Repository: googleapis/gapic-generator-go (go)

Issue:
feat: support service overriding
As part of internal issue 360155816, we will be supporting the ability to override the default Service name provided in the proto and generate Clients and other structs with a custom service name. For example, we wish to override Pub/Sub's `PublisherService` to generate `TopicAdminClient` instead of `PublisherClient`

Pull request description:
feat: add service renaming
This PR adds support for service name overriding (renaming).

~~This PR cannot be merged until the new client.proto changes land to support the `renamed_services` field and the actual code in `generator.getServiceNameOverride` is uncommented.~~

Pieces of the generator that are currently not changed by service renaming:
- Custom operations (in genrest.go)
- gencli
-  [snippets](https://github.com/googleapis/gapic-generator-go/tree/624962423ddf8b57b9b0cd4138bde6bbdd491427/internal/snippets)

Diff for Pub/Sub is viewable here: https://github.com/googleapis/google-cloud-go/compare/main...hongalex:google-cloud-go:new-gapic-diff?expand=1

Fixes #1581

Patch:
diff --git a/internal/gengapic/doc_file.go b/internal/gengapic/doc_file.go
index 5f8e53b..2c07ec2 100644
--- a/internal/gengapic/doc_file.go
+++ b/internal/gengapic/doc_file.go
@@ -81,7 +81,8 @@ func (g *generator) genDocFile(year int, serv *descriptorpb.ServiceDescriptorPro
 	p("//")
 	p("// To get started with this package, create a client.")
 	// Code block for client creation
-	servName := pbinfo.ReduceServName(serv.GetName(), g.opts.pkgName)
+	override := g.getServiceNameOverride(serv)
+	servName := pbinfo.ReduceServNameWithOverride(serv.GetName(), g.opts.pkgName, override)
 	tmpClient := g.pt
 	g.pt = printer.P{}
 	g.exampleInitClientWithOpts(g.opts.pkgName, servName, true)
diff --git a/internal/gengapic/example.go b/internal/gengapic/example.go
index 2061dd0..218c98b 100644
--- a/internal/gengapic/example.go
+++ b/internal/gengapic/example.go
@@ -26,7 +26,8 @@ import (
 
 func (g *generator) genExampleFile(serv *descriptorpb.ServiceDescriptorProto) error {
 	pkgName := g.opts.pkgName
-	servName := pbinfo.ReduceServName(serv.GetName(), pkgName)
+	override := g.getServiceNameOverride(serv)
+	servName := pbinfo.ReduceServNameWithOverride(serv.GetName(), pkgName, override)
 
 	g.exampleClientFactory(pkgName, servName)
 
@@ -42,7 +43,8 @@ func (g *generator) genExampleFile(serv *descriptorpb.ServiceDescriptorProto) er
 
 func (g *generator) genExampleIteratorFile(serv *descriptorpb.ServiceDescriptorProto) error {
 	pkgName := g.opts.pkgName
-	servName := pbinfo.ReduceServName(serv.GetName(), pkgName)
+	override := g.getServiceNameOverride(serv)
+	servName := pbinfo.ReduceServNameWithOverride(serv.GetName(), pkgName, override)
 	methods := append(serv.GetMethod(), g.getMixinMethods()...)
 	for _, m := range methods {
 		// Don't need streaming RPCs
diff --git a/internal/gengapic/generator.go b/internal/gengapic/generator.go
index 731bd7b..77d9644 100644
--- a/internal/gengapic/generator.go
+++ b/internal/gengapic/generator.go
@@ -350,3 +350,19 @@ func (g *generator) autoPopulatedFields(_ string, m *descriptorpb.MethodDescript
 	}
 	return validated
 }
+
+// getServiceNameOverride checks to see if the service has a defined service name override.
+func (g *generator) getServiceNameOverride(s *descriptorpb.ServiceDescriptorProto) string {
+	ls := g.serviceConfig.GetPublishing().GetLibrarySettings()
+	if len(ls) == 0 {
+		return ""
+	}
+
+	renamedServices := ls[0].GetGoSettings().GetRenamedServices()
+
+	if v, ok := renamedServices[s.GetName()]; ok {
+		return v
+	}
+
+	return ""
+}
diff --git a/internal/gengapic/gengapic.go b/internal/gengapic/gengapic.go
index 1475a70..dcc1feb 100644
--- a/internal/gengapic/gengapic.go
+++ b/internal/gengapic/gengapic.go
@@ -111,7 +111,8 @@ func gen(genReq *pluginpb.CodeGeneratorRequest) (*pluginpb.CodeGeneratorResponse
 		// so even though the client for LoggingServiceV2 is just "Client"
 		// the file name is "logging_client.go".
 		// Keep the current behavior for now, but we could revisit this later.
-		servName := pbinfo.ReduceServName(s.GetName(), "")
+		override := g.getServiceNameOverride(s)
+		servName := pbinfo.ReduceServNameWithOverride(s.GetName(), "", override)
 		outFile := camelToSnake(servName)
 		outFile = filepath.Join(g.opts.outDir, outFile)
 
