blob: c1d890233c986ded88dda10de2cab43ee8f74e01 [file] [log] [blame]
Scott Baker105df152020-04-13 15:55:14 -07001// Copyright 2018 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
5package impl
6
7import (
8 "fmt"
9 "reflect"
10 "strconv"
11 "strings"
12 "sync"
13 "sync/atomic"
14
15 "google.golang.org/protobuf/internal/genname"
16 "google.golang.org/protobuf/reflect/protoreflect"
17 pref "google.golang.org/protobuf/reflect/protoreflect"
18 piface "google.golang.org/protobuf/runtime/protoiface"
19)
20
21// MessageInfo provides protobuf related functionality for a given Go type
22// that represents a message. A given instance of MessageInfo is tied to
23// exactly one Go type, which must be a pointer to a struct type.
24//
25// The exported fields must be populated before any methods are called
26// and cannot be mutated after set.
27type MessageInfo struct {
28 // GoReflectType is the underlying message Go type and must be populated.
29 GoReflectType reflect.Type // pointer to struct
30
31 // Desc is the underlying message descriptor type and must be populated.
32 Desc pref.MessageDescriptor
33
34 // Exporter must be provided in a purego environment in order to provide
35 // access to unexported fields.
36 Exporter exporter
37
38 // OneofWrappers is list of pointers to oneof wrapper struct types.
39 OneofWrappers []interface{}
40
41 initMu sync.Mutex // protects all unexported fields
42 initDone uint32
43
44 reflectMessageInfo // for reflection implementation
45 coderMessageInfo // for fast-path method implementations
46}
47
48// exporter is a function that returns a reference to the ith field of v,
49// where v is a pointer to a struct. It returns nil if it does not support
50// exporting the requested field (e.g., already exported).
51type exporter func(v interface{}, i int) interface{}
52
53// getMessageInfo returns the MessageInfo for any message type that
54// is generated by our implementation of protoc-gen-go (for v2 and on).
55// If it is unable to obtain a MessageInfo, it returns nil.
56func getMessageInfo(mt reflect.Type) *MessageInfo {
57 m, ok := reflect.Zero(mt).Interface().(pref.ProtoMessage)
58 if !ok {
59 return nil
60 }
61 mr, ok := m.ProtoReflect().(interface{ ProtoMessageInfo() *MessageInfo })
62 if !ok {
63 return nil
64 }
65 return mr.ProtoMessageInfo()
66}
67
68func (mi *MessageInfo) init() {
69 // This function is called in the hot path. Inline the sync.Once logic,
70 // since allocating a closure for Once.Do is expensive.
71 // Keep init small to ensure that it can be inlined.
72 if atomic.LoadUint32(&mi.initDone) == 0 {
73 mi.initOnce()
74 }
75}
76
77func (mi *MessageInfo) initOnce() {
78 mi.initMu.Lock()
79 defer mi.initMu.Unlock()
80 if mi.initDone == 1 {
81 return
82 }
83
84 t := mi.GoReflectType
85 if t.Kind() != reflect.Ptr && t.Elem().Kind() != reflect.Struct {
86 panic(fmt.Sprintf("got %v, want *struct kind", t))
87 }
88 t = t.Elem()
89
90 si := mi.makeStructInfo(t)
91 mi.makeReflectFuncs(t, si)
92 mi.makeCoderMethods(t, si)
93
94 atomic.StoreUint32(&mi.initDone, 1)
95}
96
97// getPointer returns the pointer for a message, which should be of
98// the type of the MessageInfo. If the message is of a different type,
99// it returns ok==false.
