move generic code from grpc server implementation

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

server/extractor.go

@@ -0,0 +1,107 @@
+package server
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+
+	"github.com/unistack-org/micro/v3/registry"
+)
+
+func extractValue(v reflect.Type, d int) *registry.Value {
+	if d == 3 {
+		return nil
+	}
+	if v == nil {
+		return nil
+	}
+
+	if v.Kind() == reflect.Ptr {
+		v = v.Elem()
+	}
+
+	arg := &registry.Value{
+		Name: v.Name(),
+		Type: v.Name(),
+	}
+
+	switch v.Kind() {
+	case reflect.Struct:
+		for i := 0; i < v.NumField(); i++ {
+			f := v.Field(i)
+			val := extractValue(f.Type, d+1)
+			if val == nil {
+				continue
+			}
+
+			// if we can find a json tag use it
+			if tags := f.Tag.Get("json"); len(tags) > 0 {
+				parts := strings.Split(tags, ",")
+				if parts[0] == "-" || parts[0] == "omitempty" {
+					continue
+				}
+				val.Name = parts[0]
+			}
+
+			// if there's no name default it
+			if len(val.Name) == 0 {
+				val.Name = v.Field(i).Name
+			}
+
+			arg.Values = append(arg.Values, val)
+		}
+	case reflect.Slice:
+		p := v.Elem()
+		if p.Kind() == reflect.Ptr {
+			p = p.Elem()
+		}
+		arg.Type = "[]" + p.Name()
+	}
+
+	return arg
+}
+
+func extractEndpoint(method reflect.Method) *registry.Endpoint {
+	if method.PkgPath != "" {
+		return nil
+	}
+
+	var rspType, reqType reflect.Type
+	var stream bool
+	mt := method.Type
+
+	switch mt.NumIn() {
+	case 3:
+		reqType = mt.In(1)
+		rspType = mt.In(2)
+	case 4:
+		reqType = mt.In(2)
+		rspType = mt.In(3)
+	default:
+		return nil
+	}
+
+	// are we dealing with a stream?
+	switch rspType.Kind() {
+	case reflect.Func, reflect.Interface:
+		stream = true
+	}
+
+	request := extractValue(reqType, 0)
+	response := extractValue(rspType, 0)
+
+	ep := &registry.Endpoint{
+		Name:     method.Name,
+		Request:  request,
+		Response: response,
+		Metadata: make(map[string]string),
+	}
+
+	if stream {
+		ep.Metadata = map[string]string{
+			"stream": fmt.Sprintf("%v", stream),
+		}
+	}
+
+	return ep
+}

server/extractor_test.go

@@ -0,0 +1,65 @@
+package server
+
+import (
+	"context"
+	"reflect"
+	"testing"
+
+	"github.com/unistack-org/micro/v3/registry"
+)
+
+type testHandler struct{}
+
+type testRequest struct{}
+
+type testResponse struct{}
+
+func (t *testHandler) Test(ctx context.Context, req *testRequest, rsp *testResponse) error {
+	return nil
+}
+
+func TestExtractEndpoint(t *testing.T) {
+	handler := &testHandler{}
+	typ := reflect.TypeOf(handler)
+
+	var endpoints []*registry.Endpoint
+
+	for m := 0; m < typ.NumMethod(); m++ {
+		if e := extractEndpoint(typ.Method(m)); e != nil {
+			endpoints = append(endpoints, e)
+		}
+	}
+
+	if i := len(endpoints); i != 1 {
+		t.Errorf("Expected 1 endpoint, have %d", i)
+	}
+
+	if endpoints[0].Name != "Test" {
+		t.Errorf("Expected handler Test, got %s", endpoints[0].Name)
+	}
+
+	if endpoints[0].Request == nil {
+		t.Error("Expected non nil request")
+	}
+
+	if endpoints[0].Response == nil {
+		t.Error("Expected non nil request")
+	}
+
+	if endpoints[0].Request.Name != "testRequest" {
+		t.Errorf("Expected testRequest got %s", endpoints[0].Request.Name)
+	}
+
+	if endpoints[0].Response.Name != "testResponse" {
+		t.Errorf("Expected testResponse got %s", endpoints[0].Response.Name)
+	}
+
+	if endpoints[0].Request.Type != "testRequest" {
+		t.Errorf("Expected testRequest type got %s", endpoints[0].Request.Type)
+	}
+
+	if endpoints[0].Response.Type != "testResponse" {
+		t.Errorf("Expected testResponse type got %s", endpoints[0].Response.Type)
+	}
+
+}

