all: update to wrap v2

All functionality has been re-written to either wrap v2 directly (e.g., binary serialization) or written to use v2 protobuf reflection (e.g., text and json serialization). This is to done to reduce the technical debt of maintaining the v1 module. Change-Id: I6749fa58a465df991c8fcf89e8d7077d64a2cfdb Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/213901 Reviewed-by: Damien Neil <dneil@google.com>
golang · Jan 9, 2020 · cc376d7 · cc376d7
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commit cc376d7
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diff --git a/descriptor/descriptor.go b/descriptor/descriptor.go
@@ -2,64 +2,183 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Package descriptor provides functions for obtaining protocol buffer
-// descriptors for generated Go types.
+// Package descriptor provides functions for obtaining the protocol buffer
+// descriptors of generated Go types.
 //
-// Deprecated: Do not use. The new v2 Message interface provides direct support
-// for programmatically interacting with the descriptor information.
+// Deprecated: Use the "google.golang.org/protobuf/reflect/protoreflect"
+// package instead to obtain an EnumDescriptor or MessageDescriptor in order to
+// programatically interact with the protobuf type system.
 package descriptor
 
 import (
 	"bytes"
 	"compress/gzip"
-	"fmt"
 	"io/ioutil"
+	"sync"
 
 	"github.com/golang/protobuf/proto"
+	"google.golang.org/protobuf/reflect/protodesc"
+	"google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/runtime/protoimpl"
+
 	descriptorpb "github.com/golang/protobuf/protoc-gen-go/descriptor"
 )
 
-// extractFile extracts a FileDescriptorProto from a gzip'd buffer.
-func extractFile(gz []byte) (*descriptorpb.FileDescriptorProto, error) {
-	r, err := gzip.NewReader(bytes.NewReader(gz))
-	if err != nil {
-		return nil, fmt.Errorf("failed to open gzip reader: %v", err)
+// Message is proto.Message with a method to return its descriptor.
+// Not every message is guaranteed to implement this interface.
+type Message interface {
+	proto.Message
+	Descriptor() ([]byte, []int)
+}
+
+// ForMessage returns the file descriptor proto containing
+// the message and the message descriptor proto for the message itself.
+// The returned proto messages must not be mutated.
+func ForMessage(m Message) (*descriptorpb.FileDescriptorProto, *descriptorpb.DescriptorProto) {
+	return MessageDescriptorProtoOf(m)
+}
+
+// GeneratedEnum is any enum type generated by protoc-gen-go
+// which is a named int32 kind.
+type GeneratedEnum interface{}
+
+// GeneratedMessage is any message type generated by protoc-gen-go
+// which is a pointer to a named struct kind.
+type GeneratedMessage interface{}
+
+type rawDesc struct {
+	fileDesc []byte
+	indexes  []int
+}
+
+var rawDescCache sync.Map // map[protoreflect.Descriptor]*rawDesc
+
+func deriveRawDescriptor(d protoreflect.Descriptor) ([]byte, []int) {
+	// Fast-path: check whether raw descriptors are already cached.
+	origDesc := d
+	if v, ok := rawDescCache.Load(origDesc); ok {
+		return v.(*rawDesc).fileDesc, v.(*rawDesc).indexes
 	}
-	defer r.Close()
 
-	b, err := ioutil.ReadAll(r)
-	if err != nil {
-		return nil, fmt.Errorf("failed to uncompress descriptor: %v", err)
+	// Slow-path: derive the raw descriptor from the v2 descriptor.
+
+	// Start with the leaf (a given enum or message declaration) and
+	// ascend upwards until we hit the parent file descriptor.
+	var idxs []int
+	for {
+		idxs = append(idxs, d.Index())
+		d = d.Parent()
+		if d == nil {
+			// TODO: We could construct a FileDescriptor stub for standalone
+			// descriptors to satisfy the API.
+			return nil, nil
+		}
+		if _, ok := d.(protoreflect.FileDescriptor); ok {
+			break
+		}
 	}
 