@@ -334,7 +335,9 @@ func (g *generator) genAndCommitHelpers(scopes []string) error {
 
 // gen generates client for the given service.
 func (g *generator) gen(serv *descriptorpb.ServiceDescriptorProto) error {
-	servName := pbinfo.ReduceServName(serv.GetName(), g.opts.pkgName)
+	// If using service name overrides, use that directly for the rest of generation.
+	override := g.getServiceNameOverride(serv)
+	servName := pbinfo.ReduceServNameWithOverride(serv.GetName(), g.opts.pkgName, override)
 
 	g.clientHook(servName)
 	if err := g.clientOptions(serv, servName); err != nil {
diff --git a/internal/gengapic/gengrpc.go b/internal/gengapic/gengrpc.go
index 51f1671..5baf1d6 100644
--- a/internal/gengapic/gengrpc.go
+++ b/internal/gengapic/gengrpc.go
@@ -160,8 +160,9 @@ func (g *generator) emptyUnaryGRPCCall(servName string, m *descriptorpb.MethodDe
 }
 
 func (g *generator) grpcStubCall(method *descriptorpb.MethodDescriptorProto) string {
-	service := g.descInfo.ParentElement[method]
-	stub := pbinfo.ReduceServName(service.GetName(), g.opts.pkgName)
+	service := g.descInfo.ParentElement[method].(*descriptorpb.ServiceDescriptorProto)
+	override := g.getServiceNameOverride(service)
+	stub := pbinfo.ReduceServNameWithOverride(service.GetName(), g.opts.pkgName, override)
 	return fmt.Sprintf("executeRPC(ctx, c.%s.%s, req, settings.GRPC, c.logger, %q)", grpcClientField(stub), method.GetName(), method.GetName())
 }
 
@@ -311,7 +312,11 @@ func (g *generator) grpcClientInit(serv *descriptorpb.ServiceDescriptorProto, se
 func (g *generator) grpcClientUtilities(serv *descriptorpb.ServiceDescriptorProto, servName string, imp pbinfo.ImportSpec, hasRPCForLRO bool) {
 	p := g.printf
 
-	clientName := camelToSnake(serv.GetName())
+	clientName := serv.GetName()
+	if override := g.getServiceNameOverride(serv); override != "" {
+		clientName = override
+	}
+	clientName = camelToSnake(clientName)
 	clientName = strings.Replace(clientName, "_", " ", -1)
 	lowcaseServName := lowcaseGRPCClientName(servName)
 
diff --git a/internal/gengapic/genrest.go b/internal/gengapic/genrest.go
index b4efd7d..44df5e5 100644
--- a/internal/gengapic/genrest.go
+++ b/internal/gengapic/genrest.go
@@ -147,9 +147,15 @@ func (g *generator) restClientOptions(serv *descriptorpb.ServiceDescriptorProto,
 
 func (g *generator) restClientUtilities(serv *descriptorpb.ServiceDescriptorProto, servName string, hasRPCForLRO bool) {
 	p := g.printf
-	lowcaseServName := lowcaseRestClientName(servName)
-	clientName := camelToSnake(serv.GetName())
+
+	clientName := serv.GetName()
+	if override := g.getServiceNameOverride(serv); override != "" {
+		clientName = override
+	}
+	clientName = camelToSnake(clientName)
 	clientName = strings.Replace(clientName, "_", " ", -1)
+	lowcaseServName := lowcaseRestClientName(servName)
+
 	opServ, hasCustomOp := g.customOpServices[serv]
 
 	p("// New%sRESTClient creates a new %s rest client.", servName, clientName)
diff --git a/internal/pbinfo/pbinfo.go b/internal/pbinfo/pbinfo.go
index a0566d6..e7499dc 100644
--- a/internal/pbinfo/pbinfo.go
+++ b/internal/pbinfo/pbinfo.go
@@ -197,6 +197,15 @@ func (in *Info) ImportSpec(e ProtoType) (ImportSpec, error) {
 	return imp, err
 }
 
