forked from grpc-ecosystem/grpc-gateway
/
template.go
280 lines (256 loc) · 8.37 KB
/
template.go
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package gengateway
import (
"bytes"
"fmt"
"strings"
"text/template"
"github.com/gengo/grpc-gateway/protoc-gen-grpc-gateway/descriptor"
"github.com/gengo/grpc-gateway/utilities"
"github.com/golang/glog"
)
type param struct {
*descriptor.File
Imports []descriptor.GoPackage
}
type binding struct {
*descriptor.Binding
}
// HasQueryParam determines if the binding needs parameters in query string.
//
// It sometimes returns true even though actually the binding does not need.
// But it is not serious because it just results in a small amount of extra codes generated.
func (b binding) HasQueryParam() bool {
if b.Body != nil && len(b.Body.FieldPath) == 0 {
return false
}
fields := make(map[string]bool)
for _, f := range b.Method.RequestType.Fields {
fields[f.GetName()] = true
}
if b.Body != nil {
delete(fields, b.Body.FieldPath.String())
}
for _, p := range b.PathParams {
delete(fields, p.FieldPath.String())
}
return len(fields) > 0
}
func (b binding) QueryParamFilter() queryParamFilter {
var seqs [][]string
if b.Body != nil {
seqs = append(seqs, strings.Split(b.Body.FieldPath.String(), "."))
}
for _, p := range b.PathParams {
seqs = append(seqs, strings.Split(p.FieldPath.String(), "."))
}
return queryParamFilter{utilities.NewDoubleArray(seqs)}
}
// queryParamFilter is a wrapper of utilities.DoubleArray which provides String() to output DoubleArray.Encoding in a stable and predictable format.
type queryParamFilter struct {
*utilities.DoubleArray
}
func (f queryParamFilter) String() string {
encodings := make([]string, len(f.Encoding))
for str, enc := range f.Encoding {
encodings[enc] = fmt.Sprintf("%q: %d", str, enc)
}
e := strings.Join(encodings, ", ")
return fmt.Sprintf("&utilities.DoubleArray{Encoding: map[string]int{%s}, Base: %#v, Check: %#v}", e, f.Base, f.Check)
}
func applyTemplate(p param) (string, error) {
w := bytes.NewBuffer(nil)
if err := headerTemplate.Execute(w, p); err != nil {
return "", err
}
var methodSeen bool
for _, svc := range p.Services {
for _, meth := range svc.Methods {
glog.V(2).Infof("Processing %s.%s", svc.GetName(), meth.GetName())
methodSeen = true
for _, b := range meth.Bindings {
if err := handlerTemplate.Execute(w, binding{Binding: b}); err != nil {
return "", err
}
}
}
}
if !methodSeen {
return "", errNoTargetService
}
if err := trailerTemplate.Execute(w, p.Services); err != nil {
return "", err
}
return w.String(), nil
}
var (
headerTemplate = template.Must(template.New("header").Parse(`
// Code generated by protoc-gen-grpc-gateway
// source: {{.GetName}}
// DO NOT EDIT!
/*
Package {{.GoPkg.Name}} is a reverse proxy.
It translates gRPC into RESTful JSON APIs.
*/
package {{.GoPkg.Name}}
import (
{{range $i := .Imports}}{{if $i.Standard}}{{$i | printf "%s\n"}}{{end}}{{end}}
{{range $i := .Imports}}{{if not $i.Standard}}{{$i | printf "%s\n"}}{{end}}{{end}}
)
var _ codes.Code
var _ io.Reader
var _ = runtime.String
var _ = json.Marshal
var _ = utilities.PascalFromSnake
`))
handlerTemplate = template.Must(template.New("handler").Parse(`
{{if .Method.GetClientStreaming}}
{{template "client-streaming-request-func" .}}
{{else}}
{{template "client-rpc-request-func" .}}
{{end}}
`))
_ = template.Must(handlerTemplate.New("request-func-signature").Parse(strings.Replace(`
{{if .Method.GetServerStreaming}}
func request_{{.Method.Service.GetName}}_{{.Method.GetName}}_{{.Index}}(ctx context.Context, client {{.Method.Service.GetName}}Client, req *http.Request, pathParams map[string]string) ({{.Method.Service.GetName}}_{{.Method.GetName}}Client, error)
{{else}}
func request_{{.Method.Service.GetName}}_{{.Method.GetName}}_{{.Index}}(ctx context.Context, client {{.Method.Service.GetName}}Client, req *http.Request, pathParams map[string]string) (proto.Message, error)
{{end}}`, "\n", "", -1)))
_ = template.Must(handlerTemplate.New("client-streaming-request-func").Parse(`
{{template "request-func-signature" .}} {
stream, err := client.{{.Method.GetName}}(ctx)
if err != nil {
glog.Errorf("Failed to start streaming: %v", err)
return nil, err
}
dec := json.NewDecoder(req.Body)
for {