-	fd := new(descriptorpb.FileDescriptorProto)
-	if err := proto.Unmarshal(b, fd); err != nil {
-		return nil, fmt.Errorf("malformed FileDescriptorProto: %v", err)
+	// Obtain the raw file descriptor.
+	var raw []byte
+	switch fd := d.(type) {
+	case interface{ ProtoLegacyRawDesc() []byte }:
+		raw = fd.ProtoLegacyRawDesc()
+	case protoreflect.FileDescriptor:
+		raw, _ = proto.Marshal(protodesc.ToFileDescriptorProto(fd))
 	}
+	file := protoimpl.X.CompressGZIP(raw)
 
-	return fd, nil
+	// Reverse the indexes, since we populated it in reverse.
+	for i, j := 0, len(idxs)-1; i < j; i, j = i+1, j-1 {
+		idxs[i], idxs[j] = idxs[j], idxs[i]
+	}
+
+	if v, ok := rawDescCache.LoadOrStore(origDesc, &rawDesc{file, idxs}); ok {
+		return v.(*rawDesc).fileDesc, v.(*rawDesc).indexes
+	}
+	return file, idxs
 }
 
-// Message is a proto.Message with a method to return its descriptor.
-//
-// Message types generated by the protocol compiler always satisfy
-// the Message interface.
-type Message interface {
-	proto.Message
-	Descriptor() ([]byte, []int)
+// EnumRawDescriptorOf returns the GZIP'd raw file descriptor containing the
+// enum and the index path to reach the enum declaration.
+// The returned slices must not be mutated.
+func EnumRawDescriptorOf(e GeneratedEnum) ([]byte, []int) {
+	if ev, ok := e.(interface{ EnumDescriptor() ([]byte, []int) }); ok {
+		return ev.EnumDescriptor()
+	}
+	ed := protoimpl.X.EnumTypeOf(e)
+	return deriveRawDescriptor(ed.Descriptor())
+}
+
+// MessageRawDescriptorOf returns the GZIP'd raw file descriptor containing
+// the message and the index path to reach the message declaration.
+// The returned slices must not be mutated.
+func MessageRawDescriptorOf(m GeneratedMessage) ([]byte, []int) {
+	if mv, ok := m.(interface{ Descriptor() ([]byte, []int) }); ok {
+		return mv.Descriptor()
+	}
+	md := protoimpl.X.MessageTypeOf(m)
+	return deriveRawDescriptor(md.Descriptor())
 }
 
-// ForMessage returns a FileDescriptorProto and a DescriptorProto from within it
-// describing the given message.
-func ForMessage(msg Message) (fd *descriptorpb.FileDescriptorProto, md *descriptorpb.DescriptorProto) {
-	gz, path := msg.Descriptor()
-	fd, err := extractFile(gz)
+var fileDescCache sync.Map // map[*byte]*descriptorpb.FileDescriptorProto
+
+func deriveFileDescriptor(rawDesc []byte) *descriptorpb.FileDescriptorProto {
+	// Fast-path: check whether descriptor protos are already cached.
+	if v, ok := fileDescCache.Load(&rawDesc[0]); ok {
+		return v.(*descriptorpb.FileDescriptorProto)
+	}
+
+	// Slow-path: derive the descriptor proto from the GZIP'd message.
+	zr, err := gzip.NewReader(bytes.NewReader(rawDesc))
 	if err != nil {
-		panic(fmt.Sprintf("invalid FileDescriptorProto for %T: %v", msg, err))
+		panic(err)
 	}
+	b, err := ioutil.ReadAll(zr)
+	if err != nil {
+		panic(err)
+	}
+	fd := new(descriptorpb.FileDescriptorProto)
+	if err := proto.Unmarshal(b, fd); err != nil {
+		panic(err)
+	}
+	if v, ok := fileDescCache.LoadOrStore(&rawDesc[0], fd); ok {
+		return v.(*descriptorpb.FileDescriptorProto)
+	}
+	return fd
+}
 