+// ReduceServNameWithOverride returns the override string if present,
+// otherwise calls ReduceServName.
+func ReduceServNameWithOverride(svc, pkg, override string) string {
+	if override != "" {
+		return override
+	}
+	return ReduceServName(svc, pkg)
+}
+
 // ReduceServName removes redundant components from the service name.
 // For example, FooServiceV2 -> Foo.
 // The returned name is used as part of longer names, like FooClient.


Test patch:
diff --git a/internal/gengapic/gengrpc_test.go b/internal/gengapic/gengrpc_test.go
new file mode 100644
index 0000000..b9498c5
--- /dev/null
+++ b/internal/gengapic/gengrpc_test.go
@@ -0,0 +1,126 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package gengapic
+
+import (
+	"bytes"
+	"path/filepath"
+	"testing"
+
+	conf "github.com/googleapis/gapic-generator-go/internal/grpc_service_config"
+	"github.com/googleapis/gapic-generator-go/internal/pbinfo"
+	"github.com/googleapis/gapic-generator-go/internal/txtdiff"
+	"google.golang.org/genproto/googleapis/api/annotations"
+	"google.golang.org/genproto/googleapis/api/serviceconfig"
+	"google.golang.org/protobuf/encoding/protojson"
+	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/types/descriptorpb"
+	duration "google.golang.org/protobuf/types/known/durationpb"
+)
+
+func TestServiceRenaming(t *testing.T) {
+	inputType := &descriptorpb.DescriptorProto{
+		Name: proto.String("InputType"),
+	}
+	outputType := &descriptorpb.DescriptorProto{
+		Name: proto.String("OutputType"),
+	}
+	metadataType := &descriptorpb.DescriptorProto{
+		Name: proto.String("MetadataType"),
+	}
+
+	file := &descriptorpb.FileDescriptorProto{
+		Package: proto.String("my.pkg"),
+		Options: &descriptorpb.FileOptions{
+			GoPackage: proto.String("mypackage"),
+		},
+	}
+	serv := &descriptorpb.ServiceDescriptorProto{
+		Name: proto.String("Foo"),
+	}
+
+	var g generator
+	g.imports = map[pbinfo.ImportSpec]bool{}
+	g.opts = &options{
+		pkgName:    "pkg",
+		transports: []transport{grpc},
+	}
+	cpb := &conf.ServiceConfig{
+		MethodConfig: []*conf.MethodConfig{
+			{
+				Name: []*conf.MethodConfig_Name{
+					{
+						Service: "my.pkg.Foo",
+					},
+				},
+				Timeout: &duration.Duration{Seconds: 10},
+			},
+		},
+	}
+	data, err := protojson.Marshal(cpb)
+	if err != nil {
+		t.Error(err)
+	}
+	in := bytes.NewReader(data)
+	g.grpcConf, err = conf.New(in)
+	if err != nil {
+		t.Error(err)
+	}
+
+	commonTypes(&g)
+	for _, typ := range []*descriptorpb.DescriptorProto{
+		inputType, outputType, metadataType,
+	} {
+		g.descInfo.Type[".my.pkg."+*typ.Name] = typ
+		g.descInfo.ParentFile[typ] = file
+	}
+	g.descInfo.ParentFile[serv] = file
+	g.descInfo.ParentElement = map[pbinfo.ProtoType]pbinfo.ProtoType{}
+	g.serviceConfig = &serviceconfig.Service{
+		Publishing: &annotations.Publishing{
+			LibrarySettings: []*annotations.ClientLibrarySettings{
+				{
+					GoSettings: &annotations.GoSettings{
+						RenamedServices: map[string]string{"Foo": "Bar"},
+					},
+				},
+			},
+		},
+	}
+
+	m := &descriptorpb.MethodDescriptorProto{
+		Name:       proto.String("Baz"),
+		InputType:  proto.String(".my.pkg.InputType"),
+		OutputType: proto.String(emptyType),
+	}
+
+	serv.Method = []*descriptorpb.MethodDescriptorProto{
+		m,
+	}
+	g.descInfo.ParentFile[serv] = file
+	g.descInfo.ParentElement[m] = serv
+	imp, err := g.descInfo.ImportSpec(serv)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Test the generation of the client boilerplate and single gRPC method rename.