server/options.go

@@ -10,9 +10,9 @@ import (
 	"github.com/unistack-org/micro/v3/broker"
 	"github.com/unistack-org/micro/v3/codec"
 	"github.com/unistack-org/micro/v3/logger"
+	"github.com/unistack-org/micro/v3/network/transport"
 	"github.com/unistack-org/micro/v3/registry"
 	"github.com/unistack-org/micro/v3/tracer"
-	"github.com/unistack-org/micro/v3/network/transport"
 )
 
 type Options struct {

server/subscriber.go

@@ -0,0 +1,88 @@
+package server
+
+import (
+	"fmt"
+	"reflect"
+	"unicode"
+	"unicode/utf8"
+)
+
+const (
+	subSig = "func(context.Context, interface{}) error"
+)
+
+var (
+	// Precompute the reflect type for error. Can't use error directly
+	// because Typeof takes an empty interface value. This is annoying.
+	typeOfError = reflect.TypeOf((*error)(nil)).Elem()
+)
+
+// Is this an exported - upper case - name?
+func isExported(name string) bool {
+	rune, _ := utf8.DecodeRuneInString(name)
+	return unicode.IsUpper(rune)
+}
+
+// Is this type exported or a builtin?
+func isExportedOrBuiltinType(t reflect.Type) bool {
+	for t.Kind() == reflect.Ptr {
+		t = t.Elem()
+	}
+	// PkgPath will be non-empty even for an exported type,
+	// so we need to check the type name as well.
+	return isExported(t.Name()) || t.PkgPath() == ""
+}
+
+func ValidateSubscriber(sub Subscriber) error {
+	typ := reflect.TypeOf(sub.Subscriber())
+	var argType reflect.Type
+
+	if typ.Kind() == reflect.Func {
+		name := "Func"
+		switch typ.NumIn() {
+		case 2:
+			argType = typ.In(1)
+		default:
+			return fmt.Errorf("subscriber %v takes wrong number of args: %v required signature %s", name, typ.NumIn(), subSig)
+		}
+		if !isExportedOrBuiltinType(argType) {
+			return fmt.Errorf("subscriber %v argument type not exported: %v", name, argType)
+		}
+		if typ.NumOut() != 1 {
+			return fmt.Errorf("subscriber %v has wrong number of outs: %v require signature %s",
+				name, typ.NumOut(), subSig)
+		}
+		if returnType := typ.Out(0); returnType != typeOfError {
+			return fmt.Errorf("subscriber %v returns %v not error", name, returnType.String())
+		}
+	} else {
+		hdlr := reflect.ValueOf(sub.Subscriber())
+		name := reflect.Indirect(hdlr).Type().Name()
+
+		for m := 0; m < typ.NumMethod(); m++ {
+			method := typ.Method(m)
+
+			switch method.Type.NumIn() {
+			case 3:
+				argType = method.Type.In(2)
+			default:
+				return fmt.Errorf("subscriber %v.%v takes wrong number of args: %v required signature %s",
+					name, method.Name, method.Type.NumIn(), subSig)
+			}
+
+			if !isExportedOrBuiltinType(argType) {
+				return fmt.Errorf("%v argument type not exported: %v", name, argType)
+			}
+			if method.Type.NumOut() != 1 {
+				return fmt.Errorf(
+					"subscriber %v.%v has wrong number of outs: %v require signature %s",
+					name, method.Name, method.Type.NumOut(), subSig)
+			}
+			if returnType := method.Type.Out(0); returnType != typeOfError {
+				return fmt.Errorf("subscriber %v.%v returns %v not error", name, method.Name, returnType.String())
+			}
+		}
+	}
+
+	return nil
+}