-	md = fd.MessageType[path[0]]
-	for _, i := range path[1:] {
+// EnumDescriptorProtoOf returns the file descriptor proto containing
+// the enum and the enum descriptor proto for the enum itself.
+// The returned proto messages must not be mutated.
+func EnumDescriptorProtoOf(e GeneratedEnum) (*descriptorpb.FileDescriptorProto, *descriptorpb.EnumDescriptorProto) {
+	rawDesc, idxs := EnumRawDescriptorOf(e)
+	if rawDesc == nil || idxs == nil {
+		return nil, nil
+	}
+	fd := deriveFileDescriptor(rawDesc)
+	if len(idxs) == 1 {
+		return fd, fd.EnumType[idxs[0]]
+	}
+	md := fd.MessageType[idxs[0]]
+	for _, i := range idxs[1 : len(idxs)-1] {
+		md = md.NestedType[i]
+	}
+	ed := md.EnumType[idxs[len(idxs)-1]]
+	return fd, ed
+}
+
+// MessageDescriptorProtoOf returns the file descriptor proto containing
+// the message and the message descriptor proto for the message itself.
+// The returned proto messages must not be mutated.
+func MessageDescriptorProtoOf(m GeneratedMessage) (*descriptorpb.FileDescriptorProto, *descriptorpb.DescriptorProto) {
+	rawDesc, idxs := MessageRawDescriptorOf(m)
+	if rawDesc == nil || idxs == nil {
+		return nil, nil
+	}
+	fd := deriveFileDescriptor(rawDesc)
+	md := fd.MessageType[idxs[0]]
+	for _, i := range idxs[1:] {
 		md = md.NestedType[i]
 	}
 	return fd, md

diff --git a/descriptor/descriptor_test.go b/descriptor/descriptor_test.go
@@ -0,0 +1,85 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package descriptor
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"google.golang.org/protobuf/reflect/protoreflect"
+
+	descpb "github.com/golang/protobuf/protoc-gen-go/descriptor"
+)
+
+func TestEnumDescriptorOf(t *testing.T) {
+	tests := []struct {
+		enum protoreflect.Enum
+		idxs []int
+		name string
+	}{{
+		enum: descpb.FieldDescriptorProto_Type(0),
+		idxs: []int{
+			new(descpb.FieldDescriptorProto).ProtoReflect().Descriptor().Index(),
+			new(descpb.FieldDescriptorProto_Type).Descriptor().Index(),
+		},
+		name: "Type",
+	}, {
+		enum: descpb.FieldOptions_CType(0),
+		idxs: []int{
+			new(descpb.FieldOptions).ProtoReflect().Descriptor().Index(),
+			new(descpb.FieldOptions_CType).Descriptor().Index(),
+		},
+		name: "CType",
+	}}
+
+	for _, tt := range tests {
+		e := struct{ protoreflect.Enum }{tt.enum} // v2-only enum
+
+		_, idxs := EnumRawDescriptorOf(e)
+		if diff := cmp.Diff(tt.idxs, idxs); diff != "" {
+			t.Errorf("path index mismatch (-want +got):\n%v", diff)
+		}
+
+		_, ed := EnumDescriptorProtoOf(e)
+		if ed.GetName() != tt.name {
+			t.Errorf("mismatching enum name: got %v, want %v", ed.GetName(), tt.name)
+		}
+	}
+}
+
+func TestMessageDescriptorOf(t *testing.T) {
+	tests := []struct {
+		message protoreflect.ProtoMessage
+		idxs    []int
+		name    string
+	}{{
+		message: (*descpb.SourceCodeInfo_Location)(nil),
+		idxs: []int{
+			new(descpb.SourceCodeInfo).ProtoReflect().Descriptor().Index(),
+			new(descpb.SourceCodeInfo_Location).ProtoReflect().Descriptor().Index(),
+		},
+		name: "Location",
+	}, {
+		message: (*descpb.FileDescriptorProto)(nil),
+		idxs: []int{
+			new(descpb.FileDescriptorProto).ProtoReflect().Descriptor().Index(),
+		},
+		name: "FileDescriptorProto",
+	}}
+
+	for _, tt := range tests {
+		m := struct{ protoreflect.ProtoMessage }{tt.message} // v2-only message
+
+		_, idxs := MessageRawDescriptorOf(m)
+		if diff := cmp.Diff(tt.idxs, idxs); diff != "" {
+			t.Errorf("path index mismatch (-want +got):\n%v", diff)
+		}
+
+		_, md := MessageDescriptorProtoOf(m)
+		if md.GetName() != tt.name {
+			t.Errorf("mismatching message name: got %v, want %v", md.GetName(), tt.name)
+		}
+	}
+}
diff --git a/go.mod b/go.mod
@@ -3,6 +3,6 @@ module github.com/golang/protobuf
 go 1.9
 