var protoReq {{.Method.RequestType.GoType .Method.Service.File.GoPkg.Path}}
err = dec.Decode(&protoReq)
if err == io.EOF {
break
}
if err != nil {
glog.Errorf("Failed to decode request: %v", err)
return nil, grpc.Errorf(codes.InvalidArgument, "%v", err)
}
if err = stream.Send(&protoReq); err != nil {
glog.Errorf("Failed to send request: %v", err)
return nil, err
}
}
{{if .Method.GetServerStreaming}}
if err = stream.CloseSend(); err != nil {
glog.Errorf("Failed to terminate client stream: %v", err)
return nil, err
}
return stream, nil
{{else}}
return stream.CloseAndRecv()
{{end}}
}
`))
_ = template.Must(handlerTemplate.New("client-rpc-request-func").Parse(`
{{if .HasQueryParam}}
var (
filter_{{.Method.Service.GetName}}_{{.Method.GetName}}_{{.Index}} = {{.QueryParamFilter}}
)
{{end}}
{{template "request-func-signature" .}} {
var protoReq {{.Method.RequestType.GoType .Method.Service.File.GoPkg.Path}}
{{if .Body}}
if err := json.NewDecoder(req.Body).Decode(&{{.Body.RHS "protoReq"}}); err != nil {
return nil, grpc.Errorf(codes.InvalidArgument, "%v", err)
}
{{end}}
{{if .PathParams}}
var (
val string
ok bool
err error
_ = err
)
{{range $param := .PathParams}}
val, ok = pathParams[{{$param | printf "%q"}}]
if !ok {
return nil, grpc.Errorf(codes.InvalidArgument, "missing parameter %s", {{$param | printf "%q"}})
}
{{if $param.IsNestedProto3 }}
err = runtime.PopulateFieldFromPath(&protoReq, {{$param | printf "%q"}}, val)
{{else}}
{{$param.RHS "protoReq"}}, err = {{$param.ConvertFuncExpr}}(val)
{{end}}
if err != nil {
return nil, err
}
{{end}}
{{end}}
{{if .HasQueryParam}}
if err := runtime.PopulateQueryParameters(&protoReq, req.URL.Query(), filter_{{.Method.Service.GetName}}_{{.Method.GetName}}_{{.Index}}); err != nil {
return nil, grpc.Errorf(codes.InvalidArgument, "%v", err)
}
{{end}}
return client.{{.Method.GetName}}(ctx, &protoReq)
}`))
trailerTemplate = template.Must(template.New("trailer").Parse(`
{{range $svc := .}}
// Register{{$svc.GetName}}HandlerFromEndpoint is same as Register{{$svc.GetName}}Handler but
// automatically dials to "endpoint" and closes the connection when "ctx" gets done.
func Register{{$svc.GetName}}HandlerFromEndpoint(ctx context.Context, mux *runtime.ServeMux, endpoint string) (err error) {
conn, err := grpc.Dial(endpoint)
if err != nil {
return err
}
defer func() {
if err != nil {
if cerr := conn.Close(); cerr != nil {
glog.Errorf("Failed to close conn to %s: %v", endpoint, cerr)
}
return
}
go func() {
<-ctx.Done()
if cerr := conn.Close(); cerr != nil {
glog.Errorf("Failed to close conn to %s: %v", endpoint, cerr)
}
}()
}()
return Register{{$svc.GetName}}Handler(ctx, mux, conn)
}
// Register{{$svc.GetName}}Handler registers the http handlers for service {{$svc.GetName}} to "mux".
// The handlers forward requests to the grpc endpoint over "conn".
func Register{{$svc.GetName}}Handler(ctx context.Context, mux *runtime.ServeMux, conn *grpc.ClientConn) error {
client := New{{$svc.GetName}}Client(conn)
{{range $m := $svc.Methods}}
{{range $b := $m.Bindings}}
mux.Handle({{$b.HTTPMethod | printf "%q"}}, pattern_{{$svc.GetName}}_{{$m.GetName}}_{{$b.Index}}, func(w http.ResponseWriter, req *http.Request, pathParams map[string]string) {
resp, err := request_{{$svc.GetName}}_{{$m.GetName}}_{{$b.Index}}(runtime.AnnotateContext(ctx, req), client, req, pathParams)
if err != nil {
runtime.HTTPError(ctx, w, err)
return
}
{{if $m.GetServerStreaming}}
forward_{{$svc.GetName}}_{{$m.GetName}}_{{$b.Index}}(ctx, w, req, func() (proto.Message, error) { return resp.Recv() })
{{else}}
forward_{{$svc.GetName}}_{{$m.GetName}}_{{$b.Index}}(ctx, w, req, resp)
{{end}}
})
{{end}}
{{end}}
return nil
}
var (
{{range $m := $svc.Methods}}
{{range $b := $m.Bindings}}
pattern_{{$svc.GetName}}_{{$m.GetName}}_{{$b.Index}} = runtime.MustPattern(runtime.NewPattern({{$b.PathTmpl.Version}}, {{$b.PathTmpl.OpCodes | printf "%#v"}}, {{$b.PathTmpl.Pool | printf "%#v"}}, {{$b.PathTmpl.Verb | printf "%q"}}))
{{end}}
{{end}}
)
var (
{{range $m := $svc.Methods}}
{{range $b := $m.Bindings}}
forward_{{$svc.GetName}}_{{$m.GetName}}_{{$b.Index}} = {{if $m.GetServerStreaming}}runtime.ForwardResponseStream{{else}}runtime.ForwardResponseMessage{{end}}
{{end}}
{{end}}
)
{{end}}`))
)