Add pub/sub to client/server and make broker more low level

server/subscriber.go

@@ -0,0 +1,154 @@
+package server
+
+import (
+	"encoding/json"
+	"reflect"
+
+	"github.com/golang/protobuf/proto"
+	"github.com/myodc/go-micro/broker"
+	c "github.com/myodc/go-micro/context"
+	"github.com/myodc/go-micro/registry"
+	"golang.org/x/net/context"
+)
+
+type handler struct {
+	method  reflect.Value
+	reqType reflect.Type
+	ctxType reflect.Type
+}
+
+type subscriber struct {
+	topic      string
+	rcvr       reflect.Value
+	typ        reflect.Type
+	subscriber interface{}
+	handlers   []*handler
+	endpoints  []*registry.Endpoint
+}
+
+func newSubscriber(topic string, sub interface{}) Subscriber {
+	var endpoints []*registry.Endpoint
+	var handlers []*handler
+
+	if typ := reflect.TypeOf(sub); typ.Kind() == reflect.Func {
+		h := &handler{
+			method: reflect.ValueOf(sub),
+		}
+
+		switch typ.NumIn() {
+		case 1:
+			h.reqType = typ.In(0)
+		case 2:
+			h.ctxType = typ.In(0)
+			h.reqType = typ.In(1)
+		}
+
+		handlers = append(handlers, h)
+
+		endpoints = append(endpoints, &registry.Endpoint{
+			Name:    "Func",
+			Request: extractSubValue(typ),
+			Metadata: map[string]string{
+				"topic": topic,
+			},
+		})
+	} else {
+		for m := 0; m < typ.NumMethod(); m++ {
+			method := typ.Method(m)
+			h := &handler{
+				method: method.Func,
+			}
+
+			switch method.Type.NumIn() {
+			case 2:
+				h.reqType = method.Type.In(1)
+			case 3:
+				h.ctxType = method.Type.In(1)
+				h.reqType = method.Type.In(2)
+			}
+
+			handlers = append(handlers, h)
+
+			endpoints = append(endpoints, &registry.Endpoint{
+				Name:    method.Name,
+				Request: extractSubValue(method.Type),
+				Metadata: map[string]string{
+					"topic": topic,
+				},
+			})
+		}
+	}
+
+	return &subscriber{
+		rcvr:       reflect.ValueOf(sub),
+		typ:        reflect.TypeOf(sub),
+		topic:      topic,
+		subscriber: sub,
+		handlers:   handlers,
+		endpoints:  endpoints,
+	}
+}
+
+func createSubHandler(sb *subscriber) broker.Handler {
+	return func(msg *broker.Message) {
+		hdr := make(map[string]string)
+		for k, v := range msg.Header {
+			hdr[k] = v
+		}
+		delete(hdr, "Content-Type")
+		ctx := c.WithMetadata(context.Background(), hdr)
+		rctx := reflect.ValueOf(ctx)
+
+		for _, handler := range sb.handlers {
+			var isVal bool
+			var req reflect.Value
+			var uerr error
+
+			if handler.reqType.Kind() == reflect.Ptr {
+				req = reflect.New(handler.reqType.Elem())
+			} else {
+				req = reflect.New(handler.reqType)
+				isVal = true
+			}
+
+			switch msg.Header["Content-Type"] {
+			case "application/octet-stream":
+				uerr = proto.Unmarshal(msg.Body, req.Interface().(proto.Message))
+			case "application/json":
+				uerr = json.Unmarshal(msg.Body, req.Interface())
+			}
+
+			if uerr != nil {
+				continue
+			}
+
+			if isVal {
+				req = req.Elem()
+			}
+
+			var vals []reflect.Value
+			if sb.typ.Kind() != reflect.Func {
+				vals = append(vals, sb.rcvr)
+			}
+
+			if handler.ctxType != nil {
+				vals = append(vals, rctx)
+			}
+
+			vals = append(vals, req)
+			go handler.method.Call(vals)
+		}
+	}
+}
+
+func (s *subscriber) Topic() string {
+	return s.topic
+}
+
+func (s *subscriber) Subscriber() interface{} {
+	return s.subscriber
+}
+
+func (s *subscriber) Endpoints() []*registry.Endpoint {
+	return s.endpoints
+}