 require (
-	github.com/google/go-cmp v0.3.1 // indirect
-	google.golang.org/protobuf v0.0.0-20191108002925-e9187326c3ff
+	github.com/google/go-cmp v0.3.1
+	google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd
 )
diff --git a/go.sum b/go.sum
@@ -1,34 +1,5 @@
-github.com/golang/protobuf v1.2.1-0.20190514181236-7800af189d76/go.mod h1:Zfz6qcDoDBESdv6JsKsGpgNHnkvwJAJwcA9eL+mOkgc=
-github.com/golang/protobuf v1.2.1-0.20190515194842-7574ba03306e/go.mod h1:GjgUz9uwrRQmdPBBrFqiVbojAmlpy6ryM6DCzC+20rE=
-github.com/golang/protobuf v1.2.1-0.20190516201927-a2cd3ac1b343/go.mod h1:PScGDF2x230A126tLt9Ol9RjhXzbiPJrt/CogooD2mE=
-github.com/golang/protobuf v1.2.1-0.20190516215712-ae2eaafab405/go.mod h1:UmP8hhPKR5WWIjbT9v0JEVT+U0DBSjbW8KaZVeyFfRE=
-github.com/golang/protobuf v1.2.1-0.20190523175523-a1331f0b4ab4/go.mod h1:G+fNMoyvKWZDB7PCDHF+dXbH9OeE3+JoozCd9V7i66U=
-github.com/golang/protobuf v1.2.1-0.20190605195750-76c9e09470ba/go.mod h1:S1YIJXvYHGRCG2UmZsOcElkAYfvZLg2sDRr9+Xu8JXU=
-github.com/golang/protobuf v1.2.1-0.20190617175902-f94016f5239f/go.mod h1:G+HpKX7pYZAVkElkAWZkr08MToW6pTp/vs+E9osFfbg=
-github.com/golang/protobuf v1.2.1-0.20190620192300-1ee46dfd80dd/go.mod h1:+CMAsi9jpYf/wAltLUKlg++CWXqxCJyD8iLDbQONsJs=
-github.com/golang/protobuf v1.2.1-0.20190806214225-7037721e6de0/go.mod h1:tDQPRlaHYu9yt1wPgdx85inRiLvUCuJZXsYjC0mwc1c=
-github.com/golang/protobuf v1.2.1-0.20190820204156-2da1b93405dd/go.mod h1:x87I3ou7ehf/yR6iQ88MkyDogdxXN04TELJ7HVy7V7I=
-github.com/golang/protobuf v1.2.1-0.20190820213554-ae1d65bc5435/go.mod h1:k7dGkiTZ3rjVDhKSpGt+x1zDzAePJk4jdhoBwIkQgBo=
-github.com/golang/protobuf v1.2.1-0.20191004062209-62f67f1ea9df/go.mod h1:o4el5ABfDjqFlwwvAq2OIgAPeNXQYUkhtrjNPXy6T6I=
-github.com/google/go-cmp v0.3.0 h1:crn/baboCvb5fXaQ0IJ1SGTsTVrWpDsCWC8EGETZijY=
 github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 github.com/google/go-cmp v0.3.1 h1:Xye71clBPdm5HgqGwUkwhbynsUJZhDbS20FvLhQ2izg=
 github.com/google/go-cmp v0.3.1/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
-google.golang.org/protobuf v0.0.0-20190514172829-e89e6244e0e8/go.mod h1:791zQGC15vDqjpmPRn1uGPu5oHy/Jzw/Q1n5JsgIIcY=