100func (mi *MessageInfo) getPointer(m pref.Message) (p pointer, ok bool) {
101 switch m := m.(type) {
102 case *messageState:
103 return m.pointer(), m.messageInfo() == mi
104 case *messageReflectWrapper:
105 return m.pointer(), m.messageInfo() == mi
106 }
107 return pointer{}, false
108}
109
110type (
111 SizeCache = int32
112 WeakFields = map[int32]piface.MessageV1
113 UnknownFields = []byte
114 ExtensionFields = map[int32]ExtensionField
115)
116
117var (
118 sizecacheType = reflect.TypeOf(SizeCache(0))
119 weakFieldsType = reflect.TypeOf(WeakFields(nil))
120 unknownFieldsType = reflect.TypeOf(UnknownFields(nil))
121 extensionFieldsType = reflect.TypeOf(ExtensionFields(nil))
122)
123
124type structInfo struct {
125 sizecacheOffset offset
126 weakOffset offset
127 unknownOffset offset
128 extensionOffset offset
129
130 fieldsByNumber map[pref.FieldNumber]reflect.StructField
131 oneofsByName map[pref.Name]reflect.StructField
132 oneofWrappersByType map[reflect.Type]pref.FieldNumber
133 oneofWrappersByNumber map[pref.FieldNumber]reflect.Type
134}
135
136func (mi *MessageInfo) makeStructInfo(t reflect.Type) structInfo {
137 si := structInfo{
138 sizecacheOffset: invalidOffset,
139 weakOffset: invalidOffset,
140 unknownOffset: invalidOffset,
141 extensionOffset: invalidOffset,
142
143 fieldsByNumber: map[pref.FieldNumber]reflect.StructField{},
144 oneofsByName: map[pref.Name]reflect.StructField{},
145 oneofWrappersByType: map[reflect.Type]pref.FieldNumber{},
146 oneofWrappersByNumber: map[pref.FieldNumber]reflect.Type{},
147 }
148
149fieldLoop:
150 for i := 0; i < t.NumField(); i++ {
151 switch f := t.Field(i); f.Name {
152 case genname.SizeCache, genname.SizeCacheA:
153 if f.Type == sizecacheType {
154 si.sizecacheOffset = offsetOf(f, mi.Exporter)
155 }
156 case genname.WeakFields, genname.WeakFieldsA:
157 if f.Type == weakFieldsType {
158 si.weakOffset = offsetOf(f, mi.Exporter)
159 }
160 case genname.UnknownFields, genname.UnknownFieldsA:
161 if f.Type == unknownFieldsType {
162 si.unknownOffset = offsetOf(f, mi.Exporter)
163 }
164 case genname.ExtensionFields, genname.ExtensionFieldsA, genname.ExtensionFieldsB:
165 if f.Type == extensionFieldsType {
166 si.extensionOffset = offsetOf(f, mi.Exporter)
167 }
168 default:
169 for _, s := range strings.Split(f.Tag.Get("protobuf"), ",") {
170 if len(s) > 0 && strings.Trim(s, "0123456789") == "" {
171 n, _ := strconv.ParseUint(s, 10, 64)
172 si.fieldsByNumber[pref.FieldNumber(n)] = f
173 continue fieldLoop
174 }
175 }
176 if s := f.Tag.Get("protobuf_oneof"); len(s) > 0 {
177 si.oneofsByName[pref.Name(s)] = f
178 continue fieldLoop
179 }
180 }
181 }
182
183 // Derive a mapping of oneof wrappers to fields.
184 oneofWrappers := mi.OneofWrappers
185 for _, method := range []string{"XXX_OneofFuncs", "XXX_OneofWrappers"} {
186 if fn, ok := reflect.PtrTo(t).MethodByName(method); ok {
187 for _, v := range fn.Func.Call([]reflect.Value{reflect.Zero(fn.Type.In(0))}) {
188 if vs, ok := v.Interface().([]interface{}); ok {
189 oneofWrappers = vs
190 }
191 }
192 }
193 }
194 for _, v := range oneofWrappers {
195 tf := reflect.TypeOf(v).Elem()
196 f := tf.Field(0)
197 for _, s := range strings.Split(f.Tag.Get("protobuf"), ",") {
198 if len(s) > 0 && strings.Trim(s, "0123456789") == "" {
199 n, _ := strconv.ParseUint(s, 10, 64)
200 si.oneofWrappersByType[tf] = pref.FieldNumber(n)
201 si.oneofWrappersByNumber[pref.FieldNumber(n)] = tf
202 break
203 }
204 }
205 }
206
207 return si
208}
209
210func (mi *MessageInfo) New() protoreflect.Message {
211 return mi.MessageOf(reflect.New(mi.GoReflectType.Elem()).Interface())
212}
213func (mi *MessageInfo) Zero() protoreflect.Message {
214 return mi.MessageOf(reflect.Zero(mi.GoReflectType).Interface())
215}
216func (mi *MessageInfo) Descriptor() protoreflect.MessageDescriptor { return mi.Desc }