+	g.grpcClientInit(serv, "Bar", imp, false)
+	if err := g.genGRPCMethod("Bar", serv, m); err != nil {
+		t.Fatal(err)
+	}
+
+	txtdiff.Diff(t, g.pt.String(), filepath.Join("testdata", "service_rename.want"))
+}
diff --git a/internal/gengapic/testdata/service_rename.want b/internal/gengapic/testdata/service_rename.want
new file mode 100644
index 0000000..d452b94
--- /dev/null
+++ b/internal/gengapic/testdata/service_rename.want
@@ -0,0 +1,87 @@
+// barGRPCClient is a client for interacting with  over gRPC transport.
+//
+// Methods, except Close, may be called concurrently. However, fields must not be modified concurrently with method calls.
+type barGRPCClient struct {
+	// Connection pool of gRPC connections to the service.
+	connPool gtransport.ConnPool
+
+	// Points back to the CallOptions field of the containing BarClient
+	CallOptions **BarCallOptions
+
+	// The gRPC API client.
+	barClient mypackagepb.FooClient
+
+	// The x-goog-* metadata to be sent with each request.
+	xGoogHeaders []string
+
+	logger *slog.Logger
+}
+
+// NewBarClient creates a new bar client based on gRPC.
+// The returned client must be Closed when it is done being used to clean up its underlying connections.
+func NewBarClient(ctx context.Context, opts ...option.ClientOption) (*BarClient, error) {
+	clientOpts := defaultBarGRPCClientOptions()
+	if newBarClientHook != nil {
+		hookOpts, err := newBarClientHook(ctx, clientHookParams{})
+		if err != nil {
+			return nil, err
+		}
+		clientOpts = append(clientOpts, hookOpts...)
+	}
+
+	connPool, err := gtransport.DialPool(ctx, append(clientOpts, opts...)...)
+	if err != nil {
+		return nil, err
+	}
+	client := BarClient{CallOptions: defaultBarCallOptions()}
+
+	c := &barGRPCClient{
+		connPool:    connPool,
+		barClient: mypackagepb.NewFooClient(connPool),
+		CallOptions: &client.CallOptions,
+		logger: internaloption.GetLogger(opts),
+
+	}
+	c.setGoogleClientInfo()
+
+	client.internalClient = c
+
+	return &client, nil
+}
+
+// Connection returns a connection to the API service.
+//
+// Deprecated: Connections are now pooled so this method does not always
+// return the same resource.
+func (c *barGRPCClient) Connection() *grpc.ClientConn {
+	return c.connPool.Conn()
+}
+
+// setGoogleClientInfo sets the name and version of the application in
+// the `x-goog-api-client` header passed on each request. Intended for
+// use by Google-written clients.
+func (c *barGRPCClient) setGoogleClientInfo(keyval ...string) {
+	kv := append([]string{"gl-go", gax.GoVersion}, keyval...)
+	kv = append(kv, "gapic", getVersionClient(), "gax", gax.Version, "grpc", grpc.Version)
+	c.xGoogHeaders = []string{
+		"x-goog-api-client", gax.XGoogHeader(kv...),
+	}
+}
+
+// Close closes the connection to the API service. The user should invoke this when
+// the client is no longer required.
+func (c *barGRPCClient) Close() error {
+	return c.connPool.Close()
+}
+
+func (c *barGRPCClient) Baz(ctx context.Context, req *mypackagepb.InputType, opts ...gax.CallOption) error {
+	ctx = gax.InsertMetadataIntoOutgoingContext(ctx, c.xGoogHeaders...)
+	opts = append((*c.CallOptions).Baz[0:len((*c.CallOptions).Baz):len((*c.CallOptions).Baz)], opts...)
+	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
+		var err error
+		_, err = executeRPC(ctx, c.barClient.Baz, req, settings.GRPC, c.logger, "Baz")
+		return err
+	}, opts...)
+	return err
+}
+