-google.golang.org/protobuf v0.0.0-20190514231807-cdb777356907/go.mod h1:HeRLsKXv4+wE27dOIGwnqcOgq6a1O/GJ7mGhiEPnBrU=
-google.golang.org/protobuf v0.0.0-20190516201745-40b83d67fc75/go.mod h1:jf+u8AHuKtkib+0J4/bQXPNzCmT3V9a02hVzYKtatuw=
-google.golang.org/protobuf v0.0.0-20190516215540-a95b29fbf623/go.mod h1:cWWmz5lsCWIcqGLROrKq5Lu231IJw2PzqOZ8cgspbfY=
-google.golang.org/protobuf v0.0.0-20190522194032-21ade498bd69/go.mod h1:cJytyYi/6qdwy/+gD49hmgHcwD7zhWxE/1KPEslaZ3M=
-google.golang.org/protobuf v0.0.0-20190605195314-89d49632e5cf/go.mod h1:Btug4TBaP5wNYcb2zGKDTS7WMcaPPLuqEAKfEAZWYbo=
-google.golang.org/protobuf v0.0.0-20190617175724-bd7b7a9e0c26/go.mod h1:+FOB8T5/Yw4ywwdyeun9/KlDeuwFYBkNQ+kVuwj9C94=
-google.golang.org/protobuf v0.0.0-20190620020611-d888139e7b59/go.mod h1:of3pt14Y+dOxz2tBOHXEoapPpKFC15/0zWhPAddkfsU=
-google.golang.org/protobuf v0.0.0-20190717230113-f647c82cc3c7 h1:U6U+Hb+UKNGJB0eMAjUGk0wTmy73kduTIvdsEgA4Gf8=
-google.golang.org/protobuf v0.0.0-20190717230113-f647c82cc3c7/go.mod h1:yGm7aNHn9Bp1NIvj6+CVUkcJshu+Usshfd3A+YxEuI8=
-google.golang.org/protobuf v0.0.0-20190820203659-c0f8c0a24ece h1:AFYGmds8FWBGNw0zddlFiGtDvkVFSnQ7J2bAdH4X9Xk=
-google.golang.org/protobuf v0.0.0-20190820203659-c0f8c0a24ece/go.mod h1:tRqhEyKwbKqwt5CQZAuOtj09RfhLNklDOhndhYA9blU=
-google.golang.org/protobuf v0.0.0-20190820213257-f1e905b04207 h1:ulV4hvtdAg7XsymkxyxHtKYxQoSq88XU1bmtCELxG38=
-google.golang.org/protobuf v0.0.0-20190820213257-f1e905b04207/go.mod h1:UJqt2ZERO8/qk5A9t8Ujq6OJ+MNvOQpg9X4RKyYz9Ho=
-google.golang.org/protobuf v0.0.0-20190828183429-79bfdbe45be2 h1:g52BKWg08C9Z3iSV/mBCfoP+ObYXKCgdXF+p1EB9zD0=
-google.golang.org/protobuf v0.0.0-20190828183429-79bfdbe45be2/go.mod h1:fYMzYhnMXLj/kGDPzNOptS3IFFlQjWTlu2j3ZPET2lw=
-google.golang.org/protobuf v0.0.0-20191108002925-e9187326c3ff h1:owlmxbzMXWq78QqeFT2Xj1ySspP/ot+aFzxHoz79YLQ=
-google.golang.org/protobuf v0.0.0-20191108002925-e9187326c3ff/go.mod h1:qKrTvhhUFcTIUF6KuejTfRdHXKeBPoa4mtynR6usTss=
+google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd h1:zSMqFwpTkfj+1nNFgmgu4B+Qv5Kpf4jpd11lCmHKuwQ=
+google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd/go.mod h1:DFci5gLYBciE7Vtevhsrf46CRTquxDuWsQurQQe4oz8=