forked from goadesign/goa
/
example_server.go
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/
example_server.go
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package codegen
import (
"os"
"path"
"path/filepath"
"strings"
"goa.design/goa/codegen"
"goa.design/goa/codegen/example"
"goa.design/goa/expr"
)
// ExampleServerFiles returns an example gRPC server implementation.
func ExampleServerFiles(genpkg string, root *expr.RootExpr) []*codegen.File {
var fw []*codegen.File
for _, svr := range root.API.Servers {
if m := exampleServer(genpkg, root, svr); m != nil {
fw = append(fw, m)
}
}
return fw
}
// exampleServer returns an example gRPC server implementation.
func exampleServer(genpkg string, root *expr.RootExpr, svr *expr.ServerExpr) *codegen.File {
var (
mainPath string
svrdata = example.Servers.Get(svr)
)
{
mainPath = filepath.Join("cmd", svrdata.Dir, "grpc.go")
if _, err := os.Stat(mainPath); !os.IsNotExist(err) {
return nil // file already exists, skip it.
}
}
var (
specs []*codegen.ImportSpec
scope = codegen.NewNameScope()
)
{
specs = []*codegen.ImportSpec{
{Path: "context"},
{Path: "log"},
{Path: "net"},
{Path: "net/url"},
{Path: "os"},
{Path: "sync"},
{Path: "goa.design/goa/middleware"},
{Path: "goa.design/goa/grpc/middleware", Name: "grpcmdlwr"},
{Path: "google.golang.org/grpc"},
{Path: "google.golang.org/grpc/reflection"},
{Path: "github.com/grpc-ecosystem/go-grpc-middleware", Name: "grpcmiddleware"},
{Path: "goa.design/goa/grpc", Name: "goagrpc"},
}
for _, svc := range root.API.GRPC.Services {
sd := GRPCServices.Get(svc.Name())
svcName := codegen.SnakeCase(sd.Service.VarName)
specs = append(specs, &codegen.ImportSpec{
Path: path.Join(genpkg, "grpc", svcName, "server"),
Name: scope.Unique(sd.Service.PkgName + "svr"),
})
specs = append(specs, &codegen.ImportSpec{
Path: path.Join(genpkg, svcName),
Name: scope.Unique(sd.Service.PkgName),
})
specs = append(specs, &codegen.ImportSpec{
Path: path.Join(genpkg, "grpc", svcName, pbPkgName),
Name: scope.Unique(svcName + pbPkgName),
})
}
}
var (
rootPath string
apiPkg string
)
{
// genpkg is created by path.Join so the separator is / regardless of operating system
idx := strings.LastIndex(genpkg, string("/"))
rootPath = "."
if idx > 0 {
rootPath = genpkg[:idx]
}
apiPkg = scope.Unique(strings.ToLower(codegen.Goify(root.API.Name, false)), "api")
}
specs = append(specs, &codegen.ImportSpec{Path: rootPath, Name: apiPkg})
var (
sections []*codegen.SectionTemplate
)
{
var svcdata []*ServiceData
for _, svc := range svr.Services {
if data := GRPCServices.Get(svc); data != nil {
svcdata = append(svcdata, data)
}
}
sections = []*codegen.SectionTemplate{
codegen.Header("", "main", specs),
&codegen.SectionTemplate{
Name: "server-grpc-start",
Source: grpcSvrStartT,
Data: map[string]interface{}{
"Services": svcdata,
},
},
&codegen.SectionTemplate{Name: "server-grpc-logger", Source: grpcSvrLoggerT},
&codegen.SectionTemplate{
Name: "server-grpc-init",
Source: grpcSvrInitT,
Data: map[string]interface{}{
"Services": svcdata,
},
},
&codegen.SectionTemplate{
Name: "server-grpc-register",
Source: grpcRegisterSvrT,
Data: map[string]interface{}{
"Services": svcdata,
},
FuncMap: map[string]interface{}{
"goify": codegen.Goify,
"needStream": needStream,
},
},
&codegen.SectionTemplate{
Name: "server-grpc-end",
Source: grpcSvrEndT,
Data: map[string]interface{}{
"Services": svcdata,
},
},
}
}
return &codegen.File{Path: mainPath, SectionTemplates: sections, SkipExist: true}
}
// needStream returns true if at least one method in the defined services
// uses stream for sending payload/result.
