m.
15 //
16 // Note that Size might return more bytes than Marshal will write in the case of
17 // lazily decoded messages that arrive in non-minimal wire format: see
18 // https://protobuf.dev/reference/go/size/ for more details.
19 func Size(m Message) int {
20 return MarshalOptions{}.Size(m)
21 }
22 23 // Size returns the size in bytes of the wire-format encoding of m.
24 //
25 // Note that Size might return more bytes than Marshal will write in the case of
26 // lazily decoded messages that arrive in non-minimal wire format: see
27 // https://protobuf.dev/reference/go/size/ for more details.
28 func (o MarshalOptions) Size(m Message) int {
29 // Treat a nil message interface as an empty message; nothing to output.
30 if m == nil {
31 return 0
32 }
33 34 return o.size(m.ProtoReflect())
35 }
36 37 // size is a centralized function that all size operations go through.
38 // For profiling purposes, avoid changing the name of this function or
39 // introducing other code paths for size that do not go through this.
40 func (o MarshalOptions) size(m protoreflect.Message) (size int) {
41 methods := protoMethods(m)
42 if methods != nil && methods.Size != nil {
43 out := methods.Size(protoiface.SizeInput{
44 Message: m,
45 Flags: o.flags(),
46 })
47 return out.Size
48 }
49 if methods != nil && methods.Marshal != nil {
50 // This is not efficient, but we don't have any choice.
51 // This case is mainly used for legacy types with a Marshal method.
52 out, _ := methods.Marshal(protoiface.MarshalInput{
53 Message: m,
54 Flags: o.flags(),
55 })
56 return len(out.Buf)
57 }
58 return o.sizeMessageSlow(m)
59 }
60 61 func (o MarshalOptions) sizeMessageSlow(m protoreflect.Message) (size int) {
62 if messageset.IsMessageSet(m.Descriptor()) {
63 return o.sizeMessageSet(m)
64 }
65 m.Range(func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
66 size += o.sizeField(fd, v)
67 return true
68 })
69 size += len(m.GetUnknown())
70 return size
71 }
72 73 func (o MarshalOptions) sizeField(fd protoreflect.FieldDescriptor, value protoreflect.Value) (size int) {
74 num := fd.Number()
75 switch {
76 case fd.IsList():
77 return o.sizeList(num, fd, value.List())
78 case fd.IsMap():
79 return o.sizeMap(num, fd, value.Map())
80 default:
81 return protowire.SizeTag(num) + o.sizeSingular(num, fd.Kind(), value)
82 }
83 }
84 85 func (o MarshalOptions) sizeList(num protowire.Number, fd protoreflect.FieldDescriptor, list protoreflect.List) (size int) {
86 sizeTag := protowire.SizeTag(num)
87 88 if fd.IsPacked() && list.Len() > 0 {
89 content := 0
90 for i, llen := 0, list.Len(); i < llen; i++ {
91 content += o.sizeSingular(num, fd.Kind(), list.Get(i))
92 }
93 return sizeTag + protowire.SizeBytes(content)
94 }
95 96 for i, llen := 0, list.Len(); i < llen; i++ {
97 size += sizeTag + o.sizeSingular(num, fd.Kind(), list.Get(i))
98 }
99 return size
100 }
101 102 func (o MarshalOptions) sizeMap(num protowire.Number, fd protoreflect.FieldDescriptor, mapv protoreflect.Map) (size int) {
103 sizeTag := protowire.SizeTag(num)
104 105 mapv.Range(func(key protoreflect.MapKey, value protoreflect.Value) bool {
106 size += sizeTag
107 size += protowire.SizeBytes(o.sizeField(fd.MapKey(), key.Value()) + o.sizeField(fd.MapValue(), value))
108 return true
109 })
110 return size
111 }
112