func needStream(data []*ServiceData) bool {
for _, svc := range data {
for _, e := range svc.Endpoints {
if e.ServerStream != nil || e.ClientStream != nil {
return true
}
}
}
return false
}
const (
// input: map[string]interface{}{"Services":[]*ServiceData}
grpcSvrStartT = `{{ comment "handleGRPCServer starts configures and starts a gRPC server on the given URL. It shuts down the server if any error is received in the error channel." }}
func handleGRPCServer(ctx context.Context, u *url.URL{{ range $.Services }}{{ if .Service.Methods }}, {{ .Service.VarName }}Endpoints *{{ .Service.PkgName }}.Endpoints{{ end }}{{ end }}, wg *sync.WaitGroup, errc chan error, logger *log.Logger, debug bool) {
`
grpcSvrLoggerT = `
// Setup goa log adapter.
var (
adapter middleware.Logger
)
{
adapter = middleware.NewLogger(logger)
}
`
// input: map[string]interface{}{"Services":[]*ServiceData}
grpcSvrInitT = `
// Wrap the endpoints with the transport specific layers. The generated
// server packages contains code generated from the design which maps
// the service input and output data structures to gRPC requests and
// responses.
var (
{{- range .Services }}
{{ .Service.VarName }}Server *{{.Service.PkgName}}svr.Server
{{- end }}
)
{
{{- range .Services }}
{{- if .Endpoints }}
{{ .Service.VarName }}Server = {{ .Service.PkgName }}svr.New({{ .Service.VarName }}Endpoints{{ if .HasUnaryEndpoint }}, nil{{ end }}{{ if .HasStreamingEndpoint }}, nil{{ end }})
{{- else }}
{{ .Service.VarName }}Server = {{ .Service.PkgName }}svr.New(nil{{ if .HasUnaryEndpoint }}, nil{{ end }}{{ if .HasStreamingEndpoint }}, nil{{ end }})
{{- end }}
{{- end }}
}
`
// input: map[string]interface{}{"Services":[]*ServiceData}
grpcRegisterSvrT = `
// Initialize gRPC server with the middleware.
srv := grpc.NewServer(
grpcmiddleware.WithUnaryServerChain(
grpcmdlwr.UnaryRequestID(),
grpcmdlwr.UnaryServerLog(adapter),
),
{{- if needStream .Services }}
grpcmiddleware.WithStreamServerChain(
grpcmdlwr.StreamRequestID(),
grpcmdlwr.StreamServerLog(adapter),
),
{{- end }}
)
// Register the servers.
{{- range .Services }}
{{ .PkgName }}.Register{{ goify .Service.VarName true }}Server(srv, {{ .Service.VarName }}Server)
{{- end }}
for svc, info := range srv.GetServiceInfo() {
for _, m := range info.Methods {
logger.Printf("serving gRPC method %s", svc + "/" + m.Name)
}
}
// Register the server reflection service on the server.
// See https://grpc.github.io/grpc/core/md_doc_server-reflection.html.
reflection.Register(srv)
`
// input: map[string]interface{}{"Services":[]*ServiceData}
grpcSvrEndT = `
(*wg).Add(1)
go func() {
defer (*wg).Done()
{{ comment "Start gRPC server in a separate goroutine." }}
go func() {
lis, err := net.Listen("tcp", u.Host)
if err != nil {
errc <- err
}
logger.Printf("gRPC server listening on %q", u.Host)
errc <- srv.Serve(lis)
}()
<-ctx.Done()
logger.Printf("shutting down gRPC server at %q", u.Host)
srv.Stop()
}()
